The societal burden of airflow obstruction and the potential impact of interventions amongst adults in Malawi.

Abstract

Background

In Malawi previous studies report a high prevalence of abnormal lung function indicative of chronic respiratory disease (CRD) of which asthma and chronic obstructive pulmonary disease (COPD) are the most common. The natural history, health, and economic impact of abnormal lung function in Malawi is largely unknown.

Aims: 1) To estimate the health burden of airflow obstruction in Malawi; 2) To estimate current and future economic burden from a societal perspective of airflow obstruction in Malawi; 3) To estimate the cost-effectiveness of selected interventions for adults with airflow obstruction in Malawi.

Methods

We followed-up a cohort of 1481 adults recruited in 2014 and quantified their respiratory symptoms, health-related quality of life (HRQoL), and lung function spirometry. We conducted an economic study using patient health resource use and costs data obtained from

three cohort studies in southern Malawi and health provider input and costs obtained from one of these studies and a bespoke costing study at a chest clinic. We evaluated the cost effectiveness of the use of anticipatory ‘emergency packs’ of antibiotics and corticosteroids at home for COPD and inhaled beclomethasone and salbutamol for asthma using a Markov model.

Results

Forced expiratory volume in one second (FEV1) declined by 53·4 ml/year (95% CI: 49.0, 57.8) and forced vital capacity (FVC) by 45.2 ml/year (95% CI: 39.2, 50.5). Chronic airflow obstruction increased from 9.5% (7.6%, 11.6%) in 2014 to 17.5% (15.3%, 19.9%) in 2019. Rate

of FEV1 decline was not associated with diagnosed chronic obstructive pulmonary disease (COPD), asthma, or spirometry consistent with asthma, COPD, or restriction. HRQoL was adversely associated with respiratory symptoms (dyspnoea, wheeze, cough), previous tuberculosis and declining FEV1. These differences exceeded the minimal important difference. Annual cost for an asthma patient is US$ 108.25 (95% CI: 86.68, 131.75) and for COPD US$ 143.39(95% CI: 123.61, 165.11), most of these costs being for hospital treatment of exacerbation. Guideline defined needs for 74.1% of those with asthma and 77.3% of those with COPD were unmet. The COPD intervention dominated usual care in the people with mild COPD while the ICERs were US$ 72, US$ 102, and US$ 242 in people with mild asthma, moderate/severe asthma, and moderate/severe COPD respectively. The asthma intervention resulted in a life-years gain of 1.62 years in those with mild asthma and 1.29 years in those with moderate/severe asthma while the COPD intervention resulted in a life-years gain of 3.49 years in those mild COPD and 3.90 years in those moderate/severe COPD.

Implications

The high prevalence of COPD in Malawi adversely affects the quality of life and is, in part, a consequence of accelerated lung function decline. The evidence justifies the implementation of sustainable initiatives for widespread diagnosis and adoption of cost-effective CRD interventions such as antibiotics and corticosteroids at home for COPD and inhaled be clomethasone and salbutamol for asthma.