For decades, millions of patients undergoing pulmonary function tests have had their results quietly adjusted based on a checkbox on their medical intake form. If a patient was identified as Black, the software used to measure their lung capacity often applied a “correction factor,” automatically lowering the threshold for what was considered a “normal” result.
This practice, known as race-correction in lung testing, was designed to account for perceived biological differences in lung volume between racial groups. However, medical researchers and clinicians are now revealing that these adjustments were not based on sound genetics, but on a legacy of 19th-century pseudoscience. By treating race as a biological variable, the medical community may have systematically under-diagnosed lung disease and delayed critical care for Black patients.
The shift away from these adjustments represents a broader movement in medicine to decouple clinical care from social constructs of race. As the American Thoracic Society and other leading bodies move toward race-neutral standards, the focus is shifting from assumed racial differences to the actual environmental and socioeconomic factors—such as air pollution and systemic inequality—that truly impact lung health.
The Invisible Adjustment
When a patient performs a spirometry test—the most common tool for diagnosing asthma or COPD—they blow into a tube to measure how much air they can exhale and how quickly they can do it. The machine generates a raw number, but that number is rarely presented to the doctor in isolation. Instead, it is compared to a “predicted value” based on the patient’s age, height, sex and race.
For Black patients, the predicted value was typically set lower—often by 10% to 15%—than for white patients of the same height and age. This meant that a Black patient with significantly impaired lung function could be told their results were “normal” simply because they were being compared to a lowered bar. Conversely, a white patient with the same raw lung capacity might be correctly identified as having a restrictive lung disease.
The impact of this mathematical adjustment is not merely academic. it has tangible consequences for patient outcomes. Because lung function is often a primary metric for determining eligibility for lung transplants or qualifying for disability benefits, race-correction has been linked to systemic disparities in access to life-saving interventions.
A Legacy of Pseudoscience
The integration of race into lung testing did not begin with modern clinical trials, but with the racial hierarchies of the 1800s. Much of the early “evidence” for racial differences in lung capacity came from researchers like Samuel George Morton, a physician who practiced craniometry and believed that different races possessed fundamentally different biological capacities.
Throughout the early 20th century, these beliefs were codified into medical textbooks. Researchers assumed that the lower lung volumes observed in some Black populations were innate and genetic. They ignored the reality that these populations were more likely to live in impoverished conditions, face higher exposure to industrial pollutants, and suffer from chronic malnutrition—factors that physically stunt lung development during childhood.
By the time these “race-norms” were programmed into the digital spirometers used in clinics today, the original flawed assumptions had been baked into the software. The software treated race as a biological fact rather than a social category, effectively erasing the impact of environmental racism by labeling its results as “natural.”
The Clinical Cost of Normalization
The danger of race-normalization is most evident in the “gray zone” of diagnosis. When a clinician sees a result that is 85% of the predicted value, they may see it as healthy. But if that 85% was calculated using a race-corrected baseline, the patient’s actual lung function might be significantly lower than what is clinically acceptable.
This discrepancy can lead to a cascade of medical failures:
- Under-diagnosis: Patients with early-stage interstitial lung disease or asthma may not receive medication because their results appear “normal” for their race.
- Delayed Transplants: Eligibility for lung transplantation often requires a specific threshold of impairment. Race-correction can make a patient appear “too healthy” for a transplant, even when their organs are failing.
- Workplace Inequity: In occupational health screenings, race-corrected tests may fail to detect lung damage caused by toxic workplace exposures in Black laborers.
| Feature | Race-Corrected Approach (Legacy) | Race-Neutral Approach (Current Shift) |
|---|---|---|
| Baseline | Adjusted by racial category | Based on height, age, and sex only |
| Assumption | Race is a biological determinant | Race is a social construct; environment matters |
| Clinical Risk | Under-diagnosis in Black patients | More accurate detection of impairment |
| Goal | Statistical “normalization” | Individualized clinical accuracy |
Moving Toward Health Equity
The medical community is now in the process of dismantling these norms. The American Thoracic Society (ATS) and the European Respiratory Society (ERS) have been instrumental in questioning the validity of race-based equations. Recent guidelines emphasize that while lung volumes may vary across populations, these differences are better explained by ethnicity, geography, and socioeconomic status than by “race.”
Clinicians are increasingly encouraged to use “global” reference values—standards that are based on diverse populations without applying a race-based multiplier. This shift requires not only a software update in the clinic but a change in medical education. Doctors are being taught to look at the raw data and consider the patient’s specific life history—where they lived, what they breathed, and their access to healthcare—rather than relying on a racial proxy.
The transition is not without challenges. Some practitioners worry that removing corrections will lead to an over-diagnosis of lung disease in certain populations. However, advocates for health equity argue that over-diagnosis is a manageable clinical problem, whereas the systematic under-diagnosis of an entire racial group is a fundamental failure of medical ethics.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Patients should consult with a licensed healthcare provider regarding their specific diagnostic tests and treatment plans.
The next major milestone in this transition will be the widespread adoption of the updated Global Lung Function Initiative (GLI) standards across electronic health record systems, which aims to standardize race-neutral reporting globally. As these updates roll out, the medical community will continue to monitor how the removal of race-correction impacts diagnosis rates and patient outcomes across diverse demographics.
Do you believe medical software should be audited for racial bias? Share your thoughts in the comments or share this story with your healthcare provider.
