Assessment of interleukin 1 receptor antagonist (IL-1RA) levels in children with and without community acquired pneumonia: a hospital based case-control study.

The primary objective was to compare serum interleukin-1 receptor antagonist (IL-1RA) levels in cases of community acquired pneumonia (CAP) and healthy age-gender-matched controls. The secondary objective was to compare serum IL-1RA levels in cases which were positive or negative for Streptococcus pneumoniae in the blood by real-time-polymerase chain reaction (RT-PCR). Hospitalized children with World Health Organization defined CAP, aged 2-59 months, were included as cases. Healthy controls were recruited from the immunization clinic of the hospital. Enzyme-linked immunosorbent assay (ELISA) test was used to detect serum IL-1RA levels. Identification of S.pneumoniae in blood was done by RT-PCR. From October 2019 to October 2021, 330 cases (123, 37.27% female) and 330 controls (151, 45.75% females) were recruited. Mean serum IL-1RA levels (ng/ml) were 1.36 ± 0.95 in cases and 0.25 ± 0.25 in controls (p < 0.001). Within cases, serum IL-1RA levels were significantly higher in those whose RT-PCR was positive for S.pneumoniae. Thus serum IL-1RA levels may be evaluated as a surrogate marker of S.pneumoniae in future studies.