Letter to the editor Effect of aspirin for ischemic stroke in patients with dialysis Dear editor, Chen et al. conducted an 11-year follow-up to estimate the effect of aspirin and clopidogrel for ischemic stroke in patients with dialysis (1). The hazard ratios by time-dependent Cox regression analysis for primary outcome, readmission for stroke and all-cause mortality in patients treated with aspirin were all significant. As there was no significant risk of bleeding in use of aspirin, the authors recommended using aspirin as a safe and effective treatment for ischemic stroke in patients with dialysis. I have some concerns about their study. First, the authors presented Kaplan– Meier curves of freedom from readmisCorrespondence: Tomoyuki Kawada, Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo 113-8602, Japan. E-mail: [email protected] Conflict of interest: None declared. DOI: 10.1111/ijs.12377

© 2014 World Stroke Organization

sion for ischemic stroke in their fig. 2. There was a crossing and it is difficult to keep proportionality for their statistical model. I also recommend them classifying the antiplatelet users into two or three groups (single use of antiplatelets and their combination) and each group should be compared with nonantiplatelet users. As the second concern, the authors did not count the number of patients treated with single use of aspirin in their table 2. Although they conducted subgroup analysis, there is a clinical reason for the use of both aspirin and clopidogrel in patients with dialysis. In order to evaluate the net effect of aspirin and clopidogrel for the prevention of primary and secondary effect, interaction should also be evaluated in their study. As the third concern, risk factors for ischemic stroke differs in subtype (lacunar, nonlacunar and cardio-embolic) (2), and subtype should also be considered for their study. Finally, hemodialysis patients with anticoagulant therapy had a risk of hemorrhagic stroke (3), and Chen et al.

included several cause of bleeding into events. Sensitivity analysis is needed to check the adverse effect by antiplatelet drugs. Please also specify reasons why 666 patients did not receive antiplatelet therapy, which was not standard protocol for patients with ischemic stroke. T. Kawada Department of Hygiene and Public Health, Nippon Medical School, Tokyo, Japan

References 1 Chen CY, Lee KT, Lee CT, Lai WT, Huang YB. Effectiveness and safety of antiplatelet in stroke patients with end-stage renal disease undergoing dialysis. Int J Stroke 2014; 9:580– 90. 2 Ohira T, Shahar E, Chambless LE, Rosamond WD, Mosley TH Jr, Folsom AR. Risk factors for ischemic stroke subtypes: the Atherosclerosis Risk in Communities study. Stroke 2006; 37:2493–8. 3 Drew DA, Sarnak MJ. Ischemic and hemorrhagic stroke: high incidence in hemodialysis and peritoneal dialysis patients. Am J Kidney Dis 2014; 63:547–8.

Vol 10, January 2015, E9

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Effect of aspirin for ischemic stroke in patients with dialysis.

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