Mortality in babies with achondroplasia: revisited

Abstract

Background: Natural history studies performed 30 years ago identifying higher mortality among children born with achondroplasia, a genetic dwarfing condition, resulted in clinical recommendations aimed at improving mortality in childhood. The objective of this study was to determine if mortality rates have changed over the past few decades.

Methods: Children born with achondroplasia during 1996 to 2003 were ascertained from the Texas Birth Defects Registry and matched with death certificate data from the Bureau of Vital Statistics through 2007. Infant and overall mortality rates, both crude and standardized to the 2005 (SMR2005 ) and 1975 (SMR1975 ) U.S. populations, were calculated.

Results: 106 children born with achondroplasia were identified. Four deaths were reported, with all occurring in the first year of life (mortality rate: 41.4 /1000 live-births). Infant mortality was higher when standardized to the 2005 U.S. population (SMR2005 :6.02, 95% CI:1.64-15.42) than the 1975 population (SMR1975 :2.58, 95% CI:0.70-6.61).

Conclusion: The higher SMR2005 compared with SMR1975 , along with the fact that SMR1975 was nearly half that of a previous cohort reported 25 years ago (rate ratio: 0.53, 95% CI: 0.11-2.25), reflect a discrepancy in the changes in mortality in the overall population and in our cohort. Although an overall improvement in mortality, especially after the first year of life, is observed in our cohort, children with achondroplasia are still at a much higher risk of death compared with the general population. A longer follow-up is needed to elucidate whether evaluation/intervention changes have resulted in significant improvement in long-term survival among these patients.

Keywords: achondroplasia; birth defect; dwarfism; healthcare; survival.