Accuracy of death certificates for amyotrophic lateral sclerosis varies significantly from north to south of Italy: Implications for mortality studies

Objective: To evaluate the accuracy of death certificates (DCs) for amyotrophic lateral sclerosis (ALS) in different parts of Italy. Studies based on DC diagnosis for ALS have shown a reduced mortality comparing northern with southern Italy. These data are in contrast with results from other surveys on the incidence of ALS performed in Italy and other countries. Methods: Archives of neurological clinics from northern (Milano, Monza, Pavia, and Bologna) and southern Italy including islands (Napoli, Sassari, Palermo, and Messina) were searched for patients discharged with a diagnosis of ALS in the period 1970-1995. Subjects affected by definite/probable ALS according to the Scottish Motor Neuron Disease Research Group diagnostic criteria were included. DCs were obtained from the vital statistic bureau. True positive rates (TPRs) and 95% confidence intervals (CIs) for proportions were calculated for northern and southern Italy separately. Multiple logistic regression analysis was performe...