# Modelling the case for cost-effectiveness of interventions to improve medication adherence in patients with difficult to control asthma

## TL;DR

This study shows that improving medication adherence in asthma patients can significantly reduce hospital admissions and healthcare costs while improving health outcomes.

## Contribution

The study provides quantitative evidence on the health and cost benefits of improving medication adherence in asthma patients.

## Key findings

- Improved adherence reduces asthma exacerbations and increases quality-adjusted life years.
- A 20-year educational intervention increasing adherence from 50% to 70% saves £989 in healthcare costs.
- The model demonstrates the long-term health and economic benefits of adherence interventions.

## Abstract

Asthma is a prevalent non-communicable disease in high-income countries, affecting more than 10% of their populations. While often symptomatically mild it accounts for 2-3% of primary care appointments, 60,000 hospital admissions, and 1,200 deaths annually in England. Importantly, a significant proportion of these events are the result of poor adherence to prescribed and effective treatments, with 60% of hospital admissions attributed to suboptimal compliance. This study aims to support the development and commissioning of interventions by establishing the value case for improving medication adherence.

A probabilistic cohort decision model was developed with the aim of estimating the long-term health impacts and resultant costs to the healthcare system of different levels of population medication adherence for those with difficult-to-control asthma. The model applies a Markov structure based on the Global Initiative for Asthma (GINA) guidelines to define the level of asthma control. Informative parameters are drawn from existing published literature supplemented by expert input where required.

Improved adherence is associated with reduced asthma exacerbations and better overall health of the cohort, measured in life years and quality-adjusted life years (QALYs). For instance, an educational intervention that increased adherence from 50% to 70% reduced exacerbations by 1.75 over 20 years, while increasing QALYs by 0.20, and reducing the healthcare costs by £989.

Significant economic and health benefits can be achieved with effective interventions to improve treatment adherence in asthma. This study provides a value case for developing and commissioning such interventions.

Key messages:

What is already known on this topic

•    Despite the existence of extensive treatment options for asthma available many people still require hospitalisation and die as a result of the disease, often as a result of poor adherence to prescribed medication.

•    The effectiveness and cost-effectiveness of many individual treatments for asthma is well known but these are typically based on optimal adherence being achieved, with limited research available on the impact of poor adherence or the value case for investing in interventions to address it.

What this study adds - summarise what we now know as a result of this study that we did not know before

•    This study provides quantitative evidence of the health and care implications of different levels of asthma medication adherence, demonstrating the potential health gains and healthcare saving that can be achieved.

How this study might affect research, practice or policy

•    Working collaboratively between academic, clinical and policy experts this study provides a methodologically and clinically robust accessible guide for key commissioning stakeholders to support steps towards improving medication adherence in asthma in a cost-effective way.