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Study: Implicit Bias, Late Diagnosis Create Critical ALS Healthcare Gap

Neurology fellow finds diagnostic delays in Black ALS patients prevents life-altering therapies

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Written by Chris Casey on February 13, 2023
What You Need To Know

A study by Zach Cox, DO, finds greater diagnostic delays for ALS patients of color than white patients. Cox also digs into the research that shows evidence that implicit bias among providers is likely a key cause of healthcare disparities.

It was only his first visit to a hospital’s ALS clinic, but already the Black patient’s amyotrophic lateral sclerosis (ALS) had progressed beyond a point for an effective intervention. This memory sticks with Zach Cox, DO, who at the time was a resident at the multidisciplinary ALS clinic in Richmond, Va.

“It was a sad situation in which he was already experiencing lots of difficulties with breathing,” said Cox, who performed his residency at Virginia Commonwealth University (VCU) and is currently a neuromuscular fellow in the Department of Neurology at the University of Colorado School of Medicine (SOM). “The disease had progressed to a point where a lot of the interventions you could have done to improve the patient’s quality of life were no longer feasible.”

Early diagnosis essential

Cox said most ALS patients are diagnosed in a clinic setting rather than a hospital, the latter often being too late because of how quickly the progressive disease leads to motor neuron degeneration. While three therapeutics have been shown to improve patients’ quality of life and lengthen survival, there is still no cure for the disease that afflicts 5.5 per 100,000 people. Early diagnosis is essential for starting a therapeutic, including non-invasive ventilation and feeding tube placement, and enrolling in a clinical trial.

Studying Increased Access Close to Home


The Department of Neurology at the University of Colorado School of Medicine has received a $400,000 grant from the ALS Association to help increase access for underserved populations and communities at the Neuromuscular Clinic at UCHealth University of Colorado Hospital. The PI on the project is Laura Foster, MD.



  • For more about implicit bias, a Harvard University study called Project Implicit
  • For more about ALS, The ALS Association
  • To listen to Zach Cox’s grand rounds on “Understanding Care Gaps Between Black and White ALS Patients,” click here.

Cox developed an interest in racial disparities in healthcare as an undergraduate studying sociocultural anthropology. As a medical student, his interest grew during an internship, then residency, at the VCU clinic. He noticed that few studies addressed differences in ALS presentation, mortality, quality of life, and diagnostic delays in ALS patients of color.

“I just wanted to see, first, if there was a difference in ALS patients in our own clinic, which there definitely was. It takes a lot more to come up with the why,” he said.

Study examines disparities, implicit bias

From his research, Cox concluded that significant diagnostic delays occur in all ALS patients – an average of eight to 11 months for diagnosis across all patients – but with greater delays in Black patients. He also determined that implicit bias among providers is likely a key cause of care disparities.

Cox looked at electronic health records of ALS patients treated at the VCU clinic between 2014 and 2022. Patients were selected based on self-reported race in EHRs; there were 38 Black and 78 white patients. He focused on their ALS Functional Rating Scale (FRS) and upright Forced Vital Capacity (FVC) baselines because they strongly correlate with quality of life and mortality in ALS patients.

The Black patients had lower numbers for both FRS and FVC, with a “pretty striking” 20% difference on FVC baseline.

“You’re seeing a lot of patients that may be coming in for their first visit and already you need to be discussing PEG (percutaneous endoscopic gastronomy) tube placements,” Cox said. “They already may not be eligible for clinical trials, so these are important numbers.”

Disparities exist across diseases, disorders

Many studies concluded that diagnostic delays occur between white and underserved populations with other disorders and diseases, including autism, breast cancer and dementia, Cox said. Likewise, evidence shows that once in the clinic, patients of color consistently are offered poorer preventative care, fewer referrals for advanced diagnostics, and fewer treatments considered standard of care.

Also, Cox said, they are less frequently referred to clinical trials and “there’s a pretty good breadth of research in the transplant field where Black patients are less often offered a transplant.”

Implicit bias can be addressed individually

An Emory University study compared 1,095 white and 203 Black ALS patients and found similar diagnostic, FVC and FRS trends as Cox’s study. The Emory study also used controls for socioeconomic status (Cox’s study did not) and still found healthcare disparities between white patients and patients of color.

‘Implicit bias is shown to be somewhat malleable for people

and can be tackled on an individual level.’ – Zach Cox, DO

So, the “why” zeroed in on implicit bias, a concept Cox knew from his anthropology background. What is implicit basis? “It’s this stored association on a subconscious level and can be learned in medical training to things that have been ingrained over the years based on your culture where you grew up,” Cox said.

His study focused on implicit bias because it can be addressed individually by reshaping a person’s subconscious stereotypes.

“We often talk about socioeconomic status, larger systemic, institutional and legal issues, which are bigger than an individual can tackle,” he said. “Implicit bias is shown to be somewhat malleable for people and can be tackled on an individual level.”

‘Something we all have’

During a recent SOM grand rounds about his study, Cox emphasized that guilt and shame shouldn’t be wrapped up in implicit bias.

“It’s something we all have,” he said. “When they’ve done studies with healthcare providers, by and large, all say they don’t believe these stereotypes, but when they do implicit bias testing, it still bears out that it’s there. They are just not recognizing these things are affecting how they are thinking about and treating patients.”

Physicians can be especially susceptible to implicit bias because they are trained to recognize patterns and stereotype symptoms to arrive at a diagnosis, Cox said. “But it’s important to remember that when you’re having a patient encounter, just as you’re unconsciously triggering paradigms that have been established in your medical training, you’re also activating sociocultural models you’ve had from your entire life experience.”

Cox said ways to correct implicit bias include:

  • Promoting counter-stereotypes, which are directed at the subconscious levels of bias. This can include consuming media that features people/characters acting in counter-stereotypical ways or striving to think about colleagues/friends who represent counters to traditional stereotypes.
  • Self-motivating: “This is where you consciously act, in the moment, to inhibit negative stereotypes you might hold and activate positive ones.”

After Cox completes his CU Anschutz fellowship in June, he plans to practice medicine in West Virginia, where he will likely be the only neurologist in roughly 40 miles. “Another area of interest is healthcare in underserved communities,” he said. “My dream is to have a multidisciplinary clinic for patients with ALS and muscular dystrophy.”

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Staff Mention

Zach Cox, DO