Clinical correlations to distinguish severe from milder forms of obstructive sleep apnoea syndrome using overnight oximetry for prioritising adenotonsillectomy in a limited-resource setting

Abstract

BACKGROUND : In resource-poor settings with limited surgical services, it is essential to identify and prioritise children with severe and very severe obstructive sleep apnoea syndrome (OSAS) to expedite surgery. McGill's Oximetry Score (MOS) has been validated against polysomnography for OSAS and is affordable and easy to use. AIMS : The aim of this study was to assess the correlation of tonsillar size and clinical symptoms with MOS grade 3 or 4, to identify who requires overnight oximetry and who to prioritise for adenotonsillectomy. METHODS : Children with suspected OSAS were recruited from the otolaryngology clinic at the Red Cross War Memorial Children's Hospital. Demographics, symptom screening scores (SSS), patient characteristics, overnight oximetry (OO), echocardiography and MOS scores (graded 1–4) were recorded. Multivariate modified-Poisson regression models were used to examine correlations of patient characteristics ‘with grade 3 or 4 MOS. RESULTS : One-hundred-and-three children were analysed, 38% were female, and median (IQR) age was 3.8 (2.5–5.3) years. Increased tonsil size was associated with a 60% increased risk of grade 3 or 4 MOS, risk ratio (RR) 1.59, 95% CI 1.10–2.29 (p = 0.014). Children with witnessed apnoeic events during sleep had 1.3 times increased risk of MOS Grade 3 or 4, RR 1.31, 95% CI (p = 0.033). A significant correlation was shown with grade 3 or 4 MOS, RR 1.15, 95% CI 1.03–1.27 (p = 0.010) by combining tonsillar size with the following symptoms: apnoeic events; struggling to breathe during sleep and needing to stimulate the child to breathe. CONCLUSION : Identifying children with suspected OSAS who require overnight oximetry can be performed using a simple 3-question screening tool: witnessed apnoeic events, struggling to breathe and the need to shake them awake to breathe. This is more precise with an additional clinical finding of grade 3 or 4 tonsils. These children should have surgery expedited. Any child with a MOS 3 or 4 score on OO needs to have expedited surgery.