Using a Combined Quantitative and Qualitative Approach to Understand Racial Disparities in Adult Vaccination

Background:
One proposed explanation for the persistence of racial disparities in adult immunizations is that minority patients receive primary care at practices that differ substantively from practices where white patients receive care.

Objectives:
This study was designed to assess contributing factors using both quantitative and qualitative methods.

Methods:
Pneumococcal polysaccharide vaccine (PPV) and influenza vaccination rates were determined from medical record review in a sample of 2021 elderly (>65 years) patients. Their physicians, including 6 with primarily minority patients, 15 with primarily white patients and 9 with mixed patient panels were surveyed about office systems for adult immunizations. Teams of two observers conducted structured observations of practice physical features and operations. Immunization rates were compared by race. Case studies of practices with lowest and highest rates and the largest racial disparities are presented.

Results:
Overall, weighted PPV vaccination rate was 60%, but rates differed significantly by race (65.8% for whites vs. 36.5% for minorities, P<.001 by stratified Cochran-Mantel-Haenszel test). Two of six minority panels had PPV rates <20%. Overall, weighted influenza vaccination rate, as measured by receipt of the vaccine in three of the five most recent seasons, was 51.9%, but rates also differed significantly by race (55.6% for whites vs. 36.2% for minorities, P<.03 by stratified Cochran-Mantel-Haenszel test).

Conclusions:
Low rates in two minority panels, racial disparity between minorities and whites in mixed panels, and between-panel variation in the rates contributed to the overall differences in vaccination rates by race.