BACKGROUND A previous cross-national epidemiological study of first admission rates in London and in Aarhus, Denmark, found that the incidence of mania was virtually identical for both centres. This study sought to examine the corresponding rate for a defined catchment area in Dublin, Ireland, and to establish whether the impression of a higher rate could be validated.
METHOD The study combined a six-year retrospective review and one-year prospective collection of first-admission cases of mania from a defined catchment area. Diagnosis was according to ICD criteria and the Syndrome Check List of the Present State Examination (PSE). Cross-national comparisons were made using standardised incidence rate ratios (SIRs).
RESULTS The crude incidence rate for Dublin in the age range 18-60 years was established at 4.5 per 100,000 per year. A comparison of SIRs for the three centres showed the Dublin rate to be higher than expected (P < 0.02). Age-specific analysis indicated that this increase came mainly from the age range 18-29 (chi 2 = 9.08, P = 0.01).
CONCLUSIONS The study confirmed the impression that the local incidence of mania in Dublin is higher than that reported from two other North European centres. A variation in rates from contrasting socioeconomic districts within the catchment area points to some caution in the interpretation of the results and suggests further study from wider catchment areas.