Statistical Analysis
SECONDARY
We examined the likelihood of patients starting dialysis in the home setting during each month from January 1, 2016, to June 30, 2022, according to HRR ETC assignment, which was obtained from the CMS database.We examined differences in home dialysis initiation between ETC and non-ETC markets before and after January 1, 2021, and whether the difference between ETC and non-ETC markets changed (by adding a term for the interaction between pre-post implementation of ETC and ETC assignment to the model). We then included the 3-way interaction of time, ETC assignment, and pre-post implementation in the initial model to examine whether any changes in use trends after ETC onset differed by ETC assignment. We sequentially removed nonsignificant interaction terms at a significance level of .05. The final model included the interaction of ETC assignment and pre-post implementation and the interaction of time and pre-post implementation.Although our primary hypothesis was that implementation of ETC was associated with an increase in home dialysis initiation in the entire incident dialysis population, we also examined whether the association varied by Medicare FFS coverage. We repeated our modeling strategy including 2-, 3-, and 4-way interactions between Medicare FFS coverage and time, ETC assignment and pre- or post-January 2021, and then removing statistically nonsignificant interaction terms. Significant interaction terms included FFS × time × pre-post January 2021, FFS × pre-post January 2021, time × pre-post January 2021, and ETC assignment × pre-post January 2021. Stratified analyses by Medicare FFS coverage status was then performed by fitting separate models.In a sensitivity analyses, we performed the same modeling strategy excluding 2020 data from the models and using September 2020 as the ETC starting point to capture anticipatory outcomes. Our primary analysis did not include covariates, but in an additional secondary analysis, we adjusted for age (18-44, 45-64, 65-74, and ≥75 years), race and ethnicity (Asian, Black, Hispanic, non-Hispanic White, or other [Native American and Alaskan Native, Hawaiian, and Other Pacific Islander, other/multiracial, and unknown]), insurance type (Medicare FFS or other), and rural or urban residence (urban, large rural city/town, small rural town, and isolated small rural town) using data from Form CMS 2728. We adjusted for race and ethnicity and because of known differences in the use of home dialysis across race and ethnicity groups.We used SAS, version 9.4 (SAS Institute Inc) for all analyses. Results were considered statistically significant if 2-sided 