Preventive health care, 2000 update: screening and management of hyperhomocysteinemia for the prevention of coronary artery disease events
Bibliographic record
Abstract
OBJECTIVE: To establish guidelines for the screening and treatment of hyperhomocysteinemia in the investigation and management of coronary artery disease (CAD). OPTIONS: Measurement of plasma total homocysteine (tHcy) levels in the fasting state or 4-6 hours after oral methionine load; vitamin supplementation with folic acid and vitamins B6 and B12; adherence to the recommended daily allowance of dietary sources of folate and vitamins B6 and B12. OUTCOMES: This article reviews the available evidence on the association between plasma tHcy levels and CAD and the effect of lowering tHcy levels through vitamin supplementation or dietary intake. EVIDENCE: MEDLINE was searched for relevant English-language articles published from January 1966 to June 1999; also reviewed were additional articles identified from the bibliographies. BENEFITS, HARMS AND COSTS: Cardiovascular disease is the leading cause of death in Canada. Homocysteine, generated in the metabolism of methionine, may have a role in the development of cardiovascular disease. The prevalence of hyperhomocysteinemia in the general population is between 5% and 10% and may be as high as 30%-40% in the elderly population. If population-based studies are correct, tHcy may be responsible for up to 10% of CAD events and thus may represent an important and potentially modifiable risk factor for cardiovascular disease. Laboratory testing for tHcy is currently restricted to research centres, and costs range from $30 to $50 per person. Newer, less costly techniques have been developed and should become readily available with time. VALUES: The strength of evidence was evaluated using the methods of the Canadian Task Force on Preventive Health Care. RECOMMENDATIONS: Although there is insufficient evidence to recommend the screening or management of hyperhomocysteinemia at present (grade C recommendation), adherence to recommended daily allowance of dietary sources of folate and vitamins B12 and B6 should be encouraged. If elevated tHcy levels are discovered, vitamin deficiency should be ruled out to allow specific treatment and prevention of complications, such as neurological sequelae due to vitamin B12 deficiency. Experts in the field advocate treatment of elevated tHcy levels in high-risk people, such as those with a personal or family history of premature atherosclerosis or a predisposition to develop hyperhomocysteinemia. Definitive guidelines for the management of hyperhomocysteinemia await the completion of randomized trials to establish the effect of vitamin supplementation on CAD events. VALIDATION: The findings of this analysis were reviewed through an iterative process by the members of the Canadian Task Force on Preventive Health Care. SPONSORS: The Canadian Task Force on Preventive Health Care is funded through a partnership between the Provincial and Territorial Ministries of Health and Health Canada.
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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 | 0.005 | 0.018 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.011 | 0.008 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.004 | 0.004 |
| Insufficient payload (model declined to judge) | 0.009 | 0.005 |
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".