The McGill score in the diagnosis of Obstructive Sleep Apnoea in children with associated medical conditions

Abstract

Background: McGill scoring is used to stratify severity of oximetry in children referred with obstructive sleep apnoea (OSA) to identify those with more severe disease and prioritize treatment1. We hypothesized that its sensitivity and specificity in detecting OSA differs significantly between children with associated medical conditions and otherwise healthy children. Methods: 2 year retrospective analysis of children referred for investigation of OSA who underwent a cardiorespiratory(CR) polygraphy study. McGill score was calculated from the oximetry trace1 blinded to polygraphy results. We looked at 2 definitions of OSA: Obstructive Apnoea Hypopnoea Index (oAHI) ≥1 and ≥5. McGill sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) were calculated. McGill score=1 was considered normal or inconclusive, >1 abnormal. Results: There were 319 children, 192 males (60%), mean age 5.7(±4.1) years. 131/319 (41%), mean age 5.6(±4.1) were otherwise healthy, 188/319 (59%), mean age 5.7(±4.1), had medical conditions. 3 patients’ data was discarded due to artefact. McGill score specificity is similar in the 2 subgroups. However, the NPV and particularly the PPV are significantly lower in children with medical conditions (Table 1). Conclusions: The higher false positive rate in children with medical conditions may be due to increased central apnoeas. Children with underlying lung disease are also more likely to desaturate following a brief hypopnoea. The McGill score should only be used in otherwise healthy children; those with co-morbidity need CR polygraphy. Reference: 1 Pediatrics 2004;113: e19-25