Five year trends (2008–2012) in cardiac implantable electrical device utilization in five European nations: a case study in cross-country comparisons using administrative databases

Abstract

Aims

Common methodologies for analysis of analogous data sets are needed for international comparisons of treatment and outcomes. This study tests using administrative hospital discharge (HD) databases in five European countries to investigate variation/trends in pacemaker (PM) and implantable cardioverter defibrillator (ICD) implant rates in terms of patient characteristics/management, device subtype, and initial implantation vs. replacement, and compares findings with existing literature and European Heart Rhythm Association (EHRA) reports.

Methods and results

HD databases from 2008 to 2012 in Austria, England, Germany, Italy and Slovenia were interrogated to extract admissions (without patient identification) associated with PM and ICD implants and replacements, using direct cross-referencing of procedure codes and common methodology to compare aggregate data. 1 338 199 records revealed 212 952 PM and 62 567 ICD procedures/year on average for a 204.4 million combined population, a crude implant rate of about 104/100 000 inhabitants for PMs and 30.6 for ICDs. The first implant/replacement rate ratios were 81/24 (PMs) and 25/7 (ICDs). Rates have increased, with cardiac resynchronization therapy (CRT) subtypes for both devices rising dramatically. Significant between- and within-country variation persists in lengths of stay and rates (Germany highest, Slovenia lowest). Adjusting for age lessened differences for PM rates, scarcely affected ICDs. Male/female ratios remained stable at 56/44% (PMs) and 79/21% (ICDs). About 90% of patients were discharged to home; 85–100% were inpatient admissions.

Conclusion

To aid in policymaking and track outcomes, HD administrative data provides a reliable, relatively cheap, methodology for tracking implant rates for PMs and ICDs across countries, as comparisons to EHRA data and the literature indicated.

Pacemaker, Implantable cardioverter defibrillator (ICD), Cardiac resynchronization therapy (CRT), Administrative hospital discharge database, International comparison, Geographic variation

What’s new?

• Implant rates for Pacemakers (PM) and Implantable cardioverter defibrillators (ICD) continue to increase in five European countries.

• Implant rates for ICDs overall and for cardiac resynchronization therapy (CRT) PM and ICD subtypes are rising rapidly.

• Significant variation among countries and within countries at the regional level is evident.

• Big data (hospital discharge administrative databases) provides a reliable, relatively cheap, easily replicable means for tracking CIED implant rates across countries.

• Common methodology and cross-referencing of procedure codes can be used with admissions-level data to construct relevant indicators for policymakers and clinicians without compromising patient privacy.

Introduction

With rates of cardiovascular disease rising rapidly worldwide, problems of prevention and treatment of common cardiovascular conditions will challenge all health care systems. Systems for monitoring health care intervention are needed to track outcome results, access to care and compliance with clinical recommendations as well as guide health policy and resource planning.¹ An evidence-based approach to health care provision and planning requires access to information in a timely manner.² ‘Big data’ in the form of routinely collected real world data provides a solution.³ However, exemplar exploitation of such large datasets remains elusive, and few studies have tried to use common methodologies with analogous data sets in diverse countries to compare practices and outcomes for specific therapeutic areas and interventions.

Within the European Union-funded project, Methods for Health Technology Assessment of Medical Devices: a European Perspective (MedtecHTA, see www.medtechta.eu/wps/wcm/connect/Site/MedtecHTA/Home.) we sought to assess the potential and limitations of using hospital discharge (HD) administrative databases to measure implant rates of medical devices in the field of electrophysiology from 2008 to 2012 in the five European nations involved in the project (Austria, England, Germany, Italy and Slovenia). The study builds on previous studies that have used real world data to measure outcomes and new technology adoption.^4,5 We chose two classes of medical devices, pacemakers (PMs) and automatic implantable cardioverter-defibrillators (ICDs), with strong supporting evidence of efficacy,^6,7 significant health expenditure outlays,^8–10 and the potential to compare our results with an existing monitoring program conducted by the European Heart Rhythm Association (EHRA) of the European Society of Cardiology in 50 member nations.¹¹

Previous studies of trends in PM and ICD implant rates,^12,13 have considered device type,^14,15 implants vs. replacements,¹⁶ determinants of geographic variation,^17–19 and international comparisons.^20,21 However, heterogeneous data sources and measurement protocols in these studies make comparisons difficult, may bias or limit ongoing monitoring, and may preclude the application of ‘big data’ sets for routine use in policy making. To our knowledge, no studies to date have used hospital discharge administrative data to compare implant rates and patient management measurements for PMs and ICDs across countries using a common methodology.

Methods

Coding systems for HD data in Austria, England, Germany, Italy and Slovenia, MedtecHTA partners, were described (Table 1); lists of procedural codes for PMs and ICDs were compared and cross-referenced, identifying 16 device categories—implants and replacements of single chamber, dual chamber, and biventricular or cardiac resynchronization therapy (CRT) devices plus an additional unspecified device category found in some of the coding systems (Supplementary material online, Table S1 provides a list of all device variables and codes from the five countries). Codes regarding device removal or revisions or specifying only temporary or partial implantation (e.g. leads, loop recorders, temporary implants, pocket revisions) were excluded to identify only implants or replacements and avoid duplicates.

