Treatment response and determinants of asthma control in Eastern Africa

Abstract

Asthma is a heterogeneous disease characterized by chronic airway inflammation, a history of recurrent/persistent respiratory symptoms that vary in intensity over time, and variable airflow obstruction. Longitudinal studies examining asthma control patterns and predictors of clinical outcomes in African populations remain scarce. Therefore, the objective of this study was to identify treatment response, asthma control, and its predictors in Eastern African cohort. Method A multicountry prospective cohort study was conducted in three specialized hospitals in Africa. Asthmatic patients aged ≥ 12 years were followed for one year under standard care. We included participants who had complete baseline sociodemographic, spirometry, clinical data, and at least one follow-up visit. Based on these criteria, the final nested sample comprised 1,521 participants: 357 from Ethiopia, 388 from Kenya, and 776 from Uganda. The primary outcomes were asthma control, its predictors, and treatment response during follow-up. A generalized linear mixed model was used to determine predictors of asthma control. Result Of the 1,521 study participants, 1,074 (71%) were female. During follow-up, the participants’ medication adherence rates were 69% high, 21% medium, and 10% low. At baseline, 20.7% of patients had adequate asthma control (ACQ < 1.5). During follow-up, this increased to 67.6% (95% CI: 66.7–68.6%) (ACQ < 1.5), a 47-percentage point improvement from baseline. Across the eight visits, the odds of achieving asthma control ranged from 4.55 to 8.22 compared to baseline, highlighting substantial improvement over time. High adherence (p = 0.045), low-dose fluticasone inhaler (p < 0.001), and high-dose budesonide plus formoterol inhaler (p < 0.001) were associated with higher odds of asthma control. High-dose fluticasone propionate inhaler (p < 0.001) was associated with lower odds of control, likely reflecting baseline disease severity differences across treatment intensities. Conclusion The study demonstrates substantial improvement in asthma control over 12 months of structured follow-up, with nearly a threefold increase in controlled disease compared with baseline. High adherence, follow-up, low-dose fluticasone and high-dose budesonide inhalers- were independently associated with better control, underscoring the importance of standard therapy, optimizing adherence and follow-up. Despite high adherence, 35% of participants failed to achieve asthma control.