OBJECTIVES : Prader-Willi syndrome (PWS) is a neurodevelopmental genetic disorder causing developmental delay, short stature, obesity, and obsessive food seeking behavior. While short stature and poor muscle tone can be addressed via the use of human growth hormone (HGH), which can then impact obesity, the underlying hyperphagia (i.e. excess hunger and food seeking) presents a potentially significant unmet clinical need. We assessed caregivers’ evaluation of three health states (untreated PWS, PWS with obesity controlled, and PWS with both obesity and hyperphagia controlled).

METHODS : In partnership with several patient organizations and a diverse stakeholder committee (with both patient and caregiver representation) we developed and implemented an online survey. QALY estimates for the three, standardized health states were assessed using both visual analogue scale (VAS) and time-trade off (TTO) and were compared across the population.

RESULTS : Caregivers completing the survey (n=332) were predominately female (82%) and parents (96%) of people with PWS ranging from 4 to 54 years (mean=15.7). Untreated PWS was evaluated to have a QALY of 0.38 and 0.74 by the VAS and TTO respectively. If obesity was treated the QALY increased (P<0.001) to 0.56 and 0.83 respectively. Likewise, QALYs increased further if both obesity and hyperphagia could be treated (P<0.001), to 0.69 and 0.92 respectively.

CONCLUSIONS : Using disease specific QALY estimation techniques we demonstrated that significant improvements in quality of life are likely if hyperphagia could be controlled in people with PWS. While differences across the VAS and TTO were identified, they were consistent with what was predicted by Torrance (1976).