Table 1. Study-specific estimates of odds ratios that quantify associations linking occurrence of diabetes mellitus among recently active cannabis smokers: Data for the United States based on eight independent replications from the National Health and Nutrition Examination Survey (NHANES) and the National Surveys on Drug Use and Health (NSDUH), 2005-2012.
| Independent replication sample | Unadjusted CS-DM odds ratio (95% CI) | Covariatea adjusted odds ratio (95% CI) | Covariate-adjusted odds ratio additionally adjusted for BMI (95% CI)b |
|---|---|---|---|
| NHANES 2005-06 | 0.3 (0.2, 0.7) | 0.6 (0.3, 1.2) | 0.8 (0.4, 1.5) |
| NSDUH 2005-06 | 0.3 (0.2, 0.4) | 0.7 (0.5, 1.0) | ------------- |
| NHANES 2007-08 | 0.3 (0.2, 0.5) | 0.4 (0.2, 0.7) | 0.4 (0.2, 0.8) |
| NSDUH 2007-08 | 0.3 (0.2, 0.4) | 0.5 (0.4, 0.7) | ------------- |
| NHANES 2009-10 | 0.5 (0.3, 1.1) | 0.9 (0.4, 2.1) | 1.0 (0.4, 2.1) |
| NSDUH 2009-10 | 0.4 (0.3, 0.6) | 0.8 (0.5, 1.1) | ------------- |
| NHANES 2011-12 | 0.5 (0.3, 0.8) | 0.7 (0.4, 1.2) | 0.8 (0.4, 1.4) |
| NSDUH 2011-12 | 0.5 (0.4, 0.6) | 0.9 (0.6, 1.2) | ------------- |
| Meta-analytic odds ratio summaryc | 0.4 (0.3, 0.5) | 0.7 (0.6, 0.8) | 0.7 (0.5, 0.97) |
| Heterogeneity test statistic (p value) | 12.9 (0.08) | 9.8 (0.20) | 2.7 (0.43) |
Covariate adjustments for age (years), sex (male and female), ethnic self-identification (non-Hispanic Whites, non-Hispanic Blacks, Hispanics, and all others), education (less than high school, high school, and above high school), income-poverty ratio (<1 and ≥1), past-year alcohol drinking (never user, used before but not in the 12 months prior to the interview, and used in the 12 months prior to the interview) and tobacco cigarette smoking (never, former, non-daily, and daily smoker), using the multiple logistic regression model.
Additionally adjusted for BMI (kg/m2). The NSDUH study does not collect data on BMI.
This ‘random effects’ meta-analysis summary estimate makes an allowance for between-replication variability in the effect estimates. The heterogeneity test statistic (degrees of freedom. = 7) suggests no appreciable variation (i.e., as gauged in relation to alpha set at 0.05); nonetheless, the ‘random effects’ summary estimate was retained, with resulting standard errors (and 95% CI) slightly larger than those obtained using the ‘fixed effects’ meta-analysis summary estimation approach.