Critical pertussis: A multicentric analysis of risk factors and outcomes in Oman.

Abstract Objectives To identify risk factors and outcomes of patients with critical pertussis. Design A retrospective observational cohort study. Setting Sultan Qaboos University Hospital and The Royal Hospital, Muscat, Oman. Subjects: Children Measurements and Main Results There were a total of 157 patients with pertussis, of which 12% (n = 19) had critical pertussis. Those with critical pertussis had higher counts of white blood cell (WBC) (adjusted odds ratio (aOR), 1.05; 95% confidence interval (CI): 1.02-1.08; p = 0.003), absolute lymphocyte count (ALC) (aOR, 1.08; 95% CI: 1.03-1.15; p = 0.004) and absolute neutrophil count (ALC) (aOR, 1.05; 95% CI: 1.01-1.10; p = 0.032) even after multivariate adjustment. The area under the curve (AUC) for discriminatory accuracy of laboratory variables were 0.75 (95% CI: 0.65-0.85), 0.74 (95% CI: 0.64-0.84) and 0.72 (95% CI: 0.60-0.83), for maximum WBC, ALC and ANC, with the Youden’s cut-off values of 31.5 x109/L, 19.9 × 109/L and 5.0 × 109/L, respectively. Conclusions In children, higher counts of WBC, ALC and ANC were significant predictors of critical pertussis. A 31.5 × 109/L WBC cut-off was also associated with critical pertussis.