Background/Purpose: Glucose-6-phosphate dehydrogenase deficiency (G6PD) is linked to hemolytic anemia with certain medications and is the most common enzyme deficiency worldwide. Clinical hemolysis and severity of disease depends on the genotype of G6PD, which also has a different geographic distribution, with the most severe risk of hemolysis in the Mediterranean variant. Although the American College of Rheumatology does not recommend routine testing for G6PD prior to initiation of Hydroxychloroquine (HCQ), the package insert for HCQ does recommend careful use in G6PD deficient patients due to potential for hemolysis. A recent retrospective study from Duke assessed 11 G6PD deficient African American patients exposed to HCQ over 700 months cumulative exposure with no cases of hemolysis during medication exposure. Authors recommended against the routine measure of G6PD levels or withholding therapy with HCQ in African Americans given these results. However, the study population was mainly African American and had minor representation of other ethnicities.

Methods: Eligible subjects in our large, urban medical center were identified using clinical looking glass software from January 1st ,1997 to January 1st, 2018. Data was collected using the institutional EMR. Case records were analyzed for G6PD deficiency, HCQ use, length of exposure to HCQ, demographic characteristics and laboratory evidence of hemolysis.

Results: 5264 patients were prescribed HCQ during the prespecified interval, of which 49.5% (2605 patients) were screened for G6PD deficiency. Of the screened patients, 36 were found to be G6PD deficient. After chart review, 18 G6PD deficient patients were found to be exposed to HCQ. The mean age of the patients was 48 years (SD 14.1, range 18-66), 11 were female, the most common race was African American (n=10) and Hispanic (n=5), and the most common diagnosis was lupus (n=7), followed by rheumatoid arthritis (n=5 ). The mean exposure time was 32.8 months (SD 30.3, range 2-114 months), with a total cumulative exposure of 591 months. No evidence of hemolysis was found, either by clinical or laboratory criteria.

Conclusion: 5264 patients were prescribed HCQ during the prespecified interval, of which 49.5% (2605 patients) were screened for G6PD deficiency. Of the screened patients, 36 were found to be G6PD deficient. After chart review, 18 G6PD deficient patients were found to be exposed to HCQ. The mean age of the patients was 48 years (SD 14.1, range 18-66), 11 were female, the most common race was African American (n=10) and Hispanic (n=5), and the most common diagnosis was lupus (n=7), followed by rheumatoid arthritis (n=5 ). The mean exposure time was 32.8 months (SD 30.3, range 2-114 months), with a total cumulative exposure of 591 months. No evidence of hemolysis was found, either by clinical or laboratory criteria.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/retrospective-study-association-of-hydroxychloroquine-use-and-hemolytic-anemia-in-patients-with-low-levels-of-glucose-6-phosphate-dehydrogenase-g6pd/