Pain Intensity and Opioid Utilization in Response to CPAP Therapy in Veterans with Obstructive Sleep Apnea on Chronic Opioid Treatment

Abstract

Study Objectives: Sleep fragmentation has been linked to poor pain tolerance and lowered pain threshold. Little evidence exists on whether continuous positive airway pressure (CPAP) adherence in veterans with obstructive sleep apnea (OSA) who are taking opioids for non-malignant pain would ameliorate pain and reduce consumption of opioids. Methods: A retrospective case-control study was performed at a VA sleep center. Pain intensity was assessed using the Numerical Categorical Scale prior to CPAP treatment and 12-mo follow-up. Opioids intake was assessed using the morphine equivalent daily dose (MEDD). Adherence to CPAP was evaluated with the built-in meter. Results: We reviewed 113 patients with OSA (apnea-hypopnea index [AHI] 35.9 ± 29.5) using a MEDD of 61.6 mg (range 5-980 mg) and a control group of 113 veterans with OSA (AHI 33.4 ± 27.3) on no opioids treatment. CPAP adherence was significantly lower at 12 mo in opioid-treated patients compared to controls (37% versus 55%; p = 0.01). Greater pain intensity was the only independent variable associated with CPAP non-adherence at 12-mo follow-up (p = 0.03). Compared to baseline, no significant difference was observed in pain intensity or consumption of opioids in CPAP adherent patients. I NTRO DUCTI O NChronic pain is a serious and highly prevalent condition among service members. Although the prevalence of chronic pain and opioid use associated with deployment is not well known, a recent report indicated that nearly half of a group of infantry soldiers who had seen combat in Afghanistan have reported experiencing chronic pain.1 The better body armor combined with advanced medical care on the battlefield had led to improved survival rates following serious residual injuries (such as limb amputations and severe nerve and musculoskeletal damage) caused by blasts or projectiles. The multiplicity of these wounds in soldiers, coupled with cognitive impairments associated with traumatic brain injury and mental health morbidity has caused an increase in dependency on opioids to suppress these ailments.The use of opioids has been associated with development of sleep-disordered breathing, including central apneas, ataxic breathing, and nocturnal hypoxemia.2-4 However, obstructive sleep apnea (OSA) is considered the predominant form of sleep-disordered breathing among veterans receiving chronic opioid therapy.5 However, this reduced pain sensitivity has been reported in healthy volunteers with induced rather than preexisting pain. It is speculated that the sleep disruption resulting from repeated arousals alters the nociceptive system, rendering it more susceptible to maladaptive plasticity. Preliminary investigations in healthy volunteers have suggested that although pain sensitivity is increased following sleep restriction, restoring sleep architecture ameliorates pain thresholds. 6,7 Further, treatment of underlying sleep apnea with continuous positive airway pressure (CPAP) has been associated with reduced hyperalgesia in patients with sleep-disordered breathing. ...

An Examination of Pain’s Relationship to Sleep Fragmentation and Disordered Breathing Across Common Sleep Disorders

“…In keeping with population norms [32], the back was the most frequently reported location of chronic pain (48.57%). The high frequency of chronic pain in this sample is of clinical importance for treating sleep disorders as pain intensity has been shown to predict PAP nonadherence [16]. In the present study, the majority of patients diagnosed with OSA had chronic pain (81.82%).…”

“…The majority of participants reported chronic pain, and this investigation found that measures of sleep fragmentation and hypoxemia were not related to pain intensity among individuals referred to a sleep center. This study highlights the importance of identifying individuals with comorbid OSA/insomnia as effective treatment of their sleep problems may be complicated by the existence of comorbid sleep disorders [30,31] and chronic pain [16], which is likely to be present in this population.…”

“…Treatment studies have been mixed but provide some support for the impact of improved SDB on pain. A retrospective examination of veterans using continuous positive airway pressure (CPAP) did not find reductions in ether pain intensity or opioid consumption after 12 months [16]. However, in pain-free patients with OSA, treatment with PAP has been shown to decrease experimental pain sensitivity [17,18].…”

Identification and treatment of obstructive sleep apnea by a primary care team with a subset focus on chronic pain management

“…This study is also limited due to the nature of using a historical control. [ 14 ] Although the control used mimicked the experimental group in most ways (daily opioid use, MEDD, race, age, and percentages of diabetes, hypertension, and cardiovascular disease), it varied in both BMI (control group had a higher average BMI), and gender (control group had a greater number of male participants). It has been previously demonstrated that a higher BMI favors adherence to CPAP.…”

“…[ 13 ] Despite the potential morbidity of the combination of OSA, central sleep apnea and Opioid use, studies have shown that those that have this combination only remain on definitive treatment for their OSA (CPAP) 37% of the time. [ 14 ] It is, therefore, of the utmost importance that patients who chronically use opioids are evaluated for OSA, and those diagnosed, adhere to CPAP.…”