Seasonal affective disorder among primary care consulters in January: prevalence and month by month consultation patterns.

Background: Little is known about the prevalence or the consultation patterns of patients with seasonal affective disorder (SAD) in primary care settings.

Methods: Patients aged 16-64 years consulting a general practitioner (G.P.) during a three week period in January were screened with the Seasonal Pattern Assessment Questionnaire (SPAQ). Interview-confirmed cases of SAD (N = 33) were matched by age and sex to controls without seasonal morbidity and primary care consultation patterns were compared over a 5 year period.

Results: Of 692 patients screened, 64 (9.3%) satisfied SPAQ criteria for winter SAD. Patients with SAD showed no winter excess of consultations but were high year round consulters, averaging 1.8 times more consultations than controls.

Conclusions: High levels of SAD caseness on the SPAQ were found among patients consulting in primary care during January. Possible explanations for the high non-seasonal consultation patterns among SAD patients include somatisation and diagnostic inaccuracies.

Limitations: Diagnostic criteria for SAD, and the SPAQ in particular, may be over-inclusive. The SPAQ completion rate (about 39% of eligible patients consulting a G.P.) was relatively low.

Clinical Relevance: Patients with SAD (using SPAQ criteria) commonly consult their G.P.s in winter but frequency, rather than seasonality, of consultation may be a better guide to diagnosing SAD in primary care.