Figure 1.

Diagram of study exposures and end points. Preoperative opioid use was identified among patients with at least one opioid prescription fill occurring within each of 1–30 days and 31–90 days before the date of admission. For example, opioid use during the week before surgery with no accompanying prescription fill in the 31–90 days before surgery does not meet the definition of preoperative opioid use. Preoperative spending and preoperative conditions were captured in 31–365 days and 18 months before admission, respectively. Length of stay and in-hospital spending occur between admission and discharge dates. After discharge, postoperative spending is measured up to 90, 180, and 365 days. Other outcomes include 30-day readmission, 90-day surgical site infection (SSI), 18-month surgical revision (SR), 18-month opioid cessation, and nonhome discharge (not pictured). The gray rectangle gives the minimum continuous eligibility requirement (six months before admission and 18 months after discharge); nearly the entire cohort (99.6%) also had continuous eligibility 18 months before admission, although this was not an inclusion criterion.