The following states had consistent reporting of admission month data: Arizona, California, Colorado, Connecticut, Georgia, Hawaii, Iowa, Illinois, Kansas, Kentucky, Massachusetts, Michigan, Montana, North Carolina, New Jersey, New York, Oregon, South Carolina, Tennessee, Texas, Utah, Washington, Wisconsin, and West Virginia. Rates were calculated by dividing the annual number of hospitalizations by the number of children younger than 5 years residing in the participating states during that year and analyzed by admission month, sex, age group, and race.
Leshem E, Tate JE, Steiner CA, Curns AT, Lopman BA, Parashar UD. Acute Gastroenteritis Hospitalizations Among US Children Following Implementation of the Rotavirus Vaccine. JAMA. 2015;313(22):2282-2284. doi:10.1001/jama.2015.5571
Routine rotavirus vaccination of US children was implemented in 2006, with 2 or 3 doses recommended before the age of 8 months.1 Previous studies have demonstrated the association of rotavirus vaccine introduction with reductions in health care use during the early postintroduction period or with limited insurance databases.2- 4 Because laboratory testing and coding for rotavirus are not routinely performed for patients with diarrhea, we examined both all-cause acute gastroenteritis and rotavirus-coded hospitalizations among children younger than 5 years from 2000 through 2012.
We analyzed State Inpatient Databases of the Healthcare Cost and Utilization Project, which capture hospitalizations in community and academic hospitals. All-cause acute gastroenteritis hospitalizations, including bacterial, parasitic, viral, undetermined etiology or diarrhea presumed noninfectious, and rotavirus-coded hospitalizations were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, as previously described.2- 4
We restricted the analyses to 26 states that consistently reported hospital discharge data each year during 2000 through 2012. Approximately 74% of US children younger than 5 years resided in these 26 states.5 Rates were calculated by dividing the annual number of hospitalizations by the number of children younger than 5 years residing in the participating states during that year and analyzed by admission month, sex, age group, and race.5
We calculated rate ratios and 95% confidence intervals using Poisson regression analysis to compare mean annual hospitalization rates for prevaccine (2000-2006) and postvaccine (2008-2012) years; 2007 was considered a transition year. Statistical significance was defined as a 2-sided P value of <.05 using SAS version 9.3 (SAS Institute Inc) for all analyses. The study was exempt from institutional review board approval because deidentified aggregated data were used.
We examined 1 201 458 all-cause acute gastroenteritis hospitalizations among children younger than 5 years during 2000 through 2012, of which 199 812 (17%) were assigned a rotavirus-specific code. During the postvaccine years, the seasonal peak of all-cause acute gastroenteritis and rotavirus-coded hospitalizations was substantially blunted compared with prevaccine years (Figure). Furthermore, a biennial pattern emerged, with lower and delayed rotavirus seasonal peaks during 2010 and 2012.
Compared with the prevaccine mean annual acute gastroenteritis hospitalization rate of 76 per 10 000 (range, 73-83 per 10 000) among children younger than 5 years, postvaccine introduction rates declined by 31% (95% CI, 30%-31%) in 2008, 33% (95% CI, 32%-33%) in 2009, 48% (95% CI, 47%-48%) in 2010, 47% (95% CI, 47%-48%) in 2011, and 55% (95% CI, 54%-55%) in 2012 (P < .001 for all rate reductions; Table). Similar rate declines were noted in males and females, all race/ethnicity groups, and all age groups, with the greatest reductions among children aged 6 months to 23 months.
Compared with the prevaccine mean annual rotavirus-coded hospitalization rate of 16 per 10 000 (range, 13-19 per 10 000) among children younger than 5 years, rates of rotavirus-coded hospitalizations postvaccine introduction declined by 70% (95% CI 69%-71%) in 2008, 63% (95% CI, 62%-64%) in 2009, 90% (95% CI, 90%-90%) in 2010, 79% (95% CI, 79%-80%) in 2011, and 94% (95% CI, 94%-95%) in 2012 (P < .001 for all rate reductions; Table).
Following implementation of rotavirus vaccination in 2006, all-cause acute gastroenteritis hospitalization rates among US children younger than 5 years declined by 31%-55% in each of the postvaccine years from 2008 through 2012. Furthermore, greater declines of 63%-94% were noted for the more specific outcome of rotavirus-coded hospitalizations. The biennial pattern observed during postvaccine years might be explained by accumulation of susceptible, nonimmune population during seasons of markedly decreased transmission.
By 2012, children aged 48-59 months (the oldest age group studied) were age eligible for the vaccine and during this year the estimated rotavirus vaccination coverage among children aged 19-35 months reached 69% compared with 44%-67% during 2009 through 2011.6 With an increase in vaccine coverage, herd protection may have contributed to larger declines in rotavirus hospitalizations. In 2012, when vaccine coverage was highest, the greatest reductions were observed for all-cause acute gastroenteritis (55%) and rotavirus-coded (94%) hospitalizations.
Study limitations include reliance on ICD-9-CM coding and not documented disease, the lack of specificity of cause-unspecified acute gastroenteritis discharges, low use of rotavirus diagnostic tests, which may result in underestimation of rotavirus burden, and the observational or ecological nature of the study design.
The most recent reported coverage of 73% for a full rotavirus vaccine series is lower than that of other established childhood vaccines so our findings support continued efforts to increase rotavirus vaccine coverage.6
Corresponding Author: Eyal Leshem, MD, Division of Viral Diseases, US Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Mail Stop A-34, Atlanta, GA 30333 (firstname.lastname@example.org).
Author Contributions: Drs Leshem and Tate had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Leshem, Tate, Curns, Lopman, Parashar.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Leshem.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Leshem, Tate, Curns, Lopman, Parashar.
Obtained funding: Parashar.
Administrative, technical, or material support: Steiner, Curns.
Study supervision: Lopman, Parashar.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the US Centers for Disease Control and Prevention, the Agency for Healthcare Research and Quality, or the US Department of Health and Human Services.
Additional Contributions: We thank the partner states that voluntarily contributed their data to the Healthcare Cost and Utilization Project (http://www.hcup-us.ahrq.gov/partners.jsp).
Correction: This article was corrected on June 11, 2015, to fix the date range in the Figure title.