Discussion
In this study of an ongoing SWD trial to evaluate an intervention to reduce sexual risk behavior among Assiniboine and Sioux youths, we found evidence of a secular trend occurring in relation to the COVID-19 pandemic period. Results have direct implications for informing future analyses at trial end, particularly the need for sensitivity analyses to determine whether clusters affected by the pandemic during the intervention period showed differential outcomes in comparison to clusters that received the intervention outside of the pandemic period.First, we report quantitative and qualitative evidence suggesting the existence of a secular trend. The first cluster exposed to the intervention experienced school closures, social distancing, and sheltering-in-place orders between the finalization of the intervention and the 3-month post-intervention measurement period. Furthermore, individuals reporting having sex with less people due to COVID-19 reported an appreciably greater number of sex acts in comparison to those who did not report having sex with less people. Taken together, the results of this analysis suggest that more sexually active individuals reported perceiving having sex with less people and less frequent engagement in sex during the pandemic. This occurred between intervention completion and the first follow-up measurement. Qualitative evidence shows that youth continued to find ways to engage in sex despite the mitigation measures, which may have slightly decreased cumulative sexual activity during the trial. It is likely that the COVID-19 pandemic period was associated with a truncation in the distribution of otherwise normal sexual activity that would have occurred despite the existence of the intervention. While this could not be tested over time, cross-sectional evidence suggests it may be a possibility. Not accounting for this association might otherwise artificially inflate an estimate of the intervention’s effect at trial end. These findings will be informative to the specification of secular trends through sensitivity analyses that will be conducted at trial end and will also be informative toward the emerging discourse regarding scientific trials conducted in the context of CBPR with Indigenous communities.Second, our results inform an understanding of internal validity regarding the use of cluster-randomized trials implemented in community settings during the pandemic. In SWD trials, clusters (as opposed to individuals) are the unit of randomization [Finally, a large amount of attrition was observed in the first cluster randomized to the intervention. Indeed, it was logistically difficult to perform post-intervention follow-up observations with youth during the sheltering-in-place orders, changes in education delivery from in-school to remote based on parental requests, and school closures. However, attrition patterns did not vary from what might be otherwise a logical pathway to attrition (aging and/or graduating out of what would constitute membership in a cluster). Our current plans to address attrition include developing propensity scores for missing data at follow-up in a given observation period, matching cases, and repeating an imputation sequence for the models of interest [