Psychiatric disorders in a Dutch Health Area: a repeated cross-sectional survey

Decades of psychiatric epidemiology have shown a wide variation in prevalence rates, but a consistent relationship between psychiatric disorder and sociodemographic variables. In this repeated cross-sectional survey, the prevalence of psychiatric disorders and their distribution in the general population of the same area was assessed in 1983 and 1997.

With an interval of 14 years, 2 two-phase studies of psychiatric prevalence were carried out among the inhabitants of a Dutch Health Area (Nijmegen). In phase 1, a random sample of persons answered the General Health Questionnaire (GHQ-30). In phase 2, the respondents were interviewed using a clinical semi-structured interview. Only phase 1 data will be reported here.

The mean overall GHQ-score changed significantly from 3.1 (+/-1.0) in 1983 to 4.6 (+/-1.8) in 1997. On a bivariate level, higher score rates were found consistently in the age categories > or = 50 years, among divorced persons, the lower educational levels, the unemployed/chronically ill and in the urban areas. On a multivariate level (second order effect), however, the variance explained by these sociodemographic variables doubled, revealing the importance of complex interactions.

Our aim to ensure identical designs in 1983 and 1997 could not completely be achieved.

In the course of time, psychiatric prevalence increased in all sociodemographic categories, despite the improved socioeconomic conditions in the survey population as a whole. The increasing complexity of life apparently takes its toll, even of the socially best equipped.