Positive and negative predictive values of DR for patients with diabetes type 2: (TP) true positive, (TN) true negative, (FP) false positive, (FN) false negative, (ppv) positive predictive value, (npv) negative predictive value.

ppv = TP/(TP+FP) = 49% of all positively tested diabetes patients, 49% have a true DR and 51% do not. npv = TN/(TN+FN) = 98% of all negatively tested diabetes patients, 98% are truly negative for DR, while 2% are not.