Risk of self-harm and suicide in people with specific psychiatric and physical disorders: comparisons between disorders using English national record linkage

Abstract

Background Psychiatric illnesses are known risk factors for self-harm but associations between self-harm and physical illnesses are less well established. We aimed to stratify selected chronic physical and psychiatric illnesses according to their relative risk of self-harm. Design Retrospective cohort studies using a linked dataset of Hospital Episode Statistics (HES) for 1999–2011. Participants Individuals with selected psychiatric or physical conditions were compared with a reference cohort constructed from patients admitted for a variety of other conditions and procedures. Setting All admissions and day cases in National Health Service (NHS) hospitals in England. Main outcome measures Hospital episodes of self-harm. Rate ratios (RRs) were derived by comparing admission for self-harm between cohorts. Results The psychiatric illnesses studied (depression, bipolar disorder, alcohol abuse, anxiety disorders, eating disorders, schizophrenia and substance abuse) all had very high RRs (> 5) for self-harm. Of the physical illnesses studied, an increased risk of self-harm was associated with epilepsy (RR = 2.9, 95% confidence interval [CI] 2.8–2.9), asthma (1.8, 1.8–1.9), migraine (1.8, 1.7–1.8), psoriasis (1.6, 1.5–1.7), diabetes mellitus (1.6, 1.5–1.6), eczema (1.4, 1.3–1.5) and inflammatory polyarthropathies (1.4, 1.3–1.4). RRs were significantly low for cancers (0.95, 0.93–0.97), congenital heart disease (0.9, 0.8–0.9), ulcerative colitis (0.8, 0.7–0.8), sickle cell anaemia (0.7, 0.6–0.8) and Down's syndrome (0.1, 0.1–0.2). Conclusions Psychiatric illnesses carry a greatly increased risk of self-harm as well as of suicide. Many chronic physical illnesses are also associated with an increased risk of both self-harm and suicide. Identifying those at risk will allow provision of appropriate monitoring and support.