Examining the causal model linking health literacy to health outcomes of asthma patients

Aims and objectives To explore health literacy status in asthma patients and to examine the causal model linking health literacy to health outcome–related factors via mediator and moderator variables. Background Understanding how low health literacy may influence health outcomes is important. Design This is a cross‐sectional survey study. Methods A total of 326 asthma patients aged 20 years and older (average: 51 ± 18·3 years) were recruited by purposive sampling from pulmonary medicine outpatient departments at three medical centres and a regional teaching hospital in northern Taiwan. Data were collected via structured questionnaires, including measures of socio‐demographic and disease characteristics; medical decision‐making; asthma knowledge, attitudes and self‐efficacy; healthcare experience and health outcome–related factors (metered‐dose inhaler/dry‐powder inhaler usage proficiency, medical use, self‐management behaviour). Three hundred patients who met the inclusion criteria and completed the questionnaire survey were analysed. Results Overall, 217 subjects (72·3%) had adequate functional health literacy, 42 (14%) had inadequate functional health literacy, and 41 (13·7%) had marginal functional health literacy. Subjects' average asthma knowledge, attitudes and self‐efficacy scores were 7·23 ± 2·69, 51·46 ± 6·18 and 58·31 ± 8·10, respectively. Health literacy correlated positively with asthma knowledge (r = 0·605), attitudes (r = 0·192) and medical decision‐making (r = 0·413). Conclusions Health literacy is positively associated with proficiency in metered‐dose inhaler usage, asthma knowledge, attitudes and medical decision‐making, but is not significantly associated with medical care use and self‐management behaviour. Health literacy had an indirect effect on self‐management behaviour through the mediation effect of asthma attitudes. No moderator was found for the effect of health literacy on health outcome–related factors. Relevance to clinical practice Results of this study may help to develop adequate intervention strategies to improve the health outcomes of asthma patients.