P181 Obstructive sleep apnoea (OSA) severity in patients with chronic opioid use: a risk factor matched study

Introduction and objectives Concern has been raised that prescribing opioids could exacerbate underlying OSA. We previously hypothesised that this would lead to younger and/or thinner patients presenting with OSA comparing opioid taking (Op+ve) to non-opioid taking (Op-ve) patients matched for oxygen desaturation index (ODI/hr) at diagnosis. We found instead that Op+ve patients were older with the same mean BMI.1 To explore this unpredicted finding we sought new matched controls based on known risk factors, mirroring existing methodology.2 Methods We sought Op-ve matches for our original sample of 120 Op+ve patients initiated on CPAP in 2017–18. Matching was based on: age ± 5Yrs, BMI ± 1.5 kg/m2, smoking status (Y/N) and sex. We compared OSA severity, using t tests, at diagnosis and response to CPAP initiation. Results Matching was successful for 79 Op+ve patients (28 women, 70 non-smokers). Op+ve patients had a lower ODI at diagnosis than Op-ve controls (24.4 vs 30.4, p=0.048). Respectively there was no difference between mean Sp O2 (92.7vs92.6)%, min Sp O2 (75.3vs72.8)% or Epworth Sleep Score (13.4vs13.9) at diagnosis or follow-up (8.6 vs 7.1) or mean nightly hours of CPAP use (both 5.6). Compared to a larger unmatched sample of general CPAP starters Op+ve patients mean ODI was not significantly different (ODI 27vs26.1, n=192 & 120, p=0.32). Conclusion In this sample the chronic use of opioids was associated with a lower ODI at OSA diagnosis after matching for other known risk factors. Possible explanations include an attrition of patients with severe OSA on opioids but the overlap of ODI for the unmatched group argues against this. It might be that opioids ameliorate OSA lowering ODI but this raises the question of why these patients presented for treatment. Finally opioids may produce sleepiness that precipitates presentation and request for treatment in people with less severe OSA. Further work will be required to differentiate between these possibilities. References Lee K, Mason M, Smith I. Obstructive Sleep Apnoea (OSA) and response to CPAP treatment in patients with chronic opioid use. Thorax 2018;73(4):A128–9. LI K, et al. Obstructive Sleep Apnea Syndrome: A comparison between Far-East Asian and White Men. Laryngoscope 2000;110:1689–93.