The new england journal of medicine n engl j med 369;19 nejm.org november 7, 2013 1864 vided the rationale for our own study evaluating longitudinal measures of renal function and de- mentia risk. 1 It would be very difficult to evaluate two time-varying exposures captured sporadically in clinical care. Because we did not find a strong relationship between the level of renal function- ing and dementia risk in our cohort, 1 we doubt that the associations that we found in our cohort between glucose levels and dementia risk are confounded by renal function. We agree that more research is needed to elucidate the underlying causes of the association between glucose levels and dementia risk. Paul K. Crane, M.D., M.P.H. University of Washington Seattle, WA pcrane@uw.edu Rod Walker, M.S. Eric B. Larson, M.D., M.P.H. Group Health Research Institute Seattle, WA Since publication of their article, the authors report no fur- ther potential conflict of interest. 1. O’Hare AM, Walker R, Haneuse S, et al. Relationship be- tween longitudinal measures of renal function and onset of de- mentia in a community cohort of older adults. J Am Geriatr Soc 2012;60:2215-22. DOI: 10.1056/NEJMc1311765 Induction Regimens for ANCA-Associated Vasculitis To the Editor: In the 18-month follow-up report of the Rituximab in ANCA-Associated Vasculitis (RAVE) trial, Specks et al. (Aug. 1 issue) 1 reported a noninferiority of intravenous rituximab (375 mg per square meter of body-surface area adminis- tered weekly for 4 weeks) as compared with oral cyclophosphamide (taken daily) followed by aza- thioprine. Complete remission was maintained in 39% of the patients in the rituximab group and in 33% of the patients in the comparison group. As compared with the results of the CYCLOPS trial, the relapse rate in the control group ex- ceeded expectations (20.8% in the CYCLOPS trial vs. 29% in the RAVE trial), although the median follow-up in the CYCLOPS trial was 4.3 years. 1,2 One explanation might be the rigorous tapering of glucocorticoids in the RAVE trial, because early discontinuation of glucocorticoids is one of the most significant risk factors for relapse. 3 These differences were not discussed thoroughly, but clinical trials should address the need to prevent relapses in order to reduce treatment-related ad- verse events. Repeated administration of rituximab has shown encouraging results. 4 Further trials that are now being conducted will reassess these preliminary data. Nonetheless, the results of the RAVE trial have disproved the hypothesis that prolonged immunosuppressive treatment is ab- solutely necessary in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis. Andreas Kronbichler, M.D. Julia Kerschbaum, M.D. Michael Rudnicki, M.D. Medical University Innsbruck Innsbruck, Austria Andreas.Kronbichler@i-med.ac.at No potential conflict of interest relevant to this letter was re- ported. 1. Specks U, Merkel PA, Seo P, et al. Efficacy of remission- induction regimens for ANCA-associated vasculitis. N Engl J Med 2013;369:417-27. 2. Harper L, Morgan MD, Walsh M, et al. Pulse versus daily oral cyclophosphamide for induction of remission in ANCA-associated vasculitis: long-term follow-up. Ann Rheum Dis 2012;71:955-60. 3. Walsh M, Merkel PA, Mahr AD, Jayne D. Effects of duration of glucocorticoid therapy on relapse rate in antineutrophil cyto- plasmic antibody-associated vasculitis: a meta-analysis. Arthri- tis Care Res (Hoboken) 2010;62:1166-73. 4. Smith RM, Jones RB, Guerry MJ, et al. Rituximab for remis- sion maintenance in relapsing antineutrophil cytoplasmic anti- body-associated vasculitis. Arthritis Rheum 2012;64:3760-9. DOI: 10.1056/NEJMc1311108 To the Editor: Specks et al. report that for the treatment of severe ANCA-associated vasculitis, a single course of rituximab is noninferior to 18 months of the conventional regimen of daily cyclophosphamide followed by azathioprine. How- ever, there are several reasons for advocating cau- tion in using rituximab in such patients, particu- larly those with newly diagnosed disease. First, 20 patients (29%) in the cyclophosphamide–aza- thioprine group had a relapse before 18 months. The considerably higher proportion of patients The New England Journal of Medicine Downloaded from nejm.org by ANDREAS KRONBICHLER on January 29, 2015. For personal use only. No other uses without permission. Copyright © 2013 Massachusetts Medical Society. All rights reserved.