Epidemiology of distal symmetrical neuropathies in the Italian elderly

Abstract

To estimate prevalence and incidence of distal symmetric neuropathies (DSN) in the Italian elderly, and to evaluate the accuracy of our procedure to screen for DSN. In eight Italian municipalities, a population-based sample was directly evaluated both at baseline (1992) and after a 3-year follow-up. Cohort members who had died were studied. DSN diagnosis and subtyping were made according to specified diagnostic criteria. Our screening procedure proved accurate (sensitivity 94.7%, specificity 70%, positive predictive value 18.9%), and provided an adjusted prevalence of 7.0 (95% CI, 6.9 to 7.0). Women outnumber men both in the oldest age groups and as a whole. Rates increase with increasing age in both genders. Among the 2,845 individuals re-screened at the follow-up and the 221 deceased subjects with reliable information, we identified 100 incident cases of DSN. Adjusted annual incidence rate (per 1,000 person-years) in the population 65 to 84 years of age is 7.9 (95% CI, 6.3 to 9.5), and for the nondiabetic DSN is 5.76 (95% CI, 4.3 to 7.3). Age significantly predicted the onset of DSN both in diabetic individuals (for every increasing year of age RR = 1.07; 95% CI, 1.01 to 1.14) and in the entire study population (RR = 1.05; 95% CI, 1.02 to 1.09). We provide the first population-based distal symmetric neuropathies incidence data, as well as prevalence rates from an unselected sample of Italian elderly. Distal symmetric neuropathies are an age-associated condition, but the frequency of diabetic distal symmetric neuropathies declines with age, coincident with an increase in nondiabetic cases.