Simple-to-use nomogram for predicting the risk of syphilis among MSM in Guangdong Province: results from a serial cross-sectional study

Developing a symptoms-based risk score for infectious syphilis among men who have sex with men

Background

Syphilis incidence is rising among men who have sex with men (MSM). An online tool based on a risk score identifying men with higher risk of infectious syphilis could motivate MSM to seek care. We aimed therefore to develop a symptoms-based risk score for infectious syphilis.

Methods

We included data from all consultations by MSM attending the Amsterdam Centre for Sexual Health in 2018–2019. Infectious syphilis (ie, primary, secondary or early latent syphilis) was diagnosed according to the centre’s routine protocol. Associations between symptoms and infectious syphilis were expressed as odds ratios (OR), with 95% confidence intervals (CI). Based on multivariable logistic regression models, we created risk scores, combining various symptoms. We assessed the area under the curve (AUC) and cut-off based on the Youden Index. We estimated which percentage of MSM should be tested based on a positive risk score and which percentage of infectious syphilis cases would then be missed.

Results

We included 21,646 consultations with 11,594 unique persons. The median age was 34 years (IQR 27–45), and 14% were HIV positive (93% on antiretroviral treatment). We diagnosed 538 cases of infectious syphilis. Associations with syphilis symptoms/signs were strong and highly significant, for example, OR for a painless penile ulcer was 35.0 (CI 24.9 to 49.2) and OR for non-itching rash 57.8 (CI 36.8 to 90.9). Yet, none of the individual symptoms or signs had an AUC >0.55. The AUC of risk scores combining various symptoms varied from 0.68 to 0.69. For all risk scores using cut-offs based on Youden Index, syphilis screening would be recommended in 6% of MSM, and 59% of infectious syphilis cases would be missed.

Conclusion

Symptoms-based risk scores for infectious syphilis perform poorly and cannot be recommended to select MSM for syphilis screening. All MSM with relevant sexual exposure should be regularly tested for syphilis.

Coerced syphilis self-testing among men who have sex with men: a nationwide cross-sectional study in China

BACKGROUND

Syphilis testing uptake remains low among men who have sex with men (MSM) in many low-and middle-income countries. Syphilis self-testing is an efficacious approach on increasing syphilis testing coverage. However, one unintended consequence is the syphilis self-testing coercion from others (including partners, healthcare providers, friends, etc.). This study aimed to examine the prevalence, pattern and correlates of coerced syphilis self-testing among MSM in China.

METHODS

A nationwide online cross-sectional study was conducted from 14 to 28 July 2018. Sociodemographic characteristics, sexual behaviors and coerced syphilis self-testing variables were collected through a questionnaire that targeted MSM in China. Multivariable logistic regression was used to explore associated factors with syphilis self-testing coercion.

RESULTS

Overall, 174 MSM were recruited in this study, 31 men (17.8%) reported ever experiencing syphilis self-testing coercion. The most common types of coercion before syphilis self-testing were verbal abuse (38.7%, 12/31) and threatening to end a relationship (38.7%, 12/31). After obtaining the self-test results, men were mostly subjected to end a relationship (45.2%, 14/31) and threaten of violence (35.5%, 11/31). Multivariable logistic regression indicated that men who used condoms inconsistently in the past three months, ever used substances before or during sex, ever had group sex with males and commercial sex were more likely to experience syphilis self-testing coercion.

CONCLUSIONS

Coerced syphilis self-testing was prevalent among MSM in China. Innovative intervention to reduce coerced syphilis self-testing is necessary among MSM in China.