BACKGROUND: One-third of patients with steroid-refractory ulcerative colitis (UC) do not respond to cyclosporine and require colectomy. Since alternative pharmacological treatments for this condition are available, it is pertinent to identify factors that predict response. The objective of this study was to determine predictive factors of response prior to cyclosporine administration, with validation in an independent cohort. METHODS: The 2 cohorts of patients were identified from prospectively established databases. All patients had received 1 mg/kg/day prednisolone or equivalent for at least 5 days before cyclosporine. The efficacy measure was need of early surgery (within 3 months). RESULTS: From 1998 to 2005, 34 patients were treated in 1 institution (derivation cohort) and 38 patients in the second institution (validation cohort). Eleven patients in the derivation cohort and 9 patients in the validation cohort underwent early colectomy. Univariate analysis in the derivation cohort demonstrated a significant association of colectomy with C-reactive protein (P = 0.012) and the Ho index before initiation of cyclosporine (P = 0.013). Regression analysis showed that only the Ho index (P = 0.011) had an independent predictive value. The Ho index predicted need of colectomy, with an area under the characteristic receiver operating curve of 0.79 (95% confidence interval [CI], 0.59-0.99) in the derivation cohort and 0.74 (95% CI, 0.53-0.96) in the validation cohort. The cutoff point with the best sensitivity and specificity ratio was > or =5. CONCLUSIONS: The Ho-based predictive score is a good predictor of response to cyclosporine and avoidance of colectomy, and may aid in the indication of this treatment for management of steroid-resistant UC.