Discussion
This study evaluated the effectiveness of APMaT, a workplace-based alcohol prevention program, by examining changes in hazardous alcohol use among employees. A larger decrease in hazardous alcohol use among employees in the intervention group was detected. However, this difference was not statistically significant. Similar results were observed after adjusting the association for sociodemographic characteristics, in line with previous literature [In our previous evaluation of APMaT, we found effects of the intervention on managers’ inclination to intervene [In order to identify possible reasons for the non-significant findings, we conducted a series of additional analyses. We did not detect any major differences in our additional analyses (presented in the supplementary materials) compared to our primary analyses; however, some insights into the factors that could have influenced our findings arose. Firstly, we could not detect any moderation effect of policy awareness on changes in hazardous alcohol use (Table S2). This made it difficult to understand whether and/or how the intervention was implemented at the highest level of the organizations (i.e. managerial level). Here, we can only speculate that our estimates were due to insufficient program implementation rather than other contextual factors, such as being informed of the workplace participation in KAPRI, or previous experiences regarding alcohol-related issues in the workplace. Such factors, although beyond the scope of the current study, could have influenced our findings. For instance, some organizations may be more engaged in APMaT because of their previous experiences of alcohol-related issues in the workplace. The engagement towards the intervention could therefore influence employees’ attitudes towards alcohol, and possibly their behaviors, which could consequently, bias the intervention’s effects on alcohol use.Secondly, our stratified analyses by sex (Table S3) and age (Table S4) did not show any statistically significant differences in terms of the intervention effects on hazardous alcohol use. This was somewhat surprising, given that findings from previous literature showed that females tend to have lower alcohol use compared to their male peers [Thirdly, the intervention effect on alcohol use was unlikely to be influenced by the dichotomization of the total AUDIT score, as the estimates of alcohol use as a linear outcome did not change the overall findings of this study (Table S5). The skewed distribution of the total AUDIT scores in our initial analysis determined that setting the cut-off of abstention/low-risk and hazardous alcohol use based on the Swedish recommendation would provide a better overview regarding the importance of early interventions within the Swedish workplace context.Fourthly, the large loss to follow-up could be attributed to some difficulties when distributing the survey. We found that the survey that was distributed via general link through the organization’s internal website had the highest attrition compared to the survey that was distributed through e-mail. We re-examined our primary analyses; however, we could not detect any significant differences in the intervention effects on alcohol use with a larger sample size (Tables S6 and S7).Some strengths and limitations of the current study were identified. First, hazardous alcohol use was measured using a scale validated by the WHO, making the results of this study comparable to other research on the topic. Second, randomization ensured that the differences between the control and intervention groups at the organizational level were small, which minimized the risk of selection bias [This study was limited by the distal outcome of interest to the intervention components, particularly within the current follow-up time. The one-year follow-up period constitutes quite a sparse grid that might miss capturing short-term changes. It is possible that hazardous alcohol use was not an ideal outcome since the implied level of severity could require more comprehensive types of interventions (spanning more domains than work-life) and changes might take a longer time. Moreover, the survey design may have influenced the findings. The self-administered survey may lead to social desirability bias since employees may underestimate their alcohol use or overestimate their policy awareness. It is possible that responding to the survey in and of itself led to increased awareness among respondents regarding their alcohol use rather than their policy awareness. In addition, it was not possible to distinguish hazardous alcohol use within and beyond the workplace due to data availability. The data regarding other potential indicators of alcohol use to understand employees’ attitudes towards alcohol, experiences of alcohol-related harms, and general workplace culture surrounding alcohol was not available—something that could explain current study findings in understanding the influence of factors outside of the workplace on alcohol use. Finally, one of the major limitations was the fact that the study population was smaller than originally planned largely due to a low response rate at baseline and loss to follow-up, which limited the ability to detect the previously hypothesized effect size. In the current study, a post-hoc power analysis of the crude model showed that a sample size of at least 1,255 employees would have been required to achieve 80% power at an alpha level of 0.05, something that could not be achieved due to the loss of follow-up and internal missing values of the outcome measures. Since the power of the current study was lower than expected, this could explain the study findings. The discrepancy between the total number of participants between the control and intervention groups was largely due to organizational dropout after randomization and a large proportion of loss to follow-up. As such, this may bias the intervention effect, resulting in a decrease in the generalizability of the current findings. Nevertheless, in the additional analyses, where the larger sample size was obtained using the maximum likelihood approach, the overall conclusions did not change.