Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996-2010.
BACKGROUND
Use of diagnostic imaging has increased significantly within fee-for-service models of care. Little is known about patterns of imaging among members of integrated health care systems.


OBJECTIVE
To estimate trends in imaging utilization and associated radiation exposure among members of integrated health care systems.


METHODS
Retrospective analysis of electronic records of members of 6 large integrated health systems from different regions of the United States. Review of medical records allowed direct estimation of radiation exposure from selected tests. Between 1 million and 2 million member-patients were included each year from 1996 to 2010.


METHODS
Advanced diagnostic imaging rates and cumulative annual radiation exposure from medical imaging.


RESULTS
During the 15-year study period, enrollees underwent a total of 30.9 million imaging examinations (25.8 million person-years), reflecting 1.18 tests (95% CI, 1.17-1.19) per person per year, of which 35% were for advanced diagnostic imaging (computed tomography [CT], magnetic resonance imaging [MRI], nuclear medicine, and ultrasound). Use of advanced diagnostic imaging increased from 1996 to 2010; CT examinations increased from 52 per 1000 enrollees in 1996 to 149 per 1000 in 2010, 7.8% annual increase (95% CI, 5.8%-9.8%); MRI use increased from 17 to 65 per 1000 enrollees, 10% annual growth (95% CI, 3.3%-16.5%); and ultrasound rates increased from 134 to 230 per 1000 enrollees, 3.9% annual growth (95% CI, 3.0%-4.9%). Although nuclear medicine use decreased from 32 to 21 per 1000 enrollees, 3% annual decline (95% CI, 7.7% decline to 1.3% increase), PET imaging rates increased after 2004 from 0.24 to 3.6 per 1000 enrollees, 57% annual growth. Although imaging use increased within all health systems, the adoption of different modalities for anatomic area assessment varied. Increased use of CT between 1996 and 2010 resulted in increased radiation exposure for enrollees, with a doubling in the mean per capita effective dose (1.2 mSv vs 2.3 mSv) and the proportion of enrollees who received high (>20-50 mSv) exposure (1.2% vs 2.5%) and very high (>50 mSv) annual radiation exposure (0.6% vs 1.4%). By 2010, 6.8% of enrollees who underwent imaging received high annual radiation exposure (>20-50 mSv) and 3.9% received very high annual exposure (>50 mSv).


CONCLUSIONS
Within integrated health care systems, there was a large increase in the rate of advanced diagnostic imaging and associated radiation exposure between 1996 and 2010.
Department of Radiology and Biomedical Imaging, 350 Parnassus Ave, Ste 307, University of California, San Francisco, CA 94143-0336, USA. rebecca.smith-bindman@ucsf.edu
Rebecca
R
Smith-Bindman
Diana L
DL
Miglioretti
Eric
E
Johnson
Choonsik
C
Lee
Heather Spencer
HS
Feigelson
Michael
M
Flynn
Robert T
RT
Greenlee
Randell L
RL
Kruger
Mark C
MC
Hornbrook
Douglas
D
Roblin
Leif I
LI
Solberg
Nicholas
N
Vanneman
Sheila
S
Weinmann
Andrew E
AE
Williams
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D019033:Delivery of Health Care, Integrated; D005260:Female; D006279:Health Maintenance Organizations / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data* / Q000639:trends; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D011829:Radiation Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data* / Q000639:trends; D014481:United States; D055815:Young Adult