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 5 Test–retest reliability of the PMMSA Scores

	Period 1^* (N = 12)	Period 2^† (N = 28)
4FS	0.96	0.91
Tiredness at rest	0.88	0.81
Tiredness during activities	0.94	0.85
Muscle weakness at rest	0.90	0.90
Muscle weakness during activities	0.98	0.92
Balance problems	0.82	0.92
Vision problems	0.98	0.96
Abdominal discomfort	0.93	0.93
Muscle pain	0.94	0.95
Numbness	0.96	0.98
Headache	0.80	0.81

4FS = 4-item Fatigue Scale; PMMSA = Primary Mitochondrial Myopathy Symptom Assessment; TRT = test–retest
^*Test–retest estimates were calculated as the Pearson correlation coefficients relating weekly scores generated during screening Week 1 (Days − 13 to − 7) and screening Week 2 (Days − 6 to 0)
^†Test–retest estimates were calculated as the Pearson correlation coefficients relating weekly scores generated during Study Week 7 and Week 8 (last two weeks of the washout period)