The Calgary Kids' Hand Rule: External Validation of a Prediction Model to Triage Pediatric Hand Fractures

Background: The Calgary Kids' Hand Rule (CKHR) is a clinical prediction rule intended to guide referral decisions for pediatric hand fractures presenting to the emergency department, identifying "complex" fractures that require surgical referral and optimizing care through better matching of patients' needs to provider expertise. The objective of this study was to externally validate the CKHR in two different tertiary pediatric hospitals in Canada. Methods: We partnered with British Columbia Children's Hospital (BCCH) and the Children's Hospital of Eastern Ontario (CHEO) to externally validate the CKHR using data from retrospective cohorts of pediatric hand fractures (via electronic medical record and x-ray review). Model performance was evaluated at each site using sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and the C-statistic. Results: A total of 954 hand fractures were included in the analysis (524 at BCCH and 430 at CHEO. At BCCH, the CKHR had a sensitivity of 91.1% (133 predicted complex out of 146 total complex fractures), specificity of 71.4% (269 predicted simple out of 377 total simple fractures), and C-statistic of .81, 95% CI [0.78-0.84]. At CHEO, the CKHR had a sensitivity of 98.3%, specificity of 30.2%, and C-statistic of .64, 95% CI [0.61-0.67]. Conclusion: The CKHR performed well at two different tertiary care centres with high sensitivity, supporting its ability to facilitate hand fracture triage in other populations without further modification. This work should be followed by rigorous implementation analysis to determine its impact on patient care.