An Analysis of Cardiologic Interventional Procedures in Croatia between 2010 and 2014: Towards the Establishment of a National Registry

    Authors

    Abstract

    Although there has been progress in interventional cardiology in Croatia over the last two decades, there has been no analysis of interventional cardiologic procedures at the national level. The aim of this article was to analyze of the number of coronary angiographies (CA) and percutaneous coronary interventions (PCI) in the period from 2010 to 2014. Diagnostic and treatment procedures were analyzed based on the CA and PCI hospital claims of Croatian patients in 13 Croatian centers. The average rate of CA in the observed period was 4 390 per million population annually, with a growth of 8.5% over the observed period. The average rate of PCI was 2 208 with an increase of 15%. The PCI/CA ratio grew from 0.48 to 0.52. Of the 47 470 PCI procedures performed in Croatia between 2010 and 2014, 18.6% were performed in the Magdalena Special Hospital for Cardiovascular Surgery and Cardiology, 13.8% in the University Hospital Centre Zagreb, 11.9% in the University Hospital Centre Rijeka, and 11.3% in the University Hospital Dubrava, while other centers had shares below 10%. Based on PCI numbers, 7 Croatian centers (54%) can be classified as high volume centers, and 4 (30.7%) as medium volume centers. The Dubrovnik General Hospital since 2013 had a sufficient annual number of PCIs (>200), while the Karlovac General Hospital only performed CA. Results indicate that Croatian interventional cardiology has achieved a great success over the last two decades: in 2010, Croatia already had an above-average rate of PCIs compared with the Organization for Economic Co-operation and Development and 21 countries of the European Union, as well as a larger annual growth (26.8%) than all analyzed countries except Romania. PCI rates were higher than most European countries except Germany, Belgium, Austria, and Norway. Further analysis of the success of interventional procedures and further development plans require the formation of a unified Croatian Registry of Cardiologic Procedures.

