Delivery of vaccines to adults: correlations with physician knowledge and patient variables.

Our objective was to explore reasons why vaccines are not provided to adult patients receiving primary health care. The study setting was a primary health care clinic in a urban hospital staffed primarily by residents and teaching faculty. The patients were identified as all continuity care patients with a scheduled visit to the clinic during the 4-week study period in April 1995. The providers were all primary care providers for the patients during the study period. The providers were given two surveys before the study: one to assess their knowledge of published preventive health care guidelines and one to assess their perspective of the guidelines. During the study period, the charts of the patients were reviewed for the services they had received. An assessment was placed in each patient's chart for the provider's completion during the visit. The assessment enabled the provider to explain why services had not been provided. The results showed that influenza, pneumococcal, and diphtheria-tetanus vaccines were provided at varying rates. Each vaccine had a different profile as to noncompliance with guidelines. Lack of provider knowledge of the guideline was most apparent with pneumococcal vaccine. Providers' ambivalence regarding the scientific basis and/or clinical importance was most apparent with influenza vaccine. Patient refusal was a prominent cause with influenza vaccine in the elderly. Patient appointment behavior (opportunity for care and compliance) also seemed to play an important role. We conclude that explanations for nondelivery of vaccines to adults seem to be multiple. Lack of physician knowledge and physician perception of the guidelines provide some explanations. Patient-related factors including refusal, decreased opportunity for care, and noncompliance also play important roles in why vaccinations are not provided. Improvement in the rates at which immunizations to adults are provided will require interventions in multiple areas.