Incidence of suicide within two years of a first diagnosis of depression, anxiety, or mixed anxiety and depression: an exploratory cohort study in primary care using the Clinical Practice Research Datalink.

Background: The risk of suicide following first diagnosis of depression or anxiety in primary care is uncertain. We investigated suicide incidence within two years of a first diagnosis of depression, anxiety, or mixed anxiety and depression in primary care, analysing variation by diagnosis, age, sex, and social deprivation at lower layer Super Output Area level.

Methods: We conducted a cohort study using the Clinical Practice Research Datalink, a large primary care electronic health records database, linked to mortality records. Adults with their first diagnosis of depression, anxiety, or mixed anxiety and depression between 1 January 1999 and 31 December 2018 were included. The outcome was suicides per 100,000 person-years at risk (PYAR) within two years of diagnosis. Adjusted incidence rate ratios (aIRR) were calculated using Poisson regression.

Findings: Among 1,454,102 individuals diagnosed there were 1439 suicides within two years of diagnosis. Rates were higher in men across all cohorts. The highest rate for men was after depression diagnosis: 115·85 per 100,000 PYAR (95% confidence interval [CI] 107·60-124·58), five times higher than women: aIRR 4·99 (95% CI 4·29-5·79). For women the highest rate was after a mixed diagnosis: 27·73 per 100,000 PYAR (95% CI 21·70-34·92). The highest rate across all groups was seen in men aged 70+ after a mixed diagnosis: 156·43 per 100,000 PYAR (95% CI 89·41-254·03). There was no association between rate and deprivation.

Interpretation: Suicide rates within two years of a diagnosis were higher than the UK general population rate as reported by the Office for National Statistics. Men consistently exhibited higher rates, with men aged 70 and over diagnosed with mixed anxiety and depression experiencing the highest rate. Women aged 50-59 with a first diagnosis of anxiety had over three times the rate of those aged 18-29 at diagnosis. These findings align with findings from other settings and add to the literature by quantifying the effects in primary care. Further analysis is required, particularly for older men and middle-aged women with anxiety-related conditions.

Funding: James Bailey is funded by a National Institute for Health and Care Research Doctoral Fellowship [NIHR302551].