CVD risk scores may be inappropriate in newly diagnosed type 2 diabetes
medwireNews: An evaluation of several cardiovascular disease (CVD) risk scores has highlighted poor performance of these tools among individuals with newly diagnosed type 2 diabetes.
Without recalibration, QRISK2, created for the general population, along with five risk scores developed among diabetes patients, “do not currently meet the standard for application to real-world patients in Scotland,” Stephanie Read (University of Edinburgh, UK) and co-investigators remark.
Among 181,399 people with type 2 diabetes and no history of CVD identified from the Scottish national diabetes register there were 14,081 incident CVD events during 5 years of follow-up. This corresponded to an observed 5-year CVD risk of 9.7%.
Using QRISK2, a risk score not previously validated in type 2 diabetes, the median predicted 5-year CVD risk was 24.1% and 86.8% of the cohort were classified as high risk.
Agreement between the observed and predicted scores was generally better for the ADVANCE, Freemantle diabetes study, Swedish National Diabetes Register (NDR), Cardiovascular Healthy Study (CHS), and New Zealand Diabetes Cohort Study (NZ DCS) risk scores, which were all developed in diabetes populations.
Specifically, median predicted 5-year risks for CVD using these methods were 2.0%, 5.2%, 8.3%, 11.7%, and 16.2%, respectively, and the corresponding proportions classified as high risk were 3.2%, 25.8%, 37.3%, 58.8%, 82.6%.
The researchers also report that C statistics, which measure the ability of the scores to discriminate between people who did and did not develop CVD, ranged from 0.66 to 0.67 for all risk scores, and all decreased with increasing age.
Writing in Diabetes Care, Read and co-authors highlight the importance of risk scores in guiding treatment and communicating risks to patients.
“Unfortunately, we have shown that many existing risk scores do not accurately predict incident CVD risk in people with newly diagnosed type 2 diabetes, though risk scores developed in diabetes populations generally performed better than QRISK2,” they write.
They add: “Current guidelines that recommend using QRISK2 would classify 87% of people with type 2 diabetes in Scotland as high risk, leading to the potential overtreatment of individuals at low risk.
“This approach is therefore not dissimilar to classifying all people aged over 40 years and with type 2 diabetes as high risk, as recommended in several existing clinical guidelines.”
By Laura Cowen
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