US estimates of hospitalized pediatric patients with ulcerative colitis: implications for multicenter clinical studies

Abstract

Background: The optimal clinical management of children hospitalized with ulcerative colitis (UC) is evolving. There are limited data quantifying the number of pediatric patients with UC admitted to hospitals in the United States. We analyzed the Kids' Inpatient Database (KID, 2003), to estimate the distribution of hospitalized children with UC and estimate sample sizes available for clinical research.

Methods: We limited our analysis to subjects age less than 18 years. We defined cases of UC as discharge records associated with an ICD-9 code of 556.0-556.9 in the first position. We defined colectomy as principal procedure code of 45.8. We generated weighted estimates for these analyses. To estimate the relationship between number of patients and number of hospitals necessary for clinical trials, we generated 1000 simulated datasets.

Results: A total of 2311 UC cases were identified. The mean age at admission was 13.1 (standard error [SE] 0.1) years, and 9% (SE 0.9%) underwent colectomy during their hospitalization. 1008 UC cases were treated at high-volume hospitals; the majority of these children were treated at children's hospitals. Simulation studies suggest that approximately 5 high-volume hospitals would be necessary to generate sample sizes necessary for a pilot clinical trial of refractory UC.

Conclusions: Approximately half of all young patients hospitalized with UC in the US were treated at a limited number of high-volume hospitals, and approximately 5 such centers would be adequate for pilot clinical trials of hospitalized patients with refractory UC.