Going into another flu season, a new study reports that hospitalizing children for influenza may cost up to three or four times the previously accepted estimates. Pediatric researchers from the Children’s Hospital of Philadelphia say their finding strengthens the economic justification for broadly vaccinating children against flu. The cost of influenza-related hospitalizations in children was about $13,000 each — compared to prior estimates of $3,000 to $4,000.
“We found the cost of influenza-related hospitalizations in children was about $13,000 each–compared to most prior studies that estimated the cost at three to four thousand dollars,” said study leader Ron Keren, M.D., M.P.H., a pediatrician at The Children’s Hospital of Philadelphia. “This suggests that annual influenza vaccinations for children, especially for those with certain high-risk conditions, may be more cost-effective than previously thought.”
The study appears in the November issue of Pediatrics.
The researchers analyzed billing data for 727 patients up to age 21 who were admitted to Children’s Hospital with laboratory-confirmed influenza over four consecutive flu seasons, from 2000 to 2004. The study team statistically adjusted the direct medical costs to account for geographic variations in those costs.
“We found a broad range of hospital costs in the study, from approximately $7,000 each for patients treated only on the ward, to nearly $40,000 each for children cared for in the intensive care unit,” said Dr. Keren. Children with low-risk conditions had hospital costs averaging $9,000 each, compared to those with high-risk conditions, whose costs averaged $15,000 each.
The study team used risk categories defined by the American Committee on Immunization Practices (ACIP), which has designated medically vulnerable patients who should receive influenza vaccinations. For instance, high-risk conditions include children with heart disease, chronic lung disease, asthma, and disorders of hemoglobin such as sickle-cell disease.
Even in the group with the lowest hospital costs, low-risk patients hospitalized exclusively on the ward, costs were higher than previously estimated. For patients in that group, the hospital costs were $6,000 per patient, double the figure reported in prior studies. “We conclude that most previous studies systematically underestimated true costs of influenza by including children with diseases attributed to influenza, such as pneumonia and bronchitis, which probably incur lower costs than actual influenza cases,” said Dr. Keren. “In contrast, we included only patients who had influenza confirmed by laboratory testing.”
The highest-cost patients in the study were 18-to-21-year-olds and those who had particular high-risk chronic conditions such as cardiac, metabolic, and neurological and neuromuscular diseases. A 2005 study by Dr. Keren’s group identified children with neurological and neuromuscular diseases as being at particularly high risk of respiratory failure caused by influenza. That research reinforced last year’s decision by the ACIP to add neurological and neuromuscular diseases to the list of chronic conditions that warrant annual flu vaccination.
The current study further buttresses the ACIP’s public health recommendations for general pediatric flu immunization. “During the period we studied, the ACIP recommended that all children aged 6 months to two years receive an influenza vaccine,” said Dr. Keren. “Since that time, the ACIP has extended the recommended age from age two to age five. Our findings support the ACIP’s recommendations by strengthening the economic case for vaccinating children against influenza. This economic case is even more compelling for children with high-risk conditions.”