Predictive factors for sleep apnoea in patients on opioids for chronic pain

Abstract

Background: The risk of death is elevated in patients taking opioids for chronic non-cancer pain. Respiratory depression is the main cause of death due to opioids and sleep apnoea is an important associated risk factor.

Methods: In chronic pain clinics, we assessed the STOP-Bang questionnaire (a screening tool for sleep apnoea; Snoring, Tiredness, Observed apnoea, high blood Pressure, Body mass index, age, neck circumference and male gender), Epworth Sleepiness Scale, thyromental distance, Mallampati classification, daytime oxyhaemoglobin saturation (SpO2) and calculated daily morphine milligram equivalent (MME) approximations for each participant, and performed an inlaboratory polysomnogram. The primary objective was to determine the predictive factors for sleep apnoea in patients on chronic opioid therapy using multivariable logistic regression models.

Results: Of 332 consented participants, 204 underwent polysomnography, and 120 (58.8%) had sleep apnoea (AHI ≥5) (72% obstructive, 20% central and 8% indeterminate sleep apnoea), with a high prevalence of moderate (23.3%) and severe (30.8%) sleep apnoea. The STOP-Bang questionnaire and SpO2 are predictive factors for sleep apnoea (AHI ≥15) in patients on opioids for chronic pain. For each one-unit increase in the STOP-Bang score, the odds of moderate-to-severe sleep apnoea (AHI ≥15) increased by 70%, and for each 1% SpO2 decrease the odds increased by 33%. For each 10 mg MME increase, the odds of Central Apnoea Index ≥5 increased by 3%, and for each 1% SpO2 decrease the odds increased by 45%.

Conclusion: In patients on opioids for chronic pain, the STOP-Bang questionnaire and daytime SpO2 are predictive factors for sleep apnoea, and MME and daytime SpO2 are predictive factors for Central Apnoea Index ≥5.

Trial registration number: NCT02513836.

Keywords: Chronic Pain; Opioids; clinical epidemiology; sleep apnoea.

Conflict of interest statement

Competing interests: FC reports research support from the Ontario Ministry of Health and Long-Term Care and the University Health Network Foundation; and UpToDate royalties and STOP-Bang proprietary to the University Health Network. JW reports grants from the Ontario Ministry of Health and Long-Term Care, Anesthesia Patient Safety Foundation and the University of Toronto Merit Research Award. MMM: reports support from Novo Nordisk, Allergan and Amgen. DNJ reports personal fees from universities, colleges and professional medical associations. He is an unpaid member of the Physicians for Responsible Opioid Prescribing (PROP), which is sometimes cast as an 'anti-opioid' group, but in actuality is invested in prescribing that is safer and more evidence-based. He is also a member of the American College of Medical Toxicology. Both groups have publicly available positions on this issue. Other coauthors have no conflict of interest reported.

© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Study flow chart showing the number of participants involved in different phases. OSA, obstructive sleep apnoea; PSG, polysomnography.

Figure 2

Predicted probabilities for sleep apnoea with the different cut-offs of STOP-Bang score. Vertical bars represent SEM. AHI, Apnoea-Hypopnoea Index; STOP-Bang, a screening tool for sleep apnoea (Snoring, Tiredness, Observed apnoea, high blood Pressure, Body mass index, age, neck circumference and male gender).

Figure 3

Apnoea-Hypopnoea Index and Central Apnoea Index for the different categories of daytime oxyhaemoglobin saturation (SpO2). Lower and upper boundaries of boxplot indicate 25th and 75th percentile.

Figure 4

Increase in the OR of patients with CAI ≥5 by increasing morphine milligram equivalents adjusting for oxyhaemoglobin saturation and STOP-Bang score. Vertical bars represent SE of OR. CAI, Central Apnoea Index; STOP-Bang, a screening tool for sleep apnoea (Snoring, Tiredness, Observed apnoea, high blood Pressure, Body mass index, age, neck circumference and male gender.

Figure 5

Cognitive aid model for sleep apnoea (AHI ≥15) and Central Apnoea Index (CAI ≥5). AHI, Apnoea-Hypopnoea Index; SpO2, oxyhaemoglobin saturation.