Objective: To revise the first diagnosis of amyotrophic lateral sclerosis (ALS) in patients from a well-defined population.
Methods: Patients diagnosed with ALS in the years 1998-2002 and resident of Lombardy Region, Northern Italy were followed until death or April 30 2016 to assess long-term survival. During follow-up, the caring neurologists were asked to confirm the first diagnosis. Revised diagnoses were classified as confirmed and unconfirmed motor neuron disease (MND) with further specification where available. The two groups were compared for age, sex, disease duration at diagnosis, site of onset, and El Escorial category. Survival with predictors were also compared.
Results: Included were 280 men and 203 women aged 18-93 years. During follow-up, 25 cases (5.2%) received a diagnosis different from MND. Diseases of spinal roots and peripheral nerves and vascular encephalopathy predominated. Patients with definite (OR 0.15; 95%CI 0.04-0.52) and probable (OR 0.15; 95%CI 0.04-0.62) ALS were least likely to have an unconfirmed MND diagnosis. At end of follow-up, 2.2% of patients with confirmed MND and 44.0% of patients with unconfirmed MND were reported alive (HR 0.14; 95%CI 0.08-0.25).
Conclusions: At the time of a first diagnosis of ALS, the possibility still exists that another, less severe clinical condition, is present.
Keywords: Amyotrophic lateral sclerosis; epidemiology; false positive diagnosis; motor neuron disease.