Across England, the health records of more than sixty million people have been read with unusual patience, and in them a quiet truth appears: rare illnesses do not fall evenly across the many peoples who make up the country. Broad labels such as "Asian" or "Black" gather together populations whose differences the finer categories reveal. The study, published in Scientific Reports, does not settle why these patterns exist, and its own authors leave the deeper explanations for later careful work. What it offers is a reminder that to see the uncommon clearly, one must sometimes look more closely
Broad ethnic labels mask rare disease differences across 62.5 million people in England
Broad ethnic categories concealed substantial differences
Across England, the health records of more than sixty million people have been read with unusual patience, and in them a quiet truth appears: rare illnesses do not fall evenly across the many peoples who make up the country. Broad labels such as "Asian" or "Black" gather together populations whose differences the finer categories reveal. The study, published in Scientific Reports, does not settle why these patterns exist, and its own authors leave the deeper explanations for later careful work. What it offers is a reminder that to see the uncommon clearly, one must sometimes look more closely at the particular people who carry it.
Of the 62,539,740 people in England whose health records were examined, 1,051,470 had at least one of 406 rare diseases chosen by the researchers. That amounts to 1.7 percent, and it describes only those selected conditions, not rare disease as a whole. The study's most striking result came when the team stopped sorting people into broad ethnic categories and looked at finer ones.
The analysis drew on linked records from general practices, hospitals and national mortality data, held in a secure NHS England environment. It counted diagnoses recorded between 1990 and July 31, 2023, and measured how many living people had each condition. The work begins from a familiar difficulty: more than 6,000 rare diseases together touch an estimated 3.5 to 5.9 percent of people worldwide, yet each is so uncommon that counting them is hard. People from minoritized backgrounds often face longer paths to diagnosis, more misdiagnosis and weaker access to specialists, and broad labels can hide differences that matter.
When the detailed categories were used, the picture shifted. Interatrial communication, for example, was far more common among people of White and Caribbean background than among those of White and African background. Within communities too, patterns diverged: Pakistani individuals showed higher odds of several conditions compared with White British individuals, and Bangladeshi individuals showed higher odds of others. Some conditions appeared more often in one sex, and several differences held across mixed-ethnicity groups.
Recorded COVID-19 infection was 32.8 percent among those with rare diseases and 29.0 percent among those without. The rate was highest among White British people and lower among several other groups, though these are unadjusted counts of positive tests, and age, disease mix, behavior and testing may account for much of the gap.
The researchers are candid about what remains open. Their odds ratios have not yet been adjusted for age or deprivation, so the differences are signals rather than conclusions. Their call is for finer ethnic data in diagnosis and research, and for careful, confounder-controlled work that can show which differences truly reflect biology, access, or chance.
Of the 62,539,740 people in England whose health records were examined for a study in Scientific Reports, 1,051,470 had at least one of 406 rare diseases the researchers had selected. That is 1.7 percent, a figure that applies only to those chosen conditions and not to rare disease as a whole. The more striking finding was what happened when the researchers stopped grouping people into broad ethnic categories and looked at finer ones.
The work was a cross-sectional analysis of linked electronic records for people registered with English general practices who were alive on July 31, 2023. Data came through the NHS England Secure Data Environment, via the British Heart Foundation Data Science Centre's CVD-COVID-UK/COVID-IMPACT Consortium. It combined primary care records, hospital inpatient and outpatient records, and Office for National Statistics mortality data. Diagnoses recorded between January 1, 1990, and that end date were counted using ICD-10 and SNOMED CT codes. The study measured point prevalence among the living, not new diagnoses.
The background is a familiar difficulty. More than 6,000 rare diseases together affect an estimated 3.5 to 5.9 percent of people worldwide, but each is so uncommon that population-level estimates are hard to make. Many begin in childhood and have genetic causes. People from minoritized ethnic backgrounds can face longer routes to diagnosis, more misdiagnosis and poorer access to specialist services, and broad labels may hide differences that matter.
People with a studied rare disease were more likely to be female (54.7 percent versus 49.9 percent) and older, with a median age of 46 against 40. Most had a single condition. Among them, 77.8 percent fell into an "Other" category, 18.9 percent had cardiovascular conditions, 2.3 percent mixed categories and 1.0 percent metabolic conditions. Age- and sex-standardized prevalence, using the 2021 Census population as the reference, ran from under one per million for the rarest diseases to 3,139.5 per million for polymyalgia rheumatica. Interatrial communication followed at 2,449.7 per million, then infantile apnea at 1,057.5.
Ethnicity changed the picture. Under the six broad ONS categories, polymyalgia rheumatica was most prevalent in the White group and interatrial communication in the Mixed group. The 19 detailed NHS categories sharpened this: interatrial communication stood at 3,721.5 per million among people of White and Caribbean background, against 2,372.1 per million among those of White and African background.
Odds ratios were calculated for the 227 diseases with at least 100 affected people. Compared with White individuals, 104 differed significantly for Asian or Asian British people: 38 had higher odds, including lamellar ichthyosis and maple syrup urine disease, and 66 lower. For Black or Black British people, 83 differed: 28 higher, including Moyamoya disease, and 55 lower. These odds ratios were not adjusted for age, deprivation or other confounders.
Within communities, patterns diverged further. Pakistani individuals had higher odds than White British individuals of medium-chain acyl-coenzyme A dehydrogenase deficiency, dextrocardia, congenital laryngomalacia and retinopathy of prematurity. Bangladeshi individuals had higher odds of recorded Kawasaki disease and retinopathy of prematurity. Discoid lupus erythematosus was more likely among Black Caribbean individuals and less likely among Black African individuals. Kawasaki disease showed elevated odds across the mixed-ethnicity groups. Males had higher odds of Legg-Calvé-Perthes disease, and females of several inflammatory conditions.
Recorded COVID-19 infection, based on positive PCR or lateral flow tests through July 31, 2023, was 32.8 percent among people with rare diseases and 29.0 percent among those without. Within the rare disease group it was highest among White British (33.7 percent) and White (33.5 percent) people, and lower among Black African (23.8 percent), Gypsy or Irish Traveller (24.1 percent), Bangladeshi (27.2 percent) and Pakistani (27.7 percent) people. These are unadjusted counts of documented positive tests, not all infections, and age, disease mix, protective behavior and testing practices may explain them. Among the 25 most common rare diseases the rate ranged from 24.6 percent to 41.2 percent. The lowest were congenital laryngomalacia, retinopathy of prematurity, polymyalgia rheumatica and infantile apnea. The findings point toward finer ethnic data and confounder-adjusted follow-up work.
Citações Notáveis
Recorded infection figures are unadjusted and may reflect age, disease composition, protective behaviors and testing practices.— Study authors, Scientific Reports
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