The natural history of depression up to 15 years after stroke: the South London Stroke Register.

BACKGROUND AND PURPOSE Evidence on the natural history of depression after stroke is still insufficient to inform prognosis and treatment strategies. This study estimates the incidence, cumulative incidence, prevalence, time of onset, duration, and recurrence rate of depression up to 15 years after stroke. METHODS Data from patients registered in the South London Stroke Register between 1995 and 2009 were used (N=4022 at registration. Maximum number of participants for these analyses n=1233). Depression was assessed in all patients with the Hospital Anxiety and Depression Scale (scores >7=depression) 3 months after stroke, 1 year after stroke, and annually thereafter up to 15 years after stroke. Inverse probability weighting was used to calculate the estimates accounting for missing data. RESULTS The poststroke incidence of depression ranged from 7% to 21% in the 15 years after a stroke, with cumulative incidence of 55% and prevalence ranging from 29% to 39%. Most episodes of depression started within a year of stroke, with 33% of the cases starting in the 3 months after a stroke, and none from year 10 onward. Fifty percent of the patients with depression at 3 months had recovered 1 year after stroke. The proportion of recurrent episodes of depression after stroke increased gradually from 38% in year 2 to 100% in years 14 and 15. CONCLUSIONS The natural history of depression after stroke is dynamic. Depression affects most of the stroke patients with episodes that have a short duration but a high risk of recurrence in the long term.