Longitudinal medication adherence group-based trajectories of aging adults in the US: A retrospective analysis using monthly proportion of days covered calculations.

BACKGROUND: It is thought that half of the patients with chronic conditions are not adherent to their medications, which contributes to significant health and economic burden. Many studies estimate medication non-adherence by implementing a threshold of ≥80% of Proportion of Days Covered (PDC), categorizing patients as either adherent or non-adherent. Healthcare quality metrics pertaining to medication use are based on this dichotomous approach of medication adherence, including the Medicare Part D Star Ratings. Among others, the Medicare Part D Star Ratings rewards part D plan sponsors with quality bonus payments based on this dichotomous categorization of beneficiaries' medication adherence. OBJECTIVES: Describe the longitudinal adherence trajectories of adults ≥65 years of age covered by Medicare for 3 classes of drugs in the Part D Star Ratings: diabetes medications, statins, and select antihypertensives. METHODS: This study used Medicare healthcare administrative claims data linked to participants from the Health Retirement Study between 2008 and 2016. Group-based trajectory models (GBTM) elicited the number and shape of adherence trajectories from a sample of N = 11,068 participants for the three pharmacotherapeutic classes considered in this study. Medication adherence was estimated using monthly PDC. RESULTS: GBTM were estimated for the sample population taking antihypertensives (n = 7,272), statins (n = 8,221), and diabetes medications (n = 3,214). The hypertension model found three trajectories: high to very high adherence (47.55%), slow decline (32.99%), and rapid decline (19.47%) trajectories. The statins model found 5 trajectories: high to very high adherence (35.49%), slow decline (17.12%), low then increasing adherence (23.58%), moderate decline (12.62%), and rapid decline (11.20%). The diabetes medications model displayed 6 trajectories: high to very high adherence (24.15%), slow decline (16.84%), high then increasing adherence (25.56%), low then increasing (13.58%), moderate decline (10.60%), and rapid decline (9.27%). CONCLUSIONS: This study showed the fluid nature of long-term medication adherence to the medications considered in the Medicare Part D Star Ratings and how it varies by pharmacotherapeutic class. These challenge previous assumptions about which patients were considered adherent to chronic medications. Policy and methodological implications about medication adherence are discussed.

Economic burden of renal cell carcinoma among older adults in the targeted therapy era.

OBJECTIVE: This study examined the economic burden of renal cell carcinoma (RCC) among older adults. The study also examined healthcare costs by types of resources used and stage at which RCC was diagnosed. METHODS: The study analyzed the Surveillance Epidemiology and End Result-Medicare linked data. We included a prevalent cohort of RCC patients from 2013, diagnosed and continuously enrolled in Medicare from 2005 to 2013. RCC patients were matched to controls selected from a 5% sample of noncancer beneficiaries using propensity score matching to calculate incremental costs. Total healthcare costs (THC) were calculated using a phase-based approach, which classified patients into early, continuing, and late phases of care. Costs were also examined by types of resources used and stage at which RCC was diagnosed. Generalized linear models estimated annual incremental costs per patient. The number of older RCC patients was calculated using SEER-Stat and ProjPrev software. The average incremental THC was multiplied by the estimated number of RCC patients to calculate the total economic burden of RCC among older adults. RESULTS: The study included 10,392 each of RCC and control patients. The average annual THC associated with RCC was $7,419 for all phases, $22,752 for the initial phase, $4,860 for the continuing phase, and $13,232 for the late phase of care. The average THC was $4,584 for patients diagnosed at stage I, $4,727 for stage II, $9,331 for stage III, and $31,637 for stage IV. For patients diagnosed at stages I to III, hospital cost (approximately $1,500-$3,400) was the largest component of THC. For stage IV patients, prescription drug cost ($11,747) was the largest component of THC. The projected number of older RCC patients in 2015 was 204,256. The annual economic burden of RCC after weighting for proportion of patients diagnosed at various stages was estimated to be $2.1 billion. CONCLUSIONS: RCC was associated with a significant economic burden on Medicare. Healthcare costs associated with RCC varied substantially between early stage and metastatic patients. This research provided a baseline that can be used to assess the economic value of emerging therapies among older RCC patients.