When learning how to diagnose illnesses in medical school, students are trained to be on the lookout for common ailments and not look for rare illnesses. When symptoms match more than one illness, the most likely diagnosis is the most common among all the possibilities. This is what the famous saying, “When you hear hoofbeats, think horses, not zebras,” means.
This doesn’t mean, however, that doctors must entirely ignore the possibility of an illness being a “zebra.” Those who do risk putting their patients’ health at risk.
This case study on rare Disease patients’ diagnostic “odyssey” — a long, complicated journey that inches forward towards a goal — reveals the effects of delayed and inaccurate diagnoses of rare Diseases. Researchers surveyed 3,471 patients and caregivers across 436 rare Diseases. Some of the questions asked were how often they had to undergo testing, how many physicians they needed to see, how long they waited to receive a diagnosis, and whether they were misdiagnosed. The results are not representative because of the respondents’ different experiences, but they reveal common issues in the diagnostic process.
Summary of the Study:
Recognizing the highly varied experiences of the respondents, the researchers focused on the commonalities of their experiences instead of making a conclusive statement about rare disease patients.
The key findings are as follows:
- The average waiting period before patients received a diagnosis is 4.4 years.
- The median waiting period is 1.1 years.
What this data means is that half of the survey participants received their diagnosis after a little over a year. Many, however, had to wait for a much longer period, which explains why the average (mean) waiting period skewed to 4.4. years.
Other important findings are:
- Patients took an average of seven tests before getting diagnosed.
- Patients saw an average of four physicians before diagnosis.
- Forty-six percent received a misdiagnosis.
- Forty-seven percent believed they received delayed treatment.
- One-third or 30.5% underwent genetic testing. Of this population, 66.9% believed the test helped find the correct diagnosis.
To find the common experiences of the patients surveyed, the researchers analyzed the data of 61 diseases that had 10 diagnosed patients. The ones eventually diagnosed with Primary Immunodeficiency illnesses, Ankylosing Spondylitis, Celiac Disease, Depression, Ehlers-Danlos Syndrome, Fabry, Mastocytosis, and Pompe had a median waiting period of five years and an average waiting period of 10 years. Researchers identified a couple of factors for the long wait:
- Multiple testing was necessary
- Patients needed to see many physicians
- Some were misdiagnosed
Focus on Specific Diseases
The researchers focused on the personal accounts of the respondents diagnosed with Hemophilia, Cystic Fibrosis, and Ehlers-Danlos Syndrome to uncover more details about them.
- Hemophilia - Physicians depend heavily on family history to diagnose Hemophilia in children. Unfortunately for patients who acquire the Disease through genetic mutation, the average time to diagnosis is four to seven years. Some were not diagnosed for 10+ years, and more than half of these patients were females. According to the female respondents, the assumption that females are carriers of the Disease contributed to the delay in their diagnosis.
- Cystic Fibrosis - The mandatory newborn screenings for Cystic Fibrosis have been helpful in the early diagnosis and treatment for afflicted infants in the U.S. The average diagnostic period is 3.3 years, with a median of 0.3 years. For those who were born before 2000, however, the average diagnostic period is 6.6 years, with a 47% rate of misdiagnosis.
- Ehlers-Danlos Syndrome (EDS) - Patients with EDS had the longest average diagnostic period at 21 years, with 77.6% of respondents previously misdiagnosed. Patients also had an average of 24 tests and 15 physicians consulted. The common feedback among the respondents was that physicians focused on finding a “common” diagnosis and did not consider EDS as a possibility. Many believed that an earlier diagnosis could have made their condition a lot better than they are now.
The case study highlights the common roadblocks to timely and correct diagnosis: allowing preconceptions about a Disease to influence the direction of the diagnostic process, gender biases, lack of awareness about a specific Disease, late consultations with knowledgeable specialists, and lack of insurance, among others.
It’s important to recognize these roadblocks when they materialize. Patients must overcome their fear and avoid being in denial of their condition. They must also be vocal when they feel that physicians are inattentive about their symptoms, given the latter’s inclination to “look for horses instead of zebras.” Physicians, meanwhile, need to be proactive in learning more about rare Diseases, their symptoms, and diagnostic procedures.
Late treatment can lead to a reduced quality of life for the patients and their caregivers. Timely and correct diagnosis of rare Diseases should be a priority for all physicians.