The accuracy of the clinician would increase from around 77% to nearly 90% if patients were evaluated over two appointments rather than one. Accuracy was improved with prospective examination over a longer period of three months to a year, rather than relying on a one-off assessment or case-note records.
Half of the 12% of patients who suffer from clinical depression would be correctly diagnosed. However, up to double this figure would be at risk of being misdiagnosed as being depressed if GPs relied upon a single clinical assessment.
The analysis was carried out by Dr Alex Mitchell, Dr Amol Vaze and Dr Sanjay Rao of the Leicestershire Partnership Trust. The authors reassured that ‘no data suggest that GPs do worse than other non-psychiatric medical colleagues'.
They said that the modest prevalence of depression in primary care, where only one in five people have depression, contributed to higher rates of false positives. Short appointment times could also contribute to misdiagnoses, as patients may be inhibited from fully discussing their problems.
The authors recommend additional consultation time and repeat assessments to reduce diagnostics errors and improve overall quality of care.
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