    Keywords

    coronary angiography, percutaneous coronary intervention, Croatia

    DOI

    https://doi.org/10.15836/ccar2016.142

    Full Text

    ## Introduction Mortality rates from cardiovascular diseases (CVD) have decreased over the last decade in most European countries, but they are still the leading cause of death, accounting for almost half of the total mortality i.e. more than 4 million deaths in Europe annually. Coronary heart disease (CHD) alone causes almost 1.8 million (20%) deaths in Europe annually, despite a dramatic reduction in mortality of over 50% in eight European countries. Croatia has also seen a significant 30% drop in CVD mortality over the last decade, but unfortunately that is not the case with CHD, where mortality for men has fallen by only 4% and actually increased in women by 2%. Age-standardized mortality rates in 2012 in Croatia were still high for European ranges, at 202.8/100 000 for men and 123.8/100 000 for women, as opposed to for instance Austria or Slovenia where mortality rates are lower by half, 125.5 and 94.9/100 000 for men and 65.3 and 40.5/100 000 for women, respectively. (1, 2) Interventional cardiology in Croatia has seen significant progress over the last two decades both in diagnostics and treatment. Between 1993 and 2001 the number of interventional cardiologic procedures went up sharply; for instance, the coronarography (CA) rate increased by 6.15 times, to 1 716 from 279, and the rate of percutaneous coronary interventions (PCI) by as much as 15 times, from 38 to 565 per million inhabitants. The rates of the above procedures in that period were below the average of member-states of the European Cardiac Society (ESC) and some economically more developed countries such as Austria, but did not differ significantly from other transitional countries such as Slovenia and Hungary or even the Czech Republic. (3) Despite significant advances in interventional cardiology, database searches did not yield precise data on the number of interventional cardiologic procedures in Croatia since 2000 till today. The goal of this study was to analyze the number of CA and PCI performed in Croatia from 2010 to 2014 and compare the results with other countries. ## Patients and Methods For every hospitalized patient in the Republic of Croatia, the diagnosis and diagnostic-therapeutic procedures (DTP) are coded on the claim at the end of the hospital stay. Based on this data, the Croatian Health Insurance Fund (CHIF) calculates the treatment expenses commensurate to the diagnostic-therapeutic groups (DTS) they fall under. (4) This study used data on the number of interventional cardiologic procedures (CA and PCI) coded in the claims for hospital treatment of individual patients and delivered to the CHIF in the period from 2010 to 2014. CHIF was selected as a data-source since a national registry for systematic and non-ambiguous data collection at the national level has not yet been established in Croatia. We analyzed the DTPs of all hospitalized patients in Croatia that were relevant to procedures in interventional cardiology, CA (**Table 1**) and PCI (**Table 2**). ### Table 1: Croatian Health Insurance Fund’s codes for diagnostic-therapeutic groups procedures which include coronary angiography (CA). | Code | CA | | --- | --- | | 38215-00 | coronary angiography | | 38218-00 | coronary angiography and left heart catetherisation | | 38218-01 | coronary angiography and right heart catetherisation | | 38218-02 | coronary angiography and both side heart catetherisation | ### Table 2: Croatian Health Insurance Fund’s codes for diagnostic-therapeutic groups procedures which include coronary percutaneous intervention (PCI). | Code | PCI | | --- | --- | | 35304-00 | percutaneous transluminal angioplasty with baloon (PTCA) of 1 coronary artery | | 35305-00 | percutaneous transluminal angioplasty with baloon (PTCA) of 2 or more coronary arteries | | 35310-00 | percutaneous implantation of 1 transluminal stent in 1 coronary artery | | 35310-0 | percutaneous implantation of 2 or more transluminal stents in 1 coronary artery | | 35310-02 | percutaneous implantation of 2 or more transluminal stents in more coronary arteries | Invasive cardiologic procedures are performed in thirteen centers in Croatia: university hospital centers (Zagreb, Sisters of Charity, Split, Rijeka, Osijek), university hospitals (Dubrava, Sveti Duh, and Merkur), clinics (Magdalena), and general hospitals (Zadar, Slavonski Brod, Dubrovnik, and Karlovac). Classifying centers into medium and high volume based on the annual number of PCI performed is a topic of discussion in the literature, but this study used the guidelines of the ACC/AHA Task Force which requires at least 200 PCI annually per center due to the established association between a lower number of interventions and poorer treatment outcomes. (5) Medium volume centers were defined as those with 200 to 600 PCI, and high volume centers as those with more than 600 PCI annually, since meta-analysis has shown that increasing the number of interventions above 600 per year is not associated with significantly improved intervention outcomes. (6) Descriptive statistics were used to report the results. ## Results In the period between 2010 and 2014, the average annual number of CA procedures in Croatia was 19 305, at a rate of 4 390 per million inhabitants. The number of CA procedures in that period grew by 8.5%. In the same period, the average annual number of PCI was 9 494, and the rate was 2 208 per million inhabitants annually, with a growth trend of PCI numbers of 15%. The ratio of PCI/CA grew from 0.48 in 2010 to 0.52 in 2014 (**Table 3**, **Figure 1**). ### Table 3: Coronary angiograms (CA), percutaneous coronary interventions (PCIs) and PCI/CA ratios in Croatia in the 2010 - 2014 period. | | 2010 | 2011 | 2012 | 2013 | 2014 | mean | | --- | --- | --- | --- | --- | --- | --- | | PCI | 9 039 | 8 177 | 9 706 | 9 946 | 10 602 | 9 494 | | CA | 18 806 | 19 709 | 18 607 | 18 851 | 20 555 | 19 305 | | PCI/CA | 0.48 | 0.41 | 0.52 | 0.53 | 0.52 | 0.49 | Figure 1. Coronary angiograms (red columns) and percutaneous coronary interventions (blue columns) per million population in Croatia in the 2010-2014 period. Of the 47 470 PCI performed in Croatia from 2010 to 2014, 18.6% percent or a total of 8 837 procedures were performed at the Magdalena Special Hospital for Cardiovascular Surgery and Cardiology. Next were the University Hospital Centre Zagreb had a share of 13.8% (6 536 PCI), University Hospital Centre Rijeka with 11.9% (5659 PCI), and the University Hospital Dubrava with 11.3% (5 361 PCI). Other centers had shares below 10% (**Figure 2**). Figure 2. Absolute numbers and percentages of PCIs in Croatian centers in five year period (2010-2014). The average number of PCI per center for the period between 2010 and 2014 is shown in **Figure 3**. A total of 7 centers (54%) can be classified as high volume centers (Magdalena Special Hospital for Cardiovascular Surgery and Cardiology, University Hospital Centre Zagreb, University Hospital Centre Rijeka, University Hospital Dubrava, University Hospital Centre “Sestre milosrdnice”, University