Accuracy of diagnosing depression in general practice: the impact of comorbidity.

Aim: While major depression is one of the most prevalent disorders in general practice, it is often not accurately diagnosed by general practitioners (GPs). This can adversely affect patients’ lives, either through non-treatment (underdiagnosis) or unnecessary antidepressive treatment (overdiagnosis). A possible contributing factor to the diagnostic inaccuracy is the presence of psychiatric and chronic somatic co morbidity. To advance previous findings we investigate whether underdiagnosis and overdiagnosis are related to psychiatric and/or somatic co morbidity. Methods: Data were derived from the second Dutch National Survey of General Practice (2000–2002). A standardised psychiatric interview (CIDI) was performed in 576 persons (screened positive for psychopathology; mean age: 47 years; 68% female). A CIDI diagnosis of depression was used as the gold standard and compared with diagnoses registered by GPs in patient contacts within 12 months. Psychiatric and somatic (co)morbidity were determined using the CIDI and contact registration, respectively. Persons were divided into groups depending on presence of (co)morbidity. Results: 191 persons suffered from depression, of whom 136 (71%) were not diagnosed with depression. Underdiagnosis was significantly associated with co morbidity. Underdiagnosis was most prevalent among depressives with somatic co morbidity (83%), while least prevalent among those with both psychiatric and somatic co-morbidity (60%).Of the 385 nondepressives, 20 (5%) were diagnosed as depressive. Overdiagnosis was significantly related to (co)morbidity. Overdiagnosis was most prevalent among those with psychiatric disease either alone (13%) or co morbid with somatic disease (11%). In additional multivariate analyses we will control for potential confounders such as age and depression severity. Conclusions: This study provides more insight into the impact of co morbidity on GPs’ accuracy in diagnosing depression. Diagnostic accuracy could be improved by taking into account the co morbidity of depression related to chronic somatic disease and other psychiatric diseases.(aut. ref.