Ethnic density and deliberate self harm; a small area study in south east London.

STUDY OBJECTIVE: Relative risks are frequently used to convey how strongly outcomes like mental illness and suicidal behaviour are associated with personal characteristics like ethnic background. This study examined whether RRs for deliberate self harm (DSH) in ethnic groups vary between small areas according to their ethnic mix. DESIGN: Small area study of DSH rates in ethnic groups, by local ethnic density, using negative binomial regression. SETTING: 73 south London electoral wards, 1994-1997. SUBJECTS: 1643 people attending casualty after DSH. MAIN RESULTS: African-Caribbean and Asian DSH rates, relative to the white population, varied between wards. A linear model indicated a decline by factors (relative rate ratios) 0.76 (95% confidence intervals (CI) 0.64 to 0.90) and 0.59 (95% CI 0.36 to 0.97) respectively per SD increase in the local size of these minority populations. However, for both groups, an inverted U shaped curve provided a better fit for the link between the relative DSH rate in these groups and their local population density. CONCLUSIONS: The DSH rate of minority groups relative to the white group is low (suggesting protection) in some areas, and high (suggesting risk) elsewhere. This has implications for management of suicidal behaviour in ethnic groups but also for interpretation, and policy implementation, of research on risk for suicidal behaviour, and, probably, many other outcomes. Relative risks or rates are not stable indicators of association in psychiatric epidemiology.

Childhood predictors of adult medically unexplained hospitalisations. Results from a national birth cohort study.

BACKGROUND: It has been suggested that adults with medically unexplained physical symptoms experienced greater ill-health then others (either in themselves or their families) during childhood. AIMS: To test these hypotheses. METHOD: We used data from the Medical Research Council (MRC) National Survey of Health and Development, a population-based cohort study established in 1946 (n = 5362). Subjects were followed from birth in 1946 until 1989 (age 43 years). As outcome, we used operationally defined medically unexplained hospital admissions at age 15-43 years. Exposure variables included childhood illness, and illness in parents during the childhood of the subjects. RESULTS: The risk set (n = 4603) comprised individuals still in the Survey at age 15. Ninety-five unexplained hospital admissions were identified. Subjects whose mothers reported below-average health in the father were at increased risk of subsequent unexplained admissions. Below average reported health in the mother was not associated with this increased risk. Defined physical diseases in childhood were not associated, but persistent abdominal pain at age 7-15 years was. CONCLUSIONS: Unexplained hospital admissions are associated with certain childhood experiences of illness, but defined physical illness in childhood is not a risk factor.