Trends in Reoperative Coronary Artery Bypass Graft Surgery for Older Adults in the United States, 1998 to 2017.

Background The likelihood of undergoing reoperative coronary artery bypass graft surgery (CABG) is important for older patients who are considering first-time CABG. Trends in the reoperative CABG for these patients are unknown. Methods and Results We used the Medicare fee-for-service inpatient claims data of adults undergoing isolated first-time CABG between 1998 and 2017. The primary outcome was time to first reoperative CABG within 5 years of discharge from the index surgery, treating death as a competing risk. We fitted a Cox regression to model the likelihood of reoperative CABG as a function of patient baseline characteristics. There were 1 666 875 unique patients undergoing first-time isolated CABG and surviving to hospital discharge. The median (interquartile range) age of patients did not change significantly over time (from 74 [69-78] in 1998 to 73 [69-78] in 2017); the proportion of women decreased from 34.8% to 26.1%. The 5-year rate of reoperative CABG declined from 0.77% (95% CI, 0.72%-0.82%) in 1998 to 0.23% (95% CI, 0.19%-0.28%) in 2013. The annual proportional decline in the 5-year rate of reoperative CABG overall was 6.6% (95% CI, 6.0%-7.1%) nationwide, which did not differ across subgroups, except the non-white non-black race group that had an annual decline of 8.5% (95% CI, 6.2%-10.7%). Conclusions Over a recent 20-year period, the Medicare fee-for-service patients experienced a significant decline in the rate of reoperative CABG. In this cohort of older adults, the rate of declining differed across demographic subgroups.

coronary artery bypass graft

Centers for Medicare & Medicaid Services

fee‐for‐service

percutaneous coronary intervention

Clinical Perspective

What Is New?

We characterized the contemporary rate of reoperative coronary artery bypass graft surgery within 5 years after the first‐time coronary artery bypass graft surgery and its trend over a 20‐year period.

What Are The Clinical Implications?

Older adult patients undergoing first‐time coronary artery bypass graft surgery can expect that the likelihood of having to undergo reoperative coronary artery bypass graft surgery is extremely low, with a 5‐year rate of 0.2%.

Survival after coronary revascularization procedures has steadily improved over time despite increasing patient complexity, , , but the long‐term rate of reoperative coronary artery bypass graft surgery (CABG) and how it has changed over time remain unknown. Characterizing the rate of reoperative CABG after initial revascularization is important from a patient perspective, because CABG is associated with a long recovery time and the majority of patients prefer percutaneous coronary intervention (PCI) over CABG, even in a hypothetical scenario where PCI is associated with higher risks of death and repeat revascularization. , Therefore, information regarding the chance of undergoing reoperative CABG should be part of shared‐decision making. However, evolution of this important outcome has only been characterized in a voluntary registry or within trial data.

The role of reoperative CABG is limited to select situations, including when the disease is not amenable to PCI or in patients with an occluded internal mammary artery graft to the left anterior descending artery. Reoperative CABG is also recommended when there is an indication that patients with significant coronary disease require another open‐heart operation. Patient populations with indications for reoperative CABG have likely changed substantially, because techniques for PCI have improved and transcatheter approaches to valve replacement have emerged. Furthermore, the operative mortality and morbidity of reoperative CABG are relatively high. , , , It is therefore important to identify how the rate of reoperative CABG evolved over time and what contemporary rates are.

In this study, we aimed to characterize the long‐term rate of reoperative CABG in older adults, to assess the trends in the rate of reoperative CABG over 20 years, and whether the rate differed across patient subgroups.

Methods

The Yale University Institutional Review Board reviewed the study protocol and granted a waiver of informed consent for the use of the de‐identified database. Restricted by our Data Use Agreement with the Centers for Medicare & Medicaid Services (CMS), the Medicare data used for this study cannot be made publicly available to other researchers for purposes of reproducing the results or replicating the procedure. However, Medicare data are available from CMS via the Researcher Data Assistance Center upon request (https://www.cms.gov/Research‐Statistics‐Data‐and‐Systems/Files‐for‐Order/Data‐Disclosures‐Data‐Agreements/DUA_‐_Forms.html).

