The inconsistent use of sex-specific reference ranges for transgender patients undergoing medical testing can change the way results are interpreted, investigators report.
"Operators are not consistently using sex recorded at birth or gender identification reference ranges when performing spirometry tests for transgender patients," said Dinah Foer, MD, from Brigham and Women's Health in Boston.
There was a lot of heterogeneity, but reference ranges used were biased toward women, she explained when she presented the study findings at the American College of Allergy, Asthma & Immunology 2019 Annual Scientific Meeting in Houston.
"We don't know why," she acknowledged.
In spirometry, the sex of the patient is assigned by the operator doing the test, likely after conversation with the patient. "But there's only a binary option," Foer explained. "If someone sees their gender identity as male but was recorded at birth as female, should female be chosen by default?"
Or maybe such a patient should be tested using the female reference range and then tested again using the male reference range, she suggested.
For their study, Foer and her colleagues looked at 33 spirometry tests performed on 17 transgender and nonbinary patients. In the cohort, five trans men completed 12 pulmonary function test events, eight trans women completed 17 events, and four nonbinary patients completed four events.
For the trans men, all of whom were using hormones, female reference ranges, matching sex recorded at birth, were used 83.0% of the time.
For the trans women, 70.6% of whom were using hormones, female reference ranges, which did not match sex recorded at birth, were used 70.6% of the time.
For the nonbinary patients, none of whom were using hormones, female reference ranges, matching sex recorded at birth, were used 100% of the time.
"What we're seeing is that there's no consistency," said Foer. Reference ranges did not consistently match sex assigned at birth, hormone use, or gender identity.
When the researchers used the opposite reference range to calculate forced expiratory volume in 1 second, abnormal results not identified on the original calculation were seen in seven patients.
When Foer's team performed their study, there were no guidelines to follow; operators had to make a choice.
But in September, the American Thoracic Society (ATS) released the Standardization of Spirometry 2019 Update, which states that "birth sex and ethnicity should be included in the patient information on the spirometry request. Otherwise, the operator will ask the patient to provide this information. When requesting birth sex data, patients should be given the opportunity to provide their gender identity as well and should be informed that although their gender identity is respected, it is birth sex and not gender that is the determinant of predicted lung size."
ATS Guidelines Just Released
Foer wonders whether the ATS consulted transgender patients when developing the guidelines, and expressed concern about discussions with patients. "Do we say, we respect that you identify as male or female but we are still going to use the sex you were born with in your records?" she asked. "Is that medically correct? Clinically correct? We don't know."
"We need to be having these conversations," she added. "I don't think this stems from not wanting to do the right thing; it comes from our tools being cisgender."
The guidelines offer a consistent rule to follow, but "I haven't seen any study that prospectively followed transgender patients during hormone treatments and looked at spirometry over time," Foer told Medscape Medical News.
We know sex at birth affects lung function, but "there are no data on the effect of hormone use on lung function in this population, so more research is needed," she explained.
"I don't think we can really say what reference range to use. Maybe we need a different reference range at different points in gender transition. Or maybe we need to calculate both genders," she offered.
It would be good to include more gender options in the records and algorithms, she said, because there is currently no way to document this in a patient's electronic health record.
"We need to get better reference ranges," said Vin Tangpricha, MD, PhD, from the Emory University School of Medicine in Atlanta, who president of the World Professional Association for Transgender Health.
"I don't think it's satisfactory to say we just use the sex assigned at birth. I don't think that's the right answer," he told Medscape Medical News.
Similar issues have come up for bone density reference ranges. "In the bone world, the stance we've taken is to put the affirmed gender into the algorithm. Our rationale was that there was at least some data that transgender women have similar bone density as cisgender women," Tangpricha explained.
In the absence of data, you don't want to mislabel people. If sex recorded at birth is needed for a test, then "every time people get a pulmonary function test, they are going to have to 'out' themselves," he said. "Imagine if you transitioned 20 years ago; that's not very gender affirming in a healthcare environment."
"Maybe it's time to develop a different reference range for transgender populations," he added.
Foer and Tangpricha are not the only ones calling for transgender reference ranges. In a 2017 review of the role gender plays in medical laboratory tests, the authors argue that "sex-specific reference intervals are clinically indicated for select laboratory tests. Establishing reference intervals applicable to the transgender population for these tests is important."
Improving care for transgender people will require "dismantling the sex binary that plagues most electronic medical systems and certain laboratory tests," they conclude.
Guidelines for nonbinary, or gender fluid, patients are also lacking, said Foer. If a nonbinary patient is asked to choose a binary option for a spirometry test, that choice is not necessarily permanent.
Testing Nonbinary Patients
"Maybe a nonbinary patient says, when I saw you last time, I identified more as female, but now I identify more as male," she explained. "How do you remain sensitive" to that patient's needs?
Then there's the question of health records and insurance. What if "you want to treat asthma that wasn't there 2 years ago but is there now because you changed the reference range?" she asked. There is currently no way of explaining that in the system.
This issue is arising in many fields of medicine, and "definitely highlights the need to do something," said Tangpricha.
He suggested a robust study with a few hundred participants in each gender group to arrive at better measures of lung function. "Get people to blow into a spirometer while they're healthy," he said.
American College of Allergy, Asthma & Immunology (ACAAI) 2019 Annual Scientific Meeting: Poster P200.
Medscape Medical News © 2019
Cite this: Transgender Care Ill Served by Sex-Specific Test Values - Medscape - Nov 15, 2019.