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Using Administrative Claims to Identify Children With Chronic Conditions in a Statewide Immunization Registry | Page 1

Published Online: May 20, 2014
Kevin J. Dombkowski, DrPH, MS; Lauren Costello, MSW; Shiming Dong, MS; and Sarah J. Clark, MPH
Children with chronic conditions are especially vulnerable to complications from influenza.1-5 Annual influenza vaccinations have long been recommended for this group of children.6,7 More recently, the Advisory Committee on Immunization Practices (ACIP) adopted a universal recommendation of yearly influenza vaccination for healthy children aged 6 months to 18 years.6,8 Despite this recommendation, vaccination rates for seasonal influenza remain low for children with chronic conditions.9-15 Missed opportunities, where eligible children are seen by a practitioner but no vaccination dose is administered, have been documented among this population and may contribute to low vaccination rates.9,11

Immunization registries, also known as immunization information systems (IISs), are well established in the United States and provide reminder/recall functions that are effective in increasing vaccination rates.16 However, IISs are not typically designed to track clinical information in addition to vaccinations and consequently cannot target reminder recall notices specifically to those with chronic conditions. Enhancing immunization registries with a high risk indicator may be a mechanism to promote increased vaccination rates among this population through the use of registry-based reminder/ recall capability. In 2006, Michigan’s IIS, known as the Michigan Care Improvement Registry (MCIR), was enhanced with a high risk indicator based on Medicaid administrative data to bolster vaccination rates among children with chronic conditions. This indicator has been demonstrated as being an effective mechanism to target reminder/ recall notices,17 although the benefits of that system have initially been limited to children enrolled in Medicaid.18,19

With that in mind, the objective of this study was to build on the success of the Medicaid-based MCIR high risk indicator by expanding it to include administrative data from 2 commercial health plans. First, we sought to demonstrate the feasibility of using administrative claims data from commercial health plans to establish a high risk indicator in astatewide immunization registry for enrollees with an influenza-sensitive chronic condition (hereafter referred to as a “chronic condition”). We also sought evaluate the potential utility of this expansion of the MCIR high risk indicator by assessing historical influenza vaccination experiences among children with chronic conditions.

METHODS

We assessed the feasibility and utility of using commercial health insurance administrative data to identify children with chronic conditions in the MCIR statewide IIS. Administrative data were obtained from 2 Michiganbased commercial health plans and were matched with corresponding information in the MCIR. This study was approved by the University of Michigan institutional review board.

Study Population

The commercial health plan identified 48,936 children younger than 18 years who were enrolled in either health plan (health plan 1 or health plan 2) for calendar years 2008 and 2009 and had 1 or more claim for at least 1 chronic condition during this period. Chronic conditions were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes (primary or secondary) reported on claims for conditions indicated as placing individuals at increased risk for influenza disease in the ACIP annual influenza vaccination recommendations.8 Diagnosis codes for the specified conditions were assigned using the same methods as those employed in prior studies (Appendix A).17,18 From this initial cohort, we excluded children who were younger than 6 months, had other insurance, or were not continuously enrolled (8246 [17%] in the 2008-2009 season; 7465 [15%] in the 2009-2010 season). Health plan enrollment and health services utilization were obtained for each subject for the period of 2008 to 2010; information was obtained for demographic characteristics and plan enrollment as well as claims for all outpatient office visits, including vaccine administrations.

Outcomes Measured

Feasibility. Among the commercially insured children 18 years or older who were identified as having 1 or more chronic condition (40,690 in the 2008-2009 season, 41,471 in the 2009-2010 season), we calculated the proportion of cases that could be successfully matched with their corresponding record in the MCIR. A common unique identifier was not available for linking the health plan members with the MCIR, requiring that matching be achieved using the child’s name (first/last), date of birth, and gender. Health services utilization was then evaluated among eligible children who were matched successfully with the MCIR data to determine past influenza vaccination experiences as well as missed opportunities for influenza vaccination.

Utility. Three outcomes were measured for the 2008- 2009 and 2009-2010 influenza seasons, defined to be September to February of each season: (1) primary care office visits (either ≥1 or ≥2 office visits); (2) vaccination for either seasonal or H1N1 influenza; and (3) missed opportunities for either seasonal or H1N1 influenza vaccinations. Primary care office visits were identified based on Current Procedural Terminology (CPT) procedural codes and/or ICD-9-CM diagnosis codes. Office encounters with a physician in a family practice, general practice, internal medicine, or pediatric setting were classified as a primary care visit. Immunization visits and other visits during each influenza season were identified using CPT procedure codes, and well child visits were classified using CPT procedure codes and ICD-9-CM diagnosis codes (Appendix B).

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Issue: May 2014
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