Background Follow-up participation and retention are essential in long-term cohort studies. Loss to follow up may reduce the power of statistical analyses and external validity. The aim of this analysis was to evaluate the response after different contact methods in a cohort study with Berliners of Turkish descent and to compare characteristics of participants with those of non-participants. Methods In 2012-2013, Berliners with a Turkish migration background were recruited for this cohort study that initially aimed to examine recruitment strategies. The participants were contacted again 5 years later via postal mail and were asked to complete a questionnaire on the onset of new diseases and health care utilization. Written reminders, phone calls, and home visits were used to increase the response. Study documents were available in German and Turkish language. In descriptive analyses, we examined the response rate in relation to the recruitment approach. A regression analysis was conducted to investigate associations between individual, socioeconomic, and medical factors and the response. Results Out of 560 contacted persons, the neutral non-response (unknown address or death) was 13.6%. Of the remaining 484, 234 persons participated in the follow-up (women: 63.1%, mean age±SD: 49.8±12.6 years). The response was 16.1% after the first invitation letter, 24.2% after phone calls, 33.3% and 42.1% with a first and a second reminder letter, respectively, and 48.3% after home visits. The participants had more often German citizenship and a higher net income at baseline than non-participants. Migration generation, age, sex, education, and chronic diseases were not associated with participation (preliminary results). Conclusions In our participants with a migration background, every additional contact effort including home visits further increased cohort retention. Investing in comprehensive retention efforts may lead to studies that are more valid to examine the health of migrants. Key messages Investing in different contact efforts including reminder letters and home visits can improve follow-up response in longitudinal studies. Retention strategies should be used in longitudinal studies to increase statistical power and external validity.

Retention is important for statistical power and external validity in long-term cohort studies. The aims of our study were to evaluate different retention strategies within a cohort study of adults of Turkish descent in Berlin, Germany, and to compare participants and non-participants. In 2011–2012, a population-based study was conducted among adults of Turkish descent to primarily examine recruitment strategies. 6 years later, the participants were re-contacted and invited to complete a self-report questionnaire regarding their health status, health care utilization, and satisfaction with medical services. The retention strategy comprised letters in both German and Turkish, phone calls, and home visits (by bilingual staff). We calculated the response rate and retention rate, using definitions of the American Association for Public Opinion Research, as well as the relative retention rate for each level of contact. Associations of baseline recruitment strategy, sociodemographic, migration-related and health-related factors with retention were investigated by logistic regression analysis. Of 557 persons contacted, 249 (44.7%) completed the questionnaire. This was 50.1% of those whose contact information was available. The relative retention rate was lowest for phone calls (8.9%) and highest for home visits (18.4%). Participants were more often non-smokers and German citizens than non-participants. For all remaining factors, no association with retention was found. In this study, among adults of Turkish descent, the retention rate increased considerably with every additional level of contact. Implementation of comprehensive retention strategies provided by culturally matched study personnel may lead to higher validity and statistical power in studies on migrant health issues.

Background The growing proportion of people with a migration background poses major challenges for public health and the health care system in Germany. People of Turkish descent represent the largest group within this specific population. The aim of this study was therefore to examine the use and satisfaction of medical services and barriers to health care access among adults of Turkish descent in Germany. Methods A cohort study of a group of nearly 1200 Turkish adults in Berlin and Essen constitutes the basis of this analysis. The baseline examination was carried out as part of the pretests of the German National Cohort study. This follow-up survey assessed utilization, satisfaction and subjectively perceived barriers in the German health care system, as well as socio-demography, lifestyle, health status and quality of life via self-report (paper based or online) in Turkish or German. Descriptive preliminary results are presented in this abstract. Results The first 287 participants interviewed until December 31, 2018 were on average 49 years old, with 64% being female. 90% of the participants had a family doctor and in the last 12 months, 17% were in a hospital for in-patient treatment and 23% in an emergency room. The use of screening programs varied from 15% (skin cancer screening) to 87% (mammography). The most frequently visited physician was the general practitioner (86%). The participants were satisfied regarding many aspects, with the best values for the communication with their doctor. However, 22% reported problems or barriers in the context of medical care in the last five years. Conclusions These preliminary results provide a first insight into the utilization behaviour among adults of Turkish descent, their satisfaction as well as barriers with the German health care system. However, possible consequences of our study should only be discussed after all analyses have been completed. Key messages This is one of the few cohort studies in a migrant population in Germany. Knowledge of barriers could provide indications of problems of adults of Turkish descent in the German health care system.

Background Studies have shown differences regarding prevalence and incidence of chronic diseases among first (own migration experience) compared to second (born in host country) generation migrants. The aim of this study was therefore to investigate the incidence of cardiovascular diseases (CVD) among persons of Turkish descent with and without migration experience living in Berlin, Germany. Methods In 2012-2013, Berliners with a Turkish migration background were recruited, examined, and contacted again 5 years later via postal mail. Incidence of diagnosed CVD (myocardial infarction, stroke, coronary heart disease, heart failure, cardiac arrhythmia, intermittent claudicatio or transient ischaemic attack) was assessed via self-report. Incidence of any CVD is presented as number and percentages. Associations between the incidence of any CVD and having an own migration experience were investigated with uni- and multivariable regression analyses. Results are presented as odds ratios with a 95%-confidence interval (OR, 95%-CI). Results Data of 234 persons of Turkish descent (62.8% women) with a mean age±standard deviation of 44±12.4 years were included in the analyses. Out of these, 79.9% were first generation migrants. First compared to second generation participants differed regarding CVD incidence (any CVD 16.6% vs. 4.3%, respectively; p = 0.03), socio-demographic, and lifestyle factors. After adjusting for these factors, multivariable analysis showed that only BMI (OR 1.12 per BMI point, 95%CI [1.02;1.24], and having a diagnosis of dyslipidemia (OR 4.0, 95%CI [1.45;12.05]), were independently associated with CVD incidence. Conclusions In a cohort study with Berliners of Turkish descent, CVD incidence was associated with increasing BMI and dyslipidemia, but not with own migration experience. Future migration-related public health research needs to focus on the prevention of harmful health behaviours to avoid the progression of overweight/obesity and dyslipidemia. Key messages CVD incidence is higher in persons with migration experience compared to those without. Migration experience is not associated with CVD incidence after adjusting for confounders (e.g. age, BMI).