HAS AGE AT ONSET OF DRUG-USE CHANGED OVER THE PAST 25 YEARS - SURVIVAL ANALYSIS OF CROSS-SECTIONAL SURVEY DATA 1980-1995

This study examines the age of onset of illegal drug use. Data are tak en from four general population surveys carried out between 1980 and 1 995 in West Germany with a total of over 40 000 cases. Prevalence and incidence of the time-dependent event of first drug use are investigat ed using Survival Analysis. After a period of only slightly increasing prevalence between 1970 and 1990 lifetime experience of illegal drug use has risen sharply since 1990. The observed increase of prevalence in younger age groups can not be explained with an age-shift of onset of drug use. The risk functions of first drug experience show an almos t proportional increase over time. Retrospective responses on age of f irst drug use prove to be highly consistent and do not seem to be syst ematically influenced by the age at time of survey. Data analyses of a ll four surveys according to single birth cohorts allow for a more pre cise examination of the historical process of prevalence and incidence .