Change point models for discontinuation rates of Pneumocystis carinii pneumonia prophylaxis in an Ontario HIV patient population
Bibliographic record
Abstract
Background. In an article published in the Lancet (Schneider et al., 1999), a prospective observational study's preliminary results indicated that the prophylactic treatment to eliminate the Pneumocystis carinii Pneumonia (PCP) fungi could safely be discontinued if a patient's CD4 cell count had increased above 200 cells/mm3 and later guidelines indicated the increase should be sustained for at least three months. Conclusions. The analysis of time to discontinuation of PCP prophylaxis in a cohort of HIV patients provides evidence that there was a significant change in the discontinuation rate in late January, 1999 for most sites with one site having a separate change point in early November, 1999. The adjusted rate of discontinuation rate doubles after clinical evidence was published that it was safe to discontinue PCP prophylaxis under certain conditions. Results. The adjusted discontinuation rate doubles after the change point at January 25, 1999 for all sites except site X1 where the change point is November 1, 1999 (relative rate=2.01, 95% confidence interval 1.25,3.21)). Being a patient at site X2, or having a high CD4 count, and 'after change point' are factors associated with higher discontinuation rates. Lower discontinuation rates are associated with HIV Risk (sex with men) or patients at site X1. Interpretation of the significant interaction, indicates that undetectable viral load values are related to higher discontinuation rates after the change point. Methods. An extract from the HIV Ontario Observational Database included patients who were HIV positive and had a record of initiating PCP prophylaxis before January 1, 1998. Bootstrap methods were developed to estimate the change points in the underlying discontinuation rates of PCP prophylaxis and corresponding confidence intervals for an exponential survival model with one or two change points.
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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 | 0.030 | 0.049 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.006 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.004 | 0.002 |
| Research integrity | 0.002 | 0.005 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".