Comparative epidemiology of initial drug opportunities and transitions to first use: marijuana, cocaine, hallucinogens and heroin

The earliest stages of involvement with illicit drugs have been understudie d. In a recent report, we examined initial opportunities to try marijuana a nd transitions from first opportunity to first use of that drug. This repor t extends that work by investigating early involvement with cocaine, heroin , and hallucinogens as well. We examine sex and race-ethnicity differences in estimates of having a drug opportunity, and in the probability of progre ssing from having an opportunity to try a drug to actually using the drug. Self-report interview data collected for the National Household Surveys on Drug Abuse (NHSDA) from 1979 to 1994 were analyzed. Results showed that an estimated 51% of US residents have had an opportunity to try marijuana; com parative estimates for cocaine, hallucinogens, and heroin are 23, 14, and 5 %, respectively. Among those who eventually used each drug, the vast majori ty made the transition from first opportunity to first use within 1 year. M ales were more likely than females to have opportunities to try these drugs , but were not more likely than females to progress to actual use once an o pportunity occurred. Time trends indicate recent increases from 1990 to 199 4 in the estimated probability of using an illicit drug once an opportunity occurs, particularly for hallucinogens. Exploratory analyses on race-ethni city yielded some interesting leads for future research. This study sheds l ight on the epidemiology of the earliest stages of drug involvement in the USA. Implications for prevention efforts and for our understanding of sex d ifferences in drug involvement are discussed. (C) 1999 Elsevier Science Ire land Ltd. All rights reserved.