Rising use of diagnostic medical imaging in a large integrated health system

Abstract

Little has been published characterizing specific patterns of the dramatic rise in diagnostic imaging during the past decade. In a large health plan, 377,048 patients underwent 4.9 million diagnostic tests from 1997 through 2006. Cross-sectional imaging nearly doubled over those years, rising from 260 to 478 examinations per thousand enrollees per year. Imaging with computed tomography (CT) doubled, and imaging with magnetic resonance imaging (MRI) tripled. Cross-sectional studies added to existing studies instead of replacing them, and the annual per enrollee cost of radiology imaging more than doubled. The dramatic rise in imaging raises both costs and radiation exposure.

Figures

EXHIBIT 1. Cross-Sectional Imaging Tests Per Thousand Enrollees Per Year, 1997-2006

SOURCE: Group Health Cooperative data. NOTES: Results are stratified by imaging modality and adjusted to a standard age distribution across all years of the study. CT is computed tomography. MRI is magnetic resonance imaging.

EXHIBIT 2. Number Of Imaging Tests Per Thousand Enrollees Per Year, By Modality And Age, 2000-2006

SOURCE: Group Health Cooperative data. NOTES: Results are stratified by patient age, averaged across 2000-2006. MRI is magnetic resonance imaging. CT is computed tomography.

EXHIBIT 3. Computed Tomography (CT) And Magnetic Resonance Imaging (MRI) Among Plan Enrollees Age Sixty-Five And Older, By Anatomic Area, 1997-2006

SOURCE: Group Health Cooperative data. NOTES: Data are adjusted to a standard age distribution across all years of study. CT is computed tomography. CNS is central nervous system. MRI is magnetic resonance imaging.

EXHIBIT 4. Annual Imaging Costs Per Health Plan Enrollee, 1997-2006

SOURCE: Group Health Cooperative data. NOTE: Data are adjusted to a standard age distribution across all years of study.

EXHIBIT 5. Annual Imaging Costs Per Health Plan Enrollee, By Anatomic Area, 1997-2006

SOURCE: Group Health Cooperative data. NOTES: Data are adjusted to a standard age distribution across all years of study. CNS is central nervous system. CAG is compound annual growth.

EXHIBIT 6. Number Of Repeat Imaging Tests Within One Year Among Enrollees Who Underwent Abdominal Or Central Nervous System (CNS) Imaging, 1997-2006

SOURCE: Group Health Cooperative data.