A Study Suggests that BMI doesn’t Prevent Chest Masculinization Surgery

Body mass index, or BMI, is calculated by dividing a person’s mass (weight) in kilograms by the square of their height in meters. Since its inception in the 1970s, body mass index (BMI) has been used to broadly classify people as underweight, normal weight, overweight, or obese, and hence to help assess an individual’s present health and forecast future consequences.

BMI, on the other hand, may not be a suitable way of selecting who should be eligible for gender-affirming surgery for transgender and nonbinary people.

Researchers at the Johns Hopkins Center for Transgender and Gender Expansive Health (CTH) provide evidence that BMI is a poor metric for determining who should be approved for the gender transitioning procedure in what is believed to be the largest study of the association between BMI and postoperative complications following chest masculinization surgery (CMS, also known as top surgery).

The findings were first published online in the Annals of Plastic Surgery on November 1, 2023.

“Traditional BMI requirements related to top surgery have been highly surgeon specific, not standardized, and only based on studies with small sample sizes,” says study lead author Bashar Hassan, M.D., a postdoctoral research fellow in plastic and reconstructive surgery at the CTH and the University of Maryland Medical Center’s R Adams Cowley Shock Trauma Center. “Despite the lack of solid evidence showing an association between a high BMI and serious postoperative complications in chest masculinization — such as blood clots, bleeding and infection — many people who are transgender and nonbinary get denied the surgery.”

The CTH team reviewed demographics, operative procedures, and postoperative complications for 2,317 transgender and non-binary people who underwent CMS (as a primary surgery and not concurrently with another procedure) between 2012 and 2020 to determine if the BMI barrier was appropriate. Data were gathered from the American College of Surgeons’ National Surgical Quality Improvement Program, a risk-adjusted, nationally validated database designed to assist researchers in improving the quality of surgical care.

The CTH researchers classified BMI into six categories: category 0, less than 30 kilograms per meter squared (kg/mg2); category 1, between 30 and 34.9 kg/mg2; category 2, between 35 and 39.9 kg/mg2; category 3, between 40 and 44.9 kg/mg2; category 4, between 45 and 49.9 kg/mg2; and category 5, greater than or equal to 50 kg/mg2.

The average age of individuals evaluated was 25, with a BMI of 27 kg/m2. Although nearly two-thirds (1,501 or 64.8%) were not obese (BMI less than 30 kg/mg2), those who were (816 or 35%) nevertheless made up a large share. Finally, a minor percentage (26 or 1.1%) had a BMI higher than 50 kg/m2.

According to Hassan, earlier research used to establish CMS eligibility requirements rarely included persons with extremely high BMIs. “In contrast, our study evaluated one of the largest groups of CMS patients who belong to the morbidly obese and super obese categories,” he said.

The researchers looked into how many participants in the study group experienced at least one problem, both severe and small, within 30 days of their surgery. Major complications included cardiac arrest necessitating cardiopulmonary resuscitation, myocardial infarction (heart attack), stroke, acute renal failure, unplanned intubation, pulmonary embolism (blood clot in the lungs), deep venous thrombosis (blood clot in the leg, groin, or arm), sepsis (widespread infection), septic shock, bleeding necessitating transfusion, unplanned second operation

Minor problems included surgical site infection, urinary tract infection, pneumonia, and wound disruption that was not caused by an unforeseen second surgery.

“We discovered that people with high BMIs had a slightly increased risk of complications across the board,” says study senior author Fan Liang, M.D., CTH medical director and assistant professor of plastic and reconstructive surgery at the Johns Hopkins University School of Medicine.

The researchers discovered that persons with a BMI of 3 had a higher risk of hospital readmission and surgical site infections than those who were not obese. The data revealed that members of the category 5 BMI group had a higher risk of experiencing at least one problem (particularly urinary tract infections).

According to Hassan and Liang, while rising BMI was related with an increased risk of at least one postoperative complication, no one in the research group encountered severe health concerns, regardless of BMI.

“Given that our large-scale study strongly suggests such a low risk for severe complications following CMS in people with high BMIs, we recommend that the medical community reevaluate its current approach of BMI cutoffs for CMS eligibility,” Liang said in a statement.

The other members of the Johns Hopkins Center for Transgender and Gender Expansive Health research team, in addition to Hassan and Liang, are medical student Calvin Schuster and surgical fellow Mona Asch, M.D. Gabriel Del Corral, M.D., of Medstar Georgetown University Hospital, and Beverly Fischer, M.D., of the Advanced Center for Plastic Surgery are also members of the team.

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