Are biomarker levels a good follow-up tool for evaluating obstructive sleep apnea syndrome treatments?

BACKGROUND: Polysomnography is the standard method for evaluating results of treatments for obstructive sleep apnea syndrome (OSAS), but it is time-consuming and often unavailable.
OBJECTIVES: This study aimed to analyze the correlations between sleepiness, anthropometric parameters, exhaled breath condensate (EBC) and serum cytokine levels with changes in the apnea-hypopnea index (AHI), in order to identify potential measurements that could be an alternative to polysomnography.
METHODS: Based on AHI results, 22 non-OSAS and 68 OSAS cases were followed up. Among the 68 patients, 5 underwent surgery, 2 were treated with oral appliances, 33 were treated using continuous positive airway pressure and 28 were untreated. AHI, anthropometric parameters, serum and EBC levels of interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha) and 8-isoprostane were measured at baseline and after a 2-month follow-up. Correlations between the AHI and the other parameters were examined. Akaike's information criterion (AIC) was used to evaluate the fit of logistic regression models, predicting improvements in the severity of the condition from the parameters.
RESULTS: IL-6 and TNF-alpha in EBC and serum gave the highest correlation coefficients (r = 0.62 and r = 0.71 in EBC; r = 0.58 and r = 0.66 in serum, respectively) as well as the lowest AIC values (63.87, 68.97; 62.65, 70.64, respectively). Reductions in waist circumference and weight also correlated with changes in AHI (r = 0.69, AIC = 80.26 and 88.76, respectively).
CONCLUSIONS: IL-6 and TNF-alpha measurements may be used in OSAS treatment follow-ups, when polysomnography is not available. Waist circumference and weight could also be used when cytokine laboratory facilities are unavailable. Copyright 2008 S. Karger AG, Basel.