Data Source and Patients

We used Medicare inpatient fee‐for‐service (FFS) claims data from the Centers for Medicare & Medicaid Services (CMS) to identify Medicare patients aged ≥65 years who underwent isolated CABG during an acute care hospitalization in the United States from January 1, 1998 through December 31, 2017, based on the International Classification of Diseases, Ninth and Tenth Revisions, Clinical Modification (ICD‐9 CM and ICD‐10 CM) procedure codes (Table S1). There were 2 131 269 individuals who underwent CABG, of whom 1 666 875 underwent isolated, nonconcomitant, first‐time CABG and were discharged alive. We excluded patients with evidence of prior CABG, including those with prior Medicare FFS hospitalization for CABG before the index CABG hospitalization or having the diagnosis code indicating the past history of CABG at the time of first CABG between 1998 and 2017. This cohort of first‐time isolated CABG was the baseline sample. We excluded patients who died during the index hospitalization because the aim of our study was to characterize the rate of reoperative CABG. Excluded concomitant cases were those including any valve operations, aortic operations, implantation of durable ventricular assist device, and noncardiac operations (Tables S2 and S3). We obtained information on patients’ death and transition to Medicare Advantage plans from the Medicare enrollment file obtained from CMS.

Patient Baseline Characteristics

Demographic information included age, sex, and race (white, black, or other). We identified cardiovascular risk factors (hypertension, diabetes mellitus, atherosclerotic disease, unstable angina, previous myocardial infarction, previous heart failure, peripheral vascular disease, stroke, and other cerebrovascular diseases), geriatric conditions (dementia, functional disability, and malnutrition), and other conditions (renal failure, chronic obstructive pulmonary disease, pneumonia, respiratory failure, liver disease, cancer, major psychiatric disorders, depression, and trauma). The comorbidities were defined according to the Hierarchical Condition Categories to assemble clinically coherent codes into candidate variables. This system was developed by physician and statistical consultants under a contract to CMS and has been used in prior studies. , , We determined comorbidities from a combination of secondary diagnosis codes for the index hospitalization and principal and secondary diagnosis codes for all hospitalizations over 12 months preceding the index CABG hospitalization. Because the maximum number of diagnosis codes in Medicare data increased from 10 to 25 in 2011, we restricted the 2011 to 2017 data to the first 10 diagnosis codes to calculate comorbidities, which has been demonstrated to yield the most consistent number of diagnoses when the data that cross 2011. This is also a commonly adopted approach. , ,

Outcome

The outcome was reoperative isolated or concomitant CABG within 5 years of discharge for the initial CABG. The time zero to count preoperative CABG was at the discharge. We included both isolated and concomitant reoperative CABG, because we aimed to characterize the rate of reoperative CABG irrespective of whether the indication was driven by the primary valvular disease or graft failure, in order to inform patients and clinicians. For patients with more than 1 reoperative CABG, the first reoperative CABG was selected. Patients who switched to a managed care plan before undergoing reoperative CABG were censored. We defined 1‐year crude mortality using Medicare enrollment file as all‐cause death occurring within 1 year of the index operation. Deaths during the 5‐year follow‐up period without a reoperative CABG hospitalization were treated as a competing risk.

