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Therapeutic HCQ levels associated with fewer SLE flares
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Monitoring hydroxychloroquine levels in patients with systemic lupus erythematosus allowed physicians to identify noncompliance and made dose titration easier.
In this longitudinal study, researchers followed 276 patients with systemic lupus erythematosus (SLE) who were treated with hydroxychloroquine (HCQ) in the rheumatology clinics of Tuen Mun Hospital in Hong Kong during a 9-month period starting in 2011. For inclusion in the study, patients had to be at least 18 years old, fulfill four or more of the 1997 American College of Rheumatology classification criteria for SLE and have been taking HCQ for at least 6 months.
At recruitment, the researchers assayed blood samples from the patients, 93% of whom were women, with tandem mass spectrometry. Using the Safety of Estrogens in Lupus Erythematosus National Assessment (SELENA) version of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and flares (SELENA flares instrument), the researchers followed the patients every 4 months. Follow-up was more frequent in the event of active disease, SLE flares or treatment-related adverse events.
HCQ level analysis showed 11% of patients were totally noncompliant, 77% were taking sub-therapeutic doses and 12% were taking therapeutic doses (>500 ng/ml). The researchers found significant correlation between HCQ levels and the prescribed daily dose.
The researchers found a relationship between the prescribed daily dose and baseline SLEDAI scores, which suggested higher HCQ doses were used for more active SLE cases. There was no significant correlation between HCQ levels and body weight or renal function, the authors wrote.
After a mean follow-up of 32.5 + 5.5 months, there were no statistically significant differences in mean total SLEDAI scores and the SLE flare rate among patients with varying baseline HCQ levels, the authors wrote. The researchers performed a subgroup analysis on 73 patients who did not have clinical or serologic SLE activity at baseline. They found that in these patients, therapeutic HCQ levels were associated with less disease activity and fewer disease flares. — by Colleen Owens
Disclosure: The researchers report no relevant financial disclosures.
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