Shared social environment and psychiatric disorder: a multilevel analysis of individual and ecological effects

We examined associations. in terms of relative and population-attributable risks. between shared social environment at the neighbourhood level and (1) treated incidence of non-psychotic, non-organic disorders, and (2) subsequ ent level of service consumption. The multi level analysis used linked reco rds of all individuals in contact for the first time with any catchment are a mental health service for non-psychotic, non-organic disorder over variou s specified time periods between 1981 and 1995. Socioeconomic indicators of 36 neighbourhoods in the city of Maastricht yielded a multivariately defin ed neighbourhood deprivation score. There were significant linear trends in the association between level of deprivation and treated incidence, especi ally in the population under 35 years of age (adjusted rate ratio for linea r trend 1.17, 95% confident interval 1.11-1.23)1 who constituted around hal f of the patient population. The fraction of the incidence of psychiatric d isorder attributable to deprivation was 17.8%. Multilevel analyses of rates of a second cohort. with cases divided according to level of service use o ver a standardised follow-up of 5 years after first contact with psychiatri c services, revealed that the effect of deprivation scores on rates decline d with intensity of out-patient service use, but increased with level of in -patient use. Up to 50% of inpatient episodes in this group could be attrib uted to neighbourhood level of deprivation. The increase in risk conferred by neighbourhood deprivation remained after adjustment for the individual-l evel equivalent. The findings therefore suggest that elements in the shared social environment influence both incidence and severity of non-psychotic, non-organic disorders, over and above any individual-level effect.