Validity and reliability of the nicotine and marijuana interaction expectancy (NAMIE) questionnaire.

BACKGROUND

The co-occurring use of tobacco and marijuana among young people is a concern, yet little research has examined processes of co-use. Understanding expectancies around use of the two substances will help identify intervention targets. This study examined psychometric properties of the Nicotine and Marijuana Interaction Expectancy (NAMIE) questionnaire based on three modified scales of the Nicotine and Other Substance Interaction Expectancy (NOSIE) questionnaire.

METHOD

An anonymous online survey recruited participants (N=1152) age 18-25 (mean age 20 years, 67% male, 72% Caucasian) who reported use of cigarettes and marijuana in the past 30 days. Analyses examined reliability and validity of the NAMIE.

RESULTS

A confirmatory factor analysis indicated good model fit for a 3-factor model. Scales were marijuana increases tobacco use and urges, tobacco increases marijuana use and urges, and smoking to cope with marijuana urges. Subscales correlated significantly with measures of cigarette smoking (r=.08 to .27, p<.01) and nicotine dependence (r=-.07 to -.20, p<.01), marijuana use (r=.08 to .29, p<.01) and dependence (r=.27 to .42, p<.01), percent of days using both cigarettes and marijuana in the past 30 days (r=.15 to .30, p<.01), thoughts about tobacco and marijuana abstinence (r=-.09 to .44, p<.01), and motivation to quit using marijuana (F=9.43, p<.001). When entered into a regression model, variables of use and thoughts about use remained significant.

CONCLUSIONS

The NAMIE was well-adapted for use with a marijuana-using community sample of young adult smokers.