Neutrophil-to-lymphocyte ratio decreases in obstructive sleep apnea treated with mandibular advancement devices

Obstructive sleep apnea has been associated with chronic inflammation triggered by nocturnal hypoxemia. The neutrophil-to-lymphocyte ratio (NLR) is a measure of subclinical systemic inflammation. We hypothesize that NLR levels would improve as chronic inflammation diminishes in obstructive sleep apnea (OSA) patients treated with mandibular advancement devices (MADs).

We studied patients with OSA who were treated with MAD as a first-line treatment or because they could not tolerate CPAP. We obtained pre-treatment and post-treatment complete blood counts. NLR was calculated by dividing the number of neutrophils by the number of lymphocytes obtained from the CBCs. Patients with other conditions known to affect NLR were excluded from the study.

We compared the values of NLR and oxygen desaturation index (ODI) before and after treatment with MAD in 22 patients who met inclusion criteria and completed the study protocol. There was a significant difference in NLR before and after treatment (p = 0.01). There was also a significant difference in the 3% ODI and 4% ODI before and after treatment with MAD (p = 0.014, 0.007), respectively. A subgroup analysis compared NLR in two groups of patients, the optimally treated and suboptimally treated. There was a significant decrease in the NLR in the optimally treated group (n = 10) (p < 0.01), whereas it did not change in the suboptimally treated group (n = 12) (p = 0.349).

The neutrophil-to-lymphocyte ratio may be useful in documenting improvement in inflammation for OSA patients treated with mandibular advancement devices. Our results specifically suggest that the NLR values are associated with the decrease in the ODI.