Obstructive Sleep Apnea Contributes to MS Fatigue
Diagnosing and treating OSA may eliminate 11% to 40% of the fatigue attributed to MS
Some of the fatigue that affects up to 90% of people with MS may be due to obstructive sleep apnea (OSA), according to a recent report in the Journal of Clinical Sleep Medicine from researchers at the University of Michigan (Braley et al., 2014).
MS-related fatigue has been attributed to the disease itself or its drug treatments (Bøe Lunde et al., 2012), and the National Sleep Foundation suggests that increasing fatigue parallels disease progression. Other studies have linked OSA and MS fatigue (Veauthier et al., 2011; Kaynak et al., 2006).
Confusing the issue is the high prevalence of OSA in the general population. According to the American Academy of Sleep Medicine, 7% of men and 5% of women have OSA, but the prevalence could be up to 24% for men and 9% for women if individuals without daytime sleepiness are considered. A study by Marta Kaminska, M.D., at Royal Victoria Hospital in Quebec, Canada, and colleagues that compared ambulatory MS patients without a sleep disorder diagnosis to controls found that OSA is over-represented among people with MS. Using polysomnography and multiple sleep tests, they found that 36 of 62 (58%) of MS patients had OSA compared to 15 out of 32 (46%) controls, and that severe fatigue was associated with OSA in MS but not controls (Kaminska et al., 2012). “Fatigue” means lack of energy during the day, not poor ability to fall or stay asleep at night (Neau et al., 2012).
In the current study, Tiffany J. Braley, M.D., M.S., an assistant professor of neurology at the University of Michigan’s Multiple Sclerosis and Sleep Disorders centers, Benjamin M. Segal, M.D., director of the Multiple Sclerosis Center, and Ronald D. Chervin, M.D., M.S., director of the Sleep Disorders Center, designed a questionnaire and gave it to 195 MS patients. The instrument assessed sleep quality, duration, related drug use, daytime symptoms, CPAP (continuous positive airway pressure) use, and symptoms such as pain, tingling, restlessness, anxiety, urinary urgency, twitching, and ease of falling asleep.
The researchers also used assessment scales for sleepiness, fatigue severity, insomnia severity, and a questionnaire called STOP-Bang (an acronym for Snoring, Tired, Observed apnea, Blood Pressure, BMI (>35), Age (>50), Neck circumference (>17 inches for men, >16 inches for women), and Gender). They also considered MS stage, disease duration, drugs, depression, and degree of disability.
The mean age of participants was 47 years, and 66% were female. Their mean disease duration was 10.2 years, 74% had relapsing-remitting MS, and 68% took drugs for MS.
Of the 195 patients, 110 (56%) had increased risk of OSA according to a STOP-Bang score greater than 3. Of the 41 (21%) diagnosed with OSA, 32 were prescribed CPAP, and 17 used it. Patients who reported the greatest fatigue were at higher risk for OSA.
The researchers recommend use of STOP-Bang to identify MS patients who might benefit from a formal sleep study. Although this investigation could not detect causation, the researchers suggested that diagnosing and treating OSA can potentially eliminate 11% to 40% of fatigue attributed to MS.
Key open questions
- To what extent does intervention (CPAP) to address OSA ameliorate MS-related fatigue?
- Which are the most effective instruments for identifying people with MS who might benefit from a sleep study?
- What clinical benefit might derive from treating OSA in MS patients who do not have fatigue?
Disclosures and sources of funding
Drs. Braley, Segal, and Chervin hold or have filed patents with the University of Michigan on treatment for OSA. The study was not industry-funded. Drs. Kaminska, Trojan, and Kimoff received research support from VitalAire Inc. and Philips Respironics, and Dr. Kaminska receives support also from ResMed.