Development and content validity of the Barth Syndrome Symptom Assessment (BTHS-SA) for adolescents and adults

Table 5 Key indicators of content validity for the BTHS-SA, adult version

Item	Interpreted as intended (n, %)	Relevance*		Mean response selected, range^†	Mean noticeable change rating^‡ (SD)	Mean important change rating^§ (SD)
Item	Interpreted as intended (n, %)	Experienced within the past 24 h	Experienced outside of the 24-h recall period	Mean response selected, range^†	Mean noticeable change rating^‡ (SD)	Mean important change rating^§ (SD)
Item 1: Tiredness at rest	12/12 (100.0%)	10/12 (83.3%)	1/12 (8.3%)	2.00, 0–4	1.10 (0.32)	1.78 (0.83)
Item 2: Tiredness during activities	12/12 (100.0%)	n = 12/12 (100.0%)	0/0 (0.0%)	2.42, 1–3	1.36 (0.50)	2.10 (0.57)
Item 3: Muscle weakness at rest	10/11 (90.9%)	8/11 (72.7%)	0/0 (0.0%)	1.25, 0–4	1.14 (0.38)	1.50 (1.07)
Item 4: Muscle weakness during activities	12/12 (100.0%)	10/12 (83.3%)	2/12 (16.7%)	2.17, 0–4	1.18 (0.40)	1.82 (0.60)
Item 5: Muscle pain at rest	11/12 (91.7%)	6/11 (54.5%)	4/11 (63.4%)	1.64, 0–3	1.11 (0.33)	1.75 (0.71)
Item 6: Muscle pain due to activities	12/12 (100.0%)	9/12 (75.0%)	3/12 (25.0%)	2.08, 1–4	1.55 (0.69)	1.90 (0.74)
Item 7: Dizziness/‌lightheadedness	11/11 (100.0%)	8/12 (66.7%)	2/12 (16.7%)	1.42, 0–4	1.38 (0.74)	1.63 (1.06)
Item 8: Shortness of breath	12/12 (100.0%)	10/12 (83.3%)	2/12 (16.7%)	2.00, 1–3	1.25 (0.45)	1.82 (0.60)

^*Number and percent of participants experiencing the symptom in the 24 h prior (and prior to the past 24 h) to assessment as reported during CDIs
^†Severity as reported during CDIs on a five-point response scale (“No [CONCEPT] at all” to “Very severe [CONCEPT]”)
^‡The minimum change on a five-point response scale that would represent a noticeable improvement in the symptom concept
^§The minimum change on a five-point response scale that would represent an important improvement in the symptom concept

ISSN: 1750-1172