Inadequacies of self-report data for exclusion criteria detection in marihuana research: an empirical case for...

Stringent exclusion criteria in drug abuse research are necessary to protect against methodological confounds compromising the interpretation of findings. However, reliance on self-report screening may fail to detect important exclusion variables. We compared three levels of exclusion criteria screening in a study of neurophysiological/neurocognitive sequelae of chronic marihuana use in normals. LEVEL 1 (self-report) consisted of telephone pre-screening. LEVEL 2 (also self-report) involved in-depth personal interviews. LEVEL 3 consisted of several direct examination assessments including a medical/psychiatric examination by a board certified psychiatrist, eight weeks of twice per week urine drug screens, an EEG exam and eight hours of neuropsychological testing. Results indicated that 39.0% of subjects passing self-report screening had significant exclusion criteria findings that were only detected through LEVEL 3 direct examination procedures. Of all subjects found to have exclusion criteria after being provisionally accepted following LEVEL 1 telephone pre-screening, 55.7% were detected only through more rigorous LEVEL 3 direct examination screening methods.