OBJECTIVES: Infliximab is recognized as standard-of-treatment for inflammatory bowel disease (IBD). Therapeutic drug monitoring (TDM) measures drug and antibodies to modify dosing to achieve therapeutic response and avoid loss of response. TDM improves outcomes and is more advantageous than empiric changes. Precision-guided dosing (PGD) tools such as, PredictrPK IFX, utilize patient pharmacokinetic parameters in a Bayesian data assimilation method to precisely predict the optimal infliximab dose/interval. PGD can improve outcomes by removing the guesswork often attributed to dose optimization through empiric dosing or TDM strategies. This retrospective chart review (RCR) of random patients from the PredictrPK IFX clinical experience program (CEP) evaluated the real-world outcomes (RWO) and the cost impact.

METHODS: Interim analysis of 44 RCR from 10 CEP centers. Case report forms provided anonymized data on IBD patient’s treatment disposition, PredictrPK IFX results, and RWO based on before/after testing as the index date. The cost impact was extrapolated based on 2020 US-HCUP (ahrq.gov) figures.

RESULTS: Hospitalization duration before/after the PPK-IFX testing was significant (paired t-test and Wilcoxon signed-rank) with a mean difference of 1.4 days (Cohen's d = 0.435). In a subgroup of patients with prior hospitalizations (n=8), mean difference were more pronounced; 7.75 days (paired t-test) and the effect size (Cohen's d = 1.574) was larger, indicating a substantial impact of the PredictrPK IFX test. The extrapolated cost impact estimation using US-HCUP (average length of stay/cost per stay for DIG007-gastritis & duodenitis 3.8/$10,526; DIG012-intestinal obstruction & ileus 5.1/$13,378; DIG022-noninfectious gastroenteritis 3.7/$9,160) was calculated to range from $3,466 to $3,878; for the sub-group, $19,186 to $21,468.

CONCLUSIONS: The interim analysis showed significant reduction in the hospitalization duration post PredictrPK IFX testing, especially in the subset of patients with prior hospitalizations. Favorable cost impact of utilizing the PredictrPK IFX test can be attributed to precisely predicting infliximab dosing and interval.