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 alphaa | Scale structure | ECOG PS (mean [SD]) | EQ-5D VAS | EQ-5D index | |||
|---|---|---|---|---|---|---|---|---|---|
| Range of item-subscale correlationsb | Convergentc/ Divergentd validity (% of items) | 0 (N = 39) | 1 (N = 31) | p-valuee | Correlationb | Correlationb | |||
| 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