Background Gout is a quite prevalent disorder in affluent countries, with the prevalence in males being 3–4 times higher than in females . In practice, gout may be perceived as a “males” disorder and it has been suggested that the phenotype of gout differs between males and females, due to selection bias or by nature of the disease.
Objectives To analyse whether there are differences between males and females in the phenotype of gout and in the performance of the ACR-EULAR classification criteria.
Methods We used the multi-country SUGAR data set in which the ACR-EULAR classification criteria were constructed and validated . In SUGAR, patients with at least one swollen joint or subcutaneous tophus conceivably being due to gout were consecutively included. Presence of MSU crystals in synovial fluid or tophus aspirate was the gold standard for gout, as assessed at inclusion, using microscopy by certified examiners in all included patients. Gout manifestations were standardly assessed without knowing the results of the microscopy. Gout manifestations included in the ACR-EULAR classification criteria were compared between male and female MSU positives. Sensitivity and specificity of the ACR-EULAR criteria, calculated without MSU results, were compared between males and females. To preserve power, the development and validation data sets of SUGAR were combined.
Results There were 983 subjects included (71% male), of whom 52% (509/983) were MSU crystal-positive. Sixty-three percent (440/702) of the males and 25% (69/281) of the females were MSU crystal-positive, respectively (p<0.0001). There were no large (>10%) or significant (p<0.05) differences between male and female MSU positives regarding: previous or current involvement of MTP1, mono/oligo/poly-arthritis, joint erythema, painfulness for touch, tophus, largest pain increase within 24 hours, highest level of Serum Uric Acid (SUA) level without treatment, current level of SUA, occurrence of erosions on X-ray, or double contour sign on ultrasound. Male MSU positives more frequently reported: disablement (98% versus 87%; p<0.0001), symptom resolution within 14 days (84% versus 65%; p=0.0002), complete resolution (86% versus 70%; p=0.0004).
In the complete sample of 983 subjects, the classification system lead to a median (P25-P75) score of 5 (2–8) in females and 9 (6–14) in males (p<0.0001). Sensitivity and specificity of the classification system to detect MSU crystal positivity were 86% and 79% in the complete sample, and 87% and 89% for females and 85% and 70% for males.
Conclusions Male and female gout patients are similar on most important aspects of the gout phenotype. The ACR-EULAR classification criteria perform well in both males and females; sensitivity is the same in males and females, while specificity was better in females.
Kuo CF, Grainge M, Zhang W, Doherty M. Nature Rev Rheum. 2015;11:649–662.
Neogi T, Jansen T, Dalbeth N, Fransen J, Schumacher HR et al. Ann Rheum Dis 2015;74:1789–1798.
Acknowledgement We are grateful for the contributions of all investigators who submitted subjects in the SUGAR study.
Disclosure of Interest None declared