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Using Administrative Claims to Identify Children With Chronic Conditions in a Statewide Immunization Registry | Page 2

Published Online: May 20, 2014
Kevin J. Dombkowski, DrPH, MS; Lauren Costello, MSW; Shiming Dong, MS; and Sarah J. Clark, MPH
Vaccination records for children with chronic conditions that could be matched with the MCIR were obtained for influenza seasons 2008-2009 and 2009-2010. Healthcare providers are required by Michigan law to input in the MCIR all vaccination doses administered to persons younger than 20 years of age. Seasonal and H1N1 influenza vaccination rates were classified as the receipt of a dose as recorded in the MCIR or through administrative claims. In cases where more than 1 seasonal or H1N1 vaccination dose was administered during an influenza season, we considered the first date of influenza vaccination (from either administrative claims or MCIR data) as the vaccination date for our analysis. Missed opportunities for seasonal influenza vaccination were classified as the initial office visit occurring during the influenza season (September-February) among children who remained unvaccinated throughout the entire influenza season. Since H1N1 influenza vaccine supply was limited from September to October 2009, missed opportunities for H1N1 influenza vaccination were classified as the initial office visit occurring from November 2009 through February 2010 among children who remained unvaccinated throughout the entire influenza season. Subsequent missed opportunities were not counted. The date of the missed opportunity was classified as the date of the initial office visit occurring between September and February for seasonal influenza vaccination and between November and February for H1N1 influenza vaccination in which the child remained unvaccinated. We calculated estimated seasonal and H1N1 influenza vaccination rates that could potentially be achieved if missed opportunities were successfully converted into influenza vaccination events. Seasonal and H1N1 influenza rates for the 2008-2009 and 2009-2010 seasons were contrasted between our cohort of children with a chronic condition identified by the commercial health plan with a matched group not having a chronic condition. We used the MCIR to identify children who were not designated with the system’s high risk indicator as the basis for our comparison group. However, at the time of our study, the MCIR high risk indicator process was limited to children with chronic conditions who were, or had previously been, enrolled in Medicaid. Children with only commercial insurance would not have chronic conditions identified through claims. As a result, the high risk status of children who were commercially insured in plans other than the 2 health plans used in this study was not known with certainty in the MCIR. To control for potential misclassification, we further categorized our comparison group of children without a MCIR high risk indicator into 2 subgroups: (1) children currently enrolled in Medicaid, not identified in the MCIR as having a chronic condition (since these children are or were previously enrolled in Medicaid, their claims were subject to queries to identify chronic conditions and therefore, absence of a high risk indicator in the MCIR is reflective of not having a chronic condition); and (2) children never enrolled in Medicaid, whose status in the MCIR was indicated as not high risk. While this group likely contains primarily children who did not have a chronic condition, it is possible that some may have had a chronic condition that was not detected in claims data queries, since this group had never been enrolled in Medicaid. Using this process, 1 comparison child was randomly selected for each commercially insured high-risk case, matching on birth month and year, gender, and Michigan county of residence. This resulted in a 1:1 matched set of comparison children for each high risk case. Claims data were not available for children who had never been enrolled in Medicaid; as such, seasonal and H1N1 influenza doses were compared in this subanalysis across the 3 groups using doses reported in the MCIR.

Data Analysis

To assess feasibility, we summarized the proportion of cases in the commercial health plans that were successfully matched within MCIR. Primary outcomes measured for the utility of using administrative claims were the receipt of seasonal and H1N1 vaccination and either at least 1 or at least 2 office visits. Health utilization was compared between 1 health plans (health plan 1 and health plan 2) by child characteristics, including age, gender, and rural/urban designation (US Census Metropolitan Statistical Area classification). The proportion of children with a missed opportunity was assessed and compared by influenza season (2008-2009 and 2009-2010) by each child’s age group. In addition, observed rates of seasonal and H1N1 influenza vaccinations as reported in MCIR were calculated and compared among the commercially insured high risk group and the 2 comparison groups described above. Estimated influenza vaccination rates were determined by classifying each child with a missed opportunity as a potential influenza vaccination event, and compared across seasons for the commercially insured children with chronic conditions. All analyses were conducted using SAS version 9.2 (SAS Institute Inc, Cary, North Carolina).

RESULTS

Characteristics for our study population are shown in Table 1 contrasting children enrolled in health plan 1 with those in health plan 2 for the 2008-2009 and 2009-2010 influenza seasons. In 2008-2009, health plan 2 enrollees tended to exclude rural counties of residence (P <.0001) and were skewed toward young age groups (P <.0001); similar results were found for the 2009-2010 season. The sample of children enrolled in health plan 2 included a greater proportion of children under 6 years of age than children enrolled in health plan 1 for both the 2008-2009 (32% vs 24%; P <.0001) and 2009-2010 (29% vs 22%; P <.0001) influenza seasons. We found a high degree of success in matching children with chronic conditions identified through administrative claims data with MCIR. Overall, 93% of the commercially insured children with chronic conditions were successfully matched with their respective MCIR record; this result was consistent across both seasons in our study period. There were no differences between the matched and unmatched groups by age, gender, or county of residence. Children enrolled in health plan 2 had a higher degree of match success than did children enrolled in health plan 1 for the 2008-2009 (98% vs 90%) and 2009-2010 (98% vs 91%) influenza seasons. Match rates were consistent across plans by gender and age, but were substantially lower for children from unknown counties of residence (44% for health plan 2 vs 83% for health plan 1).

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Issue: May 2014
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