Predictors of Use of Monitored Anesthesia Care for Outpatient Gastrointestinal Endoscopy in a Capitated Payment System

Abstract

Background & aims: Use of monitored anesthesia care (MAC) for gastrointestinal endoscopy has increased in the Veterans Health Administration (VHA) as in fee-for-service environments, despite the absence of financial incentives. We investigated factors associated with use of MAC in an integrated health care delivery system with a capitated payment model.

Methods: We performed a retrospective cohort study using multilevel logistic regression, with MAC use modeled as a function of procedure year, patient- and provider-level factors, and facility effects. We collected data from 2,091,590 veterans who underwent outpatient esophagogastroduodenoscopy and/or colonoscopy during fiscal years 2000-2013 at 133 facilities.

Results: The adjusted rate of MAC use in the VHA increased 17% per year (odds ratio for increase, 1.17; 95% confidence interval, 1.09-1.27) from fiscal year 2000 through 2013. The most rapid increase occurred starting in 2011. VHA use of MAC was associated with patient-level factors that included obesity, obstructive sleep apnea, higher comorbidity, and use of prescription opioids and/or benzodiazepines, although the magnitude of these effects was small. Provider-level and facility factors were also associated with use of MAC, although again the magnitude of these associations was small. Unmeasured facility-level effects had the greatest effect on the trend of MAC use.

Conclusions: In a retrospective study of veterans who underwent outpatient esophagogastroduodenoscopy and/or colonoscopy from fiscal year 2000 through 2013, we found that even in a capitated system, patient factors are only weakly associated with use of MAC. Facility-level effects are the most prominent factor influencing increasing use of MAC. Future studies should focus on better defining the role of MAC and facility and organizational factors that affect choice of endoscopic sedation. It will also be important to align resources and incentives to promote appropriate allocation of MAC based on clinically meaningful patient factors.

Keywords: Gastrointestinal Endoscopy; Monitored Anesthesia Care; Sedation; Veterans.

Figure 1. Predicted probability of MAC use over time as a function of Charlson-Deyo comorbidity index score: spline analysis

In the early years of the study period (FY 2000–2005), there was no difference in the predicted probability of MAC use between patients of different comorbidity levels. However, starting in approximately 2011, higher comorbidity patients became slightly more likely to receive MAC than lower comorbidity patients, demonstrating an interaction between comorbidity and time. In addition, spline analysis demonstrated a marked increase in MAC use starting in FY 2011.

Figure 2. Explanation of trend in MAC use by type of analysis

Model 1 (blue squares) includes time predictors while not accounting for person, physician, or facility-level influences and shows a nonlinear change over time. Model 2 (red circles) includes a time predictor and facility-level effects; adjusting for facility differences greatly attenuates the predicted trend in MAC use indicating that facility-specific influences explain much of the trend. Model 3 (green triangles) is fully specified and includes time, facility-level effects, and all other measured predictors (facility, provider, and patient). Most of the variability in MAC use trend can be explained by unmeasured facility-level influences.