OBJECTIVES:  Citing insufficient evidence, American College of Cardiology and American Heart Association guidelines have abstained from recommending routine genotyping of CYP2C19in clopidogrel patients who undergo percutaneous coronary intervention (PCI). A quantitative assessment of pharmacogenomic evidence levels may be helpful for policy makers, particularly when ‘insufficient evidence’ recommendations are common. The objective of this study was to quantify evidence levels over time using value of information (VOI) analyses for two interventions in PCI patients on clopidogrel: pharmacogenomic-guided antiplatelet therapy and drug-drug interaction avoidance. METHODS:  We conducted two cumulative meta-analyses of the relative risk for major cardiovascular events in (1) reduced-function CYP2C19carriers versus non-carriers and (2) concomitant PPI-treated patients versus those on clopidogrel monotherapy. We then utilized the cumulative estimates in VOI model analyses to assess evidence levels over time for (1) pharmacogenomic-guided antiplatelet selection, and (2) avoidance of proton pump inhibitors (PPIs) in clopidogrel patients. RESULTS: The value of conducting future research per patient fell over time for both interventions as evidence accumulated, decreasing over time from $650 and $620 per patient to $370 and $450 for pharmacogenomics and PPI avoidance, respectively.  The value of research for pharmacogenomics decreased from $370 to $110 with a decrease in test cost from $220 to $0. CONCLUSIONS:  Our findings suggest that the evidence levels for pharmacogenomics and drug-drug interaction-based interventions are generally similar, although the value of future research was slightly higher for drug-drug interactions. Our analysis demonstrates how the current evidence levels for two well-known interventions intended to improve clopidogrel therapy can be quantitatively compared using the novel approach of combining chronological evidence synthesis with value of information frameworks. Quantifying current evidence levels and the value of future research may be useful for developing more consistent and transparent pharmacogenomic testing recommendations, particularly in the era of rapidly falling testing costs.