Background: There are international differences in the epidemiology of depression and the performance of primary care physicians but the factors underlying these national differences are uncertain.
Aim: To examine the international variability in diagnostic performance of primary care physicians when diagnosing depression in primary care.
Design of study: A meta-analysis of unassisted clinical diagnoses against semi-structured interviews.
Method: A systematic literature search, critical appraisal, and pooled analysis were conducted and 25 international studies were identified involving 8917 individuals. A minimum of three independent studies per country were required to aid extrapolation.
Results: Clinicians in the Netherlands performed best at case finding (the ability to rule in cases of depression with minimal false positives) (AUC+ 0.735) and this was statistically significantly better than the ability of clinicians in Australia (AUC+ 0.622) and the US (AUC+ 0.653), who were the worst performers. Clinicians from Italy had intermediate case-finding abilities. Regarding screening (the ability to rule out cases of no depression with minimal false negatives) there were no strong differences. Looking at overall accuracy, primary care physicians in Italy and the Netherlands were most successful in their diagnoses and physicians from the US and Australia least successful (83.5%, 81.9%, 74.3%, and 67.0%, respectively). GPs in the UK appeared to have the lowest ability to detect depression, as a proportion of all cases of depression (45.6%; 95% CI = 27.7% to 64.2%). Several factors influenced detection accuracy including: collecting data on clinical outcomes; routinely comparing the clinical performance of staff; working in small practices; and having long waits to see a specialist.
Conclusion: Assuming these differences are representative, there appear to be international variations in the ability of primary care physicians to diagnose depression, but little differences in screening success. These might be explained by organisational factors.