Medication (Re)fill Adherence Measures Derived from Pharmacy Claims Data in Older Americans: A Review of the Literature

Abstract

Medication nonadherence is a significant public health problem that affects the health and well-being of older Americans while burdening the US healthcare system. Pharmacy claims data have gained importance in deriving objective medication (re)fill adherence measures; however, little is known about application of such measures in older Americans. The objective of this study was to assess the types and characteristics of pharmacy claims-derived medication (re)fill adherence measures used in older Americans. A comprehensive literature search strategy was employed to identify all articles using pharmacy claims data to measure (re)fill adherence to prescription medications in older Americans aged 65+ years. Included were articles reporting original research studies conducted and published in the USA in English between 1 January 2000 and 1 November 2012. The basic search used multiple key terms indicating adherence, combined with the term "medication" and the term "pharmacy claims or administrative claims." Due to the variety of measure names used in the literature, a more specific search was added to repeat the basic search for 29 previously used medication (re)fill adherence measure names. Articles identified through the database search were manually reviewed to select only articles meeting the inclusion criteria. The search resulted in a total of 36 articles. Information on medication (re)fill measurements were extracted and summarized. The 36 articles used 20 differently named measures under the three main concepts: medication adherence, persistence, and discontinuation. Measures of medication adherence cumulatively assessed the proportion of time at which medications were (not) filled over a predefined observation period (e.g., medication possession ratio). Measures of medication persistence assessed the continuity of medication filling over a specified time period, while medication discontinuation measures focused on termination of medication (re)fills. Overall, almost two thirds of all identified articles used a single medication (re)fill adherence measure. Among them, 77 % used a medication possession measure. The term "medication possession ratio" (MPR) was used most frequently (65 %), followed by the "proportion of days covered" (PDC; 30 %). No single measure can be generally recommended for the use in older Americans. The challenges in using pharmacy claims-based medication (re)fill adherence measures in older Americans include a lack of consensus terminology and algorithms among measures of the same concepts, insufficient transparency of individual measure operationalization, and inadequate consideration of unique characteristics of the older population, such as temporary nursing home care. Although medication (re)fill adherence measures may be well suited for measuring medication adherence in older Americans, little guidance is available on how to use them in this population. Further efforts need to be given to the development and standardization of pharmacy claims-based medication (re)fill measures that ...

Vital Signs: Disparities in Antihypertensive Medication Nonadherence Among Medicare Part D Beneficiaries — United States, 2014

“…First, PDC assesses only the availability of medication and not the actual taking of medication. However, use of measures, like PDC, which rely on administrative data to assess nonadherence have typically correlated well with self-reported nonadherence, plasma medication levels, physiologic markers, and cardiovascular disease outcomes (2,22), and might better assess nonadherence among older adults than self-reported or other objective measures (22). Second, because the PDC calculation excludes patients with only one antihypertensive fill and does not include persons who are prescribed medication but never initiate treatment, it probably underestimates nonadherence.…”

The INCATM (Inhaler Compliance AssessmentTM): A comparison with established measures of adherence

“…These methods are useful tools for helping to predict future health care utilisation and costs (Karve et al, 2009;Sattler, Lee, & Perri, 2013). However, they are undermined by the assumption that refilling a medication corresponds to actual medicationtaking behaviour, and do not provide information about when or how medication is actually taken.…”

“…PDC is the accumulation of days the medication is available (or 'covered') within a pre-determined observation period, divided by the number of days in that period, and multiplied by 100. MPR and PDC were used as continuous variables and also as dichotomised variables using ≥80% as a widely used cut-off between good and poor adherers (Karve et al, 2009;Sattler et al, 2013).…”

Não adesão à terapia biológica em pacientes com doenças reumáticas no Sistema Único de Saúde em Minas Gerais, Brasil

“…Outra limitação do estudo está relacionada à estimativa da não adesão, que foi realizada por intermédio de um método indireto. A PDC é avaliada como uma das principais medidas indiretas de ade-são 37,38 . No entanto, o registro do fornecimento do medicamento não indica indubitavelmente que o paciente o utilizou, mas sim que o medicamento ficou disponível para uso durante determinado período.…”