Table 2:
Multilevel negative binomial models predicting negative alcohol-related consequences.
| Fixed effect | Alcohol-use months (n = 11,909 person months among 754 individuals) | Months in which both alcohol and marijuana used (n = 4,469 person months among 530 individuals) | ||
|---|---|---|---|---|
|
| ||||
| RR | 95% CI | RR | 95% CI | |
| Between person | ||||
| Intercept | 0.53 | (0.37,0.75) | 0.75 | (0.59,0.96) |
| Female | 1.54 | (1.34,1.78) | 1.28 | (1.09,1.51) |
| Race/ethnicity | ||||
| Non-Hispanic White | ref. | ref. | ref. | ref. |
| Non-Hispanic Asian | 1.17 | (0.95,1.42) | 1.39 | (1.09,1.77) |
| Non-Hispanic Other | 1.21 | (1.01,1.45) | 1.15 | (0.94,1.41) |
| Hispanic | 1.03 | (0.81,1.31) | 1.07 | (0.82,1.40) |
| Age in years | 1.00 | (0.95,1.04) | 1.01 | (0.97,1.06) |
| Proportion of all months | ||||
| Alcohol use | 1.23 | (0.82,1.84) | ||
| Alcohol and marijuana use | 1.04 | (0.74,1.44) | ||
| Person average substance use quantity/frequency | ||||
| Alcohol use quantity/frequency | 1.60 | (1.39,1.84) | 1.42 | (1.25,1.62) |
| Marijuana use occasions | 1.01 | (0.94,1.09) | ||
| Proportion of alcohol-use months | ||||
| Alcohol-only | ref. | ref. | ||
| CAM | 1.03 | (0.66,1.62) | ||
| SAM | 1.49 | (1.17,1.89) | ||
| Proportion of alcohol and marijuana months | ||||
| CAM | ref. | ref. | ||
| SAM | 1.42 | (1.05,1.93) | ||
| Within-person (time-varying) | ||||
| Month of study (in years) | 0.89 | (0.85,0.93) | 0.96 | (0.91,1.02) |
| Quantity/frequency of alcohol use | 2.07 | (1.97,2.19) | 1.83 | (1.72,1.95) |
| Marijuana use occasions | 0.98 | (0.95,1.01) | ||
| Substance use category | ||||
| Alcohol-only | ref. | ref. | ||
| CAM | 1.04 | (0.97,1.12) | ref. | ref. |
| SAM | 1.17 | (1.10,1.25) | 1.20 | (1.11,1.29) |
| Random effects | ||||
|
| ||||
| Intercept variance | 0.73 | 0.60 | ||
Note. SAM=simultaneous alcohol and marijuana; CAM=concurrent alcohol and marijuana but not simultaneous use. Bold typeface indicates fixed effects p<.05