Assessing the prevalence of the Metabolic Syndrome according to NCEP ATP III in Germany: feasibility and quality aspects of a two step approach in 1550 randomly selected primary health care practices

Objective: Metabolic Syndrome (MetSyn) describes a cluster of metabolic disorders and is considered a risk factor for development of cardiovascular disease. Although a high prevalence is commonly assumed in Germany data about the degree of its occurrence in the population and in subgroups are still missing. The aim of this study was to assess the prevalence of the MetSyn according to the NCEP ATP-III (National Cholesterol Education Program Adult Treatment Panel III) criteria in persons aged ≥18 years attending a general practitioner in Germany. Here we describe in detail the methods used and the feasibility of determining the MetSyn in a primary health care setting. Research design and methods: The German-wide cross-sectional study was performed during two weeks in October 2005. Blood samples were analyzed in a central laboratory. Waist circumference and blood pressure were assessed, data on smoking, life style, fasting status, socio-demographic characteristics and core information from non-participants collected. Quality control procedures included telephone-monitoring and random on-site visits. In order to achieve a maximal number of fasting blood samples with a minimal need for follow-up appointments a stepwise approach was developed. Basic descriptive statistics were calculated, the Taylor expansion method used to estimate standard errors needed for calculation of confidence intervals for clustered observations. Results: In total, 1511 randomly selected general practices from 397 out of 438 German cities and administrative districts enrolled 35,869 patients (age range: 18-99, women 61.1%). More than 50,000 blood samples were taken. Fasting blood samples were available for 49% of the participants. Of the participating patients 99.3% returned questionnaires to the GP, only 12% were not filled out completely. The overall prevalence of the MetSyn (NCEP/ATP III 2001) was found to be 19.8%, with men showing higher prevalence rates than women (22.7% respective 18.0%). Conclusions: This study was designed to provide data as robust as possible within the confines of an epidemiological study. Judging by the low degree of missing data and the high data quality, the feasibility for this kind of a research setting (short evaluation period, practitioners as data assessment sites) was found to be very good. The results will help to gain a more comprehensive insight into the prevalence of MetSyn for patients in primary health care in Germany.