P419 Proximal Crohn’s disease location is associated with a more benign course of perianal Crohn’s disease (the PERIAPROX study)
Bibliographic record
Abstract
Abstract Background Proximal Crohn’s disease (CD) location (L4 according to the Montreal Classification) is associated with a more severe course with higher risk of abdominal surgery. However, little is known about the relation with perianal disease. The aim of our study was to investigate the impact of L4 disease location on perianal disease incidence and clinical course. Methods A case-control study was conducted in the prospectively maintained ENEIDA database for all CD with and without L4 location between January 2005 and March 2023. Demographic data, disease characteristics, perianal disease diagnosis and evolution according to biologic therapy and surgery requirement were collected. Demographic data, CD characteristics, perianal disease diagnosis and course were analyzed. Cox proportional hazards and Kaplan-Meier methods were used for the analysis of perianal incidence, and biologic and surgery requirement. Results A cohort of 14022 CD patients were included in the analysis. The mean follow-up duration was 6.4 years (SD 4.9). L4 location showed a lower prevalence of perianal disease (18.0 vs 19.9%, p=0.018), with lower rate of fistulas (60.9 vs 66.1%, p=0.021) and perianal abscesses (33.5 vs 39.4%, p=0.013). Perianal disease and L4 were associated with male sex (OR 1.29, p<0.001), younger age (43 vs 44), and the structuring phenotype (OR 2.14, p<0.001). L4 location was associated with a lower incidence of perianal disease (HR 0.891, p=0.041), while proctitis was associated with a higher risk (HR=2.161, p<0.001). L4 location was also associated with a lower requirement for biologics (HR 0.712, p=0.023), along with advanced age (HR 0.988, p<0.001). Proctitis (HR 1.292) and a history of perianal surgery (3.373) were associated with a higher requirement for biologics. At univariate analysis, L4 location was associated with a lower requirement of surgery (HR 0.833), however at multivariate analysis this finding was not confirmed (p=0.525). Instead, a history of active smoking (HR 1.419), the use of biologics (HR 2.262), and CD penetrating pattern (HR 1.277) were associated with a higher requirement for perianal surgery. Conclusion L4 location is associated with a lower incidence of perianal disease and a more benign course with lower requirement for biologics and surgery.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".