title: Reach and Validity of an Objective Medication Adherence Measure Among Safety Net Health Plan Members with Diabetes: A Cross-Sectional Study.
abstract: BACKGROUND
  With the expansion of Medicaid and low-cost health insurance plans among diverse patient populations, objective measures of medication adherence using pharmacy claims could advance clinical care and translational research for safety net care. However, safety net patients may experience fluctuating prescription drug coverage, affecting the performance of adherence measures.
  
  
  OBJECTIVE
  To evaluate the performance of continuous medication gap (CMG) for diverse, low-income managed care members with diabetes.
  
  
  METHODS
  We conducted this cross-sectional analysis using administrative and clinical data for 680 members eligible for a self-management support trial at a nonprofit, government-sponsored managed care plan. We applied CMG methodology to cardiometabolic medication claims for English- , Cantonese- , or Spanish-speaking members with diabetes. We examined inclusiveness (the proportion with calculable CMG) and selectivity (sociodemographic and medical differences from members without CMG). For validity, we examined unadjusted associations of suboptimal adherence (CMG >  20%) with suboptimal cardiometabolic control.
  
  
  RESULTS
  429 members (63%) had calculable CMG. Compared with members without CMG, members with CMG were younger, more likely employed, and had poorer glycemic control but had better blood pressure and lipid control. Suboptimal adherence occurred more frequently among members with poor cardiometabolic control than among members with optimal control (28% vs. 12%, P = 0.02).
  
  
  CONCLUSIONS
  CMG demonstrated acceptable inclusiveness and validity in a diverse, low-income safety net population, comparable with its performance in studies among other insured populations. CMG may provide a useful tool to measure adherence among increasingly diverse Medicaid populations, complemented by other strategies to reach those not captured by CMG.
authors.affiliation: UCSF Center for Vulnerable Populations at San Francisco General Hospital and Trauma Center, 1001 Potrero Ave., Box 1364, San Francisco CA 94110. neda.ratanawongsa@ucsf.edu.
authors.forename: Neda
authors.initials: N
authors.lastname: Ratanawongsa
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Karter
authors.forename: Judy
authors.initials: J
authors.lastname: Quan
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Parker
authors.forename: Margaret
authors.initials: M
authors.lastname: Handley
authors.forename: Urmimala
authors.initials: U
authors.lastname: Sarkar
authors.forename: Julie A
authors.initials: JA
authors.lastname: Schmittdiel
authors.forename: Dean
authors.initials: D
authors.lastname: Schillinger
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000175:diagnosis / Q000188:drug therapy* / Q000208:ethnology; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008484:Medicaid; D055118:Medication Adherence; D008875:Middle Aged; D011203:Poverty; D064876:Safety-net Providers; D014481:United States / Q000453:epidemiology
chemical_list: D007004:Hypoglycemic Agents