Background Several features of borderline personality disorder (BPD) are likely to be associated with sexual health problems, such as unstable attachment, unstable sexual identity and sexual impulsivity. Since the issue of sex is not openly discussed in Taiwanese society, sexual health needs, including screening and prevention of sexually transmitted infections (STI), are often neglected in this population.

Objective The study aims to determine whether BPD is associated with an increased risk of subsequent STI in Taiwan.

Methods Overall 669 patients with BPD and 2676 controls matched by gender and age were enrolled between 2000 and 2012 and followed until the end of 2013 using Taiwan’s National Health Insurance Research Database. During the follow-up period, participants who developed STI (human immunodeficiency virus, syphilis, genital warts, gonorrhoea, chlamydia and trichomoniasis) were identified. Cox regression analysis was used to calculate the hazard ratio (HR) with 95% confidence interval (CI) of the STI incidence rate between patients with BPD and unaffected controls.

Results Patients with BPD were predisposed to developing STI (HR: 4.17, 95% CI 1.62 to 10.8) after adjusting for demographic data and psychiatric comorbidities. The stratification analysis revealed a similar risk trend with BPD and subsequent STI in each gender and age group and was significant in the subgroups of male (HR: 11.3, 95% CI 2.97 to 42.7) and those aged 18–34 years (HR: 4.85, 95% CI 1.71 to 13.7). Also, the comorbidity stratification analysis revealed that, when the effect of comorbidities was excluded, patients with pure BPD significantly exhibited the risk association for subsequent STI after adjusting for all variables (HR: 4.24, 95% CI 1.25 to 14.4).

Conclusion Given the greater potential of BPD to be associated with an increased risk of STI, there should be direct implications for the development of targeted prevention interventions in Taiwan’s mental health clinics.