Rasch analysis of the EQ-5D-3L and the EQ-5D-5L in persons with back and neck pain receiving physiotherapy in a primary care context

Figures & data

Table 1. Sample characteristics by group (n = 164).

	Group 3L	Group 5L
Participants, n	114	50
Age,mean:SD	46:11.6	47:18.9
Women, n (%)	80 (70)	31 (62)
Location of pain, n (%)
Back	51 (45)	24 (48)
Neck	24 (21)	12 (24)
Both back and neck	39 (34)	14 (28)
Average pain last 7 days mean:SD (11-point numeric rating scale)	6.02:2.0	5.55:1.5
Daily pain, n (%)	48 (42)	19 (38)
Periods of pain once a year or more n (%)	87 (76)	23 (46)

Table 2. Category structure based on all persons who took EQ-5D-3L and EQ-5D-5L*.

Category label	Observed count, n (%)	Infit MnSq	Outfit MnSq	Threshold	Average category measure
EQ-5D-3L
1 No problems	322 (57)	0.96	0.96	None	−4.19
2 Moderate problems	207 (36)	1.02	0.56	−3.09	0.00
3 Extreme problems	40 (7)	1.11	1.23	3.09	4.19
EQ-5D-5L
1 No problems	101 (41)	0.93	0.94	None	−4.41
2 Slight problems	81 (33)	1.02	0.86	−3.28	−1.79
3 Moderate problems	54 (22)	1.06	1.05	−0.29	1.65
4 Severe problems	13 (5)	0.92	0.94	3.57	4.69
5 Extreme problems	0

^* All numbers are given in logits unless any other unit is set.

Figure 1. (a) Visual description of the category probability curves of the EQ-5D-3L rating scale. (b) Visual description of the category probability curves of the EQ-5D-5L rating scale.

Figure 2. (a) Item-person map indicating the targeting of the persons to the items in EQ-5D-3L. Each “#” is 2 persons and each “.” is 1 person. (b) Item-person map indicating the targeting of the persons to the items in EQ-5D-5L. Each “X” is 1 person.

Table 3. Summary of results.

Analysis*	Scale
	EQ-5D-3L	EQ-5D-5L
PCA: Rasch dimension	70.6%	72.4%
PCA: First contrast (eigenvalue)	1.5	1.6
Person separation index	1.16	1.67
Person separation reliability	0.57	0.74
Mean person measure	−3.58	−2.29
Person measure SD	0.38	0.16
Mean person SE	1.45	0.97
Mean item SE	0.31	0.30

^* All numbers are given in logits unless any other unit is set.