230
for the respective PROs at OMERACT-11 [ 36 ]. Function assessment by Health
Assessment Questionnaire-Disability Index (HAQ-DI) was not endorsed as a valid
measure, citing the need for more robust data [ 37 ]. Also, measures of non-core
domains such as work disability, joint erythema, acute phase markers, and physician
global still need validation [ 37 ].
The core set domains for chronic gout are serum urate, gout fl are recurrence,
tophus regression, joint damage imaging, health related quality of life, function,
patient global assessment, participation, safety, and tolerability [ 38 ] (Fig. 9.2 ). VAS
for pain and patient global, Short Form-36 (SF-36) for pain, and HAQ-DI for activ-
ity limitation were endorsed PROMs for these PROs [ 8 ]. Gout assessment question-
naire (GAQ) v2.0 for chronic gout needs future research and validation according to
the discussions at OMERACT-10 [ 8 ].
Some concerns by patients with gout have emerged in the recent qualitative work,
which had not emerged in previous qualitative work done at OMERACT. Therefore,
these were not taken into account while developing the current gout core set domains
endorsed by OMERACT. In particular, important areas identifi ed to consider as
potential domains or subdomains for the future are: diffi culty wearing shoes, having
to undertake a restrictive diet, and interference with sleep and sexual activity were
ranked highly by patients and not included in OMERACT domains [ 39 ].
Each PROM for PRO endorsed for acute and chronic gout has been tested for
validity, discriminative ability, and is feasible in randomized controlled trials (RCTs)
in gout. The validation data for each of these measures is presented in Table 9.1 [ 8 ].
All the measures shown in Table 9.1 have been endorsed during the OMERACT
gout workshops except GAQ v2.0, which was shown to have poor internal consis-
tency and low validity [ 8 , 40 ]. The scale of measurement, mean/median scores, and
effect sizes for these PROMs are presented in Table 9.2 [ 7 , 20 , 21 , 36 , 41 – 45 ].
In the sections that follow, we describe the validity data for the PROMs for gout
endorsed for measurement of each PRO, such as pain, function, HRQOL, mobility,
and satisfaction.
PROMs for Pain
Pain is considered the fi fth vital sign [ 46 ] and one of the commonest symptoms in
the general population [ 47 ]. Due to its critical importance, it is measured at every
patient encounter in the USA, alongside pulse rate, blood pressure, respiratory rate,
and temperature. Pain is a subjective phenomenon and the current gold standard is
the patient-report. Pain experience is unique to each person and is infl uenced by the
patient’s comorbidity and emotional and psychosocial experiences. Gout with its
characteristic acute fl ares and chronic, infl ammatory arthritis presentation has pain
as a cardinal feature. The following sections summarize the data on pain outcome
measures in patients with chronic and acute gout. The effects of various treatment
regimens on VAS pain scores for acute and chronic gout are summarized in Table 9.3
[ 48 – 52 ] and Table 9.4 [ 9 , 53 ], respectively.
J. Singh and N. Shah