Screening for Dysplasia in Primary Sclerosing Cholangitis – A Population-Based Assessment of Physician Practices
Bibliographic record
Abstract
Purpose: Patients with primary sclerosing cholangitis (PSC) and either ulcerative colitis (UC) or Crohn's disease (CD) have a high risk of developing colorectal cancer (CRC). Recent recommendations have suggested annual four quadrant multi-segmental biopsies to detect CRC or dysplasia. Physician adherence to this protocol has not been adequately assessed. Aims: 1) to determine the rate of dysplasia in PSC patients with UC or CD and 2) to assess screening practices by gastroenterologists for PSC. Methods: A population-based study of the Calgary Health Region (CHR) was conducted between April 1, 2000 and March 31, 2005 to identify all patients with a diagnosis of PSC. PSC patients were identified using regional databases (ERCP, health records, diagnostic imaging, transplant and histopathology) and were confirmed by chart review. Histopathology from colonoscopy records was reviewed in CHR patients with PSC and UC or CD for: 1) the number of biopsies taken during screening colonoscopy, 2) frequency of colonoscopies conducted between 2000 and 2005, and 3) the presence of CRC, dysplasia or a dysplasia associated lesion or mass (DALM). Results: During the study period there were 105 patients with PSC identified, 44 resided in the CHR and had UC or CD. Of the 44 patients who were eligible for screening, 5 (11.4%) were diagnosed with dysplasia (n = 2), DALM (n = 2) or CRC (n = 1) in the 5 year screening period. Two of these patients were diagnosed by screening colonoscopies, while the other three were not being screened regularly and were identified because of the development of symptoms. Of an expected 130 screening colonoscopies for dysplasia, only 56 (43%) were actually conducted and only 32% of patients had more than three quarters of their recommended colonoscopies attempted. Those patients undergoing screening colonoscopies had a median of 27 [19–33] biopsies taken. Conclusions: Patients with PSC and UC or CD have a high rate of pre-malignant or malignant colorectal lesions. A population-based assessment of the practice of screening colonoscopies for dysplasia demonstrated that the frequency of screening was low and that sampling was inadequate. Suboptimal screening may explain why two thirds of PSC patients with dysplastic or malignant pathology were identified through symptomatic presentation.
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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 | 0.004 |
| 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 | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".