Table 3.

Non-parametric and regression-based estimates of minimal clinically important differences for seven fatigue instruments in rheumatoid arthritis.

		Non-parametric MCID estimates			Regression based MCID estimates
Fatigue Instrument	About the Same *	About the same ↔ A little bit more	About the same ↔ A little bit less	P-value	Regression-based MCID **	Standardized MCID
FSS	3.4 (−1.0 – 7.9)	16.7 (8.1 – 25.2)	6.6 (−3.4 – 16.6)	0.14	20.2 (15.5 – 25.0)	0.74
VT	0.51 (−3.5 – 4.5)	11.9 (4.2 – 19.6)	11.3 (2.2 – 20.3)	0.92	14.8 (10.6 – 19.0)	0.67
MAF	3.7 (0.01 – 7.5)	17 (10.1 – 24.4)	11 (2.7 – 19.4)	0.27	18.7 (14.5 – 22.9)	0.75
MFI	0.13 (−3.1 – 3.3)	11.9 (5.8 – 18.1)	8.5 (1.3 – 15.7)	0.48	16.6 (13.0 – 20.2)	0.76
FACIT–F	1.1 (−2.2 – 4.5)	10 (3.6 – 16.5)	13 (5.5 – 20.5)	0.56	15.9 (12.3 – 19.6)	0.75
CFS	1.6 (−2.2 – 5.5)	10.5 (3.1 – 17.9)	4.4 (−4.25 – 13.1)	0.30	9.9 (5.9 – 13.8)	0.54
RS	2.2 (−2.6 – 7.0)	15.1 (6.0 – 24.3)	9.1 (−1.6 – 19.8)	0.41	19.7 (14.6 – 24.8)	0.70

Legend. Results are estimated values with 95% confidence intervals, computed for normalized scores (0–100). P-value is for test of equality of non-parametric MCID estimates for “A little bit more fatigue” and “A little bit less fatigue”.

^*Mean differences scores for the seven fatigue measurement tools for the “About the same” contrast category.

^**Accounting for the non-reproducibility of the comparison ratings, and for possible artefacts such as self-reference bias and interview-order effects.

Abbreviations. MCID: minimal clinically important difference. FSS: Fatigue Severity Scale, VT: Vitality scale of the MOS-SF36, MAF: Multidimensional Assessment of Fatigue, MFI: Multidimensional Fatigue Inventory, FACIT–F: Functional Assessment of Chronic Illness Therapy–Fatigue scale, CFS: Chalder Fatigue Scale, RS: 10-point Rating Scale.