Well-Child Care Visits and Risk of Ambulatory Care–Sensitive Hospitalizations
Published Online: May 10, 2013
Jeffrey O. Tom, MD, MS; Rita Mangione-Smith, MD, MPH; David C. Grossman, MD, MPH; Cam Solomon, PhD; and Chien-Wen Tseng, MD, MPH
Children less than 5 years old have higher hospitalization rates than older children.1 Finding approaches to minimize morbidity for these children (eg, decreasing asthma exacerbations) may reduce hospitalizations. Regular attendance at well-child care (WCC) visits may prevent unnecessary hospitalizations through timely immunizations and/or chronic disease management. WCC visits likely have a higher impact for young children due to the greater frequency of recommended WCC visits in the first 3 years of life (13 visits) compared with older children (1 visit per year through age 18 years).2 Prior studies evaluating the association between WCC visit adherence and hospitalizations have been mixed, as 3 studies found that higher WCC visit adherence was associated with decreased ambulatory care–sensitive hospitalizations (ACSHs) while 2 studies found no association.3-7 Only 3 of these studies accounted for the timeliness of WCC visits.3,5,7 No study has evaluated this relationship in integrated healthcare delivery systems. Unlike other healthcare systems, integrated healthcare delivery systems have greater control in standardizing and improving the care patients receive (ie, population-based care), which can decrease practice variation.8,9 In addition, integrated healthcare delivery systems often place high importance on preventive care and therefore encourage and provide these services at no charge. Evaluating WCC visit adherence and risk of hospitalization in this setting provides a unique opportunity to understand this relationship where all patientsreceive similar WCC visit content.
The goal of this study was to understand whether parents’ timely adherence to WCC visits was associated with risk of ACSHs among young children enrolled in an integrated healthcare delivery system. ACSHs represent hospitalizations which are potentially preventable with adequate access to and/or provision of outpatient care.10 We hypothesized that poor WCC visit adherence would be associated with increased risk for ACSHs in this integrated healthcare delivery system.
Design and Setting
This was a retrospective cohort study conducted in collaboration with Group Health Cooperative, an integrated healthcare delivery system with ~640,000 members in Washington and Idaho. Claims from both the Group Health delivery system and contracted network physicians were included. This study was approved by both the Seattle Children’s Research Institute and Group Health Research Institute’s Institutional Review Boards.
We focused on children younger than 3.5 years because this age group is at higher risk for hospitalizations than older children,11 because they have higher contact rates with healthcare providers, and because Group Health encourages 1 WCC visit between the ages of 2 and 3.5 years. Children were eligible for the study if they were enrolled by 2 months of age at GroupHealth between January 1, 1999, and December 31, 2006. Participants entered the study on either January 1, 1999 (ie, already a plan member), or on their first day of enrollment during the study period. When determining a child’s complete enrollment information, we considered gaps in enrollment of <45 days as continuous enrollment based on the Healthcare Effectiveness and Data Information Set definition.12 In addition, children needed to be enrolled on or prior to a recommended WCC visit and through at least 1 of the subsequent recommended WCC visits in order to calculate adherence and minimize misclassification (Figure).
We used a previously validated list of International Classification of Disease, Ninth Revision (ICD-9) codes to identify children with chronic disease.13 Children were classified as having at least 1 chronic disease (ie, “>1 chronic disease”) if they had 1 or more claims matching an ICD-9 diagnosis included in the validated list. Children were classified as “healthy” otherwise. Since diagnosing asthma in children less than 4 years old can be challenging,14 2 or more claims for asthma (ICD-9 493.00-493.99)11 were required for a child to be classified as having asthma. The top 5 chronic disease categories for our study were: asthma (38%), congenital heart disease (15%), congenital musculoskeletal anomalies (14%), failure to thrive (7%), and hereditary and acquired hemolytic anemias (6%).
WCC Visit Adherence
A WCC visit was identified if an outpatient claim billed by a primary care provider (pediatrician, family physician, general practitioner, osteopath, or nurse practitioner) contained the standard WCC visit ICD-9 codes (eg, V20.2) in any diagnosis field. Adherence was based on Group Health’s 2000 WCC visit schedule, which was identical to the AAP’s schedule for the first 6 months and then differed from this schedule by requiring the following WCC visits through 3.5 years old: 10 months, 15 months, 2 years, 3.5 years (ie, the AAP’s 9-month, 12-month, 18-month, and 3-year visits are not required). WCC visits were included in the adherence calculation (numerator) if the WCC visit was “timely.” For example, a “4-month WCC visit” was allowed to occur on or after a child turned 4 months old and up to less than 6 months old (ie, the “4-to-6 month” WCC interval). To allow for an appropriate window of acceptability for when WCC visits might reasonably occur, we counted a “duplicate WCC visit” in 1 interval as the WCC visit for the following interval if the duplicate visit was <14 days (visits before 15 months of age) or <30 days(visits after 15 months of age) prior to the start of a WCC visit interval where no visit had occurred. Otherwise only the first WCC visit was counted for WCC visit intervals with multiple WCC visits.
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