Population-based analyses of mortality in trisomy 13 and trisomy 18.

OBJECTIVE

Although trisomy 13 and trisomy 18 are generally considered to be lethal, long-term survival of patients has been reported. We sought to evaluate mortality in people with trisomy 13 or 18 using 2 population-based strategies.

METHODS

In the first analysis, infants who had trisomy 13 or 18 and were born during 1968-1999 were identified using the Metropolitan Atlanta Congenital Defects Program, a population-based birth defects surveillance system. Dates of death were documented using hospital records, Georgia vital records, and the National Death Index. In the second analysis, we used the Multiple-Cause Mortality Files compiled from US death certificates from 1979 through 1997. Using these 2 analyses, we examined median survival time or median age at death, survival beyond 1 year of age, and factors associated with longer survival.

RESULTS

Using Metropolitan Atlanta Congenital Defects Program, we identified 70 liveborn infants with trisomy 13 and 114 liveborn infants with trisomy 18. Median survival time was 7 days (95% confidence interval [CI]: 3-15) for people with trisomy 13 and 14.5 days (95% CI: 8-28) for people with trisomy 18. For each condition, 91% of infants died within the first year. Neither race nor gender affected survival for trisomy 13, but for trisomy 18, girls and infants of races other than white seemed to survive longer. The presence of a heart defect did not seem to affect survival for either condition. Using MCMF, we identified 5515 people with trisomy 13 and 8750 people with trisomy 18 listed on their death certificates. Median ages at death for people with trisomy 13 and trisomy 18 both were 10 days; 5.6% of people with trisomy 13 and 5.6% of people with trisomy 18 died at age 1 year or greater. Race and gender seemed to affect survival in both conditions, with girls and blacks showing higher median ages at death.

CONCLUSIONS

Although survival is greatly affected by trisomy 13 and trisomy 18, 5% to 10% of people with these conditions survive beyond the first year of life. These population-based data are useful to clinicians who care for patients with these trisomies or counsel families with infants or fetuses who have a diagnosis of trisomy 13 or 18.