Clinical determinants of severe vaso-occlusive crisis in pediatric sickle cell anemia: a retrospective cohort study

Vaso-occlusive crisis (VOC) is the most common cause of hospitalization and morbidity among children with sickle cell anemia (SCA). Identifying clinical predictors of severe VOC may help improve early risk stratification and management. This study aimed to identify clinical determinants associated with severe VOC among pediatric patients with SCA.

A retrospective observational study was conducted using hospital-based data from pediatric patients with confirmed SCA admitted with VOC in southern Saudi Arabia between August 2025 and December 2025. Severe VOC was defined using a composite outcome including severe pain, prolonged hospitalization, or intensive care unit (ICU) admission. Demographic characteristics, treatment exposures, and admission clinical parameters were analyzed. Independent predictors of severe VOC were identified using multivariable logistic regression analysis.

A total of 776 pediatric patients with SCA were included (mean age 9.5±3.6 years; 54.5% male). Severe VOC occurred in 385 patients (49.6%). In multivariable logistic regression analysis (n=596), higher admission temperature [adjusted odds ratio (aOR) 1.69, 95% confidence interval (CI): 1.34-2.15, P<0.001] and increased annual blood transfusion frequency (aOR 1.28, 95% CI: 1.16-1.40, P<0.001) were independently associated with severe VOC. Hydroxyurea therapy demonstrated a protective effect, reducing the risk of severe crisis by approximately 42% (aOR 0.58, 95% CI: 0.43-0.78, P<0.001). The predictive model showed modest but statistically significant discrimination (AUC 0.626, 95% CI: 0.587-0.665, P<0.001).

Severe VOC in children with SCA appears to be primarily associated with acute inflammatory triggers, particularly elevated admission temperature, and markers of underlying disease severity such as frequent transfusion requirements. Hydroxyurea therapy demonstrated a significant protective effect, supporting its role in reducing the risk of severe VOC complications.