Primary data collection versus use of retrospective claims data: methodology lessons learned from a linked database study in chronic obstructive pulmonary disease (COPD) Wilke T1, Gottschalk F2, Groth A2, Driessen M3, Mueller S2 1 Ingress-Health HWM GmbH, Alter Holzhafen 19, 23966 Wismar, Germany. 2 IPAM, University of Wismar, Alter Holzhafen 19, 23966 Wismar, Germany. Electronic address: kontakt@ipam-wismar.de 3 GlaxoSmithKline, Value Evidence & Outcomes, Brentford, Middlesex, United Kingdom. Primary data collection either through a retrospective medical chart review or a prospective observational study, and the utilization of retrospective claims data, are common methods in non-interventional health care research. Using the example of chronic obstructive pulmonary disease (COPD) in German patients, the objective of this study was to assess specific strengths and limitations of primary data collection versus the use of retrospective claims data and to discuss whether linking of both data sources could be of scientific value. Background In this study, which primarily aimed to describe the drug treatment of German patients with COPD and associated treatment adherence and persistence, patient-level data was collected based on: An observational multicenter study in Germany collecting primary data by the means of documentation by study physicians (general practitioners and specialists) patient questionnaires phone interviews with the patients A large German claims dataset covering the years 2010-2015, provided by the German sickness fund AOK Nordost. The dataset includes all available information for all insured patients, who were at least 18 years old and had at least two outpatient or one inpatient diagnosis of COPD (ICD-10 code J44). Methods Prospectively collected primary data referring to the time period between 04/2013 and 11/2014 was linked to the claims data provided by the sickness fund covering the same observation period at a patient level. Characteristics of both datasets were assessed by: An analysis of value differences in patient characteristics, documented exacerbations, and prescriptions of bronchodilators (ATC codes: R03*), for all linked patients A comparison of patient characteristics between both datasets Results The observational study part included 636 patients with COPD who met all primary study inclusion criteria (mean age 68.1 years, SD 10.1, 38.1% female). In the claims dataset, 74,916 patients with COPD were identified (mean age 70.9 years, SD 11.7, 46.0% female). Data linkage was possible for 536 study patients (mean age 68.0 years, SD 9.9, 36.4% female). Figure 2 Percentage of documented exacerbations from both data sources (out of all documented exacerbations) Comorbidities The number of patients with comorbidities reported by primary data was significantly lower compared to the value in the claims data, specifically with regards to hypertensive diseases (47.6% vs. 84%, p<0.001) and depression (6.7% vs. 29.3%, p<0.001) as illustrated in Figure 1. Prescriptions The recorded extent of bronchodilator prescriptions (long- and short-acting) also differed substantially as presented in Figure 3, which displays the degree of concordance of documentations between the datasets. For 440 patients with drug treatment data available in both datasets, the average number of COPD-related prescriptions per patient year was 3.7 prescriptions in the primary data as opposed to 10.3 in the claims data. Figure 1 Prevalence rates of different comorbidities in linked data patients A comorbidity was assumed to exist in a patient, if at least one outpatient or one inpatient ICD-10 diagnosis indicating a specific disease was documented in the claims data (claims dataset) or by the study physician (primary dataset). Statistical significance between primary and claims dataset for all comorbidities: p < 0.001. Degree of concordance of documented COPD-related prescriptions between datasets 30 20 10 40 50 60 Figure 3 Exacerbations Complete information for the total 1-year follow-up period in both datasets was available for 440 out of 536 linked patients. According to the primary data, 92 (20.9%) out of these patients experienced at least one exacerbation (as reported by the study physician) within one year. Based on the claims data, the respective number of patients with at least one exacerbation (ICD-10 code J44.1) is 29.1% (128 out of 440 patients). The degree of concordance between both data sources (primary data and claims data), in documented exacerbations is illustrated in Figure 2. Moreover, severe exacerbations, defined as exacerbations requiring hospitalization, were experienced by 26 patients (5.9%) according to primary data collection (28 exacerbations in total). 16 of these exacerbations (57.1%) could also be identified in the claims dataset as hospitalization with an exacerbation ICD-10 code J44.1. Generalizability For both, COPD patients in primary data collection and in the claims dataset, similar inclusion/exclusion criteria were applied. Nevertheless, in terms of generalizability, it was observed that all COPD patients in the claims dataset (N = 74,916) were on average three years older and more frequently female than those patients with matched data (N = 536). Furthermore, they were less comorbid, and less frequently visiting general practitioners and specialists than primary data patients. This study (HO12-12-8607) is funded by GlaxoSmithKline. Maurice Driessen is an employee of GlaxoSmithKline and holds stock in GlaxoSmithKline. Sabrina Mueller, Fränce Gottschalk and Antje Groth participated in this study as staff members of IPAM; IPAM work in this study was sponsored by GSK. Thomas Wilke has received honoraria from several pharmaceutical/consultancy companies e.g. Novo Nordisk, Abbvie; Merck; GSK, BMS, LEO Pharma, Astra Zeneca, Bayer, Boehringer Ingelheim, Pharmerit. Acknowledgement When applying two different data sources on the same population of patients with COPD we found that substantial differences in the values of key variables between primary data and claims data exist. Therefore, relying on a single data source might be associated with the risk of presenting an incomplete record of the patient’s health status. For this reason we conclude, that data linkage may provide a more comprehensive and precise overview and could thereby provide an opportunity to improve the scientific value. Conclusion Observational research, claims data analysis, chronic obstructive pulmonary disease, real-world evidence study, linked data study Keywords www.ingress-health.com www.twitter.com/ingressh info@ingress-health.com www.linkedin.com/company/ingress-health © Ingress-Health HWM GmbH E-Mail: info@ingress-health.com / Tel.: +49 (0)3841-758-1010