Paroxysm rate in patients with PNH before and during eculizumab treatment. A urine color scale2 was used to assess the incidence of paroxysms in 8 patients with PNH before and during treatment with eculizumab. Paroxysm was prospectively defined by a urine colorimetric score of 6 or more. Bars represent the paroxysm rates (number of paroxysms per patient per month) during the screening period, during the first 12 weeks, and over the total 64 weeks of eculizumab treatment. Three patients were not included in the analysis either because their pretreatment urine scores were inadvertently not collected (2 patients) or because an iron-chelating agent that resulted in artificially colored urine was administered during the extension study (1 patient).