Table 1

Main features of hospital discharges databases in five countries

	Austria	England	Germany	Italy	Slovenia
Name	National hospital database	Hospital Episode Statistics (HES)	National hospital discharge database	National hospital discharge database (SDO)	National hospital database
Coverage	National	National	National	National	National
Available years	Since 1989 (ICDa-10 since 2001)	Since 1990	Since 2007	Since 2000; 2008–2012 (full set)	Since 2004
Coding system for diagnosesa	ICD-10	ICD-10	ICD-10	ICD-9-CM	ICD-10-AM
Coding system for proceduresa	Country-specific classification	Operating Procedure Codes (OPCS)	Operating Procedure Codes (OPCS)	ICD-9-CM	ICD-10-ACHI (Australian Classification of Health Interventions)
Accessibility	Available and accessible by UMIT upon request	Available and accessible by CHE	Available and accessible by HCHE	Available and accessible by CERGAS	Available and accessible by IER upon request

a

ICD-10 International Classification of Diseases, 10th Revision. ICD9-CM—International Classification of Diseases. 9th Revision. Clinical Modification.

A common protocol (in Stata version 12 or SAS version 9) was developed to extract all HD records for the years 2008–2012 (except England, where data for 2012 were not yet available) where the identified codes were found in any of the procedural code fields to form each country’s database of individual records. Device subtypes (single chamber, dual chamber, CRT and unspecified) were counted separately and as grouped categories to test the ability of the methodology to discriminate types of devices associated with varying indications and costs (i.e. costs per device rise from single to dual to CRT subtypes for both devices). Limited patient characteristics (residency, gender, age, comorbidities) were available for each record, however, for privacy reasons individual patient codes were not provided. Thus, the analysis is by hospital admission, and repeat hospitalizations per patient are not discernible.

Subsequent common protocols extracted aggregate national and regional figures, measured patient characteristics and patient management practices, and applied the Charlson Comorbidity Index (CCI) methodology²² to identify comorbidities through primary and secondary diagnostic codes associated with each record. Supplementary material online, Table S2 includes a list of project variables. Aggregate data from these analyses formed a central project database, which was linked to population data (by region, age class and gender) available online from the Organisation for Economic Co-operation and Development and Eurostat websites, to calculate crude implant rates.

Regarding coding, in Germany codes were available for all types of devices for both PMs and ICDs, with very few unspecified codes. Austrian coding was detailed for PMs, less so for ICDs. In Slovenia, no codes exist to indicate CRT subtypes for either device or replacements for PMs, and all ICDs are coded as ‘unspecified’. Italy’s coding was complete for PMs but indicated only CRT or ‘unspecified system’ for ICDs, and codes for CRT devices were introduced only in 2009. England had detailed coding in general for implants but was largely unspecified for replacements. Finally, HD data in Germany only include inpatient hospitalizations; day hospital records were not available for analysis.

Results are presented as crude implant rates and as rates adjusted for age according to the direct standardization method using the age distribution of the Revised European standard population, 2013. (Eurostat. Revision of the European Standard Population: Report of Eurostat’s task force, 2013 edition. http://ec.europa.eu/eurostat/documents/3859598/5926869/KS-RA-13-028-EN.PDF/e713fa79-1add-44e8-b23d-5e8fa09b3f8f. Accessed 26 November 2015.) Comparisons to EHRA White Book data¹¹ were used to check results.

Results

Numbers and crude first implant and replacement rates

Our datasets included information on 1 338 199 hospitalizations for implants or replacements of the target medical devices from 2008–2012 for Austria, Germany, Italy and Slovenia, and 2008–2011 for England—and averaged 212 952 PM procedures and 62 567 ICD procedures per year for the 4 years for which complete data were available (Table 2). The combined population of the five countries averaged 204.4 million per year (in millions, 8.4 in Austria, 52.1 in England, 81.9 in Germany, 60.0 in Italy and 2.0 in Slovenia). This translates to an all-country crude implant rate of 104.2 PMs and 30.6 ICDs per 100 000 inhabitants per year over the 4 years for combined implants and replacements. Overall numbers of these medical devices from 2008 to 2012 have increased markedly over the 5-year period, rising at a rate of increase far outpacing population changes.

