Table 5.

Summary of activity limitation instruments used in studies of acute gout.

Method	Description	Number and type of studies with references	Feasibility	Truth	Within-group discrimination (ES)	Between-group discrimination (estimate or statistic with p-value)
Health Assessment Questionnaire (HAQ)	0-3 composite scale (0=no disability, 3=complete disability)	Total: 2 Controlled: 1 (18) using 20 item HAQ-DI Observational: 1 (26) using 10 item HAQ-II	Inexpensive, no training required, no specialist equipment required, acceptable to patients	High face validity. Improvement in the HAQ-DI score was accompanied by similar reductions in joint tenderness and swelling, pain score, C-reactive protein and PGART (18). Improvement in HAQ scores was accompanied by similar improvements in other measures of disability including the SF-36 PF score (18), Leeds Foot Impact Scale and the Lower Limb Task Questionnaire (26). Unable to calculate correlation coefficients with available information. Measure has been endorsed by OMERACT for use in chronic gout studies (7).	Both articles reported significant reduction in HAQ scores over time. In an observational study, mean (SD) HAQ-II score reduced from 1.9 (0.6) at baseline to 0.9 (0.6) at the follow up visit (>1 month after treatment). ES =1.43 (26). In an RCT of canakinumab (CAN) vs. triamcinolone acetonide (TA), reductions in HAQ-DI scores ranged from 0.46 - 0.67 at Day 7, and 0.52 - 0.85 at Week 8 across the groups (18).	In an RCT of CAN vs. TA, there was no significant difference between the treatment groups in HAQ-DI scores over time (18).
Short form (36) Health Survey (SF-36) physical function (PF) domain	Scores range from 0 to 100, where 0 represents the worst possible physical function and 100 is perfect physical function	Total: 2 Controlled: 2 (18): SF36 PF reported, (44) SF-36 PF not reported separately Observational: 0	Licensed, no training required, no specialist equipment required, acceptable to patients	High face validity. Improvement in SG-36 PF score (compared to baseline) was accompanied by reductions in pain, PGART, joint tenderness, swelling and erythema (18). Unable to calculate correlation coefficients with available information. SF-36 questionnaire has been endorsed by OMERACT for measurement of health related quality of life in chronic gout studies (3).	In an RCT of CAN vs. TA, improvements in SF-36 PF scores were observed in both groups. Mean SF-36 PF scores rapidly improved in the CAN 150 mg group from 41.5 at baseline to 80.0 at seven days post-dose (a mean increase of 39.0 points), and exceeded the value for the US general population by eight weeks post-dose (86.1 vs. 84.2 for the US general population) (18). ES could not be calculated from available data.	In patients with acute gout, mean SF-36 PF scores were much lower than those for the general US population: 31.1 to 41.5 (US general population, 84.2) (18). In an RCT of CAN vs. TA, differences between SF-36 PF scores were not reported between groups over time (18).

The properties of the two methods used most frequently have been shown as no other methods have been used in >1 study. No articles reported internal validity, feasibility, test-retest reproducibility. Effect size (ES) is provided wherever possible. If the ES could not be calculated, the statistic and associated p-value is provided.