Incidence and prevalence of "diagnosed OCD" in a primary care, treatment seeking, population

Objective. To obtain valid and accurate estimates of the incidence and prevalence of OCD in a treatment-seeking primary care population and to compare these estimates with estimates from epidemiological community studies. Methods. A retrospective cohort study (1996-2007) was conducted in a GP research database with longitudinal electronic patient record data of 800,000 patients throughout The Netherlands. OCD was ascertained and classified by systematic review of computerized longitudinal medical records. Age and gender specific incidence rates were calculated per calendar year as the number of newly diagnosed cases per 100 person years. Results. Among 577,085 eligible patients, 346 patients were newly diagnosed with OCD resulting in a 1-year treatment-seeking incidence of 0.016% (95% CI: 0.014-0.018). Across the entire study period, a total of 780 patients had a clinical diagnosis of OCD resulting in a treatment-seeking prevalence of 0.14% (95% CI: 0.126-0.145). The incidence rate was highest among women and between the age of 20 and 29. No significant changes over time were observed. Conclusions. The incidence rate and prevalence of OCD in treatment-seeking GP patients are at least 3 times lower than estimates known from the most conservative epidemiological community studies, suggesting that OCD may be under recognised and under treated.