Table 2

Numbers, changes (%) and crude implant rates for combined first implants and replacements of PMs and ICDs, by device, country and year

			% change		% change		% change		% change	% change		Crude implant rate (implants + replacements)
	2008	2009	2009/8	2010	2010/9	2011	2011/10	2012	2012/11	2012a/8	Total	2008	2009	2010	2011	2012
Pacemakersb
Austria	7932	7806	−1.6%	7975	2.2%	8204	2.9%	8327	1.5%	5.0%		95.4	93.4	95.2	97.6	99.0
England	39 473	44 807	13.5%	48 163	7.5%	53 203	10.5%			34.8%a		77.0	86.8	92.6	101.4
Germany	90 317	93 575	3.6%	96 450	3.1%	97 956	1.6%	98 657	0.7%	9.2%		109.9	114.1	117.9	119.8	120.5
Italy	62 220	63 242	1.6%	63 914	1.1%	64 057	0.2%	64 100	0.1%	3.0%		104.4	105.3	105.9	105.7	107.9
Slovenia	602	665	10.5%	638	−4.1%	609	−4.5%	673	10.5%	11.8%		29.9	32.7	31.2	29.7	32.7
Total PMs	200 544	210 095	4.8%	217 140	3.4%	224 029	3.2%	171 757	NA	11.7%a	1 023 565	98.6	103.0	106.1	109.1	113.2
ICDsb
Austria	1586	1800	13.5%	1856	3.1%	1975	6.4%	2097	6.2%	32.2%		19.1	21.5	22.2	23.5	24.9
England	5654	6841	21.0%	7999	16.9%	8454	5.7%			49.5%a		11.0	13.2	15.4	16.1
Germany	28 873	33 086	14.6%	36 693	10.9%	38 988	6.3%	40 849	4.8%	41.5%		35.1	40.3	44.9	47.7	49.9
Italy	16 554	18 117	9.4%	20 002	10.4%	21 083	5.4%	21 205	0.6%	28.1%		27.8	30.2	33.1	34.8	35.7
Slovenia	127	179	40.9%	202	12.8%	197	−2.5%	217	10.2%	70.9%		6.3	8.8	9.9	9.6	10.6
Total ICDs	52 794	60 023	13.7%	66 752	11.2%	70 697	5.9%	64 368		33.9%a	314.634	25.9	29.4	32.6	34.4	42.4
TOTAL database											1 338 199

a

Per cent change between 2008 and 2011 in England and for overall figures.

b

Figures include all device subtypes (single chamber, dual chamber, biventricular/cardiac resynchronization therapy, and unspecified).

Considering only first implants, according to coding practices, the all-country crude first implant rate per 100 000 inhabitants averaged 81 for PMs and 25 for ICDs per year over the period (Figure 1). The crude replacement rate/100 000 averaged 24 for PMs and 7 for ICDs per year over the period. Crude first implant rates increased over all years in all countries except Slovenia, which saw slight decreases in rates for PMs and ICDs in 2010 and 2011 but remained essentially stable by 2012. England had the most marked increase in crude PM first implant rates between 2008 and 2011 (40%), followed by Germany (10%), Slovenia (9%), Austria (7%), and Italy (4%) between 2008 and 2012 (Figure 1). All countries showed large increases in crude first implant rates/100 000 over the period for ICDs, ranging from 14% in Italy to 72% in Slovenia. Increases in crude replacement rates/100 000 for ICDs ranged from 30% in Slovenia to over 100% in Italy from 2008 to 2012, increasing roughly 70% in the other three countries; PM crude replacement rates remained fairly constant, with slight increases in Germany, Italy and England and a 5% drop in Austria. No codes exist for PM replacement in Slovenia.

Figure 1

Crude first implant rates and crude replacement rates per 100 000 inhabitants—Pacemakers and ICDs. *There were no codes for PM replacements in Slovenia.

Considering device subtypes for first implants (Table 3), some evidence of a shift from single chamber to dual chamber PMs is observed, but the greatest increases in the crude rate of first implant/100 000 were for CRT PMs (2.9 to 4.6 in Austria, 3.1 to 4.6 in England, 1.4 to 2.8 in Germany, 1.7 to 3.4 in Italy). Crude first implant rates/100 000 for CRT ICDs also rose markedly (5.8 to 9.5 in Austria, 0.4 to 4.9 in England, 9.6 to 18.2 in Germany and 5.0 to 12.2 in Italy).

Table 3

Crude first implant rates for pacemakers and ICDs by device subtype, comparison 2008 to 2012

Country	Austria		England		Germany		Italy		Slovenia
Year	2008	2012	2008	2011a	2008	2012	2008a	2012	2008	2012
Pacemaker subtypes—crude first implant rates per 100 000
Single chamber PM	19.4	18.9	10.7	15.3	25.1	22.6	22.6	21.5	19.2	22.7
Dual chamber PM	45.4	50.2	22.2	34.9	60.5	71.3	43.7	47.8	4.9	2.4
CRT PM	2.5	3.3	3.1	4.6	1.1	2.2	1.2a	2.2
Unspecified PM			24.1	29.4	0.5	0.3	8.0	6.2	5.9	7.6
ICD subtypes—crude first implant rates per 100 000
Single chamber ICD			2.3	1.8	13.4	15.4
Dual chamber ICD			4.0	4.0	7.3	9.3
CRT ICD	4.9	7.4	0.4	4.9	8.0	14.3	3.9a	7.9
Unspecified ICD	10.6	11.6	1.6	0.7			23.3	18.6	5.6	9.6

a

Figures for England are 2008 to 2011 (data for 2012 were not available), and CRT figures for Italy are 2009 to 2012 (data for CRT devices were not available for 2008).

