In Search of Normal Controls: A Methodological Complication When Conducting Adolescent Opiate Dependence Research

Abstract

Purpose: When designing a study choosing an appropriate control population is crucial for optimal study results. The population of youth with opiate dependence is increasing dramatically. When researching this population, recruiting and selecting a control group that provides accurate comparison is critical. The objective of this study was to describe the complexities surrounding the selection of an appropriate comparative control group for research with opiate dependent adolescents and young adults. Methods: Healthy adolescent and young adults, age 16 to 22 years, were recruited from a community shopping mall and the employee pool of the participating institution to provide a comparison group for an ongoing study of psychosocial development of adolescents and young adults in treatment for opiate dependence. Participant and guardian consent/assent was obtained as appropriate. All potential control subjects completed a modified Youth Risk Behavior Survey (YRBS), Symptom Checklist 90 (SCL-90), and Kaufman Brief Intelligence Test (K-BIT) at baseline. Controlswere classified based on historyof reported drug use as eitherusers ornon-users. To classifyas a non-user, control subjects were required to deny: 1) opiate use without a prescription in the last thirty days; 2) opiate usewithout a prescription three or more times in their lifetime; 3) needle use to inject any illegal drug; or 4) any other illicit substance use three or more times in their lifetime. Fisher's exact test and t tests were used to compare users and non-users as appropriate. Adjustments were made for unequal variances between groups. Results: Within potential control subjects, 14 of 45 (31%) were classified as users. No differences were found between users and non-users regarding gender, race, maternal/paternal education, insurance status, family history of drug use, or verbal/nonverbal intelligence. Users, as compared to non-users, reported lifetime drug use of 64.3% vs. 3.3% non-prescription opiates, 71.4% vs. 0.0% heroin, 100.0% vs. 54.8% alcohol, 92.9% vs. 25.8% marijuana, 28.6% vs. 0.0% benzodiazepines, 14.3% vs. 0.0% cocaine, respectively. Significant differences were found between users and non-users on psychosocial measures. Specifically, users, as compared to nonusers, were noted to have higher levels of psychosocial distress in domains of somatization (1.04 vs. 0.51, p = 0.01), paranoia (0.96 vs. 0.56, p = 0.09), hostility (1.61 vs. 0.65, p < 0.01), depression (1.31 vs. 0.59, p = 0.01), anxiety (1.23 vs. 0.34, p < 0.01), obsessive compulsive behavior (1.48 vs. 0.69, p = 0.01), and global psychological severity index (1.00 vs. 0.49, p = 0.01). Conclusions: Approximately one out of three healthy control subjects met criteria for illicit substance use. These illicit substance users demonstrated a distinct psychosocial profile as compared to non-using control subjects. Both using and non-using control subjects could provide a comparison group for opiate dependent youth; however, if imprecisely combined this amalgamated group does not provide appropriate comparative data. When researching opiate dependent youth, accurate selection, definition,and screeningof the control group is essential to producing valid and authentic results.