Strengths and Limitations
waitlisting
SENSITIVITY
This study has strengths and limitations. Inclusion of the whole dialysis population in the US and availability of data through the first half of 2022 are strengths. However, limitations related to study design choices deserve comment. We chose the start of ETC implementation as the point of change in our interrupted time series analysis, but ETC assignments were announced in September 2020, and facilities and professionals providing nephrology services may have begun to react in the quarter before this. Sensitivity analysis starting using September 2020 as the start of ETC implementation may support this possibility as there was a statistically significantly larger increase in the rate of increase in home dialysis use after ETC implementation in ETC markets than in non-ETC markets in this analysis. Although the nephrology group practice (and individual nephrologists) are potential sources of correlation among patients, we were not able to cluster at the nephrology clinician level. However, misspecification of the working correlation structure should have little impact on the results of our generalized estimating equation models when the sample size is large, as it is in this study. Our study did not include outcomes among patients undergoing dialysis at home and did not examine transplant waitlisting—another outcome incentivized in the ETC model. Although it will be extremely important to examine outcomes such as the duration of home dialysis therapy, these data will require more time to accrue. Despite these limitations, our study provides an early look at one of the key outcomes of ETC.