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

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.

Prevalence and phenotypic trajectories of hypoxaemia among hospitalised adults in Kenya: a single-centre, prospective cohort study

OBJECTIVE

Global medical oxygen security is limited by knowledge gaps in hypoxaemia burden and oxygen access in low-income and middle-income countries. We examined the prevalence and phenotypic trajectories of hypoxaemia among hospitalised adults in Kenya, with a focus on chronic hypoxaemia.

DESIGN

Single-centre, prospective cohort study.

SETTING

National tertiary referral hospital in Eldoret, Kenya between September 2019 and April 2022.

PARTICIPANTS

Adults (age ≥18 years) admitted to general medicine wards.

PRIMARY AND SECONDARY OUTCOME MEASURES

Our primary outcome was proportion of patients who were hypoxaemic (oxygen saturation, SpO2 ≤88%) on admission. Secondary outcomes were proportion of patients with hypoxaemia on admission who had hypoxaemia resolution, hospital discharge, transfer, or death among those with unresolved hypoxaemia or chronic hypoxaemia. Patients remaining hypoxaemic for ≤3 days after admission were enrolled into an additional cohort to determine chronic hypoxaemia. Chronic hypoxaemia was defined as an SpO2 ≤ 88% at either 1-month post-discharge follow-up or, for patients who died prior to follow-up, a documented SpO2 ≤88% during a previous hospital discharge or outpatient visit within the last 6 months.

RESULTS

We screened 4104 patients (48.5% female, mean age 49.4±19.4 years), of whom 23.8% were hypoxaemic on admission. Hypoxaemic patients were significantly older and more predominantly female than normoxaemic patients. Among those hypoxaemic on admission, 33.9% had resolution of their hypoxaemia as inpatients, 55.6% had unresolved hypoxaemia (31.0% died before hospital discharge, 13.3% were alive on discharge and 11.4% were transferred) and 10.4% were lost to follow-up. The prevalence of chronic hypoxaemia was 2.1% in the total screened population, representing 8.8% of patients who were hypoxaemic on admission. Chronic hypoxaemia was determined at 1-month post-discharge among 59/86 patients and based on prior documentation among 27/86 patients.

CONCLUSION

Hypoxaemia is highly prevalent among adults admitted to a general medicine ward at a national referral hospital in Kenya. Nearly 1 in 11 patients who are hypoxaemic on admission are chronically hypoxaemic.