Statistical Analysis

We compared patients’ baseline characteristics over the study period and fit a single‐variable Cox regression to describe the observed association between 5‐year reoperative CABG and each of the individual characteristics. To assess the change in the rate of 5‐year reoperative CABG over the study period, we fit the Cox regression to model the likelihood of reoperative CABG as a function of patient baseline characteristics, including an ordinal time variable that ranged from 0 to 19, corresponding to years 1998 (time=0) through 2017 (time=19), to represent the annual change in reoperative CABG rates. Patients without a full 5‐year follow‐up period were censored in the analysis. We also fitted the model separately for age, sex, and race subgroups. Deaths before reoperative CABG were addressed using the Fine and Gray method for competing risks. The Lee, Wei, and Amato method of robust sandwich variance matrix estimation was used to adjust for within‐hospital clustering of patients. Analyses were conducted with the use of SAS software, version 9.4 (SAS Institute). To facilitate data presentation, patient characteristics were reported in 5‐year intervals: 1998 to 2002, 2003 to 2007, 2008 to 2012, and 2013 to 2017. All statistical testing was 2‐sided, and P<0.05 was considered statistically significant. The study followed the guidelines for cohort studies described in the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: Guidelines for Reporting Observational Studies.

Results

Study Sample and Patient Characteristics

There were 1 666 875 unique Medicare FFS patients aged 65 years or older who underwent first‐time isolated CABG and were discharged alive during the 20‐year period. Between 1998 and 2017, the number of first‐time isolated CABG in the FFS Medicare population declined from 528 to 166 per 100 000 beneficiaries/y; the median (interquartile range) age of patients did not change significantly over time (from 74 [69-78] to 73 [69-78]); the proportion of women decreased from 34.8% to 26.1%; the proportion of black patients increased from 4.2% to 5.4%.

Most comorbidities increased during the study period, including renal failure, pneumonia, protein‐calorie malnutrition, dementia, functional disability, liver disease, and diabetes mellitus, while chronic atherosclerotic disease, cerebrovascular disease, and chronic obstructive pulmonary disease decreased (Table 1). Median (interquartile range) length of stay remained similar from 8 (6–11) to 8 (6–11) days. Patients discharged directly to home without home care decreased from 60.0% to 29.4% while discharge to a skilled nursing facility increased from 11.2% to 18.6%. Mortality within 30 days of the index operation, excluding in‐hospital deaths, remained stable from 0.8% to 0.8% while crude 1‐year mortality decreased from 4.6% to 4.3%.

