The challenge of pain evaluation in haemophilia: can pain evaluation and quantification be improved by using pain instruments from other clinical situations?

Pain is a critical aspect in the lives of individuals with congenital haemophilia A or B. Initially, pain serves as a warning sign for an active bleeding event; however, after multiple bleeding episodes, pain may become chronic, debilitating, and distracting. It is essential that pain instruments be developed and validated for use in persons with haemophilia, especially in paediatric cohorts, so that new therapies to treat acute bleeds can be assessed in a standardized manner. This review evaluates the existing pain instruments utilized in the English language haemophilia literature and compares their features and practicality with instruments published for other clinical pain scenarios associated with non-coagulopathic disease states, such as cancer and surgical convalescence, in paediatric, adolescent, and adult populations. In clinical trials involving haemophilia cohorts, few pain instruments have been validated. Only one instrument has addressed pain specifically in individuals less than 16 years of age. In contrast, multiple instruments have been applied extensively to other pain situations, especially in the paediatric oncology area, where the age range extends to less than 3 years. We conclude that trials quantifying pain in haemophilia would benefit from the addition and validation of instruments in use in other pain situations. Suggestions for modifying the pain instruments currently used in haemophilia are presented, specifically to address paediatric haemophilia cohorts.