Ten years of the international Pompe survey: patient reported outcomes as a reliable tool for studying treated and untreated children and adults with non-classic Pompe disease.

Pompe disease is a rare, progressive lysosomal storage disorder for which enzyme therapy (ERT) became available in 2006. Four years earlier, the IPA/Erasmus MC survey, an international longitudinal prospective survey, was established to collect information on the natural course of the disease and its burden on patients. The survey is a collaboration between Erasmus MC University Medical Center and the International Pompe Association (IPA) and comprises an annual questionnaire that was specifically designed to assess the symptoms and problems of the disease. Here we review our results of over 10 years of follow-up, and discuss the survey's contribution to the field. Tracking 408 Pompe patients between 2002 and 2013, the cumulative data reveals the broad range of clinical manifestations that interfere with patients' lives. The survey allowed us to quantify the rate of disease progression and the positive effects of ERT on patients' quality of life, fatigue, and participation in daily life. Furthermore, it showed for the first time that survival is reduced in adult Pompe disease and improved by ERT. Our results show that a patient survey can serve as a valuable and reliable tool for obtaining quantifiable information on the natural course of a rare disease and on the effects of therapy in a large cohort over a very long time. Most importantly, by working with patient reported outcomes, the survey provides the data that is truly relevant to the patient and complementary to clinical datasets.