A157 THE THRESHOLD FOR INFLIXIMAB TROUGH LEVELS LEADING TO DOSE ESCALATION DIFFERS BETWEEN CROHN’S DISEASE AND ULCERATIVE COLITIS
Bibliographic record
Abstract
Therapeutic drug monitoring (TDM) of infliximab (IFX) provides an objective measure that allows physicians to optimize the dose for patients on biologic therapies and potentially reduce loss of response (LOR). The currently accepted therapeutic range is 3 – 7 μg/mL. With the potential for LOR with low drug levels and the high cost of IFX, it is important to manage medications efficiently. To better understand how physicians at the University of Alberta Hospital are using TDM, we conducted a retrospective chart review to see the clinical decisions made in response to TDM. Major clinical decisions include: no change, dose escalate (increase in dose or shorten interval), reload (2 extra doses 2 weeks apart), or dose de-escalate (decrease in dose or lengthen interval). To measure the proportion of IFX trough levels that lead to a clinical change in therapy and compare how the cut-offs used to change therapy vary by disease type. This is a retrospective chart review of all IBD patients (17+ years) on IFX at the University of Alberta IBD Clinic who had at least one trough level measured between 2015 and 2017. Charts were reviewed for demographic data, TDM drug levels, and any clinical decisions relating to the drug levels. Numerical data and categorical data are presented as a mean (standard deviation) and proportions, respectively, using t-tests and Chi-squared tests. Statistical significance is assessed at p<0.05. The information of 758 drug levels was collected from 402 patients. Demographic data for the drug levels included: 51.7% male; 72.1% Crohn’s disease; mean age of 38.9 (±14.8). 54.5% of all levels had the patient on concomitant immunosuppressants. Of all trough levels, 344 (45.4%) led to a clinical change in therapy. A majority (52.7%) of trough levels that had an elevated fecal calprotectin (FCP) of >250μg/g led to a dose escalation (p<0.001). Drug levels with positive IFX antibodies (ATIs) correlate to switching to a new biologic (p=0.042) where the mean ATI level was 3.00 (3.39). Table 1 shows the mean IFX level for clinical changes made by disease type. Physicians at the University of Alberta IBD Clinic use FCP, a therapeutic range of ~3 – 14 μg/mL, and the presence of antibodies as major factors in making clinical changes in IFX therapy for patients with IBD. Cut-offs used to reload and dose escalate are significantly higher in UC patients compared to CD patients. Table 1. Mean infliximab level for each clinical change and how they vary by CD and UC Department of Medicine Clinical Research and Projects Studentship Grant
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.015 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".