Age, gender, and patient management measures

Crude implant rates/100 000 of PMs by age class and gender show low rates observed in younger patients, a predominance of males over females, and rates rising considerably with each age group for PM first implants and replacements (Table 4, section 4a). For ICDs, crude first implant rates/100 000 for females rise with each age group except for the 75 years and above, which fall, a phenomenon observed in Austria and Slovenia also for males, whereas in England, Germany and Italy, rates for males rise for ICD first implants through each age group (Table 4, section 4b). Differences among nations can be seen throughout: Italy and Germany show implant rates well above the levels of the other three countries for ICDs. Austria and England are on par or even exceed Germany for PM implant rates by age group, with England most often registering the highest rates among the countries for the younger age groups in PM implants and replacements. Slovenia’s crude implant rates are consistently the lowest for the categories where codes exist, with the exception of two age groups for females for ICD first implants.

Table 4

Pacemakers and ICDs—crude first implant and replacement rates per 100 000 inhabitants by age class, patient characteristics, patient management measures—2011

2011	Austria	England	Germany	Italy	Slovenia	Austria	England	Germany	Italy	Slovenia
4a—Pacemakers	Pacemaker first implants					Pacemaker replacements
Total number of HD records	5967	44 122	78 494	45 951	609	2237	9081	19 462	18 106
Crude implant or replacement rate/100 000 inhabitants by age class
0–44 years—female	1.8	5.0	2.0	1.3	0.7	1.1	1.8	1.3	0.9
45–64 years—female	17.4	29.2	21.3	14.0	4.8	5.3	6.4	4.5	5.0
65–74 years—female	126.7	153.7	163.4	110.6	43.3	37.7	26.8	32.2	35.6
75 years and above—female	427.0	408.2	533.0	384.8	190.7	193.6	99.1	146.5	161.1
0–44 years—male	2.1	6.8	3.4	1.8	0.5	1.2	1.7	1.4	1.0
45–64 years—male	34.4	76.3	39.6	28.3	13.5	9.7	11.6	6.9	9.0
65–74 years—male	247.7	331.8	288.9	224.0	127.9	69.1	57.0	56.5	71.6
75 years and above—male	810.2	855.6	863.2	740.8	382.2	310.7	181.1	233.3	313.2
Patient characteristics
Male (%)	55.9%	62.6%	54.0%	57.1%	57.0%	51.5%	58.3%	52.2%	56.4%
Ageclass 0–44 years (%)	1.5%	4.1%	1.4%	1.1%	1.1%	2.4%	5.7%	2.8%	1.6%
Ageclass 45–64 years (%)	10.0%	15.8%	9.1%	7.5%	8.9%	7.7%	13.1%	6.9%	6.3%
Ageclass 65–74 years (%)	24.7%	24.6%	26.4%	21.9%	24.3%	18.8%	20.6%	20.9%	17.8%
Ageclass 75 years and above (%)	63.9%	55.5%	63.1%	69.5%	65.7%	71.1%	60.5%	69.4%	74.3%
Comorbidities from Charlson Comorbidity Index (CCI) analysis
Mean of weighted CCI scores	0.10a	0.90	1.63	0.96	1.07	0.05a	0.58	1.14	0.30
Patients (%) with a weighted CCI score ≥2	NA	23%	43%	15%	25%	NA	13%	30%	7%
Patients (%) with a primary or secondary diagnosis of
Acute myocardial infarction (AMI)	1.1%a	1.4%	9%	5%	6%	0.1%a	0.8%	4%	2%
Congestive Heart Failure	4%a	15%	32%	13%	23%	3.2%a	10%	21%	8%
Patient management
Inpatient admission type (%)	100%	90.6%	100%	99.3%	97.2%	100%	45.6%	100%	56.3%
Mean (SD) inpatient length of stay (days)	9.2 (8.8)	6.9 (7.5)	10.1 (8.2)	6.7 (5.9)	6.7 (9.0)	4.0 (4.3)	2.3 (4.6)	3.9 (4.9)	3.3 (3.7)
Median inpatient length of stay (days)	6	5	8	5	3	3	1	2	2
In hospital mortality (%)	1.5%	1.7%	1.6%	1.0%	1.8%	0.3%	0.3%	0.4%	0.1%
4b—ICDs	ICD first implants					ICD replacements
Total number of HD records	1.540	6.010	30.484	15.819	174	435	2.444	8.504	5.264	23
Crude implant or replacement rate/100 000 inhabitants by age class
0–44 years—female	1.4	1.2	2.0	1.3	0.7	0.3	0.6	0.7	0.4	0.4
45–64 years—female	8.3	5.7	15.5	10.1	6.6	2.4	2.4	4.3	3.0	0
65–74 years—female	26.6	13.7	47.4	32.4	18.1	6.0	4.9	11.6	9.6	0
Over 74 years—female	18.3	10.9	38.8	29.4	7.6	7.0	5.4	12.9	12.2	0.0
0–44 years—male	3.4	2.2	4.7	3.8	2.1	0.5	0.8	1.1	0.8	0.3
45–64 years—male	41.1	22.3	68.0	46.6	15.5	9.8	8.3	17.0	12.6	2.4
65–74 years—male	122.1	76.1	206.4	155.7	54.8	32.7	29.9	54.4	48.3	6.1
75 years and above—male	87.6	82.3	215.2	161.0	42.3	40.7	36.8	73.2	70.6	13.4
Patient Characteristics
Male (%)	79.0%	80.6%	79.1%	79.5%	71.8%	79.3%	79.3%	78.6%	79.2%	91.3%
Ageclass 0–44 years (%)	7.3%	8.8%	4.6%	5.2%	9.2%	4.1%	9.0%	4.4%	3.7%	17.4%
Ageclass 45–64 years (%)	36.7%	30.8%	32.2%	29.1%	37.4%	32.2%	29.0%	29.4%	24.0%	30.4%
Ageclass 65–74 years (%)	37.1%	32.9%	37.3%	34.9%	36.2%	34.0%	31.3%	34.7%	32.3%	21.7%
Ageclass 75 years and above (%)	19.0%	27.5%	25.9%	30.8%	17.2%	29.7%	30.7%	31.4%	40.1%	30.4%
Comorbidities from Charlson Comorbidity Index (CCI) analysis:
Mean of weighted CCI scores	0.58a	1.32	2.50	1.27	1.52	0.36a	0.98	1.81	0.79	1.91
Patients (%) with a weighted CCI score ≥2	NA	35%	69%	29%	41%	NA	24%	48%	16%	35%
Patients (%) with a primary or secondary diagnosis of:
Acute myocardial infarction (AMI)	2%a	5%	35%	14%	26%	0.4%a	2%	16%	8%	48%
Congestive Heart Failure	54%a	60%	91%	73%	63%	34%a	40%	64%	45%	43%
Patient management
Inpatient admission type (%)	100%	92.4%	100%	97.9%	100%	100%	70.2%	100%	73.4%	100%
Mean (SD) inpatient length of stay (days)	10.3 (9.6)	6.7 (8.3)	10.4 (8.6)	8.5 (7.1)	13.1 (11.9)	4.4 (4.5)	3.0 (4.8)	4.4 (4.8)	4.4 (5.1)	9.3 (9.2)
Median inpatient length of stay (days)	7	2	8	6	10	3	1	3	2	7
In hospital mortality (%)	0.6%	0.3%	0.8%	0.5%	1.1%	0.2%	0.3%	0.3%	0.2%	0%

