Table 3.

Nonlinear mixed-effects model analyzing the longitudinal evolution of ALSFRS-r from baseline in ALS patients.

Parameter	Coefficient	SE	p value
xmid (i.e., 50% decrease of ALSFRS-r)
Intercept	−43.833	28.454	0.013
Baseline FA of Cerebral peduncle	83.085	41.435	0.047
Asym (i.e., starting value of ALSFRS-r)
Intercept	44.200	0.803	<0.001
Disease duration at baseline	−0.078	0.039	0.049
Scale	3.098	0.224	<0.001

Positive values of the estimated coefficients, in the submodel of the parameter xmid, indicate that 50% decrease of ALSFRS-r is reached later as the corresponding variable increases; whereas, in the submodel of the parameter Asym, positive values indicate that the starting value of ALSFRS-r is higher as the corresponding variable increases. Abbreviations: ALS = amyotrophic lateral sclerosis; ALSFRS-r = ALS Functional Rating Scale, revised version; CST = corticospinal tract; FA = fractional anisotropy; SE = standard error.