Table 1.

Characteristics of included studies

First author	Year of publication	Study location	Type of study	Study size	Study population	Primary exposure(s) (Infection)	Infection diagnosis	Incidence of ReA	Proportion of ReA cases with asymptomatic infection
Carter [31]	2013	Florida, USA	Prospective	149 (from 365 enrolled)	Adults attending communicable disease clinic testing positive for Chlamydia trachomatis	Chlamydia trachomatis	Laboratory diagnosis by gram stain, cell culture or NAAT	12/149 (8.1%)	8/12 (66.7%)
Rich [30]	1996	Alabama, USA	Prospective	217	Adults attending a sexually transmitted diseases clinic being treated with doxycycline for a possible or proven Chlamydia trachomatis infection	Genital infection/inflammation	Laboratory diagnosis by cervical cell culture for Neisseria gonorrhoeae and Chlamydia trachomatis. In men, a gram-stained urethral smear and a urethral Neisseria gonorrhoeae culture were obtained. Chlamydia trachomatis genital cultures were obtained for every patient who had objective ReA features.	9/217 (4.1%)	7/9 (77.8%)
Keat [29]	1978	UK	Likely prospective	531	Heterosexual men attending sexually transmitted diseases clinic with new episodes of urethritis.	Non-specific urethritis. Cultures for Chlamydia trachomatis taken to investigate association with ReA.	Urethral smear. Non-specific urethritis if over 10 polymorphs found in ≥ three consecutive high-power fields (magnification x 600), if microscopy, culture, and serology excluded gonorrhoea and syphilis.	16/531 (3.0%)	No details