Noncommunicable Lung Disease in Sub-Saharan Africa. A Community-based Cross-Sectional Study of Adults in Urban Malawi

Abstract

Rationale: Noncommunicable diseases are major causes of morbidity and mortality in sub-Saharan Africa (sSA). Valid burden of disease estimates are lacking for noncommunicable lung disease in sSA.

Objectives: We performed a community-based survey to determine the prevalence of chronic lung disease among adults 18 years or older in Malawi, using American Thoracic Society standard spirometry, internationally validated respiratory symptom and exposure questionnaires, and an assessment of HIV status.

Methods: An age- and sex-stratified random sample of 2,000 adults was taken from the population of the Chilomoni district of Blantyre, Malawi. Fieldworkers collected questionnaire data, conducted HIV testing, and performed pre- and post-bronchodilator spirometry on eligible participants. Survey-weighted population prevalence estimates of respiratory symptoms and spirometric abnormalities were computed, and bivariate and multivariable regression were used to identify associated variables.

Measurements and main results: Questionnaire data, HIV status, and standard spirometry were obtained from 1,059, 933, and 749 participants, respectively. Current respiratory symptoms, exposure to biomass, and ever-smoking were reported by 11.8, 85.2, and 10.4% of participants, respectively. HIV prevalence was 24.2%. Moderate to severe airway obstruction was seen in 3.6%. The prevalence of spirometric restriction was 38.6% using National Health and Nutrition Examination Survey III reference ranges and 9.0% using local reference ranges. Age was positively associated with obstruction, whereas low body mass index was associated with restriction.

Conclusions: More than 40% of the Malawian adults in our urban population sample had abnormal lung function (mostly restrictive) in the context of widespread exposure to biomass smoke and a high prevalence of HIV. These findings potentially have major public health implications for Malawi and the broader sSA region.

Keywords: COPD; biomass; lung function; noncommunicable disease; sub-Saharan Africa.

Figure 1.

Participant recruitment flow diagram.

Figure 2.

Age- and sex-stratified prevalence of symptoms among study participants. Upper panel depicts symptom prevalence among men; lower panel depicts symptom prevalence among women. The questions asked were as follows: Do you usually have a cough when you don’t have a cold? (n = 1,056); Do you usually bring up phlegm from your chest? (n = 1,056); Have you had wheezing/whistling in your chest at any point in in the past 12 months, in the absence of a cold? (n = 1,007); Do you have shortness of breath when hurrying on the level or walking up a slight hill? (n = 970); and Have breathing problems interfered with your usual daily activities? (n = 1,056).

Figure 3.

Age- and sex-stratified prevalence of moderate to severe airway obstruction (FEV₁/FVC <0.7 and FEV₁ <80% predicted) and spirometric restriction (FEV₁/FV >0.7 and FEV₁ <80%), defined using National Health and Nutrition Examination Survey reference ranges, among those completing American Thoracic Society standard spirometry (n = 749). Upper panel depicts the prevalence of spirometric abnormalities among men; lower panel depicts the prevalence of spirometric abnormalities among women.