Survival with Rett syndrome: comparing Rett's original sample with data from the Australian Rett Syndrome Database.

Aim: rett syndrome is a severe neurodevelopmental disorder that typically affects females. Little is known about the natural history and survival time of these females.
Method: we compared the survival of all Austrian female participants from Rett's historical cohort (1966) with that of affected females registered in the Australian Rett Syndrome Database. The analysis included both Kaplan-Meier analysis and a log-rank test for equality of survivor functions.
Results: of females in the original Austrian group, three are still alive. The median age at death was 13 years 4.8 months. The probability of survival up to the age of 25 years was 21%, compared with 71% in the Australian cohort (p<0.001). We found no practical or statistically significant differences in survival between the various birth year groups within the Australian cohort.
Interpretation: our data indicate that survival of females with Rett syndrome has improved since the late 1960s but that there has been shown no change in survival over the last 30 years, possibly because the follow-up time has been too short.