WOMAC Meaningful Within-patient Change: Results From 3 Studies of Tanezumab in Patients With Moderate-to-severe Osteoarthritis of the Hip or Knee

Philip G. Conaghan; Robert H. Dworkin; Thomas J. Schnitzer; Francis Berenbaum; Andrew G. Bushmakin; Joseph C. Cappelleri; Lars Viktrup; Lucy Abraham

doi:10.3899/jrheum.210543

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Figure 1.
Relationship between change in WOMAC domains and PGA-OA in study 3. Using PGA-OA as a continuous variable (blue lines), which implies a linear relationship with the outcome, or as a categorical variable (red lines), which does not impose any functional relationship, revealed an approximately linear relationship with all WOMAC domains in study 3. This relationship is observed when change in WOMAC is reported (A) in original units or (B) as a percentage. A negative change represents an improvement in both measures. Pct: percent; PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.
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Figure 2.
Relationship between change in WOMAC domains and PGA-OA across all studies. The relationship between change in WOMAC domains and PGA-OA was observed across all domains and studies when reported (A) in original units or (B) as a percentage. A negative change represents an improvement in both measures. Pct: percent; PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.
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Figure 3.
eCDF of change in WOMAC Pain score to support anchor-based models. eCDFs for the change in WOMAC Pain at the primary endpoint of each study, reported (A) in original units or (B) as a percentage. eCDF: empirical cumulative distribution function; PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.

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Table 1.

Baseline demographics and disease status of patients in each study.^{^a}

	Study 1, n = 696	Study 2, n = 849	Study 3, n = 2996
Age, yrs	60.8 (9.6)	64.9 (9.4)	60.6 (9.4)
Female, n, (%)	453 (65.1)	587 (69.1)	1953 (65.2)
Index joint, n, (%)
Hip	102 (14.7)	114 (17.0)	443 (14.8)
Knee	594 (85.3)	705 (83.0)	2553 (85.2)
Kellgren-Lawrence grade of index joint, n, (%)
0	0	2 (0.2)	5 (0.2)
1	1 (0.1)	0	7 (0.2)
2	184 (26.5)	166 (19.6)	892 (29.8)
3	304 (43.7)	375 (44.2)	1425 (47.6)
4	206 (29.6)	306 (36.0)	667 (22.3)
Disease duration, yrs	9.3 (8.4)	7.5 (7.0)	8.8 (8.3)
WOMAC Pain	7.2 (1.2)	6.6 (0.9)	7.0 (1.1)
WOMAC Physical Function	7.3 (1.1)	6.7 (0.9)	7.1 (1.1)
PGA-OA	3.5 (0.6)	3.6 (0.6)	3.5 (0.6)

Values are expressed as mean (SD) unless otherwise indicated.
↵^aData were analysed from 688, 844 and 2948 patients from studies 1, 2, and 3, respectively. Patients without data available at all timepoints in the respective studies were excluded from the analyses. PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.

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Table 2.

Correlations between change in WOMAC domains and change in PGA-OA.

WOMAC Domain	Study 1		Study 2		Study 3
WOMAC Domain	Original Units	Percentage	Original Units	Percentage	Original Units	Percentage
Pain	0.613	0.576	0.493	0.477	0.600	0.550
Physical Function	0.624	0.589	0.500	0.491	0.610	0.560
Stiffness	0.549	0.521	0.366	0.358	0.540	0.510
Total	0.615	0.578	0.479	0.479	0.600	0.560

Correlations between change in WOMAC domains and change in PGA-OA at the primary time points of week 16 in studies 1 and 3 and week 24 in study 2. PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.

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Table 3A.

Estimates of meaningful within-patient change by WOMAC domain and study in original units.

WOMAC Domain	Study
	1		2		3
	1-category Change in PGA-OA	2-category Change in PGA-OA	1-category Change in PGA-OA	2-category Change in PGA-OA	1-category Change in PGA-OA	2-category Chan in PGA-OA
Pain	1.14	2.28	0.91	1.82	1.15	2.30
Pain	(1.08–1.20)	(2.16–2.40)	(0.86–0.96)	(1.72–1.92)	(1.12–1.18)	(2.25–2.35)
Physical Function	1.14	2.28	0.85	1.70	1.13	2.26
Physical Function	(1.08–1.20)	(2.16–2.40)	(0.81–0.90)	(1.61–1.80)	(1.11–1.16)	(2.21–2.32)
Stiffness	1.16	2.31	0.84	1.68	1.14	2.27
Stiffness	(1.09–1.22)	(2.17–2.45)	(0.78–0.90)	(1.56–1.81)	(1.11–1.17)	(2.21–2.33)
Total	1.14	2.27	0.86	1.72	1.12	2.25
Total	(1.08–1.19)	(2.16–2.39)	(0.81–0.91)	(1.63–1.82)	(1.10–1.15)	(2.20–2.30)

95% CIs are shown for each value. PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.

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Table 3B.

Estimates of meaningful within-patient change by WOMAC domain and study as percentage change.

WOMAC Domain	Study
	1		2		3
	1-category Change in PGA-OA	2-category Change in PGA-OA	1-category Change in PGA-OA	2-category Change in PGA-OA	1-category Change in PGA-OA	2-category Chan in PGA-OA
Pain	15.51 (14.69–16.34)	31.02 (29.38–32.67)	13.51 (12.74–14.28)	27.02 (25.48–28.56)	15.93 (15.54–16.32)	31.85 (31.07–32.63)
Physical Function	15.31 (14.51–16.10)	30.61 (29.02–32.21)	12.50 (11.81–13.20)	25.01 (23.61–26.41)	15.63 (15.26–16.01)	31.27 (30.52–32.01)
Stiffness	15.36 (14.42–16.29)	30.72 (28.85–32.59)	13.24 (12.14–14.34)	26.47 (24.28–28.67)	16.23 (15.76–16.70)	32.46 (31.52–33.40)
Total	15.15 (14.37–15.93)	30.30 (28.74–31.85)	12.90 (12.19–13.62)	25.80 (24.37–27.24)	15.51 (15.14–15.88)	31.02 (30.29–31.76)

95% CIs are shown for each value. PGA-OA: patient global assessment of osteoarthritis; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index.