a

The CCI methodology was performed using the primary diagnosis plus all available secondary diagnoses for all countries except Austria, where only the primary diagnosis code was available.

Over time implants and replacements of PMs and ICDs among both males and females have increased. For PMs the male/female ratio is 56/44% for all countries combined, for ICDs, 80% of patients were male. The predominance of males over females changed markedly with rising age groups for PMs (57% male for 0–44 years, 66% for 45–64, 63% for 65–74 and 52% over 74), but remained more stable for ICDs (70% male for 0–44 years, 81% for 45–64, 81% for 65–74 and 78% for over 74). Patients over 74 years accounted for the majority of cases in the database (64.4%) for PMs, ranging among countries in 2011 as follows: England (56.3%), Germany (64.4%), Slovenia (65.7%), Austria (65.8%) and Italy (70.9%). For ICDs, the 65–74 age group for all countries combined was most numerous (36.5%), followed by 45–64 years (30.6%) and >74 years (27.4%). In 2011, the >74 age group accounted for 18.8% of cases in Slovenia, 21.3% in Austria, 27.1% in Germany, 28.4% in England and 33.1% in Italy. The >74 age group accounted for 70.5% of women receiving PMs, compared with 29.1% of women receiving ICDs. Among males receiving PMs, 59.6% were >74, compared with 27.0% for males receiving ICDs.

In all countries except England, more than 90% of patients were discharged to home, and, in those countries where detailed discharge codes were available, relatively few patients were transferred to other care facilities, mostly for acute care (Table 4). In-hospital mortality was very low and stable over time, and most deaths occurred during hospitalizations associated with PM first implants. Between 85 and 100% of procedures were performed in the inpatient setting, while some countries (Italy and England) made marked use of the day hospital setting, primarily for ICD and PM replacements. However, data regarding day hospital admissions were not available for Germany.

Mean and median lengths of stay (excluding outliers beyond the 99th percentile) showed wide variation for hospitalizations associated with first implants of PMs (e.g. means of 6.7 to 10.1 days and medians from 3 to 8 days in 2011) and ICDs (e.g. means of 6.7 to 13.1 days and medians from 2 to 10 days in 2011). Within countries, lengths of stay for hospitalizations associated with implants were generally more than double those for replacements (see also Supplementary material online, Table S3 for complete descriptive statistics by device category).

Charlson Comorbidity Index (CCI)

Mean weighted CCI scores (Table 4) measure the relative state of health of one device category group as opposed to another, but do not necessarily indicate the relative risk of death of the patients receiving the type of medical device. Percentages of CCI scores of ≥2 indicate those patients with at least two major comorbidities among the diagnoses included in the hospital records, except for Austria, where only the primary diagnostic code was available. Results for two prevalent and relevant diagnosis categories, acute myocardial infarction (AMI) and congestive heart failure, are reported in Table 4 for PMs and ICDs, respectively. The percentages indicate the share of patients where one of the major CCI categories was observed in at least one of the primary or secondary diagnostic codes; in the case of Austria, only where the CCI category was observed in the primary diagnostic code.

