Substance Use and College Completion Among Two-Year and Four-Year College Students From a Nationally Representative Longitudinal Study.

Young adults from disadvantaged populations access higher education through two-year colleges, but substance use research among young adults focuses on four-year colleges. Filling this research gap is important given recent policy changes that have increased marijuana availability for young adults. This study uses a subsample of college-enrolled participants from the National Longitudinal Study of Adolescent to Adult Health (Add Health) to evaluate whether substance use predicts educational attainment seven years later, comparing 888 students attending a two-year college with 1,398 matched students attending a four-year college. Matched students were identified using a propensity score method so that students were comparable on 15 measures, including precollege grades, precollege test scores, and precollege substance use. Compared with similar four-year college students, two-year college students were more likely to use methamphetamines, cocaine, or marijuana; more likely to report problematic substance use; and less likely to use alcohol. Two-year college students who used methamphetamines in the past year (incidence rate ratio (IRR) = 1.51, 95% CI (1.12, 2.04), p = 0.007) or past month (IRR = 1.69, 95% CI (1.09, 2.61), p = 0.02) or completed alcohol abuse treatment (IRR = 1.58, 95% CI (1.21, 2.07), p < 0.001) were less likely to complete college than two-year college students without those risk factors. Among the matched four-year college students, students who reported that drugs interfered with school or work in the past year (IRR = 1.84 (1.28, 2.64), p = 0.001), used cocaine in the past year (IRR = 1.47 (1.04, 2.08), p = 0.03), and used marijuana in the past year (IRR = 1.30 (1.07, 1.57), p = 0.007), past month (IRR = 1.31 (1.07, 1.61), p = 0.01), or ≥5 times in the past month (IRR = 1.44 (1.12, 1.85) p = 0.005) were less likely to complete college than the matched four-year college students without those risk factors. Substance use interventions should target both two-year and four-year college students. Two-year colleges that better accommodate students who complete substance use treatment may improve these students' completion. Students who use marijuana or cocaine or whose drug use impairs functioning may benefit from an incremental approach of completing a two-year degree prior to transferring to a four-year degree rather than enrolling directly in a four-year program.