Decline in varicella-related ambulatory visits and hospitalizations in the United States since routine immunization against varicella.
BACKGROUND
Widespread varicella vaccination has led to substantial decreases in varicella-related mortality and hospitalizations. The effect of the vaccine on ambulatory care utilization is poorly defined.


OBJECTIVE
To determine trends in varicella-related ambulatory care and hospital discharges before and after vaccine licensure.


METHODS
Estimates of varicella-related ambulatory and hospital discharges were calculated for the pre- (1993-1995) and post- (1996-2004) vaccine licensure periods using the National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, and National Hospital Discharge Survey.


METHODS
Ambulatory and hospital discharge rates for varicella.


RESULTS
The rate of varicella-related ambulatory discharges decreased by 66% from 106.6 per 100,000 (95% confidence interval [CI]: 80.5-132.6) in the prelicensure period to 36.4 per 100,000 population (95% CI: 29.3-43.5) in the post-licensure period (P < 0.001). The decrease was significant across all age groups <45 years, with the greatest reduction (98%) occurring among patients 0 to 4 years of age. The incidence of varicella-related hospital discharges decreased by 53% from 30.9 per 100,000 (95% CI: 24.4-37.3) to 14.5 per 100,000 population (95% CI: 12.1-16.8; P < 0.001). This difference was significant among patients <14 years of age. Rates of varicella-related ambulatory discharges decreased significantly for both whites and non-whites in the postlicensure period, but postlicensure ambulatory discharge rates remained higher for non-whites than for whites. Decreases in varicella-related hospital discharges were statistically significant for whites and non-whites. Racial differences in the incidence of varicella-related hospital discharges also persisted following vaccine licensure.


CONCLUSIONS
Varicella-related ambulatory visits and hospitalizations have decreased significantly in the period after licensure of the varicella vaccine.
Shah
Samir S
SS
Division of Infectious Diseases, The Children's Hospital of Philadelphia, Philadelphia, PA, USA. shahs@email.chop.edu
Wood
Sarah M
SM
Luan
Xiquan
X
Ratner
Adam J
AJ
D000293:Adolescent; D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data / Q000639:trends*; D000818:Animals; D002644:Chickenpox / Q000453:epidemiology*; D019433:Chickenpox Vaccine / Q000008:administration & dosage / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data / Q000639:trends*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D014481:United States / Q000453:epidemiology; D055815:Young Adult
D019433:Chickenpox Vaccine