Numbers of diagnostic fields ranged from only one in Austria to nearly 100 in Germany, making comparisons difficult, but certain patterns emerged:

• Higher mean CCI weighted scores across groups of patients for first implants vs. replacements for devices, higher mean scores for first implants of ICDs vs. PMs.

• Percentages of patients with CCI weighted scores ≥2 follow a similar pattern (excluding Austria), with highest values for ICD implants, followed by ICD replacements, PM implants and PM replacements, for example for 2011, in Germany (68.9%, 47.9%, 43.1%, 30.0%, respectively), Slovenia (41.4%, 35.0%, 25.2%), England (35.0%, 24.2% 22.5%, 13.4%) and Italy (29.1%, 16.4%, 14.7%, 6.7%).

• Less evidence of AMI among patients receiving PMs compared with ICDs: for implants, 1% vs. 5% in England, 9% vs. 35% in Germany, 5% vs. 14% in Italy, 6% vs. 26% in Slovenia, and in Austria, 1.1% vs. 2.0%.

• Congestive heart failure is observed as a primary or secondary diagnosis among patients receiving both devices, but in much larger percentages for patients receiving first implants of ICDs (54% in Austria, 60% in England, 91% in Germany, 73% in Italy and 63% in Slovenia).

Comparison to EHRA data

Table 5 shows results from several years of EHRA White Books¹¹ compared with MedtecHTA study results, classified according to White Book specifications. Though results showed fairly similar numbers for some countries and some device categories, numbers for England are only indicative since the measure for EHRA is the entire United Kingdom. Totals for PMs in Slovenia differ by as much as 100% (though numbers are small), and in fact seem largely under-reported in our data.

Table 5

Comparison of MedtecHTA (MT) data with European Heart Rhythm Association (EHRA) White Books—by country and year

	Austria			All UK	England		Germany			Italy			Slovenia
Year	EHRA	MT	Diff	EHRA	MT	Diff	EHRA	MT	Diff	EHRA	MT	Diff	EHRA	MT	Diff
Pacemakers (cardiac resynchronization therapy (CRT) subtype not included)
2008	7.570	7.690	2%	40.570	37.734	−8%	98.300	89.194	−10%	61.300	62.220	2%	1.100	586	−88%
2009	7.930	7.500	−6%	39.850	42.701	7%	102.177	92.215	−11%	63.000	62.215	−1%	935	652	−43%
2010	7.712	7.589	−2%	37.194	45.636	18%	103.423	94.659	−9%	63.400	62.202	−2%	1.153	602	−92%
2011	7.810	7.870	1%	38.239	50.540	24%	106.953	96.013	−11%	63.100	62.141	−2%	1.295	604	−114%
2012	7.870	7.950	1%	38.770	NA		106.567	96.403	−11%	61.300	62.098	1%	1.333	667	−100%
ICDs (CRT subtype not included)
2008	1.100	1.104	0%	7.403	5.086	−46%	21.600	20.948	−3%	18.000	16.554	−8%	96	103	7%
2009	1.290	1.157	−11%	5.077	5.376	6%	23.574	22.940	−3%	10.500	15.100	30%	111	145	23%
2010	1.268	1.176	−8%	5.175	5.344	3%	25.071	24.422	−3%	11.100	13.933	20%	101	176	43%
2011	1.805	1.195	−51%	5.404	5.467	1%	26.579	25.219	−5%	11.970	14.106	15%	144	174	17%
2012	1.195	1.296	8%	5.762	NA		26.536	25.956	−2%	12.000	13.943	14%	122	196	38%
CRT Pacemakers
2008	235	242	3%	1.900	1.567	−21%	1.040	1.123	7%	1.500	NA		37	NA
2009	277	306	9%	2.540	1.759	−44%	1.200	1.360	12%	1.500	1.027	−46%	36	NA
2010	307	386	20%	2.366	2.139	−11%	1.666	1.790	7%	1.800	1.712	−5%	36	NA
2011	300	334	10%	2.864	2.370	−21%	1.792	1.942	8%	2.000	1.916	−4%	35	NA
2012	258	377	32%	4.015	0		2.224	2.253	1%	1.900	2.002	5%	63	NA
CRT ICDs
2008	560	482	−16%	2.830	9		8.400	7.925	−6%	9.500	NA		19	NA
2009	672	643	−5%	3.305	841	−293%	10.516	10.146	−4%	8.700	3.017	−188%	31	NA
2010	696	680	−2%	4.155	1.882	−121%	12.868	12.271	−5%	10.000	6.069	−65%	57	NA
2011	658	780	16%	3.731	2.361	−58%	14.633	13.769	−6%	10.380	6.977	−49%	55	NA
2012	621	801	22%	2.950	NA		15.725	14.893	−6%	10.000	7.262	−38%	76	NA

Source EHRA White Books (2009–2013)¹⁰ and MedtecHTA data.

