High Doses of Hydroxychloroquine May Protect Against Thrombosis in SLE

Researchers examined the association of blood levels of hydroxychloroquine with thrombotic events in a longitudinal systemic lupus erythematous cohort.

The following article is a part of conference coverage from the 2019 American College of Rheumatology/The Association of Rheumatology Professionals (ACR/ARP) Annual Meeting, being held in Atlanta, Georgia. The team at Rheumatology Advisor will be reporting on the latest news and research conducted by leading experts in rheumatology. Check back for more from the 2019 ACR/ARP Annual Meeting.

ATLANTA — Higher prescribed doses of hydroxychloroquine (HCQ) may be associated with lower odds of thrombotic events in patients with systemic lupus erythematosus (SLE), according to study results presented at the 2019 The American College of Rheumatology/Association of Rheumatology Professionals (ACR/ARP) Annual Meeting, held November 8 to 13, 2019, in Atlanta, Georgia.

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Investigators conducted a prospective cohort study of patients with SLE, and HCQ blood levels were ascertained at study visits by liquid chromatography-tandem mass spectrometry. Thromboses were defined as venous, including deep vein thrombosis/pulmonary embolism, or arterial, including stroke, myocardial infarction digital gangrene, or other arterial thrombosis. Patients were followed-up until index thrombotic event. Mean HCQ blood levels were calculated by averaging values obtained at all cohort visits before thrombosis.

The study cohort comprised 812 patients with SLE, among whom 93% were women, 43% were black, and 46% were white. During follow-up, researchers observed thrombosis in 44 patients (5.4%): 3.0% with venous thrombosis and 2.5% with arterial thrombosis. Lupus anticoagulant was significantly associated with a prior history of any thrombosis (odds ratio [OR], 3.25; P <.0001), venous thrombosis (OR, 3.53; P <.0001), and arterial thrombosis (OR, 3.08; P <.0001). Mean HCQ blood levels were significantly reduced in patients with any thrombosis (P =.0393) and venous thrombosis (P =.0616 with superficial; P =.0249 without superficial), compared with patients with no thrombosis. In addition, higher prescribed doses of HCQ were associated with decreased odds of any thrombosis and venous thrombosis (OR, 0.88; P =.04 and OR, 0.83; P =.009, respectively, for each 1 mg/kg increase in HCQ dose).

In this prospective analysis, high HCQ blood levels appeared to be protective against thrombosis in patients with SLE. The American Academy of Ophthalmologists suggests that clinicians reduce HCQ dosing; however, such adjustments “could reduce or eliminate the benefit of [HCQ] to prevent thrombosis,” the investigators wrote.

Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Konig M, Li J, Petri M. Hydroxychloroquine blood levels and risk of thrombotic events in systemic lupus erythematosus. Presented at: 2019 ACR/ARP Annual Meeting; November 8-13, 2019; Atlanta, GA. Abstract 2783.