Improving weight of evidence approaches to chemical evaluations.

Federal and other regulatory agencies often use or claim to use a weight of evidence (WoE) approach in chemical evaluation. Their approaches to the use of WoE, however, differ significantly, rely heavily on subjective professional judgment, and merit improvement. We review uses of WoE approaches in key articles in the peer-reviewed scientific literature, and find significant variations. We find that a hypothesis-based WoE approach, developed by Lorenz Rhomberg et al., can provide a stronger scientific basis for chemical assessment while improving transparency and preserving the appropriate scope of professional judgment. Their approach, while still evolving, relies on the explicit specification of the hypothesized basis for using the information at hand to infer the ability of an agent to cause human health impacts or, more broadly, affect other endpoints of concern. We describe and endorse such a hypothesis-based WoE approach to chemical evaluation.

The cost-effectiveness of omega-3 supplements for prevention of secondary coronary events.

PURPOSE: To project the clinical and economic benefits of omega-3 supplements for prevention of secondary (repeat) cardiovascular events in U.S. males. DESIGN: Decision-analytic model. METHODOLOGY: Model clinical probabilities (rates of fatal myocardial infarction [MI] and cardiovascular death) were based on published trials. Costs were derived from standard U.S. sources. Outcomes include deaths delayed, cost per death delayed, fatal MIs avoided, and cost per fatal MI avoided. Costs, outcomes, and cost-effectiveness were determined for the initial year and over a 42-month model period. Sensitivity analyses were conducted to evaluate the robustness of key model assumptions. PRINCIPAL FINDINGS: According to the model, the use of omega-3 supplements results in fewer fatal MIs and fewer cardiovascular deaths in the short-term (1 year) and longterm (42-month) analyses. When including only direct medical treatment costs for fatal MIs, omega-3 supplementation is cost-effective compared to no supplementation. In terms of total costs (medical costs and decreased productivity), supplementation is cost-saving, providing better outcomes and lower/fewer costs. Supplementation remained cost-effective in all sensitivity analyses. CONCLUSION: Under a variety of scenarios, omega-3 supplements are likely to improve health and lower total costs. Despite model limitations, omega-3 supplementation should be considered an important and cost-effective option for prevention of secondary cardiovascular events.