Objective To determine the agreement between peripheral and central capillary refill time (pCRT/cCRT) and their diagnostic values for detecting serious bacterial infection (SBI) in febrile children attending the paediatric emergency department (ED).

Design Prospective observational study.

Setting Paediatric ED, Erasmus Medium Care-Sophia Children's hospital, the Netherlands.

Patients 1193 consecutively included, previously healthy, febrile children (1 month–16 years) with both pCRT measurements and cCRT measurements available. SBI diagnosis was based on abnormal radiographic findings and/or positive cultures from normally sterile locations in addition to clinical criteria.

Main outcome measures Agreement between pCRT and cCRT (Cohen's κ), overall and stratified for age and body temperature. The diagnostic value of pCRT and cCRT for SBI was assessed with logistic regression.

Results Overall agreement was 0.35 (95% CI 0.27 to 0.43; considered ‘fair’). Although not significant, agreement was lower in children aged 1–<5 years (κ: 0.15 (95% CI 0.04 to 0.27)) and decreased with higher body temperatures with κ ranging from 0.55 (95% CI 0.32 to 0.79) for temperature <37.5°C to 0.21 (95% CI 0.07 to 0.34) for temperature >39.5°C. Abnormal pCRT (>2 s) was observed in 153 (12.8%; 95% CI 10.9% to 14.7%) and abnormal cCRT in 55 (4.6%; 95% CI 3.4% to 5.8%) children. The OR of abnormal pCRT (>2 s) for predicting SBI was 1.10 (95% CI 0.65 to 1.84). For abnormal cCRT (>2 s), the OR was 0.43 (95% CI 0.13 to 1.39).

Conclusions The pCRT and cCRT values showed only fair agreement in a general population of febrile children at the ED, and no significant association with age or body temperature was found. Only a small part of febrile children at risk for serious infections at the ED show abnormal CRT values. Both abnormal pCRT and cCRT (defined as >2 s) performed poorly and were non-significant in this study detecting SBI in a general population of febrile children.