Natural history of depression up to 18 years after stroke: a population-based South London Stroke Register study

Background Current evidence on the long-term natural history of post-stroke depression (PSD) is limited. We aim to determine the prevalence, incidence, duration and recurrence rates of depression to 18-years after stroke and assess differences by onset-time and depression severity. Methods Data were from the South London Stroke Register (1995–2019, N = 6641 at registration). Depression was defined using the Hospital Anxiety and Depression scale (scores > 7 = depression) at 3-months, then annually to 18-years after stroke. We compared early- (3-months post-stroke) vs late-onset depression (1-year) and initial mild (HADS scores > 7) vs severe depression (scores > 10). Findings 3864 patients were assessed for depression at any time-points during the follow-up (male:55.4% (2141), median age: 68.0 (20.4)), with the number ranging from 2293 at 1-year to 145 at 18-years after stroke. Prevalence of PSD ranged from 31.3% (28.9–33.8) to 41.5% (33.6–49.3). The cumulative incidence of depression was 59.4% (95% CI 57.8–60.9), of which 87.9% (86.5–89.2) occurred within 5-years after stroke. Of patients with incident PSD at 3-months after stroke, 46.6% (42.1–51.2) recovered after 1 year. Among those recovered, 66.7% (58.0–74.5) experienced recurrent depression and 94.4% (87.5–98.2) of recurrences occurred within 5-years since recovery. Similar estimates were observed in patients with PSD at 1-year. 34.3% (27.9–41.1) of patients with severe depression had recovered at the next time-point, compared to 56.7% (50.5–62.8) with mild depression. Recurrence rate at 1-year after recovery was higher in patients with severe depression (52.9% (35.1–70.2)) compared to mild depression (23.5% (14.1–35.4)) (difference: 29.4% (7.6–51.2), p = 0.003). Interpretation Long-term depressive status may be established by 5-years post-onset. Early- and late-onset depression presented similar natural history, while severe depression had a longer duration and quicker recurrence than mild depression. These estimates were limited to alive patients completing the depression assessment, who tended to have less severe stroke than excluded patients, so may be underestimated and not generalizable to all stroke survivors. Funding National Institute for Health and Care Research (NIHR202339).