correspondence
As Macchia and colleagues highlight, our data Lewis J. Rubin, M.D. show that the change in 6-minute walk distance University of California, San Diego was not associated with long-term outcomes in La Jolla, CA pulmonary arterial hypertension. The observed Gérald Simonneau, M.D. reduction in morbidity was driven by a decrease Université Paris-Sud in the rate of worsening of pulmonary arterial Le Kremlin-Bicêtre, France hypertension, which was defined in great detail Since publication of their article, the authors report no furand required three criteria, not only a decrease ther potential conflict of interest. in the 6-minute walk distance. Our study was 1. Graf C, Battisti WP, Bridges D, et al. Research methods and approved by health authorities and ethics com- reporting: good publication practice for communicating committees. Background therapy for pulmonary ar- pany sponsored medical research: the GPP2 guidelines. BMJ terial hypertension, when available, was allowed, 2009;339:b4330. 2. AMWA position statement on the contribution of medical and we closely monitored patients for the need for writers to scientific publications. Rockville, MD: American additional treatment. In some countries, because Medical Writers Association (http://www.amwa.org). of the limited availability of approved targeted 3. Jacobs A, Wager E. European Medical Writers Association (EMWA) guidelines on the role of medical writers in developing therapies, a patient’s participation in a clinical peer-reviewed publications. Curr Med Res Opin 2005;21:317-22. trial may provide the only access to potential 4. Norris R, Bowman A, Fagan JM, et al. International Society treatment for pulmonary arterial hypertension. for Medical Publication Professionals (ISMPP) position statement: the role of the professional medical writer. Curr Med Res Tomás Pulido, M.D. Opin 2007;23:1837-40. Ignacio Chávez National Heart Institute Mexico City, Mexico
DOI: 10.1056/NEJMc1313112
Complement-Binding Anti-HLA Antibodies and Kidney Transplantation To the Editor: Loupy et al. (Sept. 26 issue)1 present data showing that the C1q-binding assay is more sensitive than the standard complementdependent microlymphocytotoxicity (CDL) assay for assessing the risk of graft loss. In their retrospective analysis of 1016 patients who had a negative CDL assay before transplantation, antibodymediated rejection developed in 7.4% during the first year. The authors predict that antibody-mediated rejection would have occurred in 3.7% of
patients (a 50% reduction) if the C1q-binding assay had been used. However, most laboratories use a more sensitive flow cytometric crossmatching (FCXM),2 not CDL alone. We have data from 11 patients who had low levels of donor-specific anti-HLA antibodies (mean fluorescence intensity [MFI],
As Macchia and colleagues highlight, our data Lewis J. Rubin, M.D. show that the change in 6-minute walk distance University of California, San Diego was not associated with long-term outcomes in La Jolla, CA pulmonary arterial hypertension. The observed Gérald Simonneau, M.D. reduction in morbidity was driven by a decrease Université Paris-Sud in the rate of worsening of pulmonary arterial Le Kremlin-Bicêtre, France hypertension, which was defined in great detail Since publication of their article, the authors report no furand required three criteria, not only a decrease ther potential conflict of interest. in the 6-minute walk distance. Our study was 1. Graf C, Battisti WP, Bridges D, et al. Research methods and approved by health authorities and ethics com- reporting: good publication practice for communicating committees. Background therapy for pulmonary ar- pany sponsored medical research: the GPP2 guidelines. BMJ terial hypertension, when available, was allowed, 2009;339:b4330. 2. AMWA position statement on the contribution of medical and we closely monitored patients for the need for writers to scientific publications. Rockville, MD: American additional treatment. In some countries, because Medical Writers Association (http://www.amwa.org). of the limited availability of approved targeted 3. Jacobs A, Wager E. European Medical Writers Association (EMWA) guidelines on the role of medical writers in developing therapies, a patient’s participation in a clinical peer-reviewed publications. Curr Med Res Opin 2005;21:317-22. trial may provide the only access to potential 4. Norris R, Bowman A, Fagan JM, et al. International Society treatment for pulmonary arterial hypertension. for Medical Publication Professionals (ISMPP) position statement: the role of the professional medical writer. Curr Med Res Tomás Pulido, M.D. Opin 2007;23:1837-40. Ignacio Chávez National Heart Institute Mexico City, Mexico
DOI: 10.1056/NEJMc1313112
Complement-Binding Anti-HLA Antibodies and Kidney Transplantation To the Editor: Loupy et al. (Sept. 26 issue)1 present data showing that the C1q-binding assay is more sensitive than the standard complementdependent microlymphocytotoxicity (CDL) assay for assessing the risk of graft loss. In their retrospective analysis of 1016 patients who had a negative CDL assay before transplantation, antibodymediated rejection developed in 7.4% during the first year. The authors predict that antibody-mediated rejection would have occurred in 3.7% of
patients (a 50% reduction) if the C1q-binding assay had been used. However, most laboratories use a more sensitive flow cytometric crossmatching (FCXM),2 not CDL alone. We have data from 11 patients who had low levels of donor-specific anti-HLA antibodies (mean fluorescence intensity [MFI],
