Perthes disease is a rare childhood disorder in a hip. Research of Perthes is challenging because Perthes disease is a long-lasting and dynamic condition characterized by high variability in the disease evolvement over time and different treatment interventions.

There are many unanswered questions regarding Perthes disease. For example, there is very limited information on how Perthes affects adults in terms of their physical functioning and quality of life, and what effect a total hip replacement has on reducing pain and returning their ability to conduct a “normal life”. A Web survey (the Adult Perthes Study) launched by the International Perthes Study Group aims to address some of these questions.  

Although a Web survey is an efficient way to reach out to people with a rare disease, a self-selected cross-sectional sample of adults who had Perthes is problematic. For example, the age at total hip replacement is not observed for all the survey participants, since some of them had not had it yet (i.e. censored), and some of them will never have it, because they will not need it. Naïve analysis of these data might be misleading and can result in wrong conclusions. One of our aims is to develop methods that account for this incompleteness. Similar problematic data arise in many other subject areas, e.g. in economics. 

This research is a collaboration with the International Perthes Study Group and is supported by a seed grant from the Data Science Research Center (DSRC) at the University of Haifa, Israel.