(HealthDay News) — New risk prediction equations have been developed and validated to estimate the risk of blindness and lower limb amputation in patients with diabetes, according to a study published in The BMJ.

Julia Hippisley-Cox, PhD, and Carol Coupland, PhD, from Nottingham University in the United Kingdom, conducted a prospective cohort study using routinely collected data from general practices to estimate the 10-year risk for blindness and lower limb amputation in patients with diabetes aged 25 to 84 years. 

The equations were developed using 454 575 patients with diabetes from QResearch practices; they were validated in two cohorts: 142 419 patients from QResearch practices and 206 050 patients from Clinical Practice Research Datalink (CPRD) practices.

The researchers found that there were 4822 new cases of lower limb amputation and 8063 new cases of blindness in the QResearch derivation cohort during follow-up. In both validation cohorts the risk equations were well calibrated. 

In men, discrimination was good for amputation and blindness in the external CPRD cohort (C-statistics, 0.77 and 0.73, respectively); similar results were seen for women and in the QResearch validation cohort. 

The algorithms were based on variables that patients are likely to know or are routinely recorded.

“[The equations] can be used to identify patients with diabetes at high risk of these complications for further assessment,” the researchers wrote. “Further research is needed to evaluate the clinical outcomes and cost-effectiveness of using these risk equations in primary care.”

One author is co-director of QResearch; both authors disclosed financial ties to ClinRisk Ltd.


  1. Hippisley-Cox J, Coupland C. Development and validation of risk prediction equations to estimate future risk of blindness and lower limb amputation in patients with diabetes: cohort study. BMJ. 2015;doi:10.1136/bmj.h5441.