Suitability of measures of self-reported medication adherence for routine clinical use: A systematic review

Abstract

BackgroundThere is a recognised need to build primary care medication adherence services which are tailored to patients' needs. Continuous quality improvement of such services requires a regular working method of measuring adherence in order to monitor effectiveness. Self report has been considered the method of choice for clinical use; it is cheap, relatively unobtrusive and able to distinguish between intentional and unintentional non-adherence, which have different underlying causes and therefore require different interventions. A self report adherence measure used in routine clinical practice would ideally be brief, acceptable to patients, valid, reliable, have the ability to distinguish between different types of non-adherence and be able to be completed by or in conjunction with carers where necessary.MethodsWe systematically reviewed the literature in order to identify self report adherence measures currently available which are suitable for primary care and evaluate the extent to which they met the criteria described above. We searched the databases Medline, Embase, International Pharmaceutical Abstracts, Pharmline, CINAHL, PsycINFO and HaPI to identify studies reporting the development, validation or reliability of generic adherence measures. One reviewer screened all abstracts and assessed all relevant full text articles obtained and a second reviewer screened/assessed 10% to check reliability.ResultsFifty eight measures were identified. While validation data were presented in support of the vast majority of self reported measures (54/58), data for a relatively small number of measures was presented for reliability (16/58) and time to complete (3/58). Few were designed to have the ability to be completed by or in conjunction with carers and few were able to distinguish between different types of non-adherence, which limited their ability be used effectively in the continuous improvement of targeted adherence enhancing interventions. The data available suggested that patients find it easier to estimate general adherence than to report a specific number of doses missed. Visual analogue scales can be easier for patients than other types of scale but are not suitable for telephone administration.ConclusionsThere is a need for a measure which can be used in the routine continual quality monitoring of adherence services.

Self-report measures of medication adherence behavior: recommendations on optimal use

“…Second, there is a paucity of research on how to optimize the validity of self-report adherence measures in clinical care or health research. The myriad of self-report adherence measures that are available in the research literature contain substantial variation in their question phrasing, response scale formats, time intervals for recall, and modes of administration [1,5,7,8]. Few studies have empirically tested the comparative validity of these varied methodologic choices [9], and most selfreport adherence measures have only been validated within single areas of chronic illness [7].…”

“…Among many approaches to assessing medication adherence, patient self-report measures remain the most common method [1][2][3][4][5][6]. These measures are defined by asking respondents to characterize their medication adherence behavior.…”

“…In the context of clinical research, proper interpretation of proof-of-concept trials testing new pharmacologic regimens requires valid adherence data, because any null findings may stem from poor adherence rather than a lack of drug efficacy. Research designed to understand and promote medication adherence also requires precise methods of adherence assessment.Among many approaches to assessing medication adherence, patient self-report measures remain the most common method [1][2][3][4][5][6]. These measures are defined by asking respondents to characterize their medication adherence behavior.…”

“…Key advantages include low-cost, noninvasiveness, minimal patient burden, ease of administration, and flexibility in timing and mode of administration. Self-report medication adherence measures are almost certainly the most practical method of measuring adherence in the context of clinical care and can provide information to providers about nonadherence prior to development of adverse clinical outcomes [1,10,[36][37][38][39]. In addition to providing estimates of medication dose-taking behavior, self-reports can uniquely provide information about adherence determinants such as understanding of the medication regimen, reasons for nonadherence, attitudes and beliefs toward medicines, and other psychosocial factors.…”

“…Similar findings have emerged in hypertension studies, although Gonzales and colleagues [53] found the best performance when asking for an estimate of the percentage of doses taken, rather than rating adherence on a Likert-type scale. This evidence suggests that self-report measures that ask for global estimates of adherence may be preferable.Self-report adherence measures which specify a time frame for recall of adherence behavior are helpful when conducting longitudinal assessments that examine adherence trends over time [1,5,12]. Determining the optimal recall period requires balancing shorter intervals (to improve recall/estimation) with longer intervals (to increase the representativeness of the sampled time period and capture cases of infrequent nonadherence).…”