Date of Award

8-2025

Degree Type

Dissertation

Degree Name

Master of Medicine (MMed)

First Advisor

Dr. Jumaa Bwika

Second Advisor

Dr. Jasmit Shah

Third Advisor

Dr. Sairabanu Sokwalla

Department

Internal Medicine (East Africa)

Abstract

BACKGROUND: Obstructive sleep apnea is a syndrome of upper airway and neuromuscular dysfunction during sleep that subsequently causes interruption of normal breathing. Polysomnography is the reference test for the diagnosis of obstructive sleep apnea. Obstructive sleep apnea can be categorised as mild, moderate or severe based on an apnea-hypopnea index (AHI) on polysomnography. The recommended treatment using Continuous Positive Airway Pressure lowers morbidity and mortality rates. The STOPBANG questionnaire has been used as a screening tool for obstructive sleep apnea due to its easy and concise approach. However, even with the increasing prevalence of obstructive sleep apnea and its risk factors in Africa, there is limited data on the validity and performance of the STOPBANG questionnaire in the clinical setting in the Sub-Saharan African population.

OBJECTIVES: The primary objective was to determine the sensitivity, specificity and accuracy of the STOPBANG questionnaire in screening patients with obstructive sleep apnea as compared to polysomnography. The secondary objective was to determine the clinical characteristics of patients with obstructive sleep apnea.

METHODS: This was a retrospective cohort study of patients who had polysomnography at the Aga Khan University Hospital, Nairobi from 1st December 2020 to 30th June 2024. Data on variables was obtained from medical records and collected using the REDCap software based on the abstraction tool. Data was analysed using SPSS software.

RESULTS: One hundred and twenty-nine patients underwent polysomnography. Out of the 129, 17 were excluded due to missing data and 112 patients were analysed. The sensitivity of the STOPBANG questionnaire was 93.98% [CI 86.5%- 98.02%] with a specificity of 34.48% [CI 17.94% -54.33%]. The positive likelihood ratio was 1.43[ CI 1.10 -1.88] with a negative likelihood ratio of 0.17 [CI 0.07-0.47]. The positive predictive value was 80.41% [CI 75.82%-84.32%] while the negative predictive value was 66.67% [CI 42.71%-84.29%]. The accuracy of the STOPBANG questionnaire was 78.57% [CI 69.81%-85.76%]. Obstructive sleep apnea was associated with increasing age (p=0.001), male gender (p=0.0272), larger neck circumference (p< 0.001), diabetes mellitus (p=0.0193), dyslipidemia (p=0.001) and hypertension(p< 0.001). Presence of snoring, nocturnal hypoxemia and apneic episodes were significantly associated with OSA (p< 0.001, p=0.003, p< 0.001 respectively). The above characteristics were also significantly associated with increasing severity of obstructive sleep apnea.

CONCLUSION AND RECOMMENDATIONS: The STOPBANG questionnaire is an ideal screening tool for obstructive sleep apnea in the clinical setting Kenya due to its high sensitivity and low specificity. Patients who are at a high risk for obstructive sleep apnea on the STOPBANG questionnaire should be offered polysomnography.

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