Figure 2. Adjusted odds of ED revisit by days from index ED visit.
A discrete time failure model was used to estimate the odds of revisit over the 180 days following the index visit. Time periods were categorized as follows: days 1–2, 3–5, 6–7, 8–14, 15–60, and 61–180. This model is adjusted for patient-level covariates (age, sex, race, insurance status, urban/rural residence, and history of nephrolithiasis), hospital-level covariates (bed number, teaching status, and designation as a children’s hospital) and geographic-level covariates (pediatrician and urologist density defined at the county level).