Federal Register March 25, 2010
Below is the VA proposed changes on Agent Orange Presumption for Heart Disease as Posted in the Federal Register - it takes at least 60 days for these rules to take effect after their are published.
Ischemic Heart Disease
The previous Committee responsible for Update 2006 was divided as to whether the evidence related to IHD and exposure to the compounds of interest was sufficient to advance IHD from the category of ‘‘inadequate or insufficient evidence to determine whether an association exists’’ to the category of ‘‘limited or suggestive evidence of an association.’’ Due to the lack of consensus, the 2006 Committee left IHD in the ‘‘inadequate or insufficient evidence’’ category.
For Update 2008, the Committee revisited the entire body of evidence relating herbicide exposure to heart disease risk and placed more emphasis on studies that had been rigorously conducted. These studies focused specifically on the chemicals of concern, compared Vietnam veterans to non-deployed Vietnam-era veterans, and had individual and reliable measures of exposure that permitted the evaluation of dose-response, to promote the VerDate Nov<24>2008 16:39 Mar 24, 2010 Jkt 220001 PO 00000 Frm 00032 Fmt 4702 Sfmt 4702 E:\FR\FM\25MRP1.SGM 25MRP1 mstockstill on DSKH9S0YB1PROD with PROPOSALS
Federal Register / Vol. 75, No. 57 / Thursday, March 25, 2010 / Proposed Rules 14393 interpretation of epidemiologic data. The Committee identified nine studies (including two new studies) that were deemed most informative. Of these nine studies, five showed strong statistically significant associations between herbicide exposure and ischemic heart
disease. The studies considered by the Committee also included data from Agent Orange sprayers, occupationally exposed populations, and environmentally exposed populations that were either prevalence surveys or mortality follow-up studies. In situations where several alternative analyses were presented, the results with the greatest specificity in the dose-response relationship were given more weight.
The Committee stated that evidence of a dose-response relationship is especially helpful in interpretation of the epidemiological data, and the Committee was impressed by the fact that those studies with the best dose information all showed evidence for risk elevations in the highest exposure categories. The Committee noted that some of the study findings could be limited by the effect of selection bias or possible confounding factors. However, the Committee noted that one of the new studies showed an association that persisted after statistical adjustments for a large number of potential confounding risk factors, which is not generally available in studies of other dioxin exposed populations. The Committee also indicated that the major potential confounders were likely inadequate to explain away the high relative risks and dose-response relationships seen in the data for IHD. Further, the Committee noted that toxicologic data supports the biologic plausibility of an association between exposure to the compounds of interest and IHD.
After considering the relative strengths and weaknesses of the evidence, and emphasizing in particular the numerous studies showing a strong dose-response relationship and good toxicology data regarding IHD, the Committee concluded that there was adequate information to advance IHD from the ‘‘inadequate or insufficient evidence’’ category to the ‘‘limited or suggestive evidence’’ category.
The Secretary has determined that the available scientific and medical evidence presented in Update 2008 and other information available to the Secretary are sufficient to establish a new presumption of service connection for IHD in veterans exposed to herbicides. After considering all of the evidence, the Secretary has concluded that the credible evidence for an association between exposure to an herbicide agent and the occurrence of IHD in humans outweighs the credible evidence against such an association.
Accordingly, the Secretary has determined that a presumption of service connection for IHD is warranted pursuant to 38 U.S.C. 1116(b).
According to Harrison’s Principles of Internal Medicine (Harrison’s Online, Chapter 237, Ischemic Heart Disease,2008), IHD is a condition in which there is an inadequate supply of blood and oxygen to a portion of the myocardium; it typically occurs when there is an imbalance between myocardial oxygen supply and demand. Therefore, for purposes of this regulation, the term ‘‘IHD’’ includes, but is not limited to, acute, subacute, and old myocardial infarction; atherosclerotic cardiovascular disease including coronary artery disease (including coronary spasm) and coronary bypass surgery; and stable, unstable and Prinzmetal’s angina. Since the term refers only to heart disease, it does not include hypertension or peripheral manifestations of arteriosclerosis such as peripheral vascular disease or stroke.