Rate-difference method proved satisfactory in estimating the influenza burden in primary care visits.
OBJECTIVE
To compare different methods to estimate the disease burden of influenza, using influenza and respiratory syncytial virus-(RSV) associated primary care data as an example.


METHODS
In a retrospective study in the Netherlands over 1997-2003, primary care attended respiratory episodes and national viral surveillance data were used to compare the rate-difference method to other, more complex methods.


RESULTS
The influenza-associated excess estimated by the different methods varied. The estimates provided by the rate-difference model lay well within this range. According to the rate-difference method, influenza-associated primary care consultations were present for all ages, including low-risk adults. The highest influenza-associated burden was demonstrated for children below the age of 5 years. The RSV-associated primary care burden was highest in the youngest age category and well above that associated with influenza. Significant RSV-associated excess was also recorded among adults, particularly in high-risk adults and the elderly.


CONCLUSIONS
The straightforward rate-difference model seemed satisfactory to estimate the influenza-associated burden. Significant influenza-associated excess was demonstrated among persons not yet recommended for influenza vaccination in The Netherlands. The RSV-associated burden was highest for the youngest children, but also significant for adults.
Jansen
Angelique G S C
AG
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, P.O. Box 85500, 3508 GA Utrecht, the Netherlands. a.g.s.c.jansen@umcutrecht.nl
Sanders
Elisabeth A M
EA
Wallinga
Jacco
J
Groen
Eelke J
EJ
van Loon
Anton M
AM
Hoes
Arno W
AW
Hak
Eelko
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology*; D016015:Logistic Models; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011320:Primary Health Care / Q000706:statistics & numerical data*; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology*; D012141:Respiratory Tract Infections / Q000453:epidemiology; D012189:Retrospective Studies