Evaluation of an adult immunization composite measure in the Indian Health Service

Government agencies, healthcare accreditation bodies and quality improvement organizations support the development of new quality measures. Composite quality measures use more than one measure to develop a broader assessment of healthcare system function. Currently, no composite measures for adult immunization coverage exist. Development of such measures could facilitate improvements in adult immunization coverage by focusing on measurement of receipt of all age-recommended vaccines.

We recruited five Indian Health Service (IHS) and Tribal health clinics to pilot an Adult Immunization Composite Measure (AICM). Data were collected monthly over seven months using a pre-programmed electronic health record (EHR) reporting tool (IHS sites); Tribal sites used third-party software or a programmable EHR reporting function. Data collected included: number of adults aged 19 years and over who were active users of the facility with at least two visits in the last three years; the cumulative number fully immunized per age-based recommendations for tetanus toxoid-containing vaccines, pertussis, zoster and pneumococcal vaccines; and the percent immunized for the AICM and for each individual vaccine. Coverage was calculated for three age groups: 19-59 years; 60-64 years; and 65 years and older.

All sites reported aggregate immunization data monthly from patient EHR records. For all adults 19 years and older, AICM coverage ranged from 49% to 87% at the end of the report period. Two sites showed increases in AICM coverage ≥ 3%. Improvements in zoster vaccine coverage accounted for most of the increase observed. One site specifically focused on improving zoster coverage as a result of using the AICM.

We demonstrated the feasibility of implementing a composite measure of adult immunization coverage. This is the first measure capable of monitoring immunization completeness, coverage improvement and overall adult vaccine program effectiveness for adults who receive all recommended, age-based vaccines.