The path to diagnosis in ALS: delay, referrals, alternate diagnoses, and clinical progression.

Objective: To provide a detailed and differentiated description of the path to receiving the correct amyotrophic lateral sclerosis (ALS) diagnosis, including delay times, referrals, alternate diagnoses, and clinical progression.Methods: Medical records until the date of ALS diagnosis were reviewed and linked to the Swedish Motor Neuron Disease Quality Registry.Results: The study included 353 Stockholm ALS patients diagnosed in 2016-2021. Patients were divided into four groups: 117 (33.1%) with lower extremity (LE), 85 (24.1%) with upper extremity (UE), 136 (38.5%) with bulbar, and 15 (4.2%) with respiratory onset. The time from onset to diagnosis was 16.0 (9.4-27.5) months in LE, 12.9 (8.8-17.8) months in UE, 11.7 (7.4-16.0) months in bulbar, and 8.3 (4.7-15.6) months in respiratory onset. Patients with UE or LE onset were often referred to orthopedics or a spinal/hand surgery clinic (29.3% for LE and 41.8% for UE), while bulbar patients were more frequently referred to ENT (66.3%). For those with LE or UE onset, the most common alternate diagnosis was spinal/foraminal stenosis whereas myasthenia gravis and stroke were more common for bulbar onset patients. For the respiratory group, cardiopulmonary diagnoses predominated. The proportion of all patients in King's stage 3 or 4 increased from 11.3% to 46.1% from the initial health care visit to diagnosis.Conclusions: There was great variation in the path to ALS diagnosis according to the onset clinical phenotype. In all groups, the diagnostic delay and clinical progression was substantial. We identified subgroups where the delay was the longest and might be reduced.