Table 2.

Summary of joint swelling 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)
Physician assessment of swelling in the index joint using a 4-point Likert scale (range 0-3)	0= no swelling; 1= mild swelling; 2=moderate swelling; 3= severe swelling (or bulging beyond joint margins)	Total: 8 Controlled: 6 (17, 18, 20, 41, 44, 58) Observational: 2 (54, 57)	Inexpensive, some training required, no specialist equipment required, acceptable to patients	High face validity. The reduction in the number of patients with severe or moderate swelling was accompanied by greater proportion of patients reporting no or mild pain on the 5- point Likert scale, the increasing proportion of patients reporting normalisation of C-reactive protein, and better responses from patient and investigator global assessment of response to treatment (18). The joint swelling scores showed similar reductions with those for pain and joint tenderness (17) and erythema (44). Unable to calculate correlation coefficients with available information. Measure captures degree of swelling in affected joint.	All articles reported significant reduction in joint swelling scores over time, typically by 72 hours. In an RCT comparing etoricoxib (ETO) and indomethacin (IND), the least squares mean change (95% CI) from baseline to Days 2-8 was −1.45 (CI −1.61 to −1.29) for ETO and −1.45 (−1.62 to −1.28) for IND (17). In another RCT comparing ETO and IND, the least square mean change (95% CI) from baseline to the mean of Days 2-5 was −1.65 (−1.80 to −1.50) for ETO, and −1.56 (−1.72 to −1.40) for IND (20). ES could not be calculated from available data.	In an RCT of canakinumab (CAN) vs. triamcinolone acetonide (TA), the CAN 150 mg group had a lower swelling score compared with the TA group from 72 hours to seven days post-dose. The odds ratio favouring CAN 150mg was 2.7 (95% CI, 1.09–6.5) (18). In two RCTs comparing ETO and IND, there was no difference between the least square mean difference in swelling scores between the ETO and IND groups (17, 20).
Physician measurement of index joint circumference/perimeter	The circumference/perimeter of the affected joint measured by tape measure, reported in cm.	Total: 7 Controlled: 3 (21, 22, 31) Observational: 4 (37, 46, 47, 59)	Inexpensive, some training required, no specialist equipment required (tape measure only), acceptable to patients	Reduction in joint circumference was accompanied by reduction in pain, swelling, erythema and joint impairment (21, 31, 46, 59). Unable to calculate correlation coefficients with available information. Large variation in circumference measured depending on affected joint eg. 8cm for big toe and 36.5cm for knee (21).	All articles reported significant reduction in joint swelling scores over time, typically at 72 hours. In an observational study of intravenous indoprofen, the average joint circumference of the affected joint decreased from 31.6cm at baseline to 27.3cm on Day 3, ES =0.46 (46). In a clinical trial of tenoxicam (TEN) dosing, the average joint circumference of the affected joint decreased from 23.6cm at baseline to 18.1cm on Day 6 following treatment with TEN 40mg, ES= 0.46 on Day 6 (22).	In an RCT of ice therapy, the mean (SD) reduction for the ice group was 5.90 (3.84) cm compared with 3.83 (4.19) cm for controls after 1 week (p=0.14) (31). In a clinical trial of two dosage regimens of indoprofen, the mean (SD) reduction for the iv bolus/24 hour infusion arm was 2.4 (1.0) and for high dose single iv bolus was 2.5 (0.53) (p=0.82) after 48 hours of treatment (21). In a clinical trial of TEN dosing, there was no significant difference between 20mg and 40mg daily dosing in joint swelling (p>0.05) (22).
Physician assessment of the number of swollen joints (swollen joint count, SJC)		Total: 3 Controlled: 2 (23, 28) Observational: 1 (26)	Inexpensive, some training required, no specialist equipment required, acceptable to patients	The reduction in the SJC was accompanied by improvement in tender joint count, pain score, C-reactive protein value, Leeds Foot Impact Scale and score of Lower Limb Task Questionnaire score (26). Unable to calculate correlation coefficients with available information. Monoarticular flares are common in patients; in an RCT comparing etoricoxib (ETO) and indomethacin (IND), 99/150 patients had a single joint affected (17). Risk of floor effect. Degree of swelling not captured within the measure.	All treatments led to significant reduction in SJC over time, with the exception of the herbal formula Danggui-Nian-Tong-Tang (DNTT) (28). Following IND treatment, mean (SD) SJC reduced from 1.3 (0.7) at baseline to 0.6 (0.5) after 72 hours ES=0.22 (28). In an observational study, mean (SD) SJC reduced from 3 (3) at baseline to 0 (1) at the follow up visit (>1 month after treatment). ES =0.67 (26).	In an RCT comparing DNTT with IND, there was a significant difference between the groups in SJC after 72 hours of treatment; mean (SD) SJC for DNTT 1.9 (1.2) and IND 0.6 (0.5), p<0.0001 (28). In an RCT of two dosage regimens of piroxicam, there was no significant difference in SJC between high dose and low dose piroxicam (23).

The properties of the three methods used most frequently have been shown. 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.