Implantable ventricular assist devices: is it time to introduce them in Canada?
Bibliographic record
Abstract
BACKGROUND: Implantable left ventricular assist devices (LVAD) are increasingly used in Europe and the United States. Any decision to use them in Canada requires estimates of their clinical value and costs. MATERIALS AND METHODS: No randomized controlled trials are available. Clinical value and costs, concerning principally the HeartMate and Novacor devices, were estimated based on reports of uncontrolled case series obtained through MEDLINE (1993 to 1999), review articles, three technology assessments and data supplied by the manufacturers. RESULTS AND DISCUSSION: Reasonably trouble-free device function can be expected for three to four years. The principal application is as a bridge to transplantation. Rarely, the heart recovers without transplantation. Use as 'permanent' support of the failing heart is still contentious. Approximately 70% of patients with an implanted LVAD survive until recovery or transplantation. Complications are hemorrhage, principally postoperative, 20% to 44%; thromboembolism, ranging from 5% to 15% for the HeartMate to 12% to 37% for Novacor; and significant infection, 50%. Quality of life is slightly inferior to that of patients with transplanted hearts. The direct cost to the health care system of installation is approximately $138,000. As a bridge to transplantation, the estimated cost effectiveness of elective interventions is $91,000 to $126,000 per life-year saved ($117,000 to $186,000, discounted at 5%), and as a permanent alternative to transplantation, the cost per life-year is $52,000 to $60,000 ($50, 000 to $58,000, discounted at 5%), according to circumstances. As a bridge to 50 transplantations per year, the approximate annual cost would be $7 to $13 million (exclusive of transplantation costs). As 'permanent' support for 7000 patients per year, the approximate cost would be $2,661 million per year. CONCLUSIONS: Limited application in a limited number of centres with collection of all data is justifiable at this stage.
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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 | 0.007 | 0.020 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.004 | 0.004 |
| Scholarly communication | 0.005 | 0.005 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.008 | 0.006 |
| Insufficient payload (model declined to judge) | 0.019 | 0.002 |
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".