CTF Summary Table: Hyperhomocysteinemia

Canadian Task Force on Preventive Health Care

Summary Table of Recommendations

Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.

Preventive Health Care, 2000 Update: Screening and Management of Hyperhomocysteinemia for the Prevention of Coronary Artery Disease Events

Prepared by Gillian L. Booth, MD, Departments of Medicine, Clinical Epidemiology and Health Care Research Program, University of Toronto, Elaine E. L. Wang, MD, Departments of Pediatrics, Clinical Epidemiology and Health Care Research Program, University of Toronto

These recommendations were finalized by the Task Force in July 1999

MANEUVER EFFECTIVENESS LEVEL OF EVIDENCE <REF> RECOMMENDATION

Fasting or post-methion-ine load plasma total homocysteine Currently available techniques for measuring tHcy have a coefficient of variation ranging from 2-11%. Testing is restricted to research centres.

(a) General population An association between total homocysteine levels and cardiac risk has been shown (the majority of studies measured fasting levels). However, the effect of screening on patient outcomes is unknown. cohort <58> case-control studies <16-39,46,49-51> (II-2) Insufficient evidence to recommend for or against screening for hyper- homocysteinemia in the general population (C).

(b) Individuals at high risk for coronary events Prospective studies have shown a more consistent relationship between total homocysteine and coronary events in patients with pre-existing coronary disease. Again, the effect of screening on patient outcomes is unknown. cohort <56-60> case-control studies <16-39,49,51> (II-2) Insufficient evidence to recommend for or against screening for hyper- homocysteinemia in high-risk populations (C). *

Vitamin therapy Treatment with folic acid (alone or with vitamin B12) is effective in lowering plasma total homocysteine; whereas vitamin B6 lowers post-methionine load levels. There are no completed studies to date regarding the effectiveness of treatment on clinical outcomes. RCTs <23,82-86, 89-91,97-99> (II-1); cohort study <101> (II-2); uncontrolled studies <89-96,102> (II-3) Insufficient evidence to recommend for or against treatment of hyperhomo- cysteinemia with vitamin therapy (C).

*Screening may identify individuals at higher risk of developing coronary artery disease, leading to aggressive risk factor modification. However, there is insufficient evidence to recommend screening for the purpose of treating homocysteine.

Link to Full Text of this review

Link to Structured Abstract of this review

Link to Selected References list of this review

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MANEUVER	EFFECTIVENESS	LEVEL OF EVIDENCE <REF>	RECOMMENDATION
Fasting or post-methion-ine load plasma total homocysteine	Currently available techniques for measuring tHcy have a coefficient of variation ranging from 2-11%. Testing is restricted to research centres.
(a) General population	An association between total homocysteine levels and cardiac risk has been shown (the majority of studies measured fasting levels). However, the effect of screening on patient outcomes is unknown.	cohort <58> case-control studies <16-39,46,49-51> (II-2)	Insufficient evidence to recommend for or against screening for hyper- homocysteinemia in the general population (C).
(b) Individuals at high risk for coronary events	Prospective studies have shown a more consistent relationship between total homocysteine and coronary events in patients with pre-existing coronary disease. Again, the effect of screening on patient outcomes is unknown.	cohort <56-60> case-control studies <16-39,49,51> (II-2)	Insufficient evidence to recommend for or against screening for hyper- homocysteinemia in high-risk populations (C). *
Vitamin therapy	Treatment with folic acid (alone or with vitamin B12) is effective in lowering plasma total homocysteine; whereas vitamin B6 lowers post-methionine load levels. There are no completed studies to date regarding the effectiveness of treatment on clinical outcomes.	RCTs <23,82-86, 89-91,97-99> (II-1); cohort study <101> (II-2); uncontrolled studies <89-96,102> (II-3)	Insufficient evidence to recommend for or against treatment of hyperhomo- cysteinemia with vitamin therapy (C).