Creating a nationally representative sample of patients from trauma centers

Background: The National Trauma Data Bank (NTDB) was developed as a convenience sample of registry data from contributing trauma centers (TCs), thus, inferences about trauma patients may not be valid at the national level. The NTDB National Sample was created to obtain nationally representative estimates of trauma patients treated in the US level I and II TCs. Methods: Level I and II TCs in the Trauma Information Exchange Program were identified and a random stratified sample of 100 TCs was selected. The probability- proportional-to-size method was used to select TCs and sample weights were calculated. National Sample Program estimates from 2003 to 2006 were compared with raw NTDB data, and to a subset of TCs in the Healthcare Cost and Utilization Project Nationwide Inpatient Sample, a population-based dataset drawn from community hospitals. Results: Weighted estimates from the NTDB National Sample range from 484,000 (2004) to 608,000 (2006) trauma incidents. Crude NTDB data over-represented the proportion of younger patients (0 years-14 years) compared with the NTDB National Sample, which does not include children's hospitals. Few TCs in Trauma Information Exchange Program are included in Healthcare Cost and Utilization Project Nationwide Inpatient Sample, but estimates based on this subset indicate a higher percentage of older patients (age 65 year or older, 23.98% versus 17.85%), lower percentage male patients, and a lower percentage of motor vehicle accidents compared with NTDB National Sample. Conclusion: Although nationally representative data regarding trauma patients are available in other population-based samples, they do not represent TCs patients and lack the specificity of National Sample Program data, which contains detailed information on injury mechanisms, diagnoses, and hospital treatment.