A US study of the effect of equal marriage rights claims gay and bisexual men lead healthier lives when those rights are introduced, regardless of whether they have a partner.

The report looked at medical data from the year before and the year after Massachusetts introduced equal marriage laws in 2003.

Authors said medical care visits, mental health care visits and mental health care costs all decreased, by 13% for health care visits and 14% for costs.

The study, entitled “Effect of Same-Sex Marriage Laws on Health Care Use and Expenditures in Sexual Minority Men: A Quasi-Natural Experiment,” is published in the American Journal of Public Health.

It found that costs associated with hypertension, depression and adjustment disorders decreased after equal marriage rights were introduced, whether a man had a partner at the time or not.

Author Mark L. Hatzenbuehler, of the Columbia University Mailman School of Public Health, said: “Our results suggest that removing these barriers improves the health of gay and bisexual men.

“These findings suggest that marriage equality may produce broad public health benefits by reducing the occurrence of stress-related health conditions in gay and bisexual men.”

The study examined 1,211 male patients from a large, community-based health clinic in Massachusetts. It said lesbians were not included because of the small initial sample size.