Prevalence and predictors of adherence to inhaled corticosteroids in young adults (15-30 years) with asthma: a systematic review and meta-analysis

Objective: Adherence to inhaled corticosteroids (ICS) is an essential part of asthma management throughout the lifespan; however, this may be particularly challenging during the transition into adulthood. This systematic review aimed to determine the prevalence and predictors of adherence to ICS in emerging adulthood. Data sources: MEDLINE, PsycINFO, EMBASE, Scopus, and CINAHL were searched with search terms for asthma, ICS, adherence, young adults, and predictors combined. Study selection: Studies with participants with diagnosed asthma, currently prescribed ICS, a mean age between 15 and 30 years and reporting the prevalence and/or assessing predictor(s) of adherence using quantitative methods were included. Results: Twenty-nine studies were identified for inclusion (K = 29, N = 187 401). A random effect meta-analysis revealed the pooled prevalence of adherence was 28% (95% CI = 20-38%, k = 16) in studies that provided quantitative information on adherence. Adherence was higher in studies with a mean age <18 years (36%; 95% CI = 36-37%, k = 4). Studies using self-report measures provided higher estimates of adherence (35%; 95% CI = 28-42%, k = 10) than studies using pharmacy refill data (20%; 95% CI = 9-38%, k = 6). A narrative review identified personality, illness perceptions, and treatment beliefs as potentially important predictors of adherence. Conclusion: Adherence is sub-optimal during emerging adulthood, particularly after age 18. More reliable and objective measures are needed to precisely characterize adherence. Greater research and practice attention to emerging adulthood are needed to guide self-management support in those living with asthma at this important lifespan stage. Systematic review registration number: CRD42018092401