Background. The relationship between ethnicity and suicide
risk is ill-understood. It is unclear
whether, and if so, how, the ethnic mix of local areas affects risk in
Methods. Coroners' records of 329 suicides were used to
obtain ethnic (White, Afro-Caribbean,
Asian) suicide rates in South London (population 902008) for 1991–3.
Geographical variation and
associations of ethnic suicide rates with small area (mean population 8274)
(proportion of residents of given ethnic groups) and deprivation, were
examined with random
effects Poisson regression.
Results. Adjusted for deprivation, age and gender, suicide
rates in wards with larger minority
groups were higher among Whites (relative rate (RR) per standard deviation
increase in minority density 1·18; 95% CI 1·02–1·37)
but lower among minority groups (RR 0·75 (0·59–0·96))
(LR-test for interaction χ2=9·2 (df=1); P=0·003).
Similar patterns were also apparent for Afro-Caribbeans and Asians
separately. With White suicide rates as baseline, ethnic minority status
risk factor for suicide in wards with small, but a protective factor in
neighbourhoods with large
minority populations. The RR of minority versus White suicide
declines with a factor (relative RR)
0·67 (0·51–0·87) per S.D. increase
in local minority density.
Conclusions. Minority suicide rates are higher in areas where minority
groups are smaller. This effect
is ethnic-specific and not due to confounding by gender, age, deprivation
or unbalanced migration.
Dependent on address, a suicide risk factor for a White individual may
protect an ethnic minority
individual and vice versa. This has implications for research and prevention.