Do patients׳ illness beliefs predict depression measures at six months in primary care; a longitudinal study

Depressive disorders are prevalent and costly but there is a lack of evidence on how best to select treatments for mild to moderate depression in primary care. Illness beliefs have been shown to affect the outcome from physical illness, but there is limited information on the beliefs of patients who are depressed.

To measure patients׳ beliefs about depression at baseline and determine whether these relate to depression severity at six months.

Primary care patients with a recently diagnosed episode of depression completed the Beliefs about Depression Questionnaire and depression severity scores at baseline. The primary outcome was the change in depression severity score on the Hospital Anxiety and Depression Scale after six months.

227/292 (78%) participants completed follow-up questionnaires. Initial severity of depression at baseline, and particular beliefs about the causes, consequences and timeline of depression predicted poorer outcomes, whereas a belief in using exercise or keeping busy to treat depression predicted improved outcomes. Prescription of antidepressants did not appear to mediate these relationships.

This was an initial study using a new validated questionnaire and it cannot be predicted whether these results are representative or would be reproduced in other populations. Although participants were primary care patients whose GP (General Practitioner) had coded as having a new incident episode of depression in the preceding six months, 43% of participants stated they had been depressed for more than a year. Sufficient participants were recruited to ensure the study was adequately powered but participation rate was 30%, raising the possibility of response bias.

Illness beliefs may help to predict outcomes in depression and therefore assessing and addressing patients׳ beliefs about their depression may enhance treatment.