High-cost imaging in elderly patients with stage IV cancer

Abstract

Background: Medicare expenditures for high-cost diagnostic imaging have risen faster than those for total cancer care and have been targeted for potential cost reduction. We sought to determine recent and long-term patterns in high-cost diagnostic imaging use among elderly (aged ≥65 years) patients with stage IV cancer.

Methods: We identified claims within the Surveillance, Epidemiology, and End Results (SEER)-Medicare database with computed tomography, magnetic resonance imaging, positron emission tomography, and nuclear medicine scans between January 1994 and December 2009 for patients diagnosed with stage IV breast, colorectal, lung, or prostate cancer between January 1995 and December 2006 (N = 100,594 patients). The proportion of these patients imaged and rate of imaging per-patient per-month of survival were calculated for each phase of care in patients diagnosed between January 2002 and December 2006 (N = 55,253 patients). Logistic regression was used to estimate trends in imaging use in stage IV patients diagnosed between January 1995 and December 2006, which were compared with trends in imaging use in early-stage (stages I and II) patients with the same tumor types during the same period (N = 192,429 patients).

Results: Among the stage IV patients diagnosed between January 2002 and December 2006, 95.9% underwent a high-cost diagnostic imaging procedure, with a mean number of 9.79 (SD = 9.77) scans per patient and 1.38 (SD = 1.24) scans per-patient per-month of survival. After the diagnostic phase, 75.3% were scanned again; 34.3% of patients were scanned in the last month of life. Between January 1995 and December 2006, the proportion of stage IV cancer patients imaged increased (relative increase = 4.6%, 95% confidence interval [CI] = 3.7% to 5.6%), and the proportion of early-stage cancer patients imaged decreased (relative decrease = -2.5%, 95% CI = -3.2% to -1.9%).

Conclusions: Diagnostic imaging is used frequently in patients with stage IV disease, and its use increased more rapidly over the decade of study than that in patients with early-stage disease.

Figure 1.

Time trends (1995–2006) in high-cost imaging for early-stage (stages I and II) and stage IV cancer patients. Relative changes (%) in high-cost imaging (CT, MRI, PET, and NM) use within each cohort between January 1995 and December 2006 are shown on the right side of each graph. Each row represents a different phase of care. A) All phases of care. B) Diagnostic phase. C) Continuing care phase. D) Last month of life. For analyses of the diagnostic and continuing care phases (A, B, and C), patients were classified based on year of diagnosis. For analyses of the last month of life (D), patients were classified based on year of death. In (A) and (C), the mean number of scans per patient was normalized per month of survival. CT = computed tomography; MRI = magnetic resonance imaging; PET = positron emission tomography; NM = nuclear medicine; + = relative increase; − = relative decrease.

Figure 2.

Time trends (1995–2006) in high-cost imaging modalities in stage IV cancer patients. Relative changes (%) in high-cost imaging procedures (CT, MRI, PET, or NM) between January 1995 and December 2006 are shown on the right side of each graph. Each row represents a different phase of care. A) All phases of care. B) Diagnostic phase. C) Continuing care phase. D) Last month of life. For (A), (B), (C), and (D), the left panels show the time trends in the proportion of patients imaged, analyzed using logistic regression method, and the right panels show the time trends in the number of procedures per patient, analyzed using robust linear regression method. Boxes represent 95% confidence intervals for use in each year. For analyses of the diagnostic and continuing care phases (A, B, and C), patients were classified based on year of diagnosis. For analyses of the last month of life (D), patients were classified based on year of death. In (A) and (C), the mean number of scans per patient is normalized per month of survival. Within each cohort, all two-sided P values for time trends from 1995 to 2006 were statistically significant (P _trend < .001). CT = computed tomography; MRI = magnetic resonance imaging; PET = positron emission tomography; NM = nuclear medicine; + = relative increase; − = relative decrease. *No relative increase is presented for PET scans given that the utilization rate approached 0 at the beginning of the study period.