Tuesday, 18 Jun 2019

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HLA-B*5801 Testing Needed in Asians and Blacks with Gout

Choi and colleagues analyzed US hospitalizations (2009–2013) to assess the frequency and racial distribution of patients hospitalized with Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) related to the use of urate-lowering (ULT) therapy (predominantly allopurinol). (Citation source http://buff.ly/269RMHy)

They found 606 SJS/TEN hospitalizations while receiving ULT. There was an overrepresentation of Asians (27%) and Blacks (26%), and an underrepresentation of Whites (29%) and Hispanics (% too low to report).

These SJS/TEN events were 12 time more frequent in Asians, and 5 times more frequent in Blacks when compared to Whites (reference group).

The HLA-B*5801 allele has been strongly linked with the allopurinol hypersensitivity syndrome and has been found in higher frequency in certain populations, especially Koreans, Japanese, Thai and Han Chinese - and in some Europeans. This study demonstrates the potential use of HLA-B*5801 in U.S. Asians and Blacks.

The authors conclude that the overrepresentation of Asians and Blacks withSJS or TENS while on ULT calls for caution when prescribing allopurinol, and that HLA-B*5801 testing may be more widely applied in the U.S. gout population.

Rheumatologists' Comments

The "headline" here ("HLA-B*5801 Testing Needed in Asians and Blacks with Gout") is NOT what the authors of this study concluded; they concluded "these findings support the use of vigilance in these minorities when considering allopurinol." And, while the relative risks looks concerning, the very low rates of SJS/TEN with allopurinol do not necessarily warrant routine screening every patient of African American or Asian descent. We would need a cost analysis to know whether it makes sense; do we know how much HLA-B*5801 testing costs? Also, this study noted that "the US Japanese population has a low allele frequency of HLA-B*5801 (0.8%)...similar to US Whites as well as the Japanese population of Japan (0.6%) .... we expect a risk level similar to that of Whites' - so, again, the study does not support the headline as stated.
Rob, I concur with your critique of the title. I did reword this title to be provacative and make others think about this paper and issue. Without this and with a conservative title of Allopurinil SJS/TENS Events are Enriched in Certain Populations" would have garnered about 12 readers. Prior to reading this I never gave much consideration of B5801 testing - it seemed reserved largely for Han Chinese and other SE Asian populations as a risk factor. The authors conclusion and call for "vigilance in these minorities when considering alcohol" to me speaks for consideration of wider testing or preferably, the need for studies that look into the predictive value first and then cost analyses second (such tests are not cheap as you suggest!). I think thoughtful comments (like yours) and smart research (TBD) are needed on this issue, if not the challenging title. Thanks!

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