Quantifying the Age of Evidence: Lessons From Cardiovascular Drugs

All evidence-based medical decisions rely on the assumption that the evidence being used is applicable to current populations. To date, the age of evidence is not typically measured nor reported in systematic reviews.

We sought to develop a method to quantify the age of evidence for medical interventions, using statins and sodium-glucose co-transporter protein 2 (SGLT-2) inhibitors as exemplars, which may facilitate evaluating its potential outdatedness. We conducted a retrospective cross-sectional study of all Cochrane reviews evaluating the effects of these drugs on cardiovascular disease (CVD) management up to August 2024, summarising the evidence and calculating the lag in time between patient enrolment in trials and current decision-making (August 2024).

We identified 57 Cochrane reviews on statins, with 9 (15.8%) meeting our criteria, and 6 reviews on SGLT-2 inhibitors, with 2 (33.3%) being eligible. The 9 statin reviews include 153 different trials, enrolling participants from 1988 to 2017, spanning 28 years. The 2 SGLT-2 inhibitor reviews involve 67 trials from 2008 to 2021, spanning 13 years. The median age of evidence for statins is 24.1 years, compared to 8.6 years for SGLT-2 inhibitors. Among the statin review topics, evidence was most robust for statins in the context of primary prevention of CVD.

Our findings highlight the potential outdatedness of long-established treatments like statins and suggest that reporting the age of evidence in systematic reviews may facilitate outdatedness assessments. We propose that future Cochrane reviews report the age of evidence, as this could significantly enhance the decision-making process in evidence-based medicine.