Study Finds Broad Ethnic Labels Conceal Rare Disease Variations
Researchers analyzing electronic health records for 62.5 million people in England have found that broad ethnic classifications conceal substantial variations in the prevalence of rare diseases and recorded COVID-19 infection rates across different communities.
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Key Clinical Takeaways:
- A cross-sectional study published in Scientific Reports examined 406 rare diseases across 62.5 million NHS patient records in England.
- Broad ethnic groupings masked significant disparities, which became clearer when researchers applied detailed NHS classifications.
- Documented COVID-19 infection rates among rare disease patients varied from 23.8% to 33.7% depending on ethnic background.
Prevalence of 406 Rare Diseases Across English Population Records
The cross-sectional analysis, published in the journal Scientific Reports, investigated how ethnicity relates to rare disease prevalence and recorded coronavirus infections. Led by researchers examining data through the CVD-COVID-UK/COVID-IMPACT Consortium, the team utilized linked electronic health records from the National Health Service England Secure Data Environment. The study evaluated individuals registered with general practices who were alive on July 31, 2023, reviewing diagnostic codes recorded between January 1, 1990, and July 31, 2023. Out of 62,539,740 individuals included in the evaluation, 1,051,470 people—or 1.7%—had at least one of the 406 targeted rare diseases.
Age- and sex-standardized prevalence rates, adjusted against the 2021 England Census, demonstrated extreme variation across the population. The rarest conditions appeared in fewer than one case per million people, whereas polymyalgia rheumatica reached a high of 3,139.5 cases per million. Atrial septal defect followed at 2,449.7 per million, and apnea in infants registered at 1,057.5 per million. Affected individuals tended to have a higher median age of 46 years compared to 40 years for the unaffected population, and 54.7% of those with a rare disease were female.
Granular Ethnic Classifications Reveal Hidden Disparities
When evaluated through six broad Office for National Statistics categories, polymyalgia rheumatica was most prevalent in the White group, while atrial septal defect peaked in the Mixed group. However, utilizing 19 detailed NHS ethnic classifications uncovered sharper divergences. According to findings highlighted by News-Medical, atrial septal defect reached 3,721.5 per million among people of White and Caribbean backgrounds, compared to 2,372.1 per million among those of White and African backgrounds.
For 227 conditions with at least 100 affected patients, the researchers calculated unadjusted odds ratios to assess demographic differences. Among Asian or Asian British individuals, 104 diseases showed significantly different odds compared to the White group, with 38 conditions displaying higher odds—including maple syrup urine disease and lamellar ichthyosis—and 66 showing lower odds. Among Black or Black British individuals, 83 diseases differed from the White baseline, featuring elevated odds for Moyamoya disease in 28 conditions and lower odds in 55.
Recorded COVID-19 Infection Rates Among Rare Disease Populations
Documented SARS-CoV-2 infections through July 31, 2023, were identified using polymerase chain reaction and lateral flow test results. Overall, a positive COVID-19 test was recorded in 32.8% of individuals living with a rare disease, compared to 29.0% of those without these conditions. Within the rare disease cohort, recorded infection rates were highest among White British individuals at 33.7%.
Conversely, documented rates were lower among several minoritized communities. As detailed in the data, recorded infections reached 23.8% for Black African individuals, 24.1% for Gypsy or Irish Traveler individuals, 27.2% for Bangladeshi individuals, and 27.7% for Pakistani individuals. Researchers noted that these figures reflect documented positive tests rather than total infections, and may be influenced by age distribution, underlying disease mix, protective behaviors, and local testing practices.