Regional variation in spending and survival for older adults with advanced cancer

Abstract

Background: Medicare spending varies substantially across the United States. We evaluated the association between mean regional spending and survival in advanced cancer.

Methods: We identified 116 523 subjects with advanced cancer from 2002 to 2007, using Surveillance, Epidemiology and End Results (SEER)-Medicare linked data. Subjects were aged 65 years and older with non-small cell lung, colon, breast, prostate, or pancreas cancer. Of these subjects, 61 083 had incident advanced-stage cancer (incident cohort) and 98 935 had death from cancer (decedent cohort); 37% of subjects were included in both cohorts. Subjects were linked to one of 80 hospital referral regions within SEER areas. We estimated mean regional spending in both cohorts. We assessed the primary outcome, survival, in the incident cohort; the exposure measure was the quintile of regional spending in the decedent cohort. Survival in quintiles 2 through 5 was compared with that in quintile 1 (lowest spending quintile) using Cox regression models.

Results: From quintile 1 to 5, mean regional spending increased by 32% and 41% in the incident and decedent cohorts (incident cohort: $28 854 to $37 971; decedent cohort: $27 446 to $38 630). The association between spending and survival varied by cancer site and quintile; hazard ratios ranged from 0.92 (95% confidence interval [CI] = 0.82 to 1.04, pancreas cancer quintile 5) to 1.24 (95% CI = 1.11 to 1.39, breast cancer quintile 3). In most cases, differences in survival between quintile 1 and quintiles 2 through 5 were not statistically significant.

Conclusion: There is substantial regional variation in Medicare spending for advanced cancer, yet no consistent association between mean regional spending and survival.

Figure 1.

Assembly of study cohorts. Exclusion criteria were applied sequentially as listed in the figure. HMO = health maintenance organization; HRR = hospital referral region.

Figure 2.

Mean 6-month spending for advanced cancer by quintile of regional spending. The left panel shows mean spending in the incident cohort stratified by incident cohort spending quintiles. The right panel shows mean spending in the decedent cohort, stratified by decedent cohort spending quintiles. Error bars represent 95% confidence intervals. NSCLC, non–small cell lung cancer.

Figure 3.

Unadjusted survival by cancer site and spending quintile. A–E) Kaplan–Meier plots of overall survival by cancer type stratified by spending quintile. A) Non–small cell lung cancer. B) Colorectal cancer. C) Pancreas cancer. D) Breast cancer. E) Prostate cancer.

Figure 4.

Adjusted survival by cancer site and spending quintile. Hazard ratios (HRs) are shown for quintiles 2 through 5 in comparison with quintile 1 (reference). Hazard ratios are adjusted for age, race, sex, and comorbidity. Error bars represent 95% confidence intervals for hazard ratio estimates. LCB = lower confidence bound; NSCLC = non–small cell lung cancer; UCB, upper confidence bound.