687 Diagnostic value of serum Procalcitonin to differentiate between systemic bacterial infection & flare in febrile children with chronic rheumatological disease

Children with chronic rheumatological diseases often suffer from various complications in the form of disease flare and bacterial sepsis. Classical laboratory markers have a very limited role in distinguishing between these two clinically close entities. This study aims to fill in the gap and explore the role of procalcitonin as a marker to separate the two phenomena.

Objectives

To evaluate the role of serum procalcitonin as a diagnostic tool to differentiate bacterial sepsis from flare-up during febrile episodes in children with known rheumatological disorders in comparison with other inflammatory markers like CRP, ESR.

Methods

Previously diagnosed patients with known rheumatological disorders presenting in ER/OPD with febrile episodes were included in the study. Blood sample was drawn for serum procalcitonin along with other routine tests at admission in search of definite laboratory/radiological feature of infection. Patients with JIA and SLE were stratified using the JADAS 27 disease activity scores and SLEDAI respectively. Patients without bacterial focus with high disease activity were included in flare-up group and rest in sepsis cohort. Diagnostic value of PCT was calculated using ROC curve analysis.

Results

In the study N=31, 18 (58.1%) patients were previously diagnosed with JIA, rest 13 (41.9%) had SLE. Total 16 patients had definite evidence of sepsis and 15 had disease flare-up as per respective disease activity scores. Among the flare-up and sepsis group, there was significant difference in PCT and CRP. For detecting sepsis, the AUC (0.963), sensitivity (93.8%) and specificity (86.7%) of PCT at cut-off of 0.275ng/ml was significantly better than those of CRP. To achieve a comparable sensitivity, the cut-off values for CRP and ESR were 11.8mg/dl and 55.5 mm/hr, respectively.

Conclusion

Serum PCT value is better diagnostic test than CRP or ESR during febrile episodes in differentiating flare-up from infection and PCT cut-off >0.275ng/ml indicates bacterial infection with good specificity and sensitivity in children with low disease activity. Figure 1 shows Receiver Operative Characteristics (ROC) curve with different marker under study to differentiate flare-up from bacterial sepsis.