Table 1

Patient Characteristics

Variables	1998 to 2002	2003 to 2007	2008 to 2012	2013 to 2017
N	637 875	477 163	299 432	252 405
Age, median (IQR), y	74 (69–78)	74 (69–79)	73 (69–79)	73 (69–78)
Female	219 042 (34.3)	154 200 (32.3)	90 341 (30.2)	67 988 (26.9)
Race
White	585 602 (91.8)	430 519 (90.2)	268 755 (89.8)	222 711 (88.2)
Black	26 618 (4.2)	24 283 (5.1)	15 835 (5.3)	13 529 (5.4)
Other	25 655 (4.0)	22 361 (4.7)	14 842 (5.0)	16 165 (6.4)
Comorbidity
Heart failure	47 118 (7.4)	31 882 (6.7)	19 059 (6.4)	17 056 (6.8)
Myocardial infarction	42 035 (6.6)	26 021 (5.5)	17 859 (6.0)	16 600 (6.6)
Unstable angina	50 930 (8.0)	23 345 (4.9)	10 919 (3.6)	8241 (3.3)
Chronic atherosclerosis	352 302 (55.2)	255 965 (53.6)	160 796 (53.7)	122 413 (48.5)
Respiratory failure	7905 (1.2)	6929 (1.5)	7284 (2.4)	7966 (3.2)
Hypertension	394 950 (61.9)	312 421 (65.5)	184 047 (61.5)	144 601 (57.3)
Stroke	5817 (0.9)	4633 (1.0)	3034 (1.0)	2694 (1.1)
Cerebrovascular disease	27 747 (4.3)	20 228 (4.2)	12 708 (4.2)	9231 (3.7)
Renal failure	26 543 (4.2)	44 145 (9.3)	47 582 (15.9)	49 758 (19.7)
Chronic obstructive pulmonary disease	116 992 (18.3)	100 203 (21.0)	48 419 (16.2)	38 016 (15.1)
Pneumonia	27 280 (4.3)	25 705 (5.4)	20 773 (6.9)	17 212 (6.8)
Protein‐calorie malnutrition	5165 (0.8)	6280 (1.3)	8730 (2.9)	8447 (3.3)
Dementia	6253 (1.0)	6339 (1.3)	5084 (1.7)	4826 (1.9)
Functional disability	4725 (0.7)	3400 (0.7)	2532 (0.8)	2484 (1.0)
Peripheral vascular disease	38 021 (6.0)	30 555 (6.4)	19 106 (6.4)	13 583 (5.4)
Metastatic cancer	22 295 (3.5)	18 212 (3.8)	11 564 (3.9)	9228 (3.7)
Trauma in past year	13 674 (2.1)	14 146 (3.0)	7716 (2.6)	4967 (2.0)
Major psychiatric disorder	5150 (0.8)	4173 (0.9)	3704 (1.2)	2802 (1.1)
Liver disease	8013 (1.3)	7236 (1.5)	5134 (1.7)	5507 (2.2)
Depression	14 504 (2.3)	14 640 (3.1)	10 710 (3.6)	9954 (3.9)
Diabetes mellitus	195 199 (30.6)	158 437 (33.2)	105 064 (35.1)	99 710 (39.5)
Outcomes
30‐d mortality	4877 (0.8)	3332 (0.7)	2176 (0.7)	1801 (0.7)
1‐y mortality	29 834 (4.7)	23 196 (4.9)	14 040 (4.7)	10 556 (4.2)
Discharge to home	356 172 (55.8)	201 450 (42.4)	103 286 (34.5)	76 868 (30.5)
Discharge to home with home health services	157 178 (24.6)	159 418 (33.4)	111 201 (37.1)	92 329 (36.6)
Discharge to skilled nursing home	72 170 (11.3)	66 086 (13.9)	50 366 (16.8)	47 981 (19.0)
Discharge to hospice	147 (0.02)	554 (0.12)	460 (0.15)	434 (0.17)
Transferred to another acute‐care hospital	43 899 (6.9)	3879 (0.8)	272 (0.1)	104 (0.04)
Other discharge destination	8309 (1.3)	45 776 (9.6)	33 847 (11.3)	34 689 (13.7)
Length of stay, median (IQR), d	8 (6–11)	8 (6–11)	8 (6–11)	8 (6–11)

IQR indicates interquartile range.

Rate of Reoperative CABG

The single‐variable Cox regression found that older age and male sex were associated with a lower likelihood of reoperative CABG. The presence of most of the comorbidities, including heart failure, renal failure, stroke, and functional disability, were associated with lower likelihood of reoperative CABG (Table 2). The rate of reoperative CABG within 5 years decreased significantly and steadily over the 20‐year period (Figure 1). When restricting to patients with a full 5‐year follow‐up period, the observed 5‐year rate of reoperative CABG declined from 0.77% (95% CI, 0.72%–0.82%) in 1998 to 0.23% (95% CI, 0.19%–0.28%) in 2013 (Table 3). This decline between 1998 and 2013 occurred across all evaluated demographic subgroups, but was most prominent in women, non‐white and non‐black race, and age 75 to 84 years old, with percent changes of 67.3% (61.1%–75.0%), 86.9% (77.5%–96.3%), and 70.5% (63.2%–77.4%), respectively (Table 3). The rate of reoperative CABG was consistently the lowest across years until 2011 in patients older than age 85 years, and non‐white and non‐black race declined rapidly to become the demographic subgroup with the lowest rate after 2011. The findings did not change substantially when accounting for patient characteristics and geographic differences. The annual proportional decline in the 5‐year rate of reoperative CABG was 6.6% (95% CI, 6.0%–7.1%) nationwide, which was consistent across subgroups, except the non‐white non‐black race group that had an annual decline of 8.5% (95% CI, 6.2%–10.7%) (Figure 2).

