Severe Obstructive Sleep Apnea Linked to Lower Pain Perception Threshold

Patients with severe obstructive sleep apnea (OSA) and obesity have a lower pain perception threshold (PT), according to study results published in the European Journal of Pain.

Patients (N=85) with obesity and who had undergone sleep recording for OSA were enrolled for this study. All participants underwent PT testing using a Von Frey electronic device and the PainMatcherÒ device. The subset of patients with severe OSA (n=11) was reevaluated after 1 month of continuous positive airway pressure (CPAP) treatment. Obesity was defined as body mass index (BMI) of 30 kg/m² or higher and severe OSA as apnea-hypopnea index (AHI) over 30.

The study population comprised patients with a mean [SD] age of 40.1[13.2] years, 69% were women, they had an average BMI of 42.0[7.2] kg/m², 24% smoked, 66% had metabolic syndrome, and AHI score was 11.5[20.1] points. In general, the participants with moderate (n=16) or severe (n=11) OSA were older (P <.0011), and fewer were women (P =.023) compared with patients without OSA.

After adjusting for age, gender, BMI, and smoking status, mechanical PT was significantly lower among patients with OSA (t, 2.40; P =.019), but electrical PT did not differ (t, 1.54; P =.12). Among only the subset with severe OSA, the significant difference in mechanical PT was more pronounced (t, 2.82; P <.01), and the difference in electrical PT reached significance (t, 2.19; P =.03) compared with the non-OSA group.

At 1 month of CPAP treatment, the 7 patients who were reevaluated had a significant increase in mechanical PT (t, 2.50; P <.05) but not in electrical PT (t, 0.72; P =.50).

Significant correlations were observed between mechanical and electrical PT (r, 0.5619; P <.001), and AHI was correlated with mechanical PT (r, -0.239; P =.03).

The major limitation of this study was that the estimated sample size was not reached.

This study found that patients with obesity and severe OSA had significantly decreased PT compared with patients who were obese without OSA, leading the study authors to conclude, “This might therefore contribute to the frequency of chronic pain phenomena in this population. CPAP therapy tends to limit this discrepancy. More than ever, screening and management of OSA is therefore a major challenge in terms of quality of life for patients with obesity.”

This article originally appeared on Clinical Pain Advisor