Plasma Interleukin-33 Cannot Predict Hip Osteonecrosis in Patients With Sickle Cell Disease: A Case-Control Study.

Background Plasma interleukin-33 (IL-33), a cytokine associated with inflammatory and autoimmune disease, has been described to be significantly raised in osteonecrosis of the femoral head (ONFH) and hence was recommended for use as a marker for ONFH. The concentration of plasma interleukin-33 level has not been estimated in any studies conducted in patients with sickle cell disease (SCD); hence, we investigated the levels of plasma interleukin-33 in patients with sickle cell disease with or without ONFH to assess whether it can be used as a marker for the early detection of ONFH in this disease also. Methods Forty-four consecutive patients with sickle cell disease with osteonecrosis of the femoral head and matched controls without ONFH were evaluated for plasma interleukin-33 levels by enzyme-linked immunosorbent assay (ELISA). All patients were confirmed for sickle cell disease using high-performance liquid chromatography (HPLC). ONFH was diagnosed in patients with sickle cell disease using clinical-radiological findings. Univariate and multivariate analyses were performed using the IL-33 level as the dependent variable. Results Plasma IL-33 levels were comparable in 44 patients with sickle cell disease with osteonecrosis of the femoral head as compared with 24 patients with sickle cell disease without ONFH (2.05 ± 4.57 pg/mL versus 1.50 ± 2.89 pg/mL, p-value = 0.590). There was no significant difference in IL-33 levels in different stages of avascular necrosis (AVN). Conclusions Plasma interleukin-33 levels cannot act as a marker of ONFH as were being considered in idiopathic ONFH or ONFH caused by other causes such as trauma and chronic steroid or alcohol usage.