240
Gout-Specifi c HRQOL Measure by Gout Assessment
Questionnaire (GAQ)
GAQ been tested for validity, reliability, and representativeness in the patient
with gout.
Validation Data for GAQ in Chronic Gout
Construct validity: SF-36 pain subscale had high correlation with well-being, produc-
tivity, gout concern, and gout pain and severity on GAQ (correlation coeffi cient rang-
ing from 0.17 to 0.45). There was also high correlation between GAQ and SF-36
physical and social functioning domains. The mean change in GAQ scores for pain
and severity were assessed in three groups based on serum uric acid levels. The three
groups were clinically improved (<6 mg/dL), clinically stable (≥6.0 to <7.8 mg/dL),
and clinically worse (≥7.8 mg/dL). The mean changes were similar at 1, 6, and
12 months in all groups. MCID was calculated using the patient-reported pain fre-
quency and pain severity items from the GAQ as anchors. These items were used to
assess the amount of change in the other scales associated with a minimum 1-point
change in the pain scale (of a 5-point scale), using linear regression. The GAQ items
for pain frequency and severity were well-being, productivity, and gout concern [ 41 ].
The minimal clinically important difference was statistically signifi cantly >0 for all
GAQ items for pain frequency and severity except well-being for pain frequency [ 41 ].
Table 9.6 Mean (±SD) change in SF-36 domain scores from baseline to week 25
Domain PF RP BP GH VT SF RE MH
Pegloticase
biweekly,
n = 61 ††11.8* † 15.4* † 24.3* † 7.7* 9.9* 13.5* † 8.2 10.1
(24.1) (27.8) (25.5) (17.5) (20.1) (28.9) (30.6) (19.2)Pegloticase
monthly,
n = 63 ††9.5* 10.5* 17.9* 4.7 4.3 8.9 4.6 1.4
(20.3) (28.6) (24.2) (17.2) (20.1) (26.5) (30.3) (16.8)Placebo,
n = 38 ††0.25 1.15 −1.13 0.26 0.33 2.63 4.61 4.3
(18.97) (20.90) (20.77) (14.97) (15.24) (23.99) (22.40) (18.1)
Reprinted with permission from Strand V, Khanna D, Singh JA, Forsythe A, Edwards NL. Improved
health-related quality of life and physical function in patients with refractory chronic gout follow-
ing treatment with pegloticase: Evidence from phase iii randomized controlled trials. The Journal
of Rheumatology. 2012 Jul;39(7):1450–1457. All rights reserved [ 9 ]
Shaded area shows changes in domain scores that are greater than or equal to minimum clinically
important differences
SF-36 Short Form-36, BP bodily pain, GH general health, MH mental health, PF physical func-
tioning, RE role emotional, RP role physical, SF social functioning, VT vitality
*p values < 0.05 based on independent-groups t tests of means for treatment groups compared to
placebo
†Approached or met age/sex-matched normative values
††Number of subjects at Week 25; only patients with complete data through Week 25 are included
in this analysis
J. Singh and N. Shah