title: Patient characteristics associated with medication adherence.
abstract: OBJECTIVE
  Despite evidence indicating therapeutic benefit for adhering to a prescribed regimen, many patients do not take their medications as prescribed. Non-adherence often leads to morbidity and to higher health care costs. The objective of the study was to assess patient characteristics associated with medication adherence across eight diseases.
  
  
  METHODS
  Retrospective data from a repository within an integrated health system was used to identify patients ≥18 years of age with ICD-9-CM codes for primary or secondary diagnoses for any of eight conditions (depression, hypertension, hyperlipidemia, diabetes, asthma or chronic obstructive pulmonary disease, multiple sclerosis, cancer, or osteoporosis). Electronic pharmacy data was then obtained for 128 medications used for treatment.
  
  
  METHODS
  Medication possession ratios (MPR) were calculated for those with one condition and one drug (n=15,334) and then for the total population having any of the eight diseases (n=31,636). The proportion of patients adherent (MPR ≥80%) was summarized by patient and living-area (census) characteristics. Bivariate associations between drug adherence and patient characteristics (age, sex, race, education, and comorbidity) were tested using contingency tables and chi-square tests. Logistic regression analysis examined predictors of adherence from patient and living area characteristics.
  
  
  RESULTS
  Medication adherence for those with one condition was higher in males, Caucasians, older patients, and those living in areas with higher education rates and higher income. In the total population, adherence increased with lower comorbidity and increased number of medications. Substantial variation in adherence was found by condition with the lowest adherence for diabetes (51%) and asthma (33%).
  
  
  CONCLUSIONS
  The expectation of high adherence due to a covered pharmacy benefit, and to enhanced medication access did not hold. Differences in medication adherence were found across condition and by patient characteristics. Great room for improvement remains, specifically for diabetes and asthma.
authors.affiliation: HealthPartners Research Foundation; 8170 33rd Ave. S.; MS 21111R; Bloomington, MN 55425, USA. Cheri.J.Rolnick@healthpartners.com
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Rolnick
authors.forename: Pamala A
authors.initials: PA
authors.lastname: Pawloski
authors.forename: Brita D
authors.initials: BD
authors.lastname: Hedblom
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Asche
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bruzek
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000188:drug therapy* / Q000208:ethnology; D015897:Comorbidity; D003863:Depression / Q000188:drug therapy* / Q000208:ethnology; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000208:ethnology; D004522:Educational Status; D005260:Female; D006801:Humans; D006949:Hyperlipidemias / Q000188:drug therapy / Q000208:ethnology; D006973:Hypertension / Q000188:drug therapy / Q000208:ethnology; D008297:Male; D055118:Medication Adherence / Q000208:ethnology; D008875:Middle Aged; D010349:Patient Compliance / Q000208:ethnology / Q000706:statistics & numerical data*; D044469:Racial Groups / Q000208:ethnology / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012737:Sex Factors; D055815:Young Adult; D016903:Drug Monitoring
keywords: Medication Adherence; Patient Compliance; Pharmacy Benefits