Standardized implant rates, national and regional–adjusted for age

To control for the effects of differences in the population makeup of each country, rates for combined first implants and replacements per 100 000 inhabitants were adjusted for age by direct standardization using the European standard population, version 2013, from Eurostat (Figure 2). With standardization, rates for PMs and ICDs were adjusted upward for Austria, England and Slovenia and generally slightly downward for Germany and Italy. Variation in adjusted PM rates for the first four countries was lessened, but Slovenia’s adjusted rates still remained well below half those of other countries. Differences in ICD rates were not significantly reduced by age standardization. Regional totals were also adjusted by age (based on 1 330 098 records where regional residency and age class data were complete); Figure 3 shows the year 2011, as a representative example of all years. Large differences in the combined first implant and replacement rates for PMs and ICDs between regions are observed, with the exception of ICDs in England.

Figure 2

Crude vs. adjusted (for age*) implant rates per 100 000 inhabitants for PMs and ICD, by year and country. *Adjusted for age using the European standard population, version 2013, from Eurostat.

Figure 3

Adjusted (for age*) first implant rates per 100 000 inhabitants for PMs and ICDs for the year 2011. *Adjusted for age using the European standard population, version 2013, from Eurostat.

Discussion

The collection of routine real world data (so-called ‘big data’) for health care management and administrative purposes has a long history. In recent years there has been increasing use of such for research on performance measurement, access to care, outcomes and quality. (See for example the ECHO (http://www.echo-health.eu), Eurohope (http://www.eurohope.info), EuroREACH (http://www.euroreach.net) and BRIDGE Health (http://www.bridge-health.eu) projects.) The use of diagnostic and procedure codes that, with few adjustments, can be used as a common language has opened up the possibility for increasing use as a policy making tool. Moreover, the cost of accessing and analysing such data for research can be relatively inexpensive compared with some other methodologies, such as registries or clinical trials. Thus, we sought to examine whether and how service use and access to medical technology in the field of electrophysiology could be compared using a common methodology with HD administrative data and how this might aid in identifying problem areas at various levels and determine opportunities for intervention. HD data was interrogated for the years 2008 to 2012, and databases were constructed in five European countries (Austria, England, Germany, Italy and Slovenia) for a combined total of 1 338 199 hospitalizations associated with first implants and replacements of PMs or ICDs.

Comparison to figures published in the EHRA White Books¹¹ was instrumental in validating our data, even if differences in how devices are classified and how implants are distinguished from replacements affect such comparisons. We were limited by partial data for the United Kingdom in our study (only England), and a suspected overestimation of PM rates in England. Efforts to adjust the rates were discussed, in particular by repeating the analysis by individual patient identification numbers; however, this would have made comparisons with the other nations inaccurate and raised privacy concerns. Apparent coding problems also limit conclusions for PMs from Slovenian data. In fact, some of the codes (38253-01 to 38253-10) were removed from the coding system on December 31, 2010, resulting in coding PM implants under other, unspecified codes. When consulted, clinical experts and hospital administrators in Slovenia reported financial disincentives to record all PM implants and estimated under-reporting by roughly 50% for PM implants, as appears to be the case in our comparison to EHRA data. The methodology, however, was instrumental in reporting this discrepancy.

In terms of results, we can confirm other studies’ findings of increases over time, with some recent levelling, in crude PM implant rates/100 000 inhabitants,²³ but that differences among nations are still evident, with Germany largely outpacing other nations. Germany did register greater numbers of comorbidities in the CCI analysis, but this was likely due to data collection methods more than real differences between the patient groups in different countries, and so cannot fully explain the higher crude rates in Germany. With ageing populations, it can be important to use data that allows for such adjustments in measuring trends where age figures prominently in patient assessment and disease progression.¹⁴ Indeed, after adjusting for age, the differences between Germany, Austria and England for PMs lessened considerably, whereas Italy dropped slightly below the others and Slovenia remained far below, though under-reporting in Slovenia compromises results.

For ICDs, differences among countries in both crude and adjusted implant rates per 100 000 inhabitants persist, as reported elsewhere.¹² Within country and between country variation remained substantial at the regional level even after adjusting for age, as has been seen in other countries.^13,14,17 The exception in our data is England, where rates for ICDs are similar across regions though generally lower than Austria, Germany and Italy. Suggestions for possible reasons behind these persistent differences include: economic factors; physician, hospital and regional factors; varying levels of adherence to clinical guidelines; and differing prescribing policies, as for example in the UK, which appears to have exerted downward pressure on implant rates for ICDs at both national and regional levels.^7,10,17,23 Slovenia remains markedly lower in ICD implant rates, which might be explained by economic factors such as lower GDP per capita in comparison to the other countries coupled with the high cost of ICDs and CRT subtypes of both medical devices, even though results have been mixed on how and how much economic factors affect access to these technologies.^14,17,18,21

