Psychometric properties of the FACT-M questionnaire in patients with Merkel cell carcinoma

Table 4 Internal consistency reliability and clinical and concurrent validity of the FACT-M and MCC-specific scores in the mMCC population

FACT-M Subscales and Summary scores	# of items	Cronbach’s alpha^a	Scale structure		ECOG PS (mean [SD])			EQ-5D VAS	EQ-5D index
FACT-M Subscales and Summary scores	# of items	Cronbach’s alpha^a	Range of item-subscale correlations^b	Convergent^c/ Divergent^d validity (% of items)	0 (N = 39)	1 (N = 31)	p-value^e	Correlation^b	Correlation^b
FACT-G subscales
Physical well-being (PWB)	7	0.86	0.49–0.81	100/57	23.21 (5.02)	20.10 (6.08)	0.0221	0.44	0.75
Social/Family well-being (SWB)	7	0.81	0.41–0.86	100/71	23.03 (4.78)	21.49 (5.30)	0.2065	0.15	0.24
Emotional well-being (EWB)	6	0.83	0.53–0.75	100/67	17.97 (4.22)	16.87 (4.95)	0.3179	0.32	0.53
Functional well-being (FWB)	7	0.87	0.49–0.82	100/71	17.41 (6.68)	15.48 (5.90)	0.2113	0.29	0.63
Melanoma-specific subscales
Melanoma Subscale (MS)	16	0.85	0.24–0.85	75/31	51.64 (8.93)	49.10 (9.02)	0.2427	0.39	0.75
Melanoma surgery Scale (MSS)	8	0.84	0.15–0.81	88/63	26.51 (6.19)	25.58 (6.03)	0.5290	0.16	0.51
Summary scales
FACT-M TOI	30	0.94	–	–	92.26 (18.75)	84.68 (19.40)	0.1026	0.41	0.78
FACT-G total score	27	0.94	–	–	81.62 (17.25)	73.95 (17.62)	0.0713	0.37	0.67
FACT-M total score	43	0.96	–	–	133.26 (24.66)	123.04 (25.21)	0.0926	0.40	0.74
MCC-specific scores
Physical Function score (PF)	6	0.88	–	–	16.38 (5.67)	13.71 (5.54)	0.0519	0.37	0.72
Psychological Impact score (PI)	6	0.85	–	–	17.82 (4.40)	16.87 (5.18)	0.4101	0.30	0.52
MCC summary score	12	0.91	–	–	34.21 (8.99)	30.58 (9.94)	0.1145	0.37	0.69

# number, ECOG PS Eastern Cooperative Oncology Group performance status, MCC Merkel cell carcinoma, PAS PRO analysis set, SD standard deviation, TOI Trial Outcome Index
^aRecommended threshold α > 0.7; ^bPearson correlation coefficients; ^c% of items correlated with its own dimension ≥0.4; ^d% of items correlated with its own dimension higher than the correlation with any other dimension; ^e p-value from t-test of score between the two ECOG PS groups at baseline
Internal consistency reliability and clinical validity were assessed in the PAS (N = 70)
ECOG PS: 0 = fully active; 1 = restricted in physically strenuous activity