Hospital Centre Split, and University Hospital Centre Osijek), while four centers (30.7%) can be classified as medium volume centers (University Hospital Merkur, Slavonski Brod General Hospital, University Hospital “Sveti Duh”, and Zadar General Hospital). The Dubrovnik General Hospital did not have a sufficient annual PCI average (>200) over the five-year period, but has fulfilled that criterion since 2013. The Karlovac General Hospital performed CA, but not PCI. Figure 3. Mean annual number of PCIs in the Croatian centers in the 2010-2014 period. Data on the number of interventional cardiologic procedures for 34 member-states of the Organisation for Economic Co-operation and Development (OECD) for 2009 and 2010 were published in special reports, and are compared with our own data in **Table 4**. (7, 8) The PCI rate in Croatia in 2010 was 2 102 PCI per million inhabitants, and in comparison with OECD data it is clear that only Germany, Belgium, Austria, and Norway have higher PCI rates than Croatia at between 2 380 and 6 240 per million inhabitants annually. The Croatian PCI rate was somewhat higher than that of the Czech Republic (2 050), while all other analyzed European countries had lower PCI rates, ranging from 530 to 1 970 per million inhabitants annually. ### Table 4: Percutaneous coronary interventions per million population in 2010 for OECD countries and Croatia. | Germany | 6240 | | --- | --- | | Belgium | 4690 | | USA* | 3770 | | Austria | 2400 | | Norway | 2380 | | Croatia** | 2102 | | Czech R. | 2050 | | Luxembourg | 1970 | | Iceland | 1980 | | Slovenia | 1930 | | France* | 1940 | | EU21 | 1910 | | Estonia | 1820 | | Sweden | 1800 | | Greece | 1770 | | Hungary | 1720 | | Netherlands | 1700 | | Switzerland | 1640 | | Denmark | 1580 | | Spain | 1360 | | Finland | 1320 | | Italy | 1310 | | Portugal | 1180 | | U. Kingdom | 940 | | Ireland | 900 | | Poland | 870 | | Romania | 530 | | Israel* | 190 | | OECD* | 1808 | | Australia* | 1590 | | New Zealand* | 1170 | | Canada* | 1050 | | Chile* | 70 | | Mexico* | 20 | [†] * data are from 2009 ** data for Croatia are from Figure 2 ## Discussion The number of CA procedures in Croatia over the past two and a half decades has, in some periods, grown almost exponentially. In the period between 1993 and 2001, for instance, there was a startling increase in CA rates of as much as 615%. The results of this study show that growth continued from 2001 to 2010 with an increase of 250%, from 1 716 to 4 363 per million inhabitants. (3) From 2010 to 2014 there was a slowdown in the growth, which was 8.5% in total over the five-year period, with a final rate of 4 780 per million inhabitants. Rate comparisons with other countries are limited by significant discontinuities in results publication for individual countries. For example, 5 437 CA procedures were performed per million inhabitants in Iceland and 4 022 in Sweden in 2007. (9) Notably, the average for ESC member states in 2004 was 3 928 CA and 1 553 PCI per million inhabitants annually. (10) PCI rates in Croatia had an even greater growth trend. Between 1993 and 2001 PCI rates grew by as much as 1500%, from 38 to 565 per million inhabitants, and between 2001 and 2010 the rate grew by another 270% to 2 102 per million inhabitants. Over the five-year period analyzed in this study a growth of 15% was noted, amounting to 2 466 per million inhabitants in 2014. The above results indicate a notable success of Croatian interventional cardiology, since in 2010 Croatia had a higher PCI rate than the OECD member-state average (1 808 PCI) or the members of EU21 (1 910 PCI). The average growth of the PCI rate in Croatia between 2001 and 2010 of 26.8% was significantly higher than the EU21 average (9.4%) and higher than that of any country in the OECD data except Romania. (7, 8) According to those data, only four European countries had a higher PCI rate in 2010 than Croatia: Germany, Belgium, Austria, and Norway, while Croatia had a somewhat higher rate even compared with the Czech Republic (**Table 4**). However, OECD data should be interpreted tentatively, since there is often an inconsistency with data from national registries of individual countries due to different data-gathering methodologies. Ireland, for instance, had a PCI rate of 900 in 2010 according to OECD data, whereas according to the Irish registry the rate was 1 770 per million inhabitants. (11) For other countries, such as Spain, OECD and national registry data match completely. (12) The Spanish national registry for 2010 shows a lower CA rate than Croatia, 2 945 vs. 4 373 per million inhabitants, as well as a lower PCI rate at 1 398 in Spain and 2 102 per million inhabitants in Croatia. (12) At the end of our observed period in 2014, Spain had 2 693 CA and 1 447 PCI procedures per million inhabitants, while Croatia had 4 780 CA and 2 466 PCI. (13) There is insufficient annual data on cardiologic intervention rates in Croatia for the first decade of the 21st century. Data for individual years has been presented anecdotally, such as for example at the meeting of national working groups for interventional cardiology of the ESC in 2009, when data for 2007 and 2008 was presented, and also for 2006 and 2005 for some countries. On that occasion, Croatian representatives presented data indicating 890 PCI per million inhabitants, but the methodology of that study and data acquisition was unclear, and the results of our study indicate that the number was an underestimate. (14) Even prior to this, there were calls for the leadership of the cardiologic society to establish a unified registry of coronary procedures in Croatia to facilitate advancements in the Croatian cardiology development. (3) Unfortunately, no such registry has been organized in the ensuing decade, and there were not even any approximate estimates of the number of cardiologic procedures, other than the result analysis of the Croatian Network for Primary PCI. (15) Globally speaking, the trend towards stagnation in the number of coronary interventions after a period of growth in developed countries such as the USA is explained by the success in introducing preventive CHD measures. It is hard to distinguish to what extent the difference in the number of coronary interventions in particular countries is determined by the prevalence of CHD, as opposed to differences in resources and organization, as well as indications for diagnostic and treatment procedures in different countries and PCI centers. Looking at the dynamics of the growth in the number of coronary interventions in Croatia based on the available data, it is notable that between 1993 and 2010 Croatia experienced the same trend we find in developing countries – a several-fold increase in less than 10 years – whereas developed countries show a growth of approximately 5% per year or stagnation in the rate of coronary interverntions. (16) Factors that generally contribute to an increase in the number of coronary interventions are increased financing for the field of cardiology at the local and national levels as well as an increase in the number of centers and trained interventional cardiologists on the one hand, and