Psychometric performance of the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA) in a randomized, double-blind, placebo-controlled crossover study in subjects with mitochondrial disease

Journal of Patient-Reported Outcomes

Table 8 Correlations between weekly PMMSA change scores and reference variable change scores (N = 27)

	4FS	Item 1 Tiredness at rest	Item 2 Tiredness during activities	Item 3 Muscle weakness at rest	Item 4 Muscle weakness during activities	Item 5 Balance problems	Item 6 Vision problems	Item 7 Abdominal discomfort	Item 8 Muscle pain	Item 9 Numbness	Item 10 Headache
Neuro-QoL Fatigue	0.71^*	0.72	0.70	0.58	0.62	0.64	0.46	0.21	0.47	0.23	0.35
PhGA	− 0.04	− 0.03	− 0.05	− 0.08	0.06	− 0.24	0.16	− 0.22	0.08	− 0.3	0.22
PGA	0.13	0.23	0.14	0.14	0.21	0.03	0.15	0.29	0.15	− 0.22	0.04
6MWT distance	− 0.46^†	− 0.37	− 0.44	− 0.53	− 0.35	− 0.31	− 0.26	− 0.01	− 0.33	− 0.08	− 0.28
3TUG time to completion	0.21	0.24	0.17	0.28	0.07	0.18	− 0.03	− 0.06	0.11	0.16	0.01

^*p < 0.001 and ^†p < 0.05
3TUG = Triple Timed Up and Go test; 4FS = Fatigue 4 Scale; 6MWT = six-minute walk test; Neuro-QoL = Quality of Life in Neurological Disorders; PGA = Patient Global Assessment; PhGA = Physician Global Assessment; PMMSA = Primary Mitochondrial Myopathy Symptom Assessment. PhGA, PGA, and 6MWT PRO Borg items are assessed using Spearman’s correlations; all other reported correlations are Pearson’s