A risk score for predicting peripheral arterial disease in individuals 75 years or older

The prevalence of peripheral arterial disease (PAD) in the elderly is high. Most are asymptomatic and the sensitivity of the physical exam is low. In Brazil, little is known in regard to PAD risk factors in the elderly.

To identify risk factors for PAD among elderly individuals (> or = 75 years) in the community and to develop a prediction score.

Cross-sectional, prospective, community-based study nested within a cohort study ("Epidoso"). A total of 176 individuals were assessed. PAD was defined as an ankle-brachial index < or = 0.9. Risk factors associated with PAD were entered into a multivariate logistic regression model. Statistical modeling was used to formulate a score according to the likelihood of PAD. A p value <0.05 was significant.

PAD was present in 36.4% of participants. Abnormal pedal pulses, hypertension, cigarette smoking, and complain of leg pain/discomfort in either leg on walking were predictors of PAD. Based on the coefficients of the logistic regression, these variables were given scores of 13, 9, 5 and 5, respectively. A cutoff point >18 points defined the "high risk" individuals and yielded sensitivity, specificity, positive predictive value and negative predictive value of 85.9%, 71.4%, 63.2% and 89.9%, respectively. Receiver-operator characteristic analysis yielded area under curve of 85%, indicating excellent discrimination and goodness-of-fit statistics indicated excellent calibration (p=0.639).

Because of its good performance, the proposed score can become a simple and useful tool to identify elderly community residents at higher risk of PAD who should be considered for further investigation.