Objective:

To investigate if there is there an association between increased interleukin-6 (IL-6) levels and the outcomes of post-acute sequelae of COVID-19 (PASC).

Background:

Hyperactivation of humoral immune pathway, including IL-6 was reported in severe COVID-19 infection. However, the association of abnormal IL-6 and PASC has not be investigated.

Design/Methods:

We conducted a retrospective analysis using the EPIC Electronic Medical Record System for the years 2020 to 2023 to identify PASC patients with normal or abnormal levels of serum IL-6. The IL-6 grouping was determined using LOINC coding procedures. Patient discharge to hospice was incorporated into mortality.

Results:

3,081 PASC patients with abnormal serum IL-6 (P1) were compared to 425 PASC patients with normal serum IL-6 (P2). The diagnostic rate with concomitant neuro-PASC symptoms was not significantly different between P1 and P2 (P1/P2: 72.7% vs 73.9%; p>0.05). P1 patients had a significantly higher mortality rate (P1/P2: 10.3% vs 2.8%; p<0.05), higher mechanical ventilation rates (P1/P2: 28.6% vs 5.2%; p<0.05), greater percentage of patients with an elevated BMI (71.3% vs 46.4%; p<0.05), higher rate of disability (P1/P2: 18.5% vs 12.0%; p<0.05), older age (P1/P2: 59±0.62 years vs 50±1.79 years; p<0.05), and longer length of hospitalization (P1/P2: 11.3±0.57 days vs 8±1.74 days; p<0.05) There was a significantly more women in P1 compared to P2 (P1 M/F: 33.4%/66.6% vs P2 M/F: 52.0%/47.9%; p<0.05).

Conclusions:

PASC patients with abnormal serum levels of IL-6 have significantly higher rates of mortality, length of stay, disability, and rate of mechanical ventilation compared to PASC patients with normal serum levels of IL-6. They also tend to have higher BMI values.