Purpose: Genetic tests can be used in high-risk individuals to see if they are genetically disposed to disease in order to target or tailor primary preventive interventions. We evaluated the cost effectiveness of this practice compared to administering the standard intervention to the whole high-risk group.
Methods: Data from peer-reviewed cost effectiveness models for preventive interventions in those identified as high-risk through common methods such as age, body mass index, or family history, were used to estimate the effect size that would be needed for an intervention in the positive genetic test group to be as cost effective as the standard intervention is in the whole high-risk population. The models used included increasing physical activity to prevent a range of common adult diseases; diet, weight reduction, and physical activity interventions to reduce the risk of type-2 diabetes; statins to reduce the risk of CVD; and aspirin to reduce the risk of stroke and myocardial infarction. The analysis was run varying the proportion of tested individuals identified as predisposed by the genetic test and varying the test cost.
Results: In many cases, testing to identify genetically predisposed candidates for non-standard primary preventive intervention is much less cost effective than administering the standard intervention to all high-risk individuals, even if the intervention costs are identical. Sensitivity analysis indicates that such genetic testing is only cost effective when the incremental effectiveness in genetically predisposed high-risk individuals is higher than is realistic. Even when test cost was $300 and the likelihood of a positive result was 15%, all interventions modeled required a relative increase in effect size among genetically predisposed high-risk individuals of at least 35% (35%-500%) to be as cost effective as the standard intervention in the high-risk group. When the test cost $1000 and the likelihood of a positive result was 5%, all interventions modeled required a relative increase in effect size among genetically predisposed high-risk individuals of at least 400% (400%-6000%) for genetic screening to be as cost effective as standard practice in the high-risk group.
Conclusions: The results indicate that unrealistic increases in effectiveness are necessary for genetic testing to be cost-effective in a primary preventive setting.
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