demographic and epidemiologic factors such as disease incidence and the aging of the population on the other. In Croatia’s case, the increase in the number of interventions is certainly partially explainable by increased financing for cardiology, an increase in the number of centers and the number of high volume centers, and a likely rise in the overall number of interventional cardiologists. The data above shows that all Croatian centers, including the Dubrovnik General Hospital since 2013, fulfill the basic criterion for independent functioning of more than 200 PCI annually, with only once center exclusively performing diagnostic procedures (the Karlovac General Hospital). Almost 85% of Croatian centers satisfy the criteria for centers with medium or high volume of procedures. In Spain in 2014, for instance, 59% of the centers (62/106) did not perform the necessary >200 PCI annually, and as many as 25% (26/106) performed less than 50 PCI per year. The literature contains studies that show that individual centers can have outstanding measurable intervention results despite a relatively low number of procedures per year. However, since a register of cardiologic interventions has not been established in Croatia, we do not have success indicators available, such as for instance the prevalence of major cardiovascular events, hospital, monthly, and annual mortality, use of consumables, periprocedural and postprocedural pharmacotherapy, drug-eluting stent (DES) penetration, intravascular ultrasound (IVUS) usage, or fractional flow reserve (FFR) measurements during interventions and data on complication incidence, which would allow a comparison with international data, quality evaluation, and improvement in clinical practice. Of epidemiological data, only mortality statistics are available in Croatia, as opposed to studying the incidence of CVD and treatment effectiveness. Thus, the dynamics of the incidence of all diseases including CHD must be interpreted with these limitations in mind. However, we can still conclude that the relative stagnation in the increase in coronary interventions in 2010 is likely not explainable by a reduction in the prevalence of CHD, since although Croatia has seen a significant drop in CVD mortality of 30% over the last decade, this has not been the case with CHD where mortality has fallen by only 4% in men, and actually increased by 2% in women. However, the stagnation and minimal drop in mortality, at least in men, is likely attributable to the exceptional results of interventional cardiologists, since there have been no significant results from preventative measures in Croatia, primarily in smoking cessation (17) and most likely also in diabetes, arterial hypertension, dyslipidemia, physical activity, and other risk factors. These factors, combined with an aging population, will certainly support a positive trend in the number in cardiologic interventions in Croatia for years to come. Since there have been no published systematic studies on the CA and PCI rates in Croatia, we undertook this study based on CHIF claims as the only currently available source of data, aware of the fact that this approach has many limitations and systemic research errors that may have influenced the final results. Firstly, CHIF provides insurance to 96% of the population, leaving approximately 170 000 citizens uninsured. (18) On the other hand, a special CHIF sub-fund sometimes still covers treatment costs for uninsured persons, causing them to be present in CHIF claims, but such patients are most likely evenly distributed across the country. Furthermore, a certain percentage of foreign citizens undergo cardiologic interventions in Croatia, but would not have been registered in the CHIF DTS prior to Croatia’s admission to the European Union (EU). After joining the EU, EU citizens register via the CHIF, but others do not. (19) This might have contributed to a reduction in the perceived total of the procedures, especially in centers along the tourist-frequented coast. However, the most significant deviations and errors are likely a result of claims coding in the PCI centers themselves. Some coding practices were systematic and illogical and were corrected for through personal contacts, such as for example double coding for coronarographies in the University Hospital Centre Osijek with the codes 38215-00 and 38218-00, which after personally contacting the laboratory resulted in the final procedure estimate being cut in half. There was no explanation for the unlikely 3 053 coronarography codes in 2010 and 4 432 in 2011 at the University Hospital Merkur even after contacting the center, so those two data-points were excluded from the analysis, which will have reduced the total number of procedures in the results. Furthermore, it is possible that for individual patients receiving both PCI and CA, CA was not separately coded on the claim, which may have reduced the total number of CA procedures. CHIF requires percutaneous transluminal coronary angioplasty (PTCA) to be coded separately from stent implantation in PCI cases. Thus only dilatations without stent implantation are coded as PTCA, and in cases of pre-dilatation followed by stet implantation, only stent implantation is coded. However, it is very likely that some centers occasionally coded a PTCA procedure on the claim in the same patients twice, once as predilatation and once as stent implantation, which would have driven total PCI numbers up as well as the individual counts of the centers themselves. Finally, some hospitals occasionally billed PCI even though the procedure was not being performed in their institutions, likely due to the procedure being performed at a PCI center the patient was transferred from that did not bill the procedure themselves. In the observed period there were 80 (0.17%) such claims, which we eliminated from the procedure count for individual institutions but included in the total number of procedures performed in Croatia. Despite these limitations, the results of this study indicate that, despite the lack of a registry for coronary interventions, the undetermined number of licensed interventional cardiologists, and financial limitations, the achievements of Croatian interventional cardiology, based on the number of procedures performed, are on par with the very top in European interventional cardiology. However, systematic and precise quality and quantity analysis for cardiologic interventions would become possible only with the individual registration of every patient in a web-form that would allow every PCI center to perform simple, valid, and timely data archiving. The Working Group for Interventional Cardiology of the Croatian Cardiac Society has issued a general statement that it is time to create a unified Croatian registry of cardiologic procedures, which requires additional funding. Success in forming the registry requires a consensus on mandatory data archiving for every patient. On the other hand, it will be necessary to define personnel dedicated to such data archiving during their working hours or hire personnel from outside the hospital, which would require additional funds.

