BMC Public Health 2007, 7:348 http://www.biomedcentral.com/1471-2458/7/348 If the results confirm our hypothesis we will have an easy, accessible, inexpensive test, which is reproducible in Pri- mary Care and which will allow a better selection of patients in whom an approach of greater therapeutic intensity may be applied to thereby avoid or slow major cardiovascular complications and events. We may then have a test to allow screening for selecting patients prior to performing more complex tests or to decide whether to intensify the interventions in lifestyle or with drugs (stat- ins, acetylsalicillic acid, etc.) On the other hand, the populational, multicentric, pro- spective design of the study, which collects most of the cardiovascular risk factors will allow our cohort to be used to verify the validity of the existing cardiovascular risk fac- tors or those of other similar future projects within the age range of this study. The PERART study may have certain limitations such as not including a population of under the age of 50 years because of the high prevalence of PAD in this age group. Likewise, according to the different studies the variability of the calculation of the AAI between previously trained observers is 7% [46]. To reduce the interobserver variabil- ity to a minumun, the AAI will only be performed by two specially trained healthcare professionals. The sensitivity of the AAI as a predictor of vascular events is low (compared to the specificity). Nonetheless, it will probably be greater than the traditional methods of calcu- lating cardiovascular risk. The Framingham tables and REGICOR are designed to calculate cardiovascular risk in patients between 35 and 74 years in age. In patients > 74 years we will calculate the risk assigning the score corre- sponding to 74 years (maximum risk for age). On the other hand, we will be working with symptomatic dis- eases and thus the patients will be receiving medication, which may modify the natural history of the disease. However, it would not be ethical to discontinue antiaggre- gant treatment in subjects with a diminished AAI. This means that any effect of PAD with respect to the appear- ance of cardiovascular events will be lower than that pro- voked by PAD left to its natural evolution without diagnosis or treatment. In conclusion, the PERART study will attempt to deter- mine the prevalence of PAD in a low cardiovascular risk, Spanish population, and especially, to determine the pre- dictive value of pathologic AAI in relation to the risk of having cardiovascular disease since it may be a better marker than the classical cardiovascular risk factors because of its being indicative of the presence of arterial lesion. Competing interests The author(s) declare that they have no competing inter- ests. 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