Prader-Willi syndrome in Victoria: Mortality and causes of death

Aim: The aim of this study was to describe the rates, predictors and causes of mortality in a population sample of individuals with PraderWilli syndrome (PWS). Methods: One hundred sixty-three individuals with PWS (90 males and 73 females, ages: 3 weeks to 60 years) were identified from the Victorian PWS Register. Information on demographics, age at diagnosis, genetic mechanism, age at which obesity developed and last known body mass index measurement were extracted. Notification and causes of death were obtained through linkage with Australian national and state of Victoria death indexes. Survival analysis was used to estimate the probability of survival and the effect of obesity on survival. Mortality rate ratios were calculated to investigate the effect of the factors listed above on mortality. Results: Fifteen deaths were recorded (nine males and six females), corresponding to an 87% probability of survival to 35 years. The probability of survival was significantly lower for individuals with known obesity (P= 0.03), but there was no strong evidence for an effect on survival for the other factors studied. Cardiac or respiratory conditions were common causes of death after the age of 15 years. Conclusions: The effect of known obesity on the probability of survival and the causes of death reported in this and other studies suggest an important association between obesity and early death in adults with PWS. This finding highlights the critical nature of preventative and intervention strategies aimed at minimising the effects of hyperphagia in individuals with PWS.