Do characteristics of practices and general practitioners influence the yield of diabetes screening in primary care? The ADDITION Netherlands study.

Objective: To investigate whether the yield of population-based diabetes screening is influenced by characteristics of the general practitioner (GP) and the practice.
Design: Cross-sectional study.
Setting: Seventy-nine general practices in the south-western region of the Netherlands.
Subjects: From 2002 to 2004, 56 978 people were screened for diabetes. GPs completed a questionnaire containing items on the GP (age, gender, employment, special interest in diabetes, providing insulin therapy) and the practice (setting, location, number of patients from ethnic minority groups, specific diabetes clinic, involvement of practice assistant, practice nurse or diabetes nurse in diabetes care).
Main Outcome Measures: The ratio screen-detected diabetic patients/known diabetic patients per practice (SDM/KDM) and the number of detected diabetic patients per practice adjusted for practice size and age distribution (SDM per standardized practice).
Results: The yield of screening per practice varied widely. Higher age of the GP (regression coefficient 0.20; 95% confidence interval, CI 0.07-0.34), urban location (-4.60; 95% CI -6.41 to -2.78) and involvement of the practice assistant (2.27; 95% CI 0.49-4.06) were independently associated with SDM/KDM. Using the other outcome variable, results were similar. Additionally, cooperation with a diabetes nurse was associated with a lower yield.
Conclusion: A lower yield of screening, reflecting a lower prevalence of undiagnosed diabetes, was found in practices of younger GPs and in urban practices. A lower yield was not associated with an appropriate practice organization regarding diabetes care nor with a specialty of the GP in diabetes. The wide variation in the yield of screening stresses the importance of a screening programme in each general practice.