Low interleukin (IL)-10 may contribute to COVID-19-related pain, according to findings published in Pain Practice.

The study assessed pain among a cohort of 20 inpatients with COVID-19 at the University Hospital of State University of Londrina in Brazil. Patients were assessed for clinical features, pain, and serum biomarkers.

Patients had a mean age of 53.2±3.5 years, 65% were men, 85% had at least 1 comorbidity, 45% had arterial hypertension, 30% type 2 diabetes mellitus, and 30% obesity. At the study conclusion, 80% had been discharged from the hospital, 20% transferred to the intensive care unit, and 5% had died.


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Nearly half of patients (45%) presented with painful conditions, among which myalgia was most common (88%). Of note, 2 patients reporting no pain indicated they had experienced pain earlier in their COVID-19 disease course.

Stratified by gender, more women reported pain (57.1% vs 38.4%), and women reported higher visual analogue scale (VAS) pain levels (median, 95 vs 80 points). Men were found to have lower plasma leptin levels than women (P=.0456), and this trend was only found among men without pain (P=.0121), not among men with pain (P=.9048).

Stratified by pain status, patients reporting pain had significantly lower IL-10 (P =.0251) and higher leptin (P=.0310) levels. IL-10 levels were significantly correlated with pain VAS scores (r, -0.8609; P=.0029). VAS scores were not correlated with leptin levels (r, 0.5204; P=.1509).

This study was limited by the small sample size and the fact that patients were recruited at hospitals. It remains unclear whether IL-10 levels differ among patients with COVID-19 experiencing pain who do not have severe enough symptoms for hospitalization.

“These data demonstrate a hitherto unknown negative strong correlation between IL-10 blood levels and pain according to VAS score in hospitalized COVID-19 patients in the acute phase of disease,” the study authors noted. “Increased systemic levels of leptin were detected in COVID-19 patients reporting pain, but only a moderate correlation between leptin levels and pain VAS score was detected.”

These findings warrant additional study to determine the biological role of IL-10 in COVID-19-related pain.

Reference

Bussmann AJC, Ferraz CR, Lima AVA, et al. Association between IL-10 systemic low level and highest pain score in patients during symptomatic SARS-CoV-2 Infection. Pain Pract. Published online January 26, 2022. doi:10.1111/papr.13101