Literacy interventions in asthma – A cost-effectiveness study in Portugal

Most Asthma patients are clinically uncontrolled, and that may be partially due to low health literacy. Several trials have tested the efficacy of literacy interventions, but their cost-effectiveness is still unclear. We performed a cost-effectiveness analysis of literacy interventions and estimate a scenario in Portugal. We developed a decision tree analysis from a healthcare perspective, according to several outcomes (poor clinical control, emergency department (ED) visits, hospitalisations, use of rescue medication or OCS) rates and costs described in previous clinical trials, and according to intervention costs. Sensitivity analysis of worst and best-case scenarios was performed to estimate thresholds for intervention affordable limits, as well as cost-saving estimations and Incremental Cost-Effectiveness Ratio (ICER) for a Portuguese scenario. We estimated a theoretical intervention model in all patients, including literacy enhancement at an annual appointment with a doctor and a nurse. Data from 8 RCTs was included. In the best-case scenario, intervention affordable budget per patient per year were estimated at: 107,38€ to avoid one patient with poor clinical control, 3,20€ to avoid an ED visit, 10,35€ to avoid a hospitalization and 1,13€ to avoid the use of rescue medication or OCS. Cost savings for Portuguese scenario were more pronounced to avoid poor clinical control, at 100,68€ per patient per year. ICER for Portugal were estimated for best-case scenarios at: Poor Clinical Control 55,83€, ED Visits 134,00€, hospitalizations 111,67€ and use of rescue medication or OCS 55,83€; each per outcome event avoided. Subgroup analysis show that for studies with 12-month follow-up and including mild to moderate asthma patients, the estimates for cost-effectiveness are more favourable to avoid poor clinical control, ED visits and hospitalisations. Literacy interventions may be potentially cost-effective according to Portuguese costs and scenarios, and this is more pronounced in patients with mild to moderate asthma severity and with longer follow-up.