Treatment effect analysis for obstructive sleep apnea

Abstract

Purpose of the study

The primary purpose of this thesis is to compare the effectiveness of four Obstructive Sleep Apnoea (OSA) treatment methods. The thesis focuses on the following treatment options: Continuous Positive Air Pressure (CPAP), Oral Appliance (OA), bariatric surgery, and upper airway surgery. The effectiveness of a treatment intervention is measured by 1) the risk of relapse and 2) cumulative relapse recurrence. Relapse is defined as the return of the signs of increased OSA severity.

Methodology and data

The data for this thesis consist of Electronic Health Records (EHR) data obtained from Turku University Central Hospital, which contains the information of approximately 24 700 sleep apnoea patients. The patients were followed between the years 2003 and 2019. In addition, the data were collected from patient visits and CPAP machines at home.

Treatment response is studied with a multistate modelling technique that measures how previous events affect the probabilities of future events. The risk of relapse is measured with Markov chain state transition probabilities, and cumulative relapse recurrence is calculated with a Nelson-Aalen procedure.

Results

The study results suggest that for all treatment arms, the risk of relapse is higher in milder OSA states. Consequently, the risk of relapse and the estimated relapse recurrence are lower in patients with severe OSA. The study findings support the previous consensus on the treatment effectiveness of CPAP. In addition, OA performs well in all severity states. Bariatric surgery and upper airway surgery showed poor performance in milder OSA states. Furthermore, the study finds a statistically significant relationship between oxygen desaturation values and OSA severity.