Autoregressive cross-lagged models of IMPACT-III and Pediatric Crohn's Disease Activity Indexes during one year infliximab therapy in pediatric patients with Crohn's disease

Background: Quality of life (QoL) is an important outcome measure in the evaluation of therapies for inflammatory bowel disease. The primary aim of this study was to determine the effect of one year infliximab treatment on QoL and clinical parameters in pediatric patients with Crohn's diseases (CD).

Methods: Our prospective study involved 51 children with conventional therapy resistant, severe CD (mean age: 15.25years, range: 11-18years). Infliximab was given according to the protocol (5mg/kg, at weeks 0, 2, 6 and every 8weeks). During the infliximab courses QoL of patients was evaluated by IMPACT-III questionnaire at weeks 0, 6, 30 and 53. At the same time, the Pediatric Crohn's Disease Activity Index (PCDAI) score was calculated. Moreover, serum C-reactive protein (CRP), serum platelets and serum albumin were followed up. Auto-regressive, cross-lagged models were used to assess relation between QoL and the clinical parameters.

Results: The initial IMPACT-III scores [median, percentile 25-75 (pc 25-75) at week 0: 115, 102.5-130.25] increased significantly (p<0.001) following infliximab therapy at week 54 (median: 141.5, 124.5-153.75). Clinical and laboratory parameters also improved significantly (p<0.001). Auto-regressive regression coefficients (β value) were significant between each variable over time. The strongest cross-lagged relations were observed between IMPACT-III and serum albumin, IMPACT-III and platelets. Reliability test of IMPACT-III revealed an excellent level of internal consistency (Cronbach's alpha=0.931).

Conclusion: Infliximab treatment has beneficial clinical effect which is confirmed by decrease of PCDAI and increase of IMPACT-III. Autoregressive regression analysis showed regression relation between IMPACT-III and PCDAI and laboratory parameters.