Association of Team-Based Primary Care With Health Care Utilization and Costs Among Chronically Ill Patients.

Importance: Empirical study findings to date are mixed on the association between team-based primary care initiatives and health care use and costs for Medicaid and commercially insured patients, especially those with multiple chronic conditions. Objective: To evaluate the association of establishing team-based primary care with patient health care use and costs. Design, Setting, and Participants: We used difference-in-differences to compare preutilization and postutilization rates between intervention and comparison practices with inverse probability weighting to balance observable differences. We fit a linear model using generalized estimating equations to adjust for clustering at 18 academically affiliated primary care practices in the Boston, Massachusetts, area between 2011 and 2015. The study included 83 953 patients accounting for 138 113 patient-years across 18 intervention practices and 238 455 patients accounting for 401 573 patient-years across 76 comparison practices. Data were analyzed between April and August 2018. Exposures: Practices participated in a 4-year learning collaborative that created and supported team-based primary care. Main Outcomes and Measures: Outpatient visits, hospitalizations, emergency department visits, ambulatory care-sensitive hospitalizations, ambulatory care-sensitive emergency department visits, and total costs of care. Results: Of 322 408 participants, 176 259 (54.7%) were female; 64 030 (19.9%) were younger than 18 years and 258 378 (80.1%) were age 19 to 64 years. Intervention practices had fewer participants, with 2 or more chronic conditions (n = 51 155 [37.0%] vs n = 186 954 [46.6%]), more participants younger than 18 years (n = 337 931 [27.5%] vs n = 74 691 [18.6%]), higher Medicaid enrollment (n = 39 541 [28.6%] vs n = 81 417 [20.3%]), and similar sex distributions (75 023 women [54.4%] vs 220 097 women [54.8%]); however, after inverse probability weighting, observable patient characteristics were well balanced. Intervention practices had higher utilization in the preperiod. Patients in intervention practices experienced a 7.4% increase in annual outpatient visits relative to baseline (95% CI, 3.5%-11.3%; P < .001) after adjusting for patient age, sex, comorbidity, zip code level sociodemographic characteristics, clinician characteristics, and plan fixed effects. In a subsample of patients with 2 or more chronic conditions, there was a statistically significant 18.6% reduction in hospitalizations (95% CI, 1.5%-33.0%; P = .03), 25.2% reduction in emergency department visits (95% CI, 6.6%-44.0%; P = .007), and a 36.7% reduction in ambulatory care-sensitive emergency department visits (95% CI, 9.2%-64.0%; P = .009). Among patients with less than 2 comorbidities, there was an increase in outpatient visits (9.2%; 95% CI, 5.10%-13.10%; P < .001), hospitalizations (36.2%; 95% CI, 12.2-566.6; P = .003), and ambulatory care-sensitive hospitalizations (50.6%; 95% CI, 7.1%-329.2%; P = .02). Conclusions and Relevance: While establishing team-based care was not associated with differences in the full patient sample, there were substantial reductions in utilization among a subset of chronically ill patients. Team-based care practice transformation in primary care settings may be a valuable tool in improving the care of sicker patients, thereby reducing avoidable use; however, it may lead to greater use among healthier patients.