Sleep specialists might want to take a closer look at the connections between obstructive sleep apnea, chronic pain, and reported pain intensity in younger patients. Young adults with a diagnosis of obstructive sleep apnea (OSA) are more likely to report moderate to severe pain intensity, compared with their peers who do not have the diagnosis, results from a large cross-sectional analysis of veterans showed.
“Because of the high burden of chronic pain conditions in younger adults, this study highlights the need to understand the impact of OSA diagnosis and treatment on pain intensity,” researchers led by, a graduate student at Yale University, New Haven, Conn., and , a professor of internal medicine at Yale, wrote in an article published in the . “This understanding would then help inform the development of interventions to promote screening for OSA among young adults with chronic pain and pain management among those with diagnosed OSA.”
In an effort to assess whether young adults with diagnosed OSA are more likely to report higher pain intensity, compared with those without OSA, the researchers drew from a sample of 858,226 veterans from Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn who had at least one visit to a VA clinic between 2001 and 2014. They used ICD-9 codes to identify OSA and assessed self-reported responses to pain measures on a 0-10 numeric scale which were recorded in each veteran’s EMR. Next, they averaged pain intensity responses over a 12-month period and categorized them as none (0), mild (1-3), and moderate/severe (4–10). Covariates included age, sex, education, race, mental health diagnoses, headache diagnoses, pain diagnoses, hypertension, diabetes, body mass index, and smoking status. The researchers used multivariate logistic regression models and multiple imputation to generate values for missing variables.
The mean age of the patients was 30 years, 64% were White, 17% were Black, 12% were Hispanic, and remainder were other/unknown race/ethnicity. Ninety percent were male, and 20% had greater than a high school education. Of the 858,226 patients, 91,244 (11%) had a diagnosis of OSA. Compared with patients who had no diagnosis of OSA, the unadjusted odds of reporting moderate/severe pain was 48% higher among those with OSA (odds ratio 1.48; P < .0001). After the researchers adjusted for all covariates in the model, the association between OSA and moderate/severe pain remained significant though attenuated, with an adjusted odds ratio of 1.09 (P < .0001).
Several characteristics were different between those who had a diagnosis of OSA and those who did not, including age (a mean of 36 vs. 26 years, respectively) and having the following diagnoses: pain (36% vs. 16%), headache (28% vs. 14%), diabetes (12% vs. 2%), hypertension (40% vs. 12%), and a body mass index of 30 kg/m2 or greater (69% vs. 35%). Certain psychiatric disorders were also common among patients with OSA, including major depressive disorder (20% vs. 10%), posttraumatic stress disorder (50% vs. 30%), and substance use disorder (26% vs. 17%). Patients with OSA were also more likely to have been prescribed benzodiazepines or opioids within 90 days of their OSA diagnosis. Although men were more likely to have a diagnosis of OSA, no differences related to sex in the association of OSA and pain were observed in sex-based stratified analyses.
“Based on these results, we suggest more thorough and more frequent pain intensity screening in patients with OSA, particularly in those patients who are younger than 60 years old without significant comorbid illness,” the researchers concluded. “Furthermore, we also recommend increased OSA screening for patients with moderate/severe pain intensity and pain diagnoses.” One tool they recommend is the(Snoring, Tiredness, Observed Apnea, Blood Pressure, Body Mass Index, Age, Neck Circumference, and Gender) questionnaire, which has been validated in multiple settings.
Commenting on the findings of this study,, medical director of the Sleep-Wake Center at the University of Utah, Salt Lake City, commended the study design. “One of the problems with sleep apnea studies is that there are always confounding effects, especially from BMI. This is a population that has a significant medical burden of disease, but I think this is a well-done study to look at the relationship between pain and OSA in a younger population. The authors tried to adjust for all these confounders and they still found a significant association. This indicates that sleep affects one’s pain threshold. And sleep apnea, by mechanisms still yet to be defined, also alters that pain threshold. It may also affect the expression of pain or management of pain, making treatment more problematic in this population,” he said in an interview.
A key limitation of the study, he continued, was the fact it evaluated only one aspect of sleep: OSA. “They didn’t look at duration of sleep, comorbid insomnia, or fragmentation of sleep from apnea or from other causes,” Dr. Sundar said. “We have multiple ways of treating sleep apnea. Clearly, we need studies of treating sleep apnea with [continuous positive airway pressure] and how that affects the occurrence of pain. The relevant practical aspect of this is that there are pain clinics all over the country that should screen for sleep apnea. Along the same lines, sleep practitioners should be aware that pain has an important association with sleep apnea.”
The study was supported by the Health Services Research & Development in the Department of Veterans Affairs of the Veterans Health Administration, the Yale School of Medicine Medical Student Fellowship, and the U.S. National Institutes of Health.
SOURCE: Athar W et al.