The Gout Attack Intensity Score (GAIS) appears to be a reliable, responsive tool for evaluating patient-reported gout attack intensity in clinical trials, according to data from a randomized controlled trial published in Rheumatology.1,2
The investigators sought to develop a patient-reported gout flare intensity score for use in clinical studies, including components for gout-related pain, tenderness, and swelling. All patients completed a 7-day flare diary that included questions about the intensity of their pain, swelling, and tenderness, ranked using a 5-point rating scale. The scalability of the items was evaluated using Mokken Scale Analysis, and reliability was assessed using greatest lower bound reliability coefficients. Known-groups validity was evaluated, along with responsiveness to change and evidence of floor and ceiling effects.
Researchers used data from a randomized controlled trial including 88 patients with crystal-proven gout attacks who were randomly assigned to receive treatment with anakinra or treatment with standard of care (colchicine, nonsteroidal anti-inflammatory drug, or corticosteroids). The baseline study population comprised predominantly middle-aged men with mono-articular gout. Overall, 86% of the participants completed the gout flare diary.
Results supported scalability of the single items evaluated, and GAIS scores were shown to be reliable (greatest lower bound, >0.80). Furthermore, GAIS scores demonstrated responsiveness to change with high effect sizes (>0.8), differentiating better between responders and nonresponders than the single-item components. No floor and ceiling effects were observed.
A major limitation of the study was the relatively small sample size. In addition, most of the patients were recruited from the rheumatology department at a hospital center in The Netherlands. Moreover, to date, the researchers were unable to link GAIS scores to such other well-known instruments as the Health Assessment Questionnaire.
The investigators concluded that future studiers are warranted to demonstrate that GAIS scores are related to other well-known measures in ways that will further support their construct validity.
Janssen CA, Oude Voshaar MAH, Ten Klooster PM, Vonkeman HE, van de Laar MAFJ. Development and validation of a patient-reported gout attack intensity score for use in gout clinical studies [published online March 11, 2019]. Rheumatology (Oxford). doi:10.1093/rheumatology/kez064