(1001) Assessing the Impact of a Health-system Specialty Pharmacy on Risk of Nonadherence to Anti-tumor Necrosis Factor Drugs: A Retrospective Cohort Study

Objectives: The primary objective of this study was to assess the risk of medication nonadherence in rheumatoid arthritis (RA) patients taking anti-tumor necrosis factor (anti-TNF) medications at a health-system specialty pharmacy (HSSP) in comparison with a national cohort. Specialty pharmacies manage patients on high-risk medications used in the treatment of complex disease states; additional monitoring and frequent follow-up is necessary for successful management of these patients. Medication nonadherence can lead to hospitalization and other poor health outcomes, particularly for patients treated with specialty medications like anti-TNF drugs. Data has shown that integrated health-system specialty pharmacies have provided value in helping patients achieve medication adherence and persistence. While prior descriptive data have signaled possible improved adherence to anti-TNF drugs at this HSSP in comparison to national figures, there exists a need to expand upon these limited results with more rigorous methodologies utilized in this study. At the studied HSSP, a highly trained team of clinical pharmacists manage patients with RA on anti-TNF medications through provision of medication counseling, adherence support, and clinical assessments. This study sought to assess the impact of these additional specialty pharmacy services on patients’ adherence to anti-TNF therapy.

Methods: This retrospective cohort study identified RA patients initiating self-administered anti-TNF therapy from this HSSP’s electronic medical record and compared them to a similar group of patients identified from the IBM MarketScan Research databases. Subjects with an RA diagnosis, initiating self-administered anti-TNF therapy (adalimumab, certolizumab, etanercept, golimumab) between June 30, 2016 and June 30, 2019, and with available follow-up data for at least one year were included. Subjects less than 18 years of age at anti-TNF initiation, or with diagnosis of comorbid inflammatory conditions were excluded. Subject prescription dispensing records were used to calculate PDC and assess the primary outcome of patient adherence. Differences in the risk of nonadherence between cohorts were assessed utilizing a multivariable logistic regression model with a backwards elimination variable selection methodology. Baseline demographics, diagnoses, and prior anti-inflammatory medication exposure were all considered as model inputs. Secondary outcomes, including medication persistence, steroid utilization, and all-cause ED visits and hospitalizations were also collected.

Results: A total of 184 subjects in the HSSP group and 2,454 in the national sample met study inclusion criteria for assessing PDC. With the exception of osteoarthritis and fibromyalgia (both of which were more prevalent among the HSSP group), demographic factors and preexisting conditions were similar between the two groups. Of HSSP subjects, 147 (80.8%) were found to be adherent to their anti-TNF medication compared to 1,814 subjects (73.9%) in the national sample (p=0.0411). Multivariable logistic regression analysis showed that, when adjusting for significant covariates (age, index anti-TNF exposure, and pre-index anti-TNF exposure), the HSSP was associated with a 39% reduction in adjusted odds of medication nonadherence compared to the national cohort [aOR 0.61 (95% CI: 0.42, 0.90)]. No significant differences were seen between groups in mean outpatient steroid prescriptions and mean prednisone milligram equivalents; however, mean steroid injections and joint replacement procedures in the HSSP were significantly lower than the national sample (p < 0.0001 and p=0.0351, respectively). The HSSP group also saw significantly lower mean all-cause ED visits (p=0.0286).

Conclusions: Findings are suggestive that the HSSP was associated with significantly higher levels of adherence to anti-TNF therapy compared to the national sample. This study demonstrates the potential advantage of HSSP involvement in patient care delivery. Further research is needed in assessing patient adherence long term as well as other patient health outcomes at HSSPs compared to other specialty pharmacies as it relates to specialty pharmacy medications and patient care delivery.