Intentional and unintentional medication nonadherence
Ng, Jamie Suat-Ling
Date of Issue2016
School of Mechanical and Aerospace Engineering
Centre for Human Factors and Ergonomics
Institute for Infocomm Research
According to the World Health Organization, chronic diseases are estimated to account for 63% of deaths globally. However, adherence to chronic diseases therapy only averages 50% in developed countries. Despite decades of research, nonadherence to medication remains an unresolved healthcare issue. It is often thought that cognitive deficiency is the main reason for medication nonadherence; however, research showed that patients’ active decision not to comply made up around half of the reasons. In the recent years, medication-taking behaviors have been considered from a reasoned decision-making perspective, where the medication nonadherence behaviors are categorized into unintentional or intentional factors. Therefore, a proper framework is necessary to explain intentional and unintentional nonadherence. In this research, a hypothetical model is investigated to explain Intentional and Unintentional nonadherence and validated with subsequent studies. Two studies to understand medication nonadherence attitude in Singapore are carried out. The investigation revealed that only about 25%-30% of respondents are considered highly adherent to their medication in Singapore, based on the Morisky Medication Adherence Scale. About 40%-55% of the respondents cited “Forgetting” (i.e. unintentional nonadherence) for not taking their medication, while intentional nonadherence made up about 20-25% of the reasons. Differences between Younger and Older adults attitude towards medication adherence are also found. Younger adults are found to be more susceptible to both intentional and unintentional nonadherence, and the latter is influenced more by “busyness” than age. We propose an Ability-Belief-Context (ABC) framework for understanding predictors of Unintentional and Intentional Medication Nonadherence. Ten variables and constructs are analyzed to identify relationships with intentional and unintentional nonadherence, through mediation analysis. The variables and constructs are modeled into Ability, Beliefs and Context to study their influence on intentional and unintentional nonadherence: Ability includes: Perceived Prospective Memory, Perceived Ability (to self-manage medication) and Lifestyle Busyness; Belief includes: Trust in Medication, Trust in Doctor and Knowledge; while the Context includes: Social Support and External Cues (e.g. pillbox use). Attitude, Beliefs, Trust in Medication and Trust in Doctor are consistently found to influence intentional medication nonadherence. Perceived Prospective Memory and Busyness are significantly associated with both adherence and attitude, and mediated by both intentional and unintentional factors. Contextual factors, such as Social Support in reminding an individual to take their medication have an effect on unintentional nonadherence. Pillbox use is however not found to contribute to intentional nor unintentional nonadherence. This research made several contributions in the understanding of medication nonadherence: First, a comprehensive study on reasons for medication nonadherence in Singapore is studied and validated through subsequently studies. Second, ten factors contributing to intentional and unintentional are analyzed to determine both intentional and unintentional mediating effects. Third, age-related differences and attitudes towards medication nonadherence are analyzed. Fourth, a combination of psychosocial and human factors approaches is adopted to understand medication nonadherence. And last but not least, a framework is proposed to identify the relationships between predictors, mediating factors of intentional and unintentional nonadherence based on Abilities, Beliefs, Context and Age.