Objective: The aim of this study is to identify population subgroups under-vaccinated for influenza through classification tree analysis to inform interventions aimed at improving future vaccine uptake.
Method: A cross-sectional community health needs assessment was conducted from 09/2012 through 11/2012 among randomly selected households in six low-income neighborhoods in New Haven, CT (N=1300 adults, aged 18-65). Known correlates of influenza vaccine uptake plus experience of medical mistreatment were used to develop a classification tree to identify under-vaccinated population subgroups
Results: Forty-five percent of respondents reported receiving the influenza vaccine. The classification tree identified healthy adults and uninsured adults at increased risk of influenza complications as subgroups with low vaccine uptake (40% and 30%, respectively). The subgroup representing insured, high-risk adults who reported experience of medical mistreatment had moderate vaccine uptake (45%). Sensitivity of the classification tree was high (83%, 95% CI=80% to 86%), indicating a strong true positive rate using these subgroups.
Conclusion: Results highlight the need for renewed attention to promoting the influenza vaccination recommendation for all adults, particularly among healthy adults, uninsured, high-risk adults and insured, high-risk adults who have experienced medical mistreatment. Further research is needed to better understand how to reach these population subgroups.
Keywords: Classification tree analysis; Influenza; Uptake; Vaccine.
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