Trends in Episode-of-Care Spending for Cancer-Directed Surgery Among US Medicare Beneficiaries From 2011 to 2019

Abstract

This cross-sectional study examines trends in the number of cancer-directed surgeries from 2011 to 2019 among US patients aged 65 years or older and in Medicare spending for those surgeries overall and by inpatient vs outpatient sites of care.

Spending on cancer care in the US continues to rise, with a projected 34% increase to $246 billion by 2030.¹ A significant portion of spending on cancer is incurred in the year following diagnosis, largely due to cancer-directed surgery.² Cancer is a disease of aging, with 53.5% of incident cancers from 2014 to 2018 among patients aged 65 years or older³; thus, most cancer spending is largely borne by the Medicare program. However, little is known about the resource utilization trajectory associated with cancer-directed surgery among Medicare beneficiaries. In this repeated cross-sectional study, we examined recent trends in oncology surgery volume and spending overall and by site of care among Medicare beneficiaries.

Methods

We identified beneficiaries who underwent cancer-directed excisional or ablative surgery between January 1, 2011, and December 31, 2019, using a 5% random sample of fee-for-service Medicare beneficiaries and previously enumerated diagnostic and procedural codes.^4,5 Surgery-related expenditures included all Part A (hospitals, skilled nursing facilities, home health agencies, and hospice organizations) and Part B (health care practitioners, imaging, laboratories, and durable medical equipment) claims for services delivered within 30 days of oncologic surgery. Payments were inflation adjusted to 2019 US dollars using the Consumer Price Index for Medical Care. Surgical site of care was classified as inpatient or outpatient. The MD Anderson Cancer Center institutional review board approved this study and waived informed consent because data were deidentified. We followed the STROBE reporting guideline.

To estimate annual growth rates in surgery-related expenditures per episode, we fitted ordinary least squares models with log-transformed episodic expenditures as the dependent variable and year as the independent variable of interest. One set of estimates used inflation-adjusted expenditures, and a second set was additionally adjusted for age, sex, race and ethnicity, dual eligibility, cancer type, and comorbidity using a generalized linear model with a γ distribution and log-link function. Statistical significance was inferred if 95% CIs excluded the null. We used a linear probability model to assess the time trend in outpatient surgery. Analyses were conducted using SAS Enterprise Guide, version 7.

Results

We studied 70 324 Medicare fee-for-service beneficiaries who underwent oncologic surgery (median age, 74 years [IQR, 69-79 years]; 64.5% female). The most common cancer diagnoses were breast (37.0%), colorectal (15.1%), lung (9.3%), and prostate (9.3%). Over the study period, inflation- and covariate-adjusted mean (SD) 30-day episode surgery expenditures decreased from $23 630 ($13 718) in 2011 to $20 239 ($11 750) in 2019, corresponding to a –2.15 annual percentage change (95% CI, –2.32 to –1.97) (Figure and Table).

Figure. Time Trends for Expenditures of 30-Day Cancer-Directed Surgical Episodes and Occurrence of Outpatient Surgeries From 2011 to 2019.

A, The fitted trend lines were generated by modeling log-transformed expenditures. B, The fitted trend was not adjusted for patient characteristics. C, The annual means were estimated by a generalized linear model adjusted for patient characteristics, including age, sex, race and ethnicity, dual eligibility, cancer type, and comorbidity. The fitted trend lines were generated by modeling log-transformed adjusted expenditures. The shaded areas represent the 95% CIs of the fitted lines.

Table. Annual Change in Expenditures for Cancer Surgery Episodes^a.

Setting	Change each year, % (95% CI)a	Difference each year, 2019 $ (95% CI)	P value
Inflation-adjusted estimate
Any setting	–2.45 (–2.71 to –2.19)	–533 (–590 to –477)	<.001
Inpatient	–0.73 (–1.02 to –0.44)	–220 (–308 to –133)	<.001
Outpatient	0.60 (0.33 to 0.87)	51 (28 to 74)	<.001
Inflation- and covariate-adjusted estimateb
Any setting	–2.15 (–2.32 to –1.97)	–468 (–505 to –429)	<.001
Inpatient	–2.27 (–2.43 to –2.12)	–687 (–735 to –641)	<.001
Outpatient	0.02 (–0.04 to 0.07)	2 (–3 to 6)	.59

^a Each model analyzed log-transformed, inflation-adjusted expenditures as a function of time.

^b Expenditures were adjusted for age, sex, race and ethnicity, dual eligibility, cancer type, and comorbidity (Centers for Medicare & Medicaid Services hierarchical chronic conditions) in addition to inflation. Because surgery for low-expenditure cancer types (eg, breast, prostate) shifted from the inpatient to the outpatient setting over the study period, adjustment for cancer type had inconsistent effects on expenditure trends for the models that included surgical episodes undertaken in any setting compared with the models restricted to either inpatient or outpatient cancer surgeries.

While outpatient surgery expenditures remained relatively stable (annual percentage change, 0.02; 95% CI, –0.04 to 0.07), mean (SD) adjusted episode spending on inpatient surgeries decreased from $31 964 ($12 631) in 2011 to $27 418 ($10 835) in 2019, corresponding to a –2.27 annual percentage change (95% CI, –2.43 to –2.12). Over this period, the proportion of outpatient operations increased from 30.3% to 46.7% (annual change, 1.95 percentage points; 95% CI, 1.81-2.09 percentage points).

Discussion

This cross-sectional study revealed that 30-day episode spending for cancer-directed surgery decreased significantly among Medicare fee-for-service beneficiaries. This overall decrease was largely attributable to lower spending associated with inpatient procedures and a concomitant increase in the proportion of surgeries performed in the less-expensive outpatient setting.

These results have important implications for policy and clinical practice, particularly because the absolute number of patients with cancer aged 65 years or older is projected to nearly double from 52 million in 2018 to 95 million by 2060. The increasing use of minimally invasive approaches may have catalyzed the shift to outpatient surgery, while broad-based improvements in perioperative care (ie, care standardization, implementation of enhanced recovery protocols, and multidisciplinary teams) may have led to reductions in surgical morbidity and mortality,⁶ contributing to the declines in 30-day episode spending for cancer-directed surgery. A limitation is that our findings may not generalize to younger patients or Medicare Advantage enrollees.