King's college progression rate at first clinical evaluation: A new measure of disease progression in amyotrophic lateral sclerosis.

BACKGROUND

To estimate King's college clinical stage progression rate (ΔKC) at first clinical evaluation in order to define its predictive and prognostic role on survival in a large cohort of Amyotrophic Lateral Sclerosis (ALS) patients.

METHODS

The ΔKC was calculated with the following formula: 0 - KC clinical stage at first clinical evaluation/disease duration from onset to first evaluation, and each result was reported as absolute value. All the evaluations were performed in two cohorts: one from our tertiary centre for motor neuron disease and the other one from a pooled resource open-access ALS clinical trials (PRO-ACT) database. C-statistic was used to evaluate the model discrimination of survival at different time points (1-3 years). Cox proportional hazard model was used to identify factors associated with survival.

RESULTS

ΔKC predicted survival at three years in our centre and in the PRO-ACT cohort (C-statistic 0.83, 95% CI 0.8-0.86, p < 0.0001; 0.7, 95% CI 0.68-0.73, p < 0.0001, respectively). At multivariate analysis, ΔKC was independently associated with survival both in our cohort (HR 3.62 95% CI 2.71-4.83 p = 0.001) and in the PRO-ACT cohort (HR 2.75 95% CI 2.1-3.6 p = 0.001).

CONCLUSIONS

Based on our results, ΔKC could be used as a novel measure of disease progression, hence as an accurate predictor of survival in ALS patients. Indeed, greater values of ΔKC were associated with a 3.5-fold higher risk to experience the event, confirming its robust prognostic value.