A Population-Based Study
International Journal of Clinical Rheumatology
Adlene J Jebakumar; Prabhu D Udayakumar; Cynthia S Crowson; Eric L Matteson
Int J Clin Rheumatol. 2013;8(4):433-437
Discussion
The co-occurrence of gout and RA is rarely reported. In addition to the widespread belief that gout and RA do not, or rarely, coexist in the same patient, it can be difficult to clinically differentiate RA from polyarticular tophaceous gout especially when gout involves the hands. Only 33 cases with coexisting RA and gout have been reported in the English literature prior to this study. These include a report of eight cases of coexisting RA and gout between 1994 and 2005 at Chang Gung Memorial Hospital (Taiwan); this report also included the features of 24 previously reported similar cases in the English literature.[8] A further case with coexisting chronic gout and RA was reported in 2007.[9] Of these 33 previously reported cases, 23 had gout preceding the diagnosis of RA, whereas in our study, only six out of 22 patients had a diagnosis of gout prior to incidence of RA.[8,9] All the previously reported cases of coexisting gout and RA had microscopic evidence of monosodium urate crystals in the synovial fluid or tophus. Rheumatoid factor was present in 24 out of the 33 previously reported cases compared with 14 out of 22 cases in our study. There was predominance of males, with 23 out of the 33 previously reported cases affecting men similar to our findings.[8,9]
The prevalence of gout in patients with RA was significantly lower than the expected age- and sex-specific prevalence rate from the general population.[7] There are a number of reasons for this, including the possibility that estrogens and progesterone cause better renal clearance of uric acid in women with RA, decreasing the risk of gout in these patients.[10] Glucocorticoids and NSAIDs used in RA can also potentially mask the clinical manifestations of gout. Urate crystals can block activation of T and B cells, and they also have antioxidant and antiphagocytic properties, which may contribute to lower incidence of coexistent RA and gout.[11] In addition, IL-6 in RA may reduce the likelihood of overt gout owing to its uricosuric properties.[12] We also consider that potential cases of gout never clinically developed, as 77% of patients with RA were on glucocorticoid therapy and 91% on NSAIDs at some point during their follow-up. Several RA patients did not have polarized microscopy performed on the synovial fluid. For these reasons it is possible that some of the patients with RA who developed gout may have been missed in our study.
The development of gout occurred more frequently in patients with RA diagnosed in recent years (1995–2007) than among patients with RA diagnosed in earlier years (1980–1994). The reasons for the increased incidence in patients diagnosed with RA in the recent years is unclear; however, this may be owing to an increase in the incidence of risk factors for gout, such as obesity, hypertension and chronic kidney disease, and increased use of IL-6 inhibitor in the recent years. The use of high doses of aspirin that have uricosuric properties in patients with RA in the earlier decades may also explain the lower occurrence of gout in RA in 1980–1994 versus 1995–2007. In our study, age, male sex and obesity were identified as risk factors for gout in patients with RA, which are risk factors for gout identified in the general population.[13] Erosions and destructive changes in RA were associated with lower incidence of gout in RA in our study. The reasons for this are speculative; a possibility may be related to increased use of glucocorticoids and/or NSAIDs in these patients.
Limitations of this study include the retrospective nature, nonavailability of anticitrullinated protein testing in some patients and absence of microscopic analysis of synovial fluid in some patients in the study. A formal analysis of incidence rate and prevalence of gout in patients with RA compared with a control group of patients without RA was not carried out.
Read more about the patients, methods, results, and conclusion: https://www.medscape.com/viewarticle/814270_4?form=fpf
