medwireNews: Implementation of widespread screening for diabetes “radically” alters the cardiovascular risk profile of people with newly detected diabetes, rendering existing cardiovascular (CV) risk prediction tools inaccurate, say researchers.
The team found that median 5-year CV risk assessed with the New Zealand Diabetes Cohort Study (NZDCS) prediction tool, based on the characteristics of people recruited between 2000 and 2006, was 14.2% in women and 17.1% in men recruited between 2004 and 2016, during which time screening rates markedly increased.
However, when assessed with a new tool developed using the more contemporary cohort, the corresponding risk rates were just 4.0% and 7.1%.
The contemporary cohort (the PREDICT-1° Diabetes subcohort) comprised 46,652 people with diabetes, aged an average of 54 years, recruited from primary care between 2004 to 2016.
Around half of this cohort was recruited after 2010, when screening was becoming increasingly common. The researchers explain that changes to government health guidelines in New Zealand, starting in 2003, led to diabetes screening rates increasing from about 15% in 2001 to 50% in 2012 and 90% in 2016.
“Recent widespread diabetes screening has radically changed the cardiovascular risk profile of patients with diabetes in New Zealand,” write Rod Jackson (University of Auckland, New Zealand) and study co-authors in The Lancet.
The PREDICT-1° Diabetes subcohort had a total of 4114 first CV disease events during a median 5.2 years of follow-up. Significant predictors of CV events included age; ethnicity; diabetes duration; smoking; socioeconomic status; levels of glycated hemoglobin, blood pressure, and cholesterol; and baseline use of medications, including glucose-lowering and blood pressure medications.
The researchers incorporated these factors into their new CV prediction tool, creating male- and female-specific versions, which they say “showed excellent calibration across all risk deciles in both sexes.”
By contrast, the CV event rates predicted by the older NZDCS tool were significantly higher than the observed rates in the PREDICT-1° Diabetes participants. The team recalibrated the NZDCS tool using CV risk data from the PREDICT-1° Diabetes cohort, resulting in a much improved fit to the observed CV risk, bar slight underestimation of risk for women in the highest three risk deciles.
Jackson and team conclude that CV risk distribution in a population with high diabetes screening levels “bears little resemblance to” that of a population assessed “just a few years before introduction of widespread screening.”
They add: “The view articulated in a number of international guidelines that the majority of patients with diabetes are at high cardiovascular risk and should receive cardioprotective treatments will no longer be valid in the presence of widespread screening.”
The researchers say that updated risk prediction tools will be required if screening becomes commonplace, otherwise, “low-risk patients might be overtreated with new-generation glucose-lowering medications that have only been shown to reduce cardiovascular events in patients at high cardiovascular risk.”
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