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    An Analysis of Cardiologic Interventional Procedures in Croatia between 2010 and 2014: Towards the Establishment of a National Registry

    Research Article
    Issue3-4
    Published
    Pages142-150
    PDF via DOIhttps://doi.org/10.15836/ccar2016.142
    coronary angiography
    percutaneous coronary intervention
    Croatia

    Authors

    Josip Lukenda*ORCIDUniversity Hospital “Sveti Duh”, Zagreb, Croatia
    Boris StarčevićORCIDUniversity Hospital Dubrava, Zagreb, Croatia
    Diana Delić BrkljačićORCIDUniversity Hospital Centre “Sestre milosrdnice”, Zagreb, Croatia
    Zrinka BiloglavORCIDUniversity of Zagreb, School of Medicine, Andrija Štampar School of Public Health, Zagreb, Croatia.

    *Correspondence email: lukendaj@hotmail.com

    Abstract

    Although there has been progress in interventional cardiology in Croatia over the last two decades, there has been no analysis of interventional cardiologic procedures at the national level. The aim of this article was to analyze of the number of coronary angiographies (CA) and percutaneous coronary interventions (PCI) in the period from 2010 to 2014. Diagnostic and treatment procedures were analyzed based on the CA and PCI hospital claims of Croatian patients in 13 Croatian centers. The average rate of CA in the observed period was 4 390 per million population annually, with a growth of 8.5% over the observed period. The average rate of PCI was 2 208 with an increase of 15%. The PCI/CA ratio grew from 0.48 to 0.52. Of the 47 470 PCI procedures performed in Croatia between 2010 and 2014, 18.6% were performed in the Magdalena Special Hospital for Cardiovascular Surgery and Cardiology, 13.8% in the University Hospital Centre Zagreb, 11.9% in the University Hospital Centre Rijeka, and 11.3% in the University Hospital Dubrava, while other centers had shares below 10%. Based on PCI numbers, 7 Croatian centers (54%) can be classified as high volume centers, and 4 (30.7%) as medium volume centers. The Dubrovnik General Hospital since 2013 had a sufficient annual number of PCIs (>200), while the Karlovac General Hospital only performed CA. Results indicate that Croatian interventional cardiology has achieved a great success over the last two decades: in 2010, Croatia already had an above-average rate of PCIs compared with the Organization for Economic Co-operation and Development and 21 countries of the European Union, as well as a larger annual growth (26.8%) than all analyzed countries except Romania. PCI rates were higher than most European countries except Germany, Belgium, Austria, and Norway. Further analysis of the success of interventional procedures and further development plans require the formation of a unified Croatian Registry of Cardiologic Procedures.

    Full Text

    Introduction

    Mortality rates from cardiovascular diseases (CVD) have decreased over the last decade in most European countries, but they are still the leading cause of death, accounting for almost half of the total mortality i.e. more than 4 million deaths in Europe annually. Coronary heart disease (CHD) alone causes almost 1.8 million (20%) deaths in Europe annually, despite a dramatic reduction in mortality of over 50% in eight European countries. Croatia has also seen a significant 30% drop in CVD mortality over the last decade, but unfortunately that is not the case with CHD, where mortality for men has fallen by only 4% and actually increased in women by 2%. Age-standardized mortality rates in 2012 in Croatia were still high for European ranges, at 202.8/100 000 for men and 123.8/100 000 for women, as opposed to for instance Austria or Slovenia where mortality rates are lower by half, 125.5 and 94.9/100 000 for men and 65.3 and 40.5/100 000 for women, respectively. (1, 2)

    Interventional cardiology in Croatia has seen significant progress over the last two decades both in diagnostics and treatment. Between 1993 and 2001 the number of interventional cardiologic procedures went up sharply; for instance, the coronarography (CA) rate increased by 6.15 times, to 1 716 from 279, and the rate of percutaneous coronary interventions (PCI) by as much as 15 times, from 38 to 565 per million inhabitants. The rates of the above procedures in that period were below the average of member-states of the European Cardiac Society (ESC) and some economically more developed countries such as Austria, but did not differ significantly from other transitional countries such as Slovenia and Hungary or even the Czech Republic. (3)

    Despite significant advances in interventional cardiology, database searches did not yield precise data on the number of interventional cardiologic procedures in Croatia since 2000 till today. The goal of this study was to analyze the number of CA and PCI performed in Croatia from 2010 to 2014 and compare the results with other countries.

    Patients and Methods

    For every hospitalized patient in the Republic of Croatia, the diagnosis and diagnostic-therapeutic procedures (DTP) are coded on the claim at the end of the hospital stay. Based on this data, the Croatian Health Insurance Fund (CHIF) calculates the treatment expenses commensurate to the diagnostic-therapeutic groups (DTS) they fall under. (4) This study used data on the number of interventional cardiologic procedures (CA and PCI) coded in the claims for hospital treatment of individual patients and delivered to the CHIF in the period from 2010 to 2014. CHIF was selected as a data-source since a national registry for systematic and non-ambiguous data collection at the national level has not yet been established in Croatia. We analyzed the DTPs of all hospitalized patients in Croatia that were relevant to procedures in interventional cardiology, CA (Table 1) and PCI (Table 2).

    Table 1: Croatian Health Insurance Fund’s codes for diagnostic-therapeutic groups procedures which include coronary angiography (CA).

    38215-00
    CA
    coronary angiography
    38218-00
    CA
    coronary angiography and left heart catetherisation
    38218-01
    CA
    coronary angiography and right heart catetherisation
    38218-02
    CA
    coronary angiography and both side heart catetherisation

    Table 2: Croatian Health Insurance Fund’s codes for diagnostic-therapeutic groups procedures which include coronary percutaneous intervention (PCI).

