Elsevier

The Lancet

Volume 374, Issue 9690, 22–28 August 2009, Pages 609-619
The Lancet

Articles
Clinical diagnosis of depression in primary care: a meta-analysis

https://doi.org/10.1016/S0140-6736(09)60879-5Get rights and content

Summary

Background

Depression is a major burden for the health-care system worldwide. Most care for depression is delivered by general practitioners (GPs). We assessed the rate of true positives and negatives, and false positives and negatives in primary care when GPs make routine diagnoses of depression.

Methods

We undertook a meta-analysis of 118 studies that assessed the accuracy of unassisted diagnoses of depression by GPs. 41 of these studies were included because they had a robust outcome standard of a structured or semi-structured interview.

Findings

50 371 patients were pooled across 41 studies and examined. GPs correctly identified depression in 47·3% (95% CI 41·7% to 53·0%) of cases and recorded depression in their notes in 33·6% (22·4% to 45·7%). 19 studies assessed both rule-in and rule-out accuracy; from these studies, the weighted sensitivity was 50·1% (41·3% to 59·0%) and specificity was 81·3% (74·5% to 87·3%). At a rate of 21·9%, the positive predictive value was 42·0% (39·6% to 44·3%) and the negative predictive value was 85·8% (84·8% to 86·7%). This finding suggests that for every 100 unselected cases seen in primary care, there are more false positives (n=15) than either missed (n=10) or identified cases (n=10). Accuracy was improved with prospective examination over an extended period (3–12 months) rather than relying on a one-off assessment or case-note records.

Interpretation

GPs can rule out depression in most people who are not depressed; however, the modest prevalence of depression in primary care means that misidentifications outnumber missed cases. Diagnosis could be improved by re-assessment of individuals who might have depression.

Funding

None.

Introduction

The burden of depression is considerable in terms of missed workdays1 and disability.2 The WHO study on psychological problems in general health care (PPGHC) across 14 countries found that 14% of individuals suffered from major depression.3 Similar rates were reported from the longitudinal investigation of depression outcomes in primary care (LIDO) study4 and the Depression 2000 study from Germany.5 However, rates are usually higher in urban than in rural settings.6, 7 Most care for depression is delivered by general practitioners (GPs) and individually many GPs have considerable expertise in managing depression.8 Yet, under-recognition of depression in primary care has been extensively described.9, 10 Evidence shows that clinicians in all medical specialties have difficulty recognising mental disorders.11 Recognition rates vary by practitioner, study, and country. The WHO primary care study3 found that 54·2% of those who met the criteria for depression were judged by their treating physician as having a psychological illness, although rates of accurate diagnosis of depression ranged from 19·3% in Nagasaki (Japan) to 74·0% in Santiago de Chile (Chile). Over-detection—ie, the generation of false positives—is less discussed but nevertheless important.

Clinicians can overestimate or underestimate levels of distress of their patients.12 Under-detection could lead to not enough treatment. Studies suggest that active treatment takes place in 15–60% of those identified as depressed.13, 14 Conversely, over-detection (misidentification) can lead to too much treatment. For example, in the European study of the epidemiology of mental disorders (ESEMeD) about 13% of individuals presenting to the GP with symptoms of depression did not have any mental disorder.15 In the national comorbidity replication study, almost 40% received an intervention for depression without a concurrent diagnosis.16

Whether under-recognition or over-recognition of depression is most problematic in routine clinical practice is not clear. We hypothesised that the absolute number of false positives (over-detections or misidentifications) would outnumber that of false negatives (under-detections). Our aim was to assess, with a quantitative analysis, the rate of true positives, true negatives, false positives, and false negatives in primary care when GPs make routine diagnoses of depression.

Section snippets

Literature search

We did a systematic literature search, critical appraisal, and pooled analysis. We searched Medline from January, 1966, to April, 2009; PsycINFO from January, 1887, to April, 2009; Embase from January, 1980, to April, 2009; and Scopus from January, 1980, to April, 2009. The search terms were “general practi$ or primary care or family practice$” and “diagnos$ or detect$ or case-finding or recogni$” and “depress$ or mood or affect$”. Refinement for psychiatric interviews was achieved with “ICD”,

Results

118 studies assessed the ability of GPs to make an unassisted diagnosis of depression, but only 41 satisfied criteria for valid studies measured against a robust outcome standard (figure 1 and table). One study that used the 10th International Classification of Diseases (ICD10) criteria was excluded because both recognition and criterion interview were done by the same GPs. One study explored anxiety alone. 26 were excluded because they examined broadly defined distress or mixed mental

Discussion

We identified 41 studies that assessed the unassisted ability of GPs to diagnose depression against a robust outcome standard of psychiatric interviews. The overall prevalence of depression was 19·5% in various mainly urban primary care practices across more than ten countries. 19 studies examined the ability of GPs to accurately rule in a diagnosis of depressed people and rule out a diagnosis of non-depressed people. We found a diagnostic sensitivity of 47·3–50·1%, suggesting that GPs can

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