Tuberculosis is Associated with Chronic Hypoxemia among Kenyan Adults (CHAKA): A Case-Control Study

Abstract

Rationale: Data on risk factors for chronic hypoxemia in low and middle-income countries are lacking. Objective: We aimed to quantify the association between potential risk factors and chronic hypoxemia among adults hospitalized in Kenya. Methods: A hospital-based case-control study was conducted at Moi Teaching and Referral Hospital in Eldoret, Kenya. Adult inpatients were screened on admission and enrolled in a 1:2 case to control ratio. Cases were patients with chronic hypoxemia, defined as a resting oxygen saturation (SpO2) < 88% on admission and either a one-month post discharge SpO2 < 88% or, if they died prior to follow-up, a documented SpO2 < 88% in the 6 months prior to enrollment. Controls were randomly selected, stratified by sex, among non-hypoxemic inpatients. Data were collected via questionnaires and structured chart review. Regression was used to assess the association between chronic hypoxemia and age, sex, smoking status, biomass fuel use, elevation, and self-reported history of tuberculosis and HIV diagnosis. Odds ratios (ORs) and 95% confidence intervals (CIs) are reported. Results: The study enrolled 108 chronically hypoxemic cases and 240 non-hypoxemic controls. In multivariable analysis, as compared to controls, chronically hypoxemic cases had significantly higher odds of older age (OR 1.2 per 5-year increase; 95% CI: 1.1-1.3), female sex (OR 3.6, 95% CI: 1.8-7.2), current or former tobacco use (OR 4.7, 95% CI: 2.3-9.6) and prior tuberculosis (OR 11.8, 95% CI: 4.7-29.6), but no increase in odds of HIV diagnosis and biomass fuel use. Conclusion: These findings highlight the potential impact of prior tuberculosis on chronic lung disease in Kenya and the need for further studies on post-tuberculosis lung disease.