    35304-00
    PCI
    percutaneous transluminal angioplasty with baloon (PTCA) of 1 coronary artery
    35305-00
    PCI
    percutaneous transluminal angioplasty with baloon (PTCA) of 2 or more coronary arteries
    35310-00
    PCI
    percutaneous implantation of 1 transluminal stent in 1 coronary artery
    35310-0
    PCI
    percutaneous implantation of 2 or more transluminal stents in 1 coronary artery
    35310-02
    PCI
    percutaneous implantation of 2 or more transluminal stents in more coronary arteries

    Invasive cardiologic procedures are performed in thirteen centers in Croatia: university hospital centers (Zagreb, Sisters of Charity, Split, Rijeka, Osijek), university hospitals (Dubrava, Sveti Duh, and Merkur), clinics (Magdalena), and general hospitals (Zadar, Slavonski Brod, Dubrovnik, and Karlovac). Classifying centers into medium and high volume based on the annual number of PCI performed is a topic of discussion in the literature, but this study used the guidelines of the ACC/AHA Task Force which requires at least 200 PCI annually per center due to the established association between a lower number of interventions and poorer treatment outcomes. (5) Medium volume centers were defined as those with 200 to 600 PCI, and high volume centers as those with more than 600 PCI annually, since meta-analysis has shown that increasing the number of interventions above 600 per year is not associated with significantly improved intervention outcomes. (6)

    Descriptive statistics were used to report the results.

    Results

    In the period between 2010 and 2014, the average annual number of CA procedures in Croatia was 19 305, at a rate of 4 390 per million inhabitants. The number of CA procedures in that period grew by 8.5%. In the same period, the average annual number of PCI was 9 494, and the rate was 2 208 per million inhabitants annually, with a growth trend of PCI numbers of 15%. The ratio of PCI/CA grew from 0.48 in 2010 to 0.52 in 2014 (Table 3, Figure 1).

    Table 3: Coronary angiograms (CA), percutaneous coronary interventions (PCIs) and PCI/CA ratios in Croatia in the 2010 - 2014 period.

    PCI
    2010
    9 039
    2011
    8 177
    2012
    9 706
    2013
    9 946
    2014
    10 602
    mean
    9 494
    CA
    2010
    18 806
    2011
    19 709
    2012
    18 607
    2013
    18 851
    2014
    20 555
    mean
    19 305
    PCI/CA
    2010
    0.48
    2011
    0.41
    2012
    0.52
    2013
    0.53
    2014
    0.52
    mean
    0.49

    Figure 1. Coronary angiograms (red columns) and percutaneous coronary interventions (blue columns) per million population in Croatia in the 2010-2014 period.

    Of the 47 470 PCI performed in Croatia from 2010 to 2014, 18.6% percent or a total of 8 837 procedures were performed at the Magdalena Special Hospital for Cardiovascular Surgery and Cardiology. Next were the University Hospital Centre Zagreb had a share of 13.8% (6 536 PCI), University Hospital Centre Rijeka with 11.9% (5659 PCI), and the University Hospital Dubrava with 11.3% (5 361 PCI). Other centers had shares below 10% (Figure 2).

    Figure 2. Absolute numbers and percentages of PCIs in Croatian centers in five year period (2010-2014).

    The average number of PCI per center for the period between 2010 and 2014 is shown in Figure 3. A total of 7 centers (54%) can be classified as high volume centers (Magdalena Special Hospital for Cardiovascular Surgery and Cardiology, University Hospital Centre Zagreb, University Hospital Centre Rijeka, University Hospital Dubrava, University Hospital Centre “Sestre milosrdnice”, University Hospital Centre Split, and University Hospital Centre Osijek), while four centers (30.7%) can be classified as medium volume centers (University Hospital Merkur, Slavonski Brod General Hospital, University Hospital “Sveti Duh”, and Zadar General Hospital). The Dubrovnik General Hospital did not have a sufficient annual PCI average (>200) over the five-year period, but has fulfilled that criterion since 2013. The Karlovac General Hospital performed CA, but not PCI.

    Figure 3. Mean annual number of PCIs in the Croatian centers in the 2010-2014 period.

    Data on the number of interventional cardiologic procedures for 34 member-states of the Organisation for Economic Co-operation and Development (OECD) for 2009 and 2010 were published in special reports, and are compared with our own data in Table 4. (7, 8) The PCI rate in Croatia in 2010 was 2 102 PCI per million inhabitants, and in comparison with OECD data it is clear that only Germany, Belgium, Austria, and Norway have higher PCI rates than Croatia at between 2 380 and 6 240 per million inhabitants annually. The Croatian PCI rate was somewhat higher than that of the Czech Republic (2 050), while all other analyzed European countries had lower PCI rates, ranging from 530 to 1 970 per million inhabitants annually.

    Table 4: Percutaneous coronary interventions per million population in 2010 for OECD countries and Croatia.

