Validation of a Novel Screening Tool for Obstructive Sleep Apnoea in Bariatric Surgery Candidates

Twigg, Gillian L (2022) Validation of a Novel Screening Tool for Obstructive Sleep Apnoea in Bariatric Surgery Candidates. Doctoral thesis (PhD), Manchester Metropolitan University.

Preview

Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (2MB) | Preview

Abstract

Undiagnosed obstructive sleep apnoea (OSA) is increasingly recognised as a serious post-operative risk with bariatric surgery. Demand for pre-operative screening for OSA in bariatric surgery candidates is rising and there is a need for simple, cost-effective screening methods to mitigate the stain on Sleep Services. WatchPAT is a relatively new device, which uses peripheral arterial tonometry rather than airflow to estimate the apnoea hypopnoea index (AHI). While WatchPAT use is increasing in the general sleep clinic population it has not yet been validated in patients with a BMI >35, i.e. the target population in bariatric surgery. The studies described in this thesis aim to validate WatchPAT against the clinical gold-standard in patients on the bariatric pathway and to assess patient acceptability of WatchPAT. 28 bariatric surgery candidates (22 female/6 male, mean ± SD age 44.1 ± 11.6 years, BMI 45.7 ± 7.5 kg/m2) wore WatchPAT 300 and Embletta MPR simultaneously for one night and the outcome measure, AHI was compared in the two devices. AHI was higher in WatchPAT than Embletta (Median (range) 23.5 (3.9-70.6) versus 11.7 (0.7-46.5) events per hour; z=-4.623, p=0.000). There was a strong positive correlation between WatchPAT and Embletta AHI measurements (r=0.849; p=0.000). Bland Altman plots revealed a systematic bias; differences diverging at higher AHI values. ROC plots were constructed for a range of AHI cut-offs; AUC was highest for an AHI ≥20 (0.986), ≥15 (0.947) and AHI ≥30 (0.979), while for AHI ≥5 the AUC was 0.850. 97% of respondents reported that WatchPAT would be acceptable to them if introduced into the bariatric surgery pathway. These results are similar to those in the non-bariatric sleep clinic population and suggest that WatchPAT may suitable for use in bariatric surgery patients requiring screening for OSA though further larger scale studies are needed to confirm these findings before incorporating into clinical guidelines.