Flare Rate Thresholds for Patient Assessment of Disease Activity States in Gout.

OBJECTIVE: To determine the relationship between gout flare rate and self-categorization into remission, low disease activity (LDA), and patient acceptable symptom state (PASS). METHODS: Patients with gout self-categorized as remission, LDA, and PASS, and reported number of flares over the preceding 6 and 12 months. Multinomial logistic regression was used to determine the association between being in each disease state (LDA and PASS were combined) and flare count, and self-reported current flare. A distribution-based approach and extended Youden index identified possible flare count thresholds for each state. RESULTS: Investigators from 17 countries recruited 512 participants. Remission was associated with a median recalled flare count of zero over both 6 and 12 months. Each recalled flare reduced the likelihood of self-perceived remission compared with being in higher disease activity than LDA/PASS, by 52% for 6 months and 23% for 12 months, and the likelihood of self-perceived LDA/PASS by 15% and 5% for 6 and 12 months, respectively. A threshold of 0 flares in preceding 6 and 12 months was associated with correct classification of self-perceived remission in 58% and 56% of cases, respectively. CONCLUSION: Flares are significantly associated with perceptions of disease activity in gout, and no flares over the prior 6 or 12 months is necessary for most people to self-categorize as being in remission. However, recalled flare counts alone do not correctly classify all patients into self-categorized disease activity states, suggesting that other factors may also contribute to self-perceived gout disease activity.

Brief Report: Validation of a Definition of Flare in Patients With Established Gout.

OBJECTIVE: To perform external validation of a provisional definition of disease flare in patients with gout. METHODS: Five hundred nine patients with gout were enrolled in a cross-sectional study during a routine clinical care visit at 17 international sites. Data were collected to classify patients as experiencing or not experiencing a gout flare, according to a provisional definition. A local expert rheumatologist performed the final independent adjudication of gout flare status. Sensitivity, specificity, predictive values, and receiver operating characteristic (ROC) curves were used to determine the diagnostic performance of gout flare definitions. RESULTS: The mean ± SD age of the patients was 57.5 ± 13.9 years, and 89% were male. The definition requiring fulfillment of at least 3 of 4 criteria (patient-defined gout flare, pain at rest score of >3 on a 0-10-point numerical rating scale, presence of at least 1 swollen joint, and presence of at least 1 warm joint) was 85% sensitive and 95% specific in confirming the presence of a gout flare, with an accuracy of 92%. The ROC area under the curve was 0.97. The definition based on a classification and regression tree algorithm (entry point, pain at rest score >3, followed by patient-defined flare "yes") was 73% sensitive and 96% specific. CONCLUSION: The definition of gout flare that requires fulfillment of at least 3 of 4 patient-reported criteria is now validated to be sensitive, specific, and accurate for gout flares, as demonstrated using an independent large international patient sample. The availability of a validated gout flare definition will improve the ascertainment of an important clinical outcome in studies of gout.