Human Immunodeficiency Virus Seropositivity and Early Syphilis Stage Associated With Ocular Syphilis Diagnosis: A Case-control Study in British Columbia, Canada, 2010-2018.

Abstract

The incidence of syphilis has been increasing worldwide in the last 20 years, disproportionately impacting those living with human immunodeficiency virus (HIV). Alongside this increase, several jurisdictions have reported increasing incidences of syphilis-related complications, including ocular syphilis. We sought to characterize ocular syphilis cases in British Columbia (BC), Canada. This case-control study compared ocular syphilis cases, matched (1:4) to syphilis controls, that were diagnosed in BC between January 2010 and December 2018. Multivariable logistic regression was used to identify potential correlates of ocular syphilis, where variables were included in the final model if significant (P ≤ .05). During the study period, there were 6716 syphilis diagnoses, including 66 (0.98%) ocular syphilis cases. The median age of cases was 49.5 years (interquartile range 39-59). Most (87.8%) patients were male, where 54.6% identified as men who have sex with men. The most common ophthalmologic diagnosis was panuveitis (42.4%). Of ocular syphilis patients, 48.5% were living with HIV at the time of their syphilis diagnosis, compared to 26.4% of controls (P = .001). The proportion of syphilis cases with ocular syphilis increased from 0.48% in 2010 to 0.83% in 2018. The final multivariable model demonstrated correlates between ocular syphilis and early syphilis stage, including primary/secondary (odds ratio [OR] 4.96, 95% confidence interval [CI] 1.86-13.24) and early latent (OR 4.29, 95% CI 1.62-11.34) stages, and HIV serostatus (OR 2.16, 95% CI 1.14-4.09). Ocular syphilis increased over the study period, both in absolute numbers and as a proportion of all syphilis cases, a finding consistent with other jurisdictions. These findings highlight the importance of vigilance for ocular syphilis, to avoid diagnostic and treatment delays.