title: Patient-Centered Medical Home Implementation in the Veterans Health Administration and Primary Care Use: Differences by Patient Comorbidity Burden.
abstract: The patient-centered medical home (PCMH) model has several components to improve care for patients with high comorbidity, including greater access to face-to-face primary care.
  
  
  
  We examined whether high-comorbidity patients had larger increases in primary care provider (PCP) visits attributable to PCMH implementation in a large integrated health system relative to other patients enrolled in primary care.
  
  
  
  This longitudinal study examined a 1 % random sample of 9.3 million patients enrolled in the Veterans Health Administration (VHA) at any time between 2003 and 2013. Face-to-face visits with PCPs per quarter were identified through VHA administrative data. Comorbidity was measured using the Gagne index and patients with a weighted score of ≥ 2 were defined as high comorbidity. We applied interrupted time-series models to estimate marginal changes in PCP visits attributable to PCMH implementation. Differences in marginal changes were calculated across comorbidity groups (high vs. low). Analyses were stratified by age group to account for Medicare eligibility.
  
  
  
  Among age 65+ patients, PCMH was associated with greater PCP visits starting four and ten quarters following implementation for high- and low-comorbidity patients, respectively. Changes were larger for high-comorbidity patients (eight to 11 greater visits per 1000 patients per quarter). Among patients age < 65, PCMH was associated with greater visits for high-comorbidity patients starting eight quarters following implementation, but fewer visits for low-comorbidity patients in all quarters. The difference in visit changes across groups ranged from 18 to 67 visits per 1000 patients per quarter.
  
  
  
  Increases in PCP visits attributable to PCMH were greater among patients with higher comorbidity. Health systems implementing PCMH should account for population-level comorbidity burden when planning for PCMH-related changes in PCP utilization.
authors: VA Puget Sound Health Care System, Center for Veteran-Centered and Value-Driven Care, 1660 S. Columbian Way, MS S-152, Seattle, WA, 98108, USA. edwin.wong@va.gov.|Department of Health Services, University of Washington, Seattle, WA, USA. edwin.wong@va.gov.
authors: Edwin S
authors: ES
authors: Wong
authors: Center for Clinical Management Research, VHA Ann Arbor Healthcare System, Ann Arbor, MI, USA.|Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.
authors: Ann-Marie
authors: AM
authors: Rosland
authors: Office of Analytics and Business Intelligence, Veterans Health Administration, Seattle, WA, USA.
authors: Stephan D
authors: SD
authors: Fihn
authors: VA Puget Sound Health Care System, Center for Veteran-Centered and Value-Driven Care, 1660 S. Columbian Way, MS S-152, Seattle, WA, 98108, USA.|Department of Health Services, University of Washington, Seattle, WA, USA.|Department of Medicine, University of Washington, Seattle, WA, USA.
authors: Karin M
authors: KM
authors: Nelson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D017281:Cost of Illness; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018802:Patient-Centered Care / Q000379:methods* / Q000706:statistics & numerical data* / Q000639:trends; D011320:Primary Health Care / Q000379:methods* / Q000706:statistics & numerical data* / Q000639:trends; D014481:United States / Q000453:epidemiology; D014493:United States Department of Veterans Affairs / Q000639:trends
keywords: multiple chronic conditions; patient-centered medical home; primary care; utilization