Summary of pain instruments used in studies of acute gout. The properties of the 3 methods used most frequently have been shown. All pain scores were patient-reported. No articles reported internal validity, feasibility, or test-retest reproducibility. Effect size (ES) is provided wherever possible. If the ES could not be calculated, the statistic and associated p value are provided. References are represented as numerals in parentheses.
| Method | Description | No. and Type of Studies with References | Feasibility | Truth | Within-group Discrimination (ES) | Between-group Discrimination (estimate or statistic with p-value) |
|---|---|---|---|---|---|---|
| Visual analog pain scale (VAS; 10 cm/100 mm) | 10 cm/100 mm, horizontal VAS with the far left (0) = no pain and far right end (10 cm/100 mm) = most severe pain patient has ever experienced | Total: 16 controlled: 11 (13–15, 18, 30–36); observational; 5 (26, 37–40) | Inexpensive, no training required, no specialist equipment required, acceptable to patients | High face validity. Reduction of pain scores was accompanied by reduction of joint swelling and tenderness, C-reactive protein value, and patient global assessment (18, 26). Similar reductions reported in pain, tenderness, swelling, erythema (15). Unable to calculate correlation coefficients with available information. Measure endorsed by OMERACT for use in chronic gout studies (7). | All articles reported significant reduction in pain scores over time. In an RCT of prednisolone (PRED) vs naproxen (NAP), decrease of pain from baseline to Day 4 was 44.7 mm for PRED and 46.0 mm for NAP, ES on Day 4 = 2.00 for PRED, and 2.21 for NAP (32). In an RCT of canakinumab (CAN) vs triamcinolone acetonide (TA), the % change from baseline in pain score after 72 h was −84.6%, ES = 9.3 for CAN 150 mg; and −57.8%, ES = 4.5 for TA (13). | In an RCT of CAN vs TA, significantly lower pain scores were reported for CAN 150 mg vs TA 72 h post dose (least square mean difference −9.7 mm, p = 0.0005) (14). In an RCT of high-dose colchicine, 73% of patients in the colchicine group and 36% of patients in the placebo group improved pain score by 50% after 48 h (p < 0.05) (15). |
| 5-point Likert scale (range 0–4) | 0 = no pain, 1 = mild pain; 2 = moderate pain, 3 = severe/strong pain and 4 = excruciating pain/very severe/extreme/very strong | Total: 16; controlled*, 12 (17–21, 27, 34, 41–45); observational: 4 (16, 46–48) | Inexpensive, no training required, no specialist equipment required, acceptable to patients | High face validity. Reduction in pain score accompanied by reduction in other secondary endpoints (joint tenderness, joint swelling and joint erythema, and global assessments of response to treatment, C-reactive protein) (17, 18). Unable to calculate correlation coefficients with available information. Patients with both monoarticular and oligoarticular disease had a clinical response, but the response was greater in those with monoarticular disease, p < 0.001 (42). Patients with both moderate pain and severe/extreme pain at baseline had a clinical response, but response was greater in those with severe/extreme pain, p < 0.001 (42). Good construct validity: significant differences in pain scores between patients categorized into None/Fair vs Good/Excellent, based on responses to patient and investigator global assessment of response to therapy (p < 0.0001) (27). | All articles reported significant reduction in pain scores over time. In untreated acute gout, pain decreased from 3.7 at baseline (Day 1) to 2.5 on Day 7. ES Day 2 = 0.05 and Day 7 = 0.87 (16). In an RCT comparing etoricoxib (ETO) and indomethacin (IND), score decreased by nearly 1.0 point from baseline to 4 h after the first dose in both groups ES at Day 2 = 2.17 for ETO and 2.47 for IND; at Day 8, ES = 3.48 for RTO and 3.77 for IND (17). | In an RCT of CAN vs TA, 92% of patients in CAN 150 mg group and 56% in TA group had no or mild pain after 48 h (p < 0.05). The reduction in pain intensity from baseline was also significantly greater for CAN 150 mg, compared with TA from 48 h to 7 days post dose (p < 0.05) (18). High-dose celecoxib led to a greater reduction in pain intensity on Day 2 compared with low-dose celecoxib (least squares mean difference −0.46, p = 0.0014) (19). |
| 4-point Likert scale (range 0–3) | 0 = no pain, 1 = mild/slight pain, 2 = moderate pain and 3 = severe pain | Total: 9; controlled: 5 (49–53); observational: 4 (54–57) | Inexpensive, no training required, no specialist equipment required, acceptable to patients | High face validity. Scores for pain, redness, tenderness, restriction of movement and swelling showed similar reductions at timepoints tested (49, 52–55). Unable to calculate correlation coefficients with available information. | All articles reported significant reduction in pain scores over time. Following ketoprofen treatment, pain decreased from 2.7 at baseline (Day 1) to 1.08 on Day 2, to 0.52 on Day 5, and 0.37 on Day 8. Following IND, the pain score on respective days were 2.76, 0.91, 0.50, and 0.30 (p < 0.05 for each timepoint compared with baseline in both treatment groups) (49). ES could not be calculated from available data. | No significant difference in pain scores between ketoprofen and IND groups (49), in percentage improvement in pain scores between meclofenamate sodium and IND treatment groups (51), or % with no/mild pain between tiaprofenic acid and ketoprofen groups (52). |
↵* Navarra and Schlesinger references were posthoc analysis of Rubin and Schumacher studies. RCT: randomized controlled trial.