Article Text
Abstract
Rationale There are no population-based studies from sub-Saharan Africa describing longitudinal lung function in adults.
Objectives To explore the lung function trajectories and their determinants, including the effects of air pollution exposures and the cleaner-burning biomass-fuelled cookstove intervention of the Cooking and Pneumonia Study (CAPS), in adults living in rural Malawi.
Methods We assessed respiratory symptoms and exposures, spirometry and measured 48-hour personal exposure to fine particulate matter (PM2.5) and carbon monoxide (CO), on three occasions over 3 years. Longitudinal data were analysed using mixed-effects modelling by maximum likelihood estimation.
Measurements and main results We recruited 1481 adults, mean (SD) age 43.8 (17.8) years, including 523 participants from CAPS households (271 intervention; 252 controls), and collected multiple spirometry and air pollution measurements for 654 (44%) and 929 (63%), respectively. Compared with Global Lung Function Initiative African-American reference ranges, mean (SD) FEV1 (forced expiratory volume in 1 s) and FVC (forced vital capacity) z-scores were −0.38 (1.14) and −0.19 (1.09). FEV1 and FVC were determined by age, sex, height, previous TB and body mass index, with FEV1 declining by 30.9 mL/year (95% CI: 21.6 to 40.1) and FVC by 38.3 mL/year (95% CI: 28.5 to 48.1). There was decreased exposure to PM2.5 in those with access to a cookstove but no effect on lung function.
Conclusions We did not observe accelerated lung function decline in this cohort of Malawian adults, compared with that reported in healthy, non-smoking populations from high-income countries; this suggests that the lung function deficits we measured in adulthood may have origins in early life.
- clinical Epidemiology
- lung Physiology
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Footnotes
Contributors Design: SR, KM and JB. Acquisition of data: SR, RN, AN, FM, KM, GF, JC and LZ. Analysis of data: SR, CJ, ML and RN. Interpretation of data: SR, CJ, JB and KM. Supervision: KM, CJ and SG. Writing the manuscript, approval of the version to be published and agreement to be accountable for all aspects of the work: all authors
Funding This work was funded by a New Investigator Research Grant from the Medical Research Council (Ref: MR/L002515/1), a Joint Global Health Trials Grant from the Medical Research Council, UK Department for International Development and Wellcome Trust (Ref: MR/K006533/1) and the Medical Research Council Doctoral Training Programme at the Liverpool School of Tropical Medicine and University of Lancaster (Ref: MR/N013514/1) and US National Institute of Environmental Health Sciences (Ref: R56ES023566). The Malawi-Liverpool-Wellcome Trust Clinical Research Programme is funded by the Wellcome Trust (Ref: 206454). Additional support was provided by the NIHR Global Health Research Unit on Lung Health and TB in Africa at LSTM - ‘IMPALA’. In relation to IMPALA (grant number 16/136/35) specifically: IMPALA was commissioned by the National Institute of Health Research using Official Development Assistance (ODA) funding. The views expressed in this publication are those of the author(s) and not necessarily those of the National Institute for Health Research or the Department of Health.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the Malawi College of Medicine Research Ethics Committee (reference P.11/12/1308) and the Liverpool School of Tropical Medicine Research Ethics Committee (reference 12.40).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. Data analysis is ongoing for PhD thesis (SR: first author ORCID ID 0000-0001-6459-9073). Datasets will be made publicly available on completion of PhD.