RESULTS
A total of 2,301, children under the age of two were hospitalized due to RSV bronchiolitis, of which 1,874 were included in the study (Figure 1). Patients’ mean age was 6.7 months (SD ± 5.9), 55.9% were male and 62.6% were of Bedouin origin. The mean hospital LOS was 3.57 days. 104 children were admitted to the PICU (5.5%), with an average PICU LOS of 5 days (SD ± 4.4 days). The mean MOS was 89%. Additionally, approximately one-quarter of the children had co-infection with a second virus, with adenovirus present in 8.9% of cases (Table 2b). additional demographic and clinical parameters are presented in Table 1.
The cohort was divided into a low-CRP group and a high-CRP group based on the median CRP value of 1.92 mg/dL (Table 2a). The two groups had similar gender, ethnicity, gestational age, and prior diagnosis of RDS. The high-CRP group had a significantly higher mean CRP level of 14 mg/dL compared to 1 mg/dL in the low-CRP group (p<0.001). Children in the high-CRP group were older (7.3 vs. 6.0 months, p<0.001) and had slightly lower birthweight (3,087 vs. 3,141 grams, p=0.047). Additionally, they had longer hospital LOS (3.83 days VS. 3.31, p=0.001) and a lower prevalence of BPD in their medical history (0.2% vs 1%, p=0.034).
Children in the higher-CRP group had lower minimal saturation (88% vs. 89%, p=0.002 ), a higher rate of prolonged LOS (defined as ≥ of 75% of LOS percentile, 4.3 days) (28.9% vs. 21.0%p<0.001 ), and a higher incidence of pneumonia (9.4% vs. 4.3%, p<0.001 ), UTI (2.2% Vs., 0.2%p<0.001 ), and AOM (1.7% Vs. 0.2%p<0.001 ). Viral co-infection was more common in the low-CRP group (28.1% Vs. 25.2% p<0.001 ), while adenovirus infection was more common in the high-CRP group (10.5% Vs. 7.4% p<0.001 ). The PICU admission rate was twice as high in the high-CRP group (7.4% Vs. 3.7% p<0.001 ). We observed a higher rate of antibiotic treatment in the high-CRP group (49.8% Vs. 37.2% p<0.001 ). No significant differences in hyponatremia rates, bacteremia, glucocorticosteroid use, ventilation duration, or readmission rates were found between the two groups.
After adjusting for age and sex in a multivariable regression model, it was found that the high-CRP group had a higher risk for PICU admission (RR = 2.25 CI 1.40, 3.71 p=0.001 ), UTI (RR = 11.6, CI 3.67, 61.4p<0.001 ), pneumonia (RR = 1.98 CI 1.39, 2.87p<0.001 ), and prolonged LOS (RR = 1.44 CI 1.23, 1.70p<0.001 ) (Table 3, Figure 2).
The optimal cutoff values of CRP for predicting severity outcomes, calculated using Youden’s index, were 1.9 mg/dL with an AUC of 0.72 for predicting UTI, 2.81 mg/dL with an AUC of 0.62 for predicting pneumonia, and 3.51 mg/dL with an AUC of 0.61 for predicting PICU admission (Figure 3).