Predictors of fatigue in obstructive sleep apnea.
OBJECTIVE
The objective of this study was to determine potential inflammatory predictors of fatigue in obstructive sleep apnea (OSA).


METHODS
Fifty-six women and men untreated OSA patients had their sleep monitored with polysomnography. Fatigue was assessed by the Multidimensional Fatigue Symptom Inventory-Short Form. Depressed mood was assessed by the Center for Epidemiologic Studies-Depression Scale. Blood was drawn to assess circulating levels of Interleukin-6 (IL-6) and soluble tumor necrosis factor receptor I (sTNF-RI). Age, gender, body mass index (BMI), blood pressure, OSA severity, depressed mood, and inflammatory biomarkers were entered into a hierarchical multiple linear regression analysis predicting self-reported fatigue.


RESULTS
Approximately 42% of the patients reported significant amounts of fatigue. Higher BMI (p = 0.014), greater depressed mood (p = 0.004), and higher sTNF-RI levels (p = 0.033) were independent predictors of fatigue in the final model (full model R2 = .571; p = .003). Age, gender, blood pressure and apnea severity were unrelated to fatigue.


CONCLUSIONS
The findings suggest that in addition to depressed mood, fatigue in OSA may be associated with increased body weight and elevated levels of the proinflammatory cytokine receptor sTNF-RI. The findings support a linkage between the widely reported fatigue in OSA and a sleep-related component of inflammation.
Mills
Paul J
PJ
Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA. pmills@ucsd.edu
Kim
Jong-Heun
JH
Bardwell
Wayne
W
Hong
Suzi
S
Dimsdale
Joel E
JE
D000328:Adult; D003863:Depression / Q000175:diagnosis*; D005221:Fatigue / Q000209:etiology* / Q000276:immunology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000097:blood*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000276:immunology
D015850:Interleukin-6; D047888:Receptors, Tumor Necrosis Factor, Type I