Epidemiology of hyaline membrane disease in the United States: analysis of national mortality statistics

Abstract

National mortality statistics for hyaline membrane disease (HMD) and respiratory distress syndrome (RDS) were examined in this study for the years 1968 to 1973. Detailed data were obtained by computer analysis of magnetic tapes from the National Center for Health Statistics. During the six-year interval, HMD/RDS was determined to be the underlying cause of death in 54,064 infants or 9,010 +/- 560 (mean +/- SD) infants per year. Analysis of individual death certificates for 1968 revealed the disease to a major contributing factor in another 24%. Thus, it may be estimated that HMD was involved in the demise of nearly 12,000 neonates per year over this period. This amounts to approximately 20% of all neonatal deaths. On the basis of mortality rates, a trend toward an increased incidence of fatal HMD/RDS was established from 1968 to 1973. Deaths tend to cluster in the summer months and January-February represent the lowest months of recorded fatalities. Analysis of the age at death, reflecting time course of the disease, revealed idential patterns for 1968 to 1970. The number of deaths was found to decline exponentially between the first and fourth 24-hour periods so that 92% of all deaths occurred by 4 days of age. Boys contributed more prominently to the death totals than girls with ratios from 1.62 to 1.76. Examination of mortality rates by race suggested that black permatures have a lower incidence of fatal HMD/RDS. In addition to nationwide figures, those of individual states were compared for three years. Generally, HMD/RDS mortality rates correlated with overall neonatal mortality statistics. Exceptions were observed, however, such as Illinois where low rates for the former coexist with relatively high neonatal death rates. These data respresent the first national mortality statistics for HMD and may prove useful in planning and providing intensive neonatal care.