    Belgium
    6240
    4690
    USA*
    6240
    3770
    Austria
    6240
    2400
    Norway
    6240
    2380
    Croatia**
    6240
    2102
    Czech R.
    6240
    2050
    Luxembourg
    6240
    1970
    Iceland
    6240
    1980
    Slovenia
    6240
    1930
    France*
    6240
    1940
    EU21
    6240
    1910
    Estonia
    6240
    1820
    Sweden
    6240
    1800
    Greece
    6240
    1770
    Hungary
    6240
    1720
    Netherlands
    6240
    1700
    Switzerland
    6240
    1640
    Denmark
    6240
    1580
    Spain
    6240
    1360
    Finland
    6240
    1320
    Italy
    6240
    1310
    Portugal
    6240
    1180
    U. Kingdom
    6240
    940
    Ireland
    6240
    900
    Poland
    6240
    870
    Romania
    6240
    530
    Israel*
    6240
    190
    OECD*
    6240
    1808
    Australia*
    6240
    1590
    New Zealand*
    6240
    1170
    Canada*
    6240
    1050
    Chile*
    6240
    70
    Mexico*
    6240
    20

    data are from 2009 * data for Croatia are from Figure 2

    Discussion

    The number of CA procedures in Croatia over the past two and a half decades has, in some periods, grown almost exponentially. In the period between 1993 and 2001, for instance, there was a startling increase in CA rates of as much as 615%. The results of this study show that growth continued from 2001 to 2010 with an increase of 250%, from 1 716 to 4 363 per million inhabitants. (3) From 2010 to 2014 there was a slowdown in the growth, which was 8.5% in total over the five-year period, with a final rate of 4 780 per million inhabitants. Rate comparisons with other countries are limited by significant discontinuities in results publication for individual countries. For example, 5 437 CA procedures were performed per million inhabitants in Iceland and 4 022 in Sweden in 2007. (9) Notably, the average for ESC member states in 2004 was 3 928 CA and 1 553 PCI per million inhabitants annually. (10) PCI rates in Croatia had an even greater growth trend. Between 1993 and 2001 PCI rates grew by as much as 1500%, from 38 to 565 per million inhabitants, and between 2001 and 2010 the rate grew by another 270% to 2 102 per million inhabitants. Over the five-year period analyzed in this study a growth of 15% was noted, amounting to 2 466 per million inhabitants in 2014. The above results indicate a notable success of Croatian interventional cardiology, since in 2010 Croatia had a higher PCI rate than the OECD member-state average (1 808 PCI) or the members of EU21 (1 910 PCI). The average growth of the PCI rate in Croatia between 2001 and 2010 of 26.8% was significantly higher than the EU21 average (9.4%) and higher than that of any country in the OECD data except Romania. (7, 8) According to those data, only four European countries had a higher PCI rate in 2010 than Croatia: Germany, Belgium, Austria, and Norway, while Croatia had a somewhat higher rate even compared with the Czech Republic (Table 4). However, OECD data should be interpreted tentatively, since there is often an inconsistency with data from national registries of individual countries due to different data-gathering methodologies. Ireland, for instance, had a PCI rate of 900 in 2010 according to OECD data, whereas according to the Irish registry the rate was 1 770 per million inhabitants. (11) For other countries, such as Spain, OECD and national registry data match completely. (12) The Spanish national registry for 2010 shows a lower CA rate than Croatia, 2 945 vs. 4 373 per million inhabitants, as well as a lower PCI rate at 1 398 in Spain and 2 102 per million inhabitants in Croatia. (12) At the end of our observed period in 2014, Spain had 2 693 CA and 1 447 PCI procedures per million inhabitants, while Croatia had 4 780 CA and 2 466 PCI. (13)

    There is insufficient annual data on cardiologic intervention rates in Croatia for the first decade of the 21st century. Data for individual years has been presented anecdotally, such as for example at the meeting of national working groups for interventional cardiology of the ESC in 2009, when data for 2007 and 2008 was presented, and also for 2006 and 2005 for some countries. On that occasion, Croatian representatives presented data indicating 890 PCI per million inhabitants, but the methodology of that study and data acquisition was unclear, and the results of our study indicate that the number was an underestimate. (14) Even prior to this, there were calls for the leadership of the cardiologic society to establish a unified registry of coronary procedures in Croatia to facilitate advancements in the Croatian cardiology development. (3) Unfortunately, no such registry has been organized in the ensuing decade, and there were not even any approximate estimates of the number of cardiologic procedures, other than the result analysis of the Croatian Network for Primary PCI. (15)

    Globally speaking, the trend towards stagnation in the number of coronary interventions after a period of growth in developed countries such as the USA is explained by the success in introducing preventive CHD measures. It is hard to distinguish to what extent the difference in the number of coronary interventions in particular countries is determined by the prevalence of CHD, as opposed to differences in resources and organization, as well as indications for diagnostic and treatment procedures in different countries and PCI centers. Looking at the dynamics of the growth in the number of coronary interventions in Croatia based on the available data, it is notable that between 1993 and 2010 Croatia experienced the same trend we find in developing countries – a several-fold increase in less than 10 years – whereas developed countries show a growth of approximately 5% per year or stagnation in the rate of coronary interverntions. (16) Factors that generally contribute to an increase in the number of coronary interventions are increased financing for the field of cardiology at the local and national levels as well as an increase in the number of centers and trained interventional cardiologists on the one hand, and demographic and epidemiologic factors such as disease incidence and the aging of the population on the other. In Croatia’s case, the increase in the number of interventions is certainly partially explainable by increased financing for cardiology, an increase in the number of centers and the number of high volume centers, and a likely rise in the overall number of interventional cardiologists. The data above shows that all Croatian centers, including the Dubrovnik General Hospital since 2013, fulfill the basic criterion for independent functioning of more than 200 PCI annually, with only once center exclusively performing diagnostic procedures (the Karlovac General Hospital). Almost 85% of Croatian centers satisfy the criteria for centers with medium or high volume of procedures. In Spain in 2014, for instance, 59% of the centers (62/106) did not perform the necessary >200 PCI annually, and as many as 25% (26/106) performed less than 50 PCI per year.

