Correlation Between the Crohn's Disease Activity and Harvey–Bradshaw Indices in Assessing Crohn's Disease Severity

Background & Aims Clinical trials of Crohn's disease generally use the Crohn's Disease Activity Index to assess disease activity; these calculations are complex, time-consuming, and impracticable. We investigated whether a simpler tool, the Harvey–Bradshaw Index, was equally effective in assessing disease severity. Methods Crohn's Disease Activity and Harvey-Bradshaw Index scores were collected from 2 large multicenter Crohn's disease studies. The PEGylated antibody fragment evaluation in Crohn's disease: safety and efficacy (PRECiSE) 1 and 2 trials assessed efficacy and tolerability of certolizumab pegol (PEGylated, humanized, Fab' fragment of an antitumor necrosis factor α antibody). PRECiSE 1 and 2 data were analyzed to determine if results from the Crohn's Disease Activity Index correlated with those from the Harvey-Bradshaw Index criteria for defining response and remission. Results Analysis of almost 1000 data pairs showed a positive correlation between scores. The correlation between the indices for pooled data from PRECiSE 1 and PRECiSE 2 was 0.800 (Spearman correlation coefficient). The correlations between indices for the PRECiSE 1 or PRECiSE 2 were 20.698 and 0.716, respectively (Kronecker product variance). A 3-point change in the Harvey-Bradshaw Index score corresponded to a 100-point change in the Crohn's Disease Activity Index (clinical response); scores ≤4 points corresponded to a Crohn's Disease Activity Index score ≤150 points (clinical remission). Conclusions Results from the Crohn's Disease Activity Index correlate with those from the Harvey-Bradshaw Index; use of the Harvey-Bradshaw Index might permit simpler Crohn's disease activity assessment in long-term clinical trials, and facilitate standardized disease activity measurements and cross-center comparisons.