Pertussis hospitalizations among infants in the United States, 1993 to 2004

We sought to describe the rates of pertussis hospitalization among infants by using databases that do not rely on passive reporting and compare with results obtained from the passive national surveillance system.

The incidence of infant pertussis hospitalization in 1993 to 2004 was determined by using 2 national hospitalization discharge databases (Nationwide Inpatient Sample and Kids' Inpatient Database) and the National Notifiable Disease Surveillance System/Supplemental Pertussis Surveillance System. Rates were determined for separate age groups among infants < 1 year of age. Pertussis complications and procedures were examined by using the Kids' Inpatient Database.

In 1993 to 2004, the pertussis hospitalization rates for infants < or = 2 months of age were generally stable, by the discharge databases. The incidence of infant pertussis hospitalization obtained from the Nationwide Inpatient Sample and Kids' Inpatient Database was approximately 2 times greater than that obtained from the passive reporting system. Infants 1 to 2 months of age had the highest incidence (239 hospitalizations per 100,000 live births in the 2003 Kids' Inpatient Database). An annual average of 2678 hospitalizations occurred in 2000 and 2003; 86% occurred in infants < or = 3 months of age. Among those with ages provided, 95% of infants who required mechanical ventilation and all of those who died were < or = 3 months of age.

Pertussis hospitalization incidence rates among the youngest infants were generally stable in 1993 to 2004 and were highest for infants 1 to 2 months of age. The impact of the new adolescent and adult tetanus-diphtheria-acellular pertussis vaccines on infant pertussis should be monitored through such discharge databases. Additional vaccination strategies should be evaluated to protect infants as early in life as possible.