    The literature contains studies that show that individual centers can have outstanding measurable intervention results despite a relatively low number of procedures per year. However, since a register of cardiologic interventions has not been established in Croatia, we do not have success indicators available, such as for instance the prevalence of major cardiovascular events, hospital, monthly, and annual mortality, use of consumables, periprocedural and postprocedural pharmacotherapy, drug-eluting stent (DES) penetration, intravascular ultrasound (IVUS) usage, or fractional flow reserve (FFR) measurements during interventions and data on complication incidence, which would allow a comparison with international data, quality evaluation, and improvement in clinical practice. Of epidemiological data, only mortality statistics are available in Croatia, as opposed to studying the incidence of CVD and treatment effectiveness. Thus, the dynamics of the incidence of all diseases including CHD must be interpreted with these limitations in mind. However, we can still conclude that the relative stagnation in the increase in coronary interventions in 2010 is likely not explainable by a reduction in the prevalence of CHD, since although Croatia has seen a significant drop in CVD mortality of 30% over the last decade, this has not been the case with CHD where mortality has fallen by only 4% in men, and actually increased by 2% in women. However, the stagnation and minimal drop in mortality, at least in men, is likely attributable to the exceptional results of interventional cardiologists, since there have been no significant results from preventative measures in Croatia, primarily in smoking cessation (17) and most likely also in diabetes, arterial hypertension, dyslipidemia, physical activity, and other risk factors. These factors, combined with an aging population, will certainly support a positive trend in the number in cardiologic interventions in Croatia for years to come.

    Since there have been no published systematic studies on the CA and PCI rates in Croatia, we undertook this study based on CHIF claims as the only currently available source of data, aware of the fact that this approach has many limitations and systemic research errors that may have influenced the final results. Firstly, CHIF provides insurance to 96% of the population, leaving approximately 170 000 citizens uninsured. (18) On the other hand, a special CHIF sub-fund sometimes still covers treatment costs for uninsured persons, causing them to be present in CHIF claims, but such patients are most likely evenly distributed across the country. Furthermore, a certain percentage of foreign citizens undergo cardiologic interventions in Croatia, but would not have been registered in the CHIF DTS prior to Croatia’s admission to the European Union (EU). After joining the EU, EU citizens register via the CHIF, but others do not. (19) This might have contributed to a reduction in the perceived total of the procedures, especially in centers along the tourist-frequented coast. However, the most significant deviations and errors are likely a result of claims coding in the PCI centers themselves. Some coding practices were systematic and illogical and were corrected for through personal contacts, such as for example double coding for coronarographies in the University Hospital Centre Osijek with the codes 38215-00 and 38218-00, which after personally contacting the laboratory resulted in the final procedure estimate being cut in half. There was no explanation for the unlikely 3 053 coronarography codes in 2010 and 4 432 in 2011 at the University Hospital Merkur even after contacting the center, so those two data-points were excluded from the analysis, which will have reduced the total number of procedures in the results. Furthermore, it is possible that for individual patients receiving both PCI and CA, CA was not separately coded on the claim, which may have reduced the total number of CA procedures. CHIF requires percutaneous transluminal coronary angioplasty (PTCA) to be coded separately from stent implantation in PCI cases. Thus only dilatations without stent implantation are coded as PTCA, and in cases of pre-dilatation followed by stet implantation, only stent implantation is coded. However, it is very likely that some centers occasionally coded a PTCA procedure on the claim in the same patients twice, once as predilatation and once as stent implantation, which would have driven total PCI numbers up as well as the individual counts of the centers themselves. Finally, some hospitals occasionally billed PCI even though the procedure was not being performed in their institutions, likely due to the procedure being performed at a PCI center the patient was transferred from that did not bill the procedure themselves. In the observed period there were 80 (0.17%) such claims, which we eliminated from the procedure count for individual institutions but included in the total number of procedures performed in Croatia.

    Despite these limitations, the results of this study indicate that, despite the lack of a registry for coronary interventions, the undetermined number of licensed interventional cardiologists, and financial limitations, the achievements of Croatian interventional cardiology, based on the number of procedures performed, are on par with the very top in European interventional cardiology. However, systematic and precise quality and quantity analysis for cardiologic interventions would become possible only with the individual registration of every patient in a web-form that would allow every PCI center to perform simple, valid, and timely data archiving. The Working Group for Interventional Cardiology of the Croatian Cardiac Society has issued a general statement that it is time to create a unified Croatian registry of cardiologic procedures, which requires additional funding. Success in forming the registry requires a consensus on mandatory data archiving for every patient. On the other hand, it will be necessary to define personnel dedicated to such data archiving during their working hours or hire personnel from outside the hospital, which would require additional funds.

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