Influence of different screening procedures on the stroke prevalence estimates: The Italian longitudinal study on aging

Stroke prevalence surveys are more and more needed for health care and faci lity planning. Prevalence estimates and costs of the definition procedure m ay vary depending on different screening strategies, We evaluated the impac t of these different strategies on the overall diagnostic procedure and on stroke prevalence estimates in the Italian Longitudinal Study on Aging. A p opulation sample of 5,632 individuals aged 65-84 years was screened for str oke by a simple question on previous stroke diagnosis, questions on possibl e stroke symptoms and a simple neurological examination. Those screened pos itive by any of these procedures were fully examined by a neurologist for c onclusive diagnosis, We determined the positive predictive value of each pr ocedure on the final stroke diagnosis and calculated prevalence as if each procedure had been used separately, Using the three procedures combined, th e prevalence rate was 6.0% (95% confidence interval, 5.4-6.7%), If each pro cedure had been used as the unique screening tool, the rates would have bee n 5.1% (4.5-5.7%), 4.1% (3.6-4.7%) and 2.3% (1.9-2.7%), a nd positive predi ctive values 66.4, 55.2 and 45.1%, respectively, Different screening proced ures can affect stroke prevalence estimates. Compared to more complex scree ning strategies, the use of a simple question about previous diagnosis as t he unique screening tool leads to only a slight underestimation of stroke p revalence and avoids a 66% increase in the number of subjects to be examine d in a second-level specialist evaluation, potentially reducing the costs o f the overall diagnostic procedure.