Test-retest reliability of a lifetime drug use questionnaire.

By adopting the investigational principle of the Lifetime Drinking History (LDH) interview, we developed a Lifetime Drug Use (LDU) Questionnaire to assess the amount and frequency of lifetime drug consumption. The Pearson Correlation Coefficients for test-retest reliability, investigated in a sample of N=47 residents of a drug rehabilitation center and averaged over the investigated seven drug categories, were r=.95 for the abstinence-corrected total duration of regular use, r=.89 for the mean number of consumption days per month of regular use, r=.89 for the mean daily amount, r=.83 for the variability in consumption days per month of regular use, and r=.75 for month variability in daily amount. Applicability and further research needs are discussed.