Table 2

Observed Patient Baseline Characteristics Associated With Reoperative CABG

Variables	Risk Ratio (95% CI)
Age, per 1‐y increase	0.95 (0.95–0.96)
Male sex (ref. female)	0.70 (0.66–0.73)
Comorbidity
Heart failure	0.88 (0.80–0.97)
Myocardial infarction	0.89 (0.81–0.99)
Unstable angina	1.49 (1.37–1.61)
Chronic atherosclerosis	1.01 (0.96–1.05)
Respiratory failure	0.83 (0.68–1.00)
Hypertension	1.15 (1.10–1.21)
Stroke	0.66 (0.49–0.88)
Cerebrovascular disease	1.08 (0.97–1.20)
Renal failure	0.70 (0.64–0.77)
Chronic obstructive pulmonary disease	0.98 (0.93–1.04)
Pneumonia	0.84 (0.75–0.94)
Protein‐calorie malnutrition	0.49 (0.38–0.65)
Dementia	0.43 (0.32–0.59)
Functional disability	0.71 (0.52–0.97)
Peripheral vascular disease	1.12 (1.03–1.23)
Trauma in past year	0.88 (0.76–1.03)
Major psychiatric disorder	0.70 (0.53–0.93)
Blood loss anemia	0.86 (0.82–0.90)
Depression	0.97 (0.84–1.11)
Diabetes mellitus	0.91 (0.87–0.96)
Asthma	1.16 (1.00–1.34)

The table shows the observed association between patient baseline characteristics and the likelihood of reoperative CABG during 5‐year follow‐up. Risk ratio > 1 is associated with increased likelihood of reoperative CABG. CABG indicates coronary artery bypass graft.

Figure 1

Kaplan‐Meier estimate of the 5‐year rate of reoperative coronary artery bypass graft by era.

The figure shows a steadily declining 5‐year rate of reoperative CABG surgery over time. Each line represents the survival estimate of the cohort that underwent CABG in the indicated year. CABG indicates coronary artery bypass graft.

Table 3

Annual Trends in the 5‐Year Rate of Reoperative CABG by Demographic Subgroup

Subgroups	1998	2000	2002	2004	2006	2008	2010	2012	2013
Age 65–74 y	0.90 (0.83–0.98)	0.86 (0.79–0.93)	0.80 (0.73–0.87)	0.71 (0.63–0.78)	0.57 (0.50–0.65)	0.52 (0.44–0.59)	0.43 (0.36–0.51)	0.36 (0.29–0.44)	0.27 (0.21–0.33)
Age 75–84 y	0.61 (0.53–0.68)	0.60 (0.53–0.67)	0.50 (0.44–0.56)	0.40 (0.33–0.46)	0.34 (0.27–0.40)	0.30 (0.23–0.37)	0.32 (0.24–0.40)	0.18 (0.12–0.25)	0.18 (0.12–0.25)
Age 85+ y	0.34 (0.14–0.54)	0.28 (0.12–0.43)	0.26 (0.11–0.41)	0.14 (0.02–0.26)	0.15 (0.02–0.28)	0.25 (0.07–0.44)	0.08 (−0.03 to 0.20)	0.14 (−0.02 to 0.29)	0.10 (−0.04 to 0.23)
White race	0.76 (0.71–0.82)	0.73 (0.68–0.78)	0.65 (0.60–0.70)	0.57 (0.52–0.62)	0.45 (0.40–0.51)	0.41 (0.36–0.47)	0.38 (0.33–0.44)	0.30 (0.24–0.35)	0.22 (0.17–0.26)
Black race	0.72 (0.45–0.99)	0.71 (0.48–0.94)	0.75 (0.51–0.99)	0.36 (0.18–0.54)	0.58 (0.33–0.84)	0.59 (0.31–0.86)	0.36 (0.14–0.59)	0.26 (0.05–0.48)	0.68 (0.34–1.0)
Other race	0.99 (0.68–1.29)	0.84 (0.58–1.10)	0.68 (0.44–0.91)	0.59 (0.36–0.83)	0.45 (0.22–0.68)	0.42 (0.18–0.66)	0.30 (0.08–0.51)	0.13 (–0.02–0.29)	0.04 (−0.04 to 0.13)
Female	0.98 (0.88–1.08)	0.85 (0.76–0.94)	0.83 (0.74–0.92)	0.65 (0.55–0.74)	0.59 (0.49–0.69)	0.49 (0.39–0.59)	0.45 (0.35–0.55)	0.32 (0.22–0.42)	0.27 (0.18–0.36)
Male	0.66 (0.60–0.72)	0.67 (0.61–0.73)	0.57 (0.52–0.62)	0.52 (0.46–0.57)	0.40 (0.34–0.46)	0.39 (0.33–0.45)	0.34 (0.29–0.40)	0.27 (0.22–0.33)	0.22 (0.17–0.27)
Overall	0.77 (0.72–0.82)	0.73 (0.68–0.78)	0.66 (0.61–0.70)	0.56 (0.51–0.61)	0.46 (0.41–0.51)	0.42 (0.37–0.47)	0.38 (0.32–0.43)	0.29 (0.24–0.34)	0.23 (0.19–0.28)

