PNH is usually classified as an uncommon or rare disease, but actual data on disease prevalence is lacking. To address this issue, the International PNH Interest Group conducted a survey of members of the American Society of Hematology. The International PNH Interest Group, a non-profit organization, is comprised of physicians and investigators whose purpose is to further the study of PNH. Alexion Pharmaceuticals, Inc. provided financial support for the survey. A cover letter accompanied the questionnaire that was mailed to 9,244 ASH members in the US and 3,415 international members. The letter stated the purpose of the survey, disclosed the role of Alexion, and informed participants that the American Society of Hematology sanctioned the study. A one-page questionnaire that could be completed within 5 minutes formed the basis of the survey. The questionnaire was designed for positive responses and negative responses (i. e., if the recipient followed no patients with PNH) were not actively solicited. Participants were asked to enumerate the patients with PNH who they actively followed. They were also asked to indicate whether a Hematologist with a special interest in PNH had evaluated any of their patients. Finally, the survey asked if respondents would be willing to participate in an international registry for patients with PNH. The responding physicians were asked to identify themselves and provide contact information. Responses were received from 901 (9.75%) of surveyed US physicians. Of those who responded, 270 (2.9%) reported that they actively followed one or more patients with PNH. In total, these 270 physicians managed 490 PNH patients. Most respondents (172, 63%) followed a single patient with PNH, 50 (18%) followed 2 patients, 25 (9%) followed 3 patients, 10 (4%) followed 4 patients, and 12 (4%) followed 5 or more patients. Approximately 51% of the positive responding US physicians reported that they referred patients for evaluation to a hematologist with a special interest in PNH. Willingness to participate in a PNH registry was indicated by 71% of all US respondent. Internationally, 172 (5.0%) of those surveyed indicated that they followed collectively 840 patients with PNH. In contrast to the management pattern for US patients, 43 (25%) of the international physicians reported following 5 or more patients with PNH. Fifty-seven (33%) followed 1 patient, 47 (27%) followed 2 patients, 21 (12%) followed 3 patients, and 3 (2%) followed 4 patients. Approximately 37% of the positive responding international physicians indicated that they referred patients for evaluation to a hematologist with a special interest in the disease. Support for the PNH registry was acknowledged by 88% of the international respondents. This survey confirms that PNH is a rare disease as the prevalence in the US appears to be in the range of 1–1.5 patients/million population. In the US, physicians who have only one patient with PNH in their practice is the most common management pattern. Internationally, management appears more centralized. Support for an International PNH Registry is strong. The results of this study provide new insights into the prevalence of PNH in the US and into differences in management patterns between the US and the international community.
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