Brief Alcohol Interventions are Effective through 6 Months: Findings from Marginalized Zero-inflated Poisson and Negative Binomial Models in a Two-step IPD Meta-analysis
This repository contains the companion data and R code Mun, E.-Y., Zhou, Z., Huh, D., Tan, L., Li, D., Tanner-Smith, E. E., Walters, S. T., & Larimer, M. E. (2022). Brief alcohol interventions are effective through 6 months: Findings from marginalized zero-inflated Poisson and negative binomial models in a two-step IPD meta-analysis. Prevention Science. https://doi.org/10.1007/s11121-022-01420-1 Abstract To evaluate and optimize brief alcohol interventions (BAIs), it is critical to have a credible overall effect size estimate as a benchmark. Estimating such an effect size has been challenging because alcohol outcomes often represent responses from a mixture of individuals: those at high-risk for alcohol misuse, occasional non-drinkers, and abstainers. Moreover, some interventions exclusively focus on heavy drinkers, whereas others provide universal coverage. Depending on sample characteristics, the outcome distribution might have zero inflation or very few zeros and overdispersion; consequently, the most appropriate statistical model may differ by study. We used individual participant data (IPD) from Project INTEGRATE (Mun, de la Torre, et al., 2015) that randomly allocated participants to intervention and control groups (19 studies for N = 7,704 participants, 38.4% men, 74.7% White, 58.5% first-year students). We sequentially estimated the marginalized zero-inflated Poisson (Long et al., 2014) or negative binomial regression models to obtain covariate-adjusted, study-specific intervention effect estimates in the first step, which were subsequently combined in a random-effects meta-analysis model in the second step. BAIs produced a statistically significant 8% advantage in the mean number of drinks at both 1-3 months (95% CI = [0.02, 0.15]) and 6 months (95% CI = [0.01, 0.15]) compared to controls. At 9-12 months, there was no statistically significant difference in the mean number of drinks between BAIs and controls. In conclusion, BAIs are effective through at least 6 months post-intervention. IPD can play a critical role in deriving findings that could not be obtained in original individual studies or standard meta-analyses that use aggregate data.
Steps to reproduce
Steps to follow: 1) Download the following files: "IPD_Proj_INTEGRATE_PS.R" (required R code) and “dat_all_PS.csv" (required data). 2) Run “IPD_Proj_INTEGRATE_PS.R" in R to replicate the analysis. It is necessary to install the following R packages: "VGAM", "metafor", "MASS", and "mcount". All necessary instructions are included.