GPs are failing to diagnose clinical depression in at least half of patients who see them because consultations are too rushed, a major study suggests.  Up to 12 per cent of patients also have depression diagnosed incorrectly on the basis of one visit to the doctor, research on more than 50,000 GP consultations found.

Researchers at the University of Leicester said that they did not want to criticise all doctors for failing to identify depression, but those operating in busy urban surgeries may not have enough time to assess patients properly during a one-off visit of only a few minutes.

The study, published today in the medical journal The Lancet, said that a family doctor practising in urban areas would be likely to see up to 100 people over two days, of whom 20 would be suffering from depression.

However, of these, he or she would correctly diagnose only ten and fail to identify the rest. Of the remaining 80 non-depressed patients, the doctor would be likely to "over-diagnose" 15 (20 per cent) and correctly reassure a further 65 (80 per cent).  The findings were based on a review of 41 studies involving one-to-one consultations between doctors and patients, to assess the signs of depression.

Depression will affect as many as one in five people in Britain at some point in their lives, earlier research has suggested.The authors of the latest study said that a number of factors could affect diagnosis of the condition in a one-off consultation, including the severity of symptoms, the accuracy of clinical questionnaires and whether patients talk openly about their problems.

“A further factor is consultation time,” they added. “Short appointments seem to compromise diagnosis in difficult cases. Patients with depression might feel under time pressure druing consultations to the extent that they might often be inhibited from fully disclosing their problems.”

The researchers, led by Alex Mitchell, honorary senior lecturer in psycho-oncology at Leicester General Hospital, said: “Because one-off brief assessments only facilitate identification of about half of those with depression, we suggest that additional consultation time should be available for those likely to have depression.

“Repeated assessments by the GP or other professional in a collaborative model with a case manager might help to reduce diagnostic errors and improve overall quality of care."  In an accompanying commentary, also published in The Lancet, Professor Peter Tyrer, of Imperial College, London, said that it would be surprising if GPs were universally successful in identifying depression, as “most consultations in primary care last only a few minutes".

Paul Farmer, chief executive of Mind, the mental health charity, said: “Assessing someone’s mental wellbeing is a difficult task that is only made harder by the relative shortness of GP appointments. Depression can be particularly difficult to spot as everyone’s experience is different, so while one patient may have more classic symptoms such as feeling low and tearful, another might complain of insomnia and back pain.

“Judging whether someone has a mental health problem, and what that problem might be, requires time and expertise. While GPs have great all-round knowledge, they are not mental health specialists, and it’s unsurprising that in a brief interview with a new patient, signs and symptoms can be missed.”