The table shows annual trends in the 5‐year rate (%) of reoperative CABG between 1998 and 2013 by demographic subgroups. Biennial data are shown, except for 2012 and 2013 data, which are consecutive. For example, the 5‐year rate of reoperative CABG was 0.77% in 1998 for the overall cohort. CABG indicates coronary artery bypass graft.

Figure 2

Adjusted annual percent reduction in the 5‐year rate of reoperative CABG by demographic subgroups.

The figure demonstrates adjusted annual percent reduction of the 5‐year rate of reoperative CABG. The overall cohort and all examined subgroups had a decline in the rate of reoperative CABG within 5 years of the initial CABG. CABG indicates coronary artery bypass graft.

Discussion

Between 1998 and 2017, the rate of reoperative CABG among Medicare FFS beneficiaries was low and declined significantly. In this cohort of older adults, the decline over time occurred across all demographic subgroups evaluated, with women, non‐white and non‐black race, and patients ages 75 to 84 years old showing the largest decline.

This study extends the prior literature in several ways. First, many studies reporting on the rate of reoperative CABG are more than a decade old, , , , often limited to the pre‐PCI era, and limited to centers that may not be representative of the national cohort. , , , Therefore, the long‐term rate of reoperative CABG in the contemporary era and how the rate had changed over time up to recent years remained unknown. With the complete follow‐up information provided by claims data, our study allowed for comprehensive characterization of 5‐year follow‐up data over 2 decades. Second, the time‐dependent likelihood of reoperative CABG since the time of initial CABG has not been characterized well in the contemporary era. While the Society of Thoracic Surgeons Adult Cardiac Surgery Database provided the national‐level utilization of reoperative CABG, the study only reported on the cross‐sectional data without patient‐level longitudinal follow‐up. A study linking the Society of Thoracic Surgeons Adult Cardiac Surgery Database and Medicare FFS data reported declining rate of repeat revascularization over time after CABG, but the study included data only up to 2007, at which time the 5‐year rate of any revascularization after CABG was about 9%. Our study provided an insight into the contemporary likelihood of reoperative CABG by demonstrating that the likelihood increased essentially linearly since the time of initial CABG. Of note, the 5‐year rate of reoperative CABG in our study matched with the report of the Society of Thoracic Surgeons data linked to Medicare data during the overlapping time period of 1991 to 2007 at 0.6%. Third, sex‐ and race‐based difference in the utilization and outcome of CABG has been demonstrated, but such differences in the rate of reoperative CABG had not been examined extensively. Our study demonstrated that the rate of reoperative CABG and time‐to‐reoperative CABG differed across sociodemographic subgroups.

