Reactive arthritis at the Sydney Sexual Health Centre 1992-2012: declining despite increasing chlamydia diagnoses.

Reactive arthritis is an under-studied complication of genital Chlamydia trachomatis infection (chlamydia). We assessed trends and risk factors for reactive arthritis in a large urban sexual health clinic. Using a case-control design, data on reactive arthritis cases and controls at the Sydney Sexual Health Centre over the period 1992-2012 were extracted and multivariate analyses were performed. Trend analyses were performed on reactive arthritis diagnoses. Over the 1992-2012 study period, 85 reactive arthritis cases were diagnosed at Sydney Sexual Health Centre. The rate of reactive arthritis diagnoses decreased over time (23 in 1992-1996 to one in 2007-2011 and none in 2012), while chlamydia diagnoses increased (770 in 1992-1996 to 2257 in 2007-2011). In multivariate analysis, factors independently associated with a reactive arthritis diagnosis were: being male (adjusted odds ratio [aOR] 3.27; 95% confidence interval [CI] 1.04-10.32; p = 0.043) or born overseas (aOR 2.69; 95% CI 1.27-5.70; p = 0.010), while a past sexually transmitted infection other than chlamydia or non-gonococcal urethritis was protective (aOR 0.21; 95% CI 0.10-0.45; p < 0.001). Reactive arthritis was not associated with current or recent chlamydia infection (p = 0.184) but was marginally associated with past non-gonococcal urethritis (p = 0.080). This study found a decline in reactive arthritis diagnoses despite an increase in chlamydia diagnoses.