Epidemiology of distal symmetrical neuropathies in the Italian elderly

OBJECTIVES: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.