Understanding geographical patterning of self-harm prevalence within a diverse urban population: a mixed methods spatial analysis and qualitative study

Abstract

BackgroundPublic health understanding of variations in self-harm prevalence between populations largely relies on routinely collected service-use data. An unexpectedly low number of hospital inpatient admissions following self-harm has been observed in inner London despite established associations of area deprivation and social fragmentation with self-harm. We aimed to measure associations between rates of attendance at an Emergency Department following self-harm and area characteristics, and to explore the processes that might underlie the incidence of self-harm observed in inner inner-city areas. MethodFor the spatial analysis, we created a dataset of Emergency Department attendances following self-harm from 2009 to 2016 by residents of four southeast London boroughs who were older than 11 years using linked electronic patient record data and Hospital Episode Statistics. Age-standardised and sex-standardised small-area rates of self-harm attendance (SARs) were spatially smoothed using Bayesian models and mapped. Associations with area deprivation (assessed using the Index of Multiple Deprivation) and social fragmentation (Congdon Index) were analysed. For the qualitative study, we identified a case-study area from within the four boroughs studied of four contiguous census lower super output areas (LSOAs; approximately 2600 households that were both in the most deprived quintile of areas in the UK and had below average SARs for self-harm). We undertook semi-structured interviews with 14 individuals working in community organisations and two focus groups of 12 people older than 16 years and resident in the study area, recruited through community organisations. Ethical approval for data access and linkage was granted by the Oxford Research Ethics Committee C, Clinical Records Interactive Search system Oversight Committee, and the NHS Health Research Authority Confidentiality Advisory Group. The qualitative study was given ethical approval by the King's College London, Psychiatry, Nursing and Midwifery Subcommittee. FindingsWe identified 20 750 Emergency Department attendances following self-harm by 12 577 individuals. The ratio of SARs in the highest versus the lowest 5% of areas was 2·87 (95% credible interval [CrI] 2·65–3·13). Associations with self-harm were found for area deprivation (most vs least deprived quintile: rate ratio 2·07, 95% CrI 1·88–2·26) and social fragmentation (1·39, 1·23–1·56); however, we identified clusters of deprived areas with a low incidence of self-harm Emergency Department attendance. Preliminary qualitative analysis suggests that individuals in the case-study population have substantial cumulative stressors and mental health difficulties despite a low incidence of Emergency Department presentation for self-harm (SARs for the four LSOAs ranged from 0·80 to 0·94 before adjustment for deprivation and 0·68–0·81 after adjustment). Frequent experiences of violence and an emphasis on appearing tough combine with discomfort with talking about self-harm and fear of negative treatment by mental health and other services, particularly within the Caribbean and African population who make up 44% of the local population. These factors might make people more likely to respond to distress in ways not defined by researchers as self-harm (even if they are also damaging); equally, these pressures might make individuals who self-harm less likely to identify themselves to services. InterpretationRelying on service-use data for self-harm risks underestimating the extent of distress and subsequent harmful behaviours in some deprived urban populations already disadvantaged by high levels of violence and minority ethnic and migrant status. FundingNational Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London.