Bipolar disorder linked to increased risk of sexually transmitted infections

Patients with bipolar disorder had a 1.67-times greater risk of sexually transmitted infections (STIs), especially HIV and syphilis, than those without bipolar disorder, Taiwan researchers have found.

The investigators, led by Yu-Chih Shen, MD, PhD, Department of Psychiatry, Tzu Chi General Hospital, Hualien, Taiwan, speculated that hypersexual activity and STI risk behaviors may increase during or immediately following manic/hypomanic episodes in bipolar patients, as has been found in past studies.

“Our study does not indicate which episode of bipolar disorder is associated with a subsequent STI,” they wrote in Sexually Transmitted Diseases. “However, this study provides strong evidence that in long-term follow-up, patients with bipolar disorder are associated with an increased risk of STI.”

Dr. Shen and colleagues used the National Health Insurance Research Database of Taiwan to longitudinally evaluate the incidence of STIs among patients diagnosed with bipolar disorder between 2000 and 2010. Researchers identified a total of 3,721 patients with bipolar disorder, whom they matched to 14,884 controls. Average age in both cohorts was about 40 years, and 56% of the patients in both cohorts were women.

The cohort with bipolar disorder had a higher prevalence of psychiatric comorbidities, including alcohol use disorder (5.24% vs 0.19%) and other substance use disorders (6.96% vs 0.52%) compared with controls. Average follow-up was 7.62 years for patients with bipolar disorder and 8.37 years for controls.

A total of 273 patients had an STI during follow-up. The incidence rate of STIs was higher in the bipolar disorder cohort than in controls (27.52 vs 15.65 per 10,000 person-years). After adjusting for demographic data and psychiatric comorbidities, the difference remained significant (HR 1.67, 95% CI 1.27-2.18, P < 0.0001).

Consistent with other studies, the rate of STI was higher in women than in men (HR 1.83, 95% CI 1.41-2.39). Both sexes with bipolar disorder had an increased risk of STI compared with their counterparts without bipolar disorder. For men with bipolar disorder, the adjusted hazard ratio for an STI was 1.79 (95% CI 1.09-2.95) compared with men without bipolar disorder. For women with bipolar disorder, the adjusted HR was 1.63 (95% CI 1.18-2.24).

The risk of contracting an STI was not significantly different between age groups and between those living in more or less densely populated communities. There was no significant difference in risk by psychiatric comorbidities.

Each age group of patients with bipolar disorder had an increased risk for incident STI compared with same-aged controls. The difference was significant in patients with bipolar disorder younger than 25 years (HR 2.11, 95% CI 1.24-3.58) and those 25 to 50 years old (HR 1.45, 95% CI 1.01-2.08).

When assessed by individual STIs, people with bipolar disorder had more than triple the risk for HIV (HR 3.59, 95% CI 1.16-11.08) and more than double the risk for syphilis (HR 2.26, 95% CI 1.06-4.85), after adjustment for demographics and psychiatric comorbidities.

The authors concluded: “This study shows that bipolar disorder is associated with an increased risk of developing STI, which has direct implications for the development of targeted prevention interventions or regular sexual health screening in mental health clinics to reduce the disproportionate burden of HIV and other STI in patients with bipolar disorder.”