Regarding changes in numbers and implant rates of the four device types (single chamber, dual chamber, CRT and unspecified), we observed results similar to studies in France and the USA^12–14 with regard to PMs: a predominance of dual chamber PMs and relatively few CRT PM device types; in Slovenia, single chamber PMs still dominate, but a lack of codes in Slovenia to indicate CRT devices makes interpretation difficult. For ICDs, the distinction into four device types is not observable in three of four coding systems, but we do see an upward trend in CRT subtypes, as expected with increased indications and as observed elsewhere.^13,15,16

In patient management, average lengths of stay (ALOS) showed distinct differences between hospitalizations associated with first implants and those associated with replacements, seen at the single device category (16 types) and in the four main groupings of ICD and PM implants and replacements. ALOS were highest for admissions associated with PM first implants, followed by ICD first implants, and decreased for replacements, similar to US and French studies.^13,23,24 As expected from initial investigations of country practices conducted for the project, the data confirmed the use of the inpatient setting for the vast majority of hospitalizations, with day hospital used largely for replacement procedures and in fewer countries, most notably Italy and England (German data were limited to inpatient admissions). Most patients were discharged to home, transfers to other facilities were limited, and although few patients died in the hospital, PM implants showed the highest percentage of in-hospital deaths, both in absolute and relative terms, as has been observed in at least one other study.²⁴

Despite increased indications for ICDs, males outnumber females roughly four-to-one, which is in line with previous studies showing a predominance of ICD and CRT ICD implants in men.^25–27 The reasons for these discrepancies are unknown, and studies suggest that even after controlling for demographic variables and comorbidities men are still more likely than women to receive ICD/CRT-D implants.²⁵

CCI analysis showed that within each country patients receiving ICDs had relatively more comorbidities registered in their HD records compared with PM patients, compared with mixed results from US studies;^16,24 however, a lack of standardization in recording the number and order of diagnoses in HD records among our countries does not allow for direct comparisons of patient groups by single diagnoses. ICD implantation for primary vs. secondary prevention of sudden cardiac death was not directly observable in the data. Nevertheless, our data can show differences over time in the employment of specific types of devices in patients with key comorbidities, providing a useful policy tool.

The small number of countries and common problems associated with administrative data, such as the absence of clinical data and difficulties related to different coding practices, limited our study. The lack of individual patient codes, which precluded direct calculation of replacement rates per patient and linking records to mortality figures, also limited the study.

While EHRA has shed considerable light on the implant rates of these medical devices in numerous countries, data sources for these reports often come from registry or survey data, which can mean significant variation in data collection methods, quality and completeness, inconsistent reporting of specific device types and an absence of patient and clinical information. Industry reports are also sometimes used, potentially introducing an upward bias for medical devices purchased but not used. Our use of HD data is arguably less biased, more complete, and more readily available for the countries studied here and appears to be a promising approach for collecting outcome data on large cohorts of patients, as has been shown previously in assessing ICDs.⁴

Overall, the methodology employed showed that common protocols and cross-referencing of codes from individual country HD databases can provide useful and reliable data for cross-country analysis, even in the absence of individual patient codes. The methodology can be replicated in many countries for medical devices—and likely for other surgical procedures, though not performed here—to measure geographic differences in access to care, patient management practices and, to some extent, compliance with clinical recommendations and appropriateness for clinical indications, as documented in diagnostic codes. Additionally, protocols were run on country databases, eliminating the need for data transfer and safeguarding patient privacy. Delays related to access to the data and privacy protection in various countries occurred, suggesting that lead times must be seriously considered in undertaking such research and monitoring on a larger scale. Methods described here may be useful in HTA to determine the present state of treatment with medical devices or specific surgical procedures when a new treatment is proposed, but they cannot replace analysis of clinical evidence gleaned from clinical studies, systematic literature reviews and meta-analyses for use in approving a new treatment on the basis of superior efficacy.

Prompt introduction of new procedural codes and greater harmonization of diagnostic and procedure codes across countries are recommended. Additional analysis by cross-referencing with Diagnosis-related groups (DRGs) could be conducted to further discern outcome measures. We recommend research to determine whether the methodology might be used to study device reliability, replacement rates per patient and primary vs. secondary prevention. We suggest extending the research on how clinical guidelines are applied at the regional and hospital levels. Finally, considering that the risk of cardiovascular disease is believed to be underestimated in women,²⁸ along with our findings of persistent gender differences in ICD implant rates, further investigation of gender effects using this type of data is encouraged.

Supplementary material

Supplementary material is available at Europace online.

Acknowledgements

The authors gratefully thank the Italian Ministry of Health for providing data from the Italian National Hospital Discharge Database for this study (http://www.salute.gov.it/portale/temi/p2_4.jsp?area=ricoveriOspedalieri).

Conflict of interest: none declared.

Funding

This research was funded by the European Union Seventh Framework Programme under grant agreement HEALTH-F3-2012-305694 (Project MedtecHTA ‘Methods for Health Technology Assessment of Medical Devices: a European Perspective’). Through participation in the MedtecHTA project, the European Heart Rhythm Association (EHRA) of the European Society of Cardiology provided funding through a temporary research contract.