Methods for additional analyses (e.g., subgroup analyses) {20b}
SECONDARY
In secondary analyses, the effects of clinic-level covariates (e.g., volume, rurality, organizational culture) and patient-level covariates (e.g., age, sex, race/ethnicity) on implementation and effectiveness outcomes will be assessed. Implementation approach-by-covariate interactions will be included in the mixed models described above to determine if the effect of the implementation strategy differs depending on levels of the covariates. Using mixed models allows us to incorporate participant- and cluster-level covariates, but there are other analysis methods that could be employed. For example, a clinic-level analysis (e.g., analysis of covariance) on the mean implementation rates within each clinic, or another individual-level approach (e.g., generalized estimating equations) could be used. Alternative methods and their strengths and weaknesses are well-documented [