ACR: Antimalarial Drug Protects Kidneys in Lupus
CHICAGO -- Treatment with hydroxychloroquine among patients with systemic lupus erythematosus was significantly protective against the development of renal failure, a researcher reported here.
Among a large cohort of patients, who have been followed since 1987 and who were not in renal failure at baseline, the use of the antimalarial drug during at least 50% of follow-up was associated with a 50% reduction in the development of renal failure (RR 0.5, 95% CI 0.3 to 0.9, P=0.026), according to Michele Petri, MD, of Johns Hopkins University, and colleagues.
Their study was presented during an oral session at the annual meeting of the American College of Rheumatology.
"We are all aware of the huge impact of nephritis among patients with lupus -- where the annual cost can be $100,000 per patient each year -- and the grave concern that the incidence is actually rising, despite treatment with cyclophosphamide or mycophenolate mofetil [CellCept]," said Petri, who heads the longitudinal Johns Hopkins lupus cohort.
To identify factors that could increase the risk of renal failure or confer protection from it, she and her colleagues analyzed data from the cohort, which included 1,996 patients, more than 90% of whom were women and whose mean age at entry was 38.
Slightly over one-third (36%) were African American, and 57% were identified as Caucasian.
During follow-up, there were 54 new cases of renal failure, for an incidence rate of 4.3 cases per 1,000 person-years.
After controlling for glomerular filtration rate at baseline, they found that African-American ethnicity was associated with an increased risk of renal failure, with a rate ratio of 2.6 (95% CI 1.5 to 4.8, P=0.0015).
Systolic blood pressure between 120-mm Hg and 129 mm Hg also was associated with a risk ratio of 2.5 (95% CI 1.2 to 5.5, P=0.020), while body mass index and diabetes were not found to contribute.
Certain serologic findings also were associated with a heightened risk for renal failure:
- Low C3: risk ratio (RR) 3.1 (95% CI 1.4 to 6.6, P=0.039)
- Low C4: RR 3 (95% CI 1.5 to 5.9, P=0.0015)
- Anti-double stranded (ds) DNA: RR 3.2 (95% CI 1.4 to 7.5, P=0.008)
- Lupus anticoagulant: RR 2.1 (95% CI 1.2 to 3.7, P=0.0075)
In addition, if anti-dsDNA was present for more than half of follow-up, the RR rose to 5.6, Petri said.
Unlike hydroxychloroquine, being on an angiotensin converting enzyme (ACE) inhibitor was not protective, nor was being on an angiotensin II receptor blocker (ARB), she said.
In a multivariable model, younger age was associated with greater risk, as was African-American ethnicity (RR 3, P=0.003) and the presence of anti-dsDNA (RR 4.8, P=0.0003).
Use of hydroxychloroquine for more than 50% of follow-up in the multivariable analysis also decreased the likelihood of renal failure (RR 0.6), but the P-value was not as significant, at 0.079, Petri said.
"Nonetheless, even though African-American ethnicity and anti-dsDNA were more important than the use of [hydroxychloroquine] in this model, anything we can do as clinicians to reduce the risk of renal failure will be helpful," she said.