Table 3.

Minimal clinically important differences (MCID) of intelligibility and speaking rate, cutoff scores, sensitivity, and specificity.

Cutoff score on ALSFRS-R subscore	MCID	AUC (95% CI)	Sensitivity (95% CI)	Specificity (95% CI)
Intelligibility
1-point change	1.44%	0.63 [0.56, 0.70]	0.48 [0.36, 0.58]	0.77 [0.72, 0.82]
2-point change	3.18%	0.83 [0.75, 0.92]	0.67 [0.46, 0.83]	0.87 [0.83, 0.91]
Score of 4 to score of 3	1.44%	0.62 [0.53, 0.70]	0.41 [0.28, 0.52]	0.79 [0.74, 0.85]
Score of 3 to score of 2	4.55%	0.67 [0.51, 0.84]	0.56 [0.33, 0.78]	0.84 [0.75, 0.91]
Score of 2 to score of 1	1.78%	0.71 [0.45, 0.97]	1 [1.00, 1.00]	0.57 [0.28, 0.86]
Speaking rate
1-point change	8.80 WPM	0.60 [0.53, 0.67]	0.70 [0.61, 0.80]	0.52 [0.46, 0.58]
2-point change	8.44 WPM	0.68 [0.58, 0.79]	0.88 [0.75, 1.00]	0.51 [0.46, 0.57]
Score of 4 to score of 3	19.7 WPM	0.61 [0.53, 0.70]	0.54 [0.43, 0.67]	0.72 [0.66, 0.79]
Score of 3 to score of 2	37.3 WPM	0.58 [0.42, 0.74]	0.50 [0.28, 0.72]	0.75 [0.65, 0.84]
Score of 2 to score of 1	17.93 WPM	0.76 [0.53, 0.99]	1 [1.00, 1.00]	0.71 [0.50, 0.93]

Note. Ninety-five percent CIs are presented in brackets. The cutoff score on the ALSFRS-R speech question was the score used to distinguish between patients who have changed and patients who have not changed. Responses on the speech question range from 4 (normal speech) to 0 (loss of useful speech). The MCIDs are relatively small, although the group who began with a score of 3 and changed to a score of 2 had the highest MCID for both intelligibility and speaking rate. The diagnostic accuracy represented by most of the AUCs, sensitivity values, and specificity values is low, except for when a 2-point change on the ALSFRS-R subscore was used as a cutoff score. ALSFRS-R = ALS Functional Rating Scale–Revised; AUC = area under the curve; CI = confidence interval; WPM = words per minute.