Comparison of rates of adherence to oral chemotherapy medications filled through an internal health-system specialty pharmacy vs external specialty pharmacies

Am J Health Syst Pharm. 2020 Jul 7;77(14):1118-1127. doi: 10.1093/ajhp/zxaa135.


Purpose: The primary objective of the study described here was to compare rates of patient adherence to anticancer medications filled at an internal health system specialty pharmacy (HSSP) vs external specialty pharmacies. The primary outcome was the medication possession ratio (MPR), and the secondary outcomes included proportion of days covered (PDC), and time to treatment (TTT).

Methods: A retrospective chart review was conducted to compare the MPR, PDC, and TTT for patients who received oral anticancer therapy using prescriptions claim data. A t test or Wilcoxon test was used to explore the effect of demographic and other factors on adherence and TTT. A multiple regression model with backward elimination was used to analyze significant factors to identify covariates significantly associated with the outcomes.

Results: Of the 300 patients screened for study inclusion, 204 patients whose records had complete MPR and PDC data and 164 whose records had TTT data were included in the analysis. There were significant between-group differences in mean MPR and mean PDC with patient use of the HSSP vs external pharmacies (1.00 vs 0.75 [P < 0.001] and 0.95 vs 0.7 [P < 0.001], respectively). Pharmacy type (P = 0.024) and tumor type (P = 0.048) were significantly associated with TTT.

Conclusion: The multiple regression analysis indicated that oncology patients who filled their anticancer medication precriptions at an internal HSSP at an academic medical center had significantly higher adherence, as measured by MPR and PDC, and quicker TTT than those who filled their prescriptions at an external specialty pharmacy.

Keywords: adherence metrics; medication possess ratio; oral anticancer medications; oral chemotherapy; proportion of days covered; specialty pharmacy; time to treatment.

Publication types

  • Comparative Study

MeSH terms

  • Administration, Oral
  • Aged
  • Antineoplastic Agents / administration & dosage*
  • Cohort Studies
  • Female
  • Humans
  • Male
  • Medication Adherence / statistics & numerical data*
  • Neoplasms / drug therapy
  • Pharmaceutical Services / organization & administration*
  • Pharmacy Service, Hospital / organization & administration*
  • Retrospective Studies
  • Specialization
  • Time-to-Treatment / statistics & numerical data


  • Antineoplastic Agents