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Incidence rates for systemic lupus erythematosus (SLE) almost doubled in Olmsted County, Minnesota, from 1976 to 2018, according to a new study, with the investigators suggesting that the area's changing demographics "at least partially explained" the trend.

From 1976 to 1988, the age-adjusted annual incidence of SLE stood at 3.32 per 100,000 population, reported Alí Duarte-Garcia, MD, of the Mayo Clinic in Rochester, Minnesota, and colleagues in. The rate then increased in successive periods, hitting 6.44 per 100,000 by 2009-2018.

It was probably not coincidental that the county's racial-ethnic mix changed markedly over this timeframe, the group noted: from essentially 100% white in 1976-1988 to 5% Hispanic, 16% Asian, and 9% Black in the most recent period. Rates for these non-white groups were higher across the entire study period than for non-Hispanic whites (8.17 vs 5.42 per 100,000, P=0.002), as had been found in previous studies.

If that's really the explanation -- and the authors had no others -- the findings have implications for the nation as a whole. "As the U.S. population grows more diverse, we might continue to see an increase in the incidence of SLE," Duarte-Garcia and colleagues concluded.

The that non-white Americans will top 50% of the overall U.S. population in a little more than 20 years.

As many 乌鸦传媒 readers know, Olmsted County is where Rochester is located and has become a laboratory for epidemiological research. Nearly all healthcare providers in the county are linked to a central database for anonymized patient records, allowing researchers to establish incidence and prevalence rates and track trends for any disease that might be found among its population that grew from about 90,000 in 1976 to 153,000 in 2018.

Duarte-Garcia and colleagues searched the database for ICD-9/10 codes for lupus-related conditions, including the systemic and cutaneous forms, as well as lab results indicative of lupus such as positivity for anti-nuclear antibodies.

Over the entire period, 188 new cases were identified. Because this was a relatively small number, it was not really possible to determine conclusively whether lupus severity or mortality had changed substantially; there was no indication that mortality had improved but a trend toward reduced severity was noted.

One other feature that did change was that the proportion of new-onset SLE cases among men increased from 7% to 22%. Even so, the incidence among both sexes increased.

Limitations to the study included the possibility of inaccurate records and the use of to ascertain diagnoses (which might have excluded some legitimate cases).

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