Asthma inhaler adherence determinants in adults: systematic review of observational data

Abstract

Nonadherence to inhaled medication leads to poor asthma control and increased healthcare utilisation. Many studies exploring adherence determinants have been conducted, but summaries of the evidence are scarce. We performed a systematic review of observational research on determinants of asthma inhaler adherence among adults.We searched for articles in English reporting quantitative observational studies on inhaler adherence correlates among adults in developed countries, published in EMBASE, Medline, PsychInfo and PsychArticles in 1990-2014. Two coders independently assessed eligibility and extracted data, and assessed study quality. Results were summarised qualitatively into social and economic, and healthcare-, therapy-, condition-and patient-related factors.The 51 studies included mainly examined patient-related factors and found consistent links between adherence and stronger inhaler-necessity beliefs, and possibly older age. There was limited evidence on the relevance of other determinants, partly due to study heterogeneity regarding the types of determinants examined. Methodological quality varied considerably and studies performed generally poorly on their definitions of variables and measures, risk of bias, sample size and data analysis.A broader adoption of common methodological standards and health behaviour theories is needed before cumulative science on the determinants of adherence to asthma inhalers among adults can develop further. @ERSpublications Major opportunities for strengthening evidence on determinants of nonadherence to asthma inhalers: methods and theory

Exploring the relationship between health beliefs and medication adherence in individuals with asthma

“…32 The factors associated with non-initiation in asthma are not well understood as there has been very little work conducted in this area. 15 When a medication is discontinued after implementation, without agreement with the prescribing doctor, this is known as discontinuation.…”

“…13 These include the patient's beliefs and perceptions about their treatment, illness and the healthcare system, the expectations they hold about the outcomes of treatment and their motivation to manage their condition. The relationship between patient-related factors and medication adherence has been widely investigated across a number of conditions including asthma, 15 patients taking lipid-lowering medication 81 antihypertensives, 73 and in older patients with multiple comorbidities. 14 A patient's beliefs accounted for the largest amount of variance in adherence in patients taking lipid-lowering medication 81 and were the most consistent predictor of medication adherence in patients with asthma.…”

“…14 A patient's beliefs accounted for the largest amount of variance in adherence in patients taking lipid-lowering medication 81 and were the most consistent predictor of medication adherence in patients with asthma. 15 Individuals are actively engaging with their medicines, making decisions about modifying their regimen to suit their needs; whether that is taking medication only when they have symptoms, altering their dose to reduce side effects or using their medication sparingly for financial reasons. 82 A patient's beliefs are likely to influence all of these decisions, making them an important factor to consider when understanding the reasons behind a patient's medication-taking behaviour.…”

“…[13][14][15][16] Models of health behaviour are useful for describing the beliefs that may affect medication-taking behaviour. Well established models of health behaviour that have been applied to medication adherence are the Health Belief Model, 17 Common Sense Model, 18 Locus of Control, 19 and Stages of Change.…”

“…66 Similar findings have been reported in asthma. 15 Overall, the literature suggests social and economic factors are not reliable predictors of adherence. 16,44,67,68 Health-System Factors A number of health-system factors have been shown to influence adherence.…”