There are several potential explanations for what we observed. First, the decline in the use of reoperative CABG over time likely is because of the combination of improvement in the secondary prevention after initial CABG, increasing utilization of PCI, transcatheter valve procedures that reduced the need for concomitant reoperative CABG in the setting of primary valve indication, and possible increase in the graft longevity with technical improvement and multi‐arterial graft use. Although long‐term outcome of initial revascularization is favorable in CABG compared with PCI, data on outcomes of reoperative CABG compared with repeat PCI are conflicting , Our finding that older age and presence of comorbidity were associated with lower likelihood of reoperative CABG may be because older and more comorbid patients were likely treated via PCI rather than CABG. A prior multicenter observational study of older adults with acute myocardial infarction suggest that there may be a treatment assignment of patients with more functional reserve toward a more invasive treatment modality.

Studies have reported that the rate of repeat revascularization, via CABG or PCI at 5 years, is 8% to 26%. , , Our observation that <0.3% of the patients underwent reoperative CABG indicates that reoperative CABG is used for only a small proportion of patients in need of repeat revascularization. This is important because having to undergo CABG is a significant event from a patient perspective, especially at the time of repeat revascularization when the patients are older. Because older adults are increasingly susceptible to functional decline after a cardiovascular event, the possibility of having to undergo reoperative CABG should be part of shared‐decision making. Significant mortality and morbidity associated with reoperative CABG may explain the current predominance of PCI for repeat revascularization. Guidelines have class II recommendations for PCI as the first choice over CABG for repeat revascularization in most scenarios, but a rigorous comparative effectiveness study to guide the optimal approach for repeat revascularization is still needed.

From the patient’s perspective, undergoing PCI rather than CABG for recurrent need for revascularization may be favorable. For example, a patient survey showed that the majority of patients prefer PCI over CABG to treat multivessel coronary artery disease even when the presented hypothetical risk of 1‐year death and repeat procedures were higher in PCI than CABG. This is an especially important consideration because in the same survey, physicians tended to prefer CABG over PCI based on the hypothetical risk differential. This potential discrepancy between physician and patient’s values highlight the significance of the perceived burden of having to undergo an open heart operation. Our finding of a steadily declining 5‐year rate of undergoing reoperative CABG to <0.3% provides important information to patients who are considering first‐time CABG.

Limitations

Limitations of this study include the following. Because our data set consisted of only patients who were hospitalized, we could not evaluate the rate of repeat PCI, the majority of which are performed in outpatient settings. We evaluated patients who were Medicare FFS beneficiaries, and the observed rate of reoperative CABG in this cohort of older adults is likely lower than the rate in a younger population. Additionally, it is possible that the findings may not extend to Medicare Advantage beneficiaries, which have increased in number over time. We censored patients who switched to a Medicare Advantage plan after undergoing the initial CABG under a Medicare FFS plan to avoid excluding this cohort altogether. Additionally, we risk adjusted our model to account for potential changes in the composition of the comorbidity profile, which is known to differ between Medicare FFS and Advantage plan beneficiaries. Claims data did not allow for assessment of granular clinical data pertinent to CABG, such as cross‐clamp time and the number of arterial grafts used. Therefore, this limited our ability to further understand which improvements in the care process had impacts on the declining rate of reoperative CABG. However, our study aim was not to elucidate factors associated with the declining rate but rather to identify the contemporary rate of reoperative CABG and how it changed over time. The long study period may be susceptible to coding practice change. While the coding practice change may have affected the captured comorbidity diagnoses, it is unlikely that a significant procedural event such as CABG was susceptible to such changes.

Conclusions

Over the last 20 years, the Medicare FFS beneficiaries experienced a significant decline in the rate of reoperative CABG. In the contemporary era, the 5‐year rate of reoperative CABG in older adults was <0.3%, indicating that only a small fraction of patients in need of repeat revascularization are treated by reoperative CABG. Patients undergoing first‐time CABG could expect an extremely low chance of having to undergo reoperative CABG at 5 years.

Sources of Funding

Makoto Mori is a PhD Student in the Investigative Medicine Program at Yale, which is supported by CTSA Grant Number UL1 TR001863 from the National Center for Advancing Translational Science (NCATS), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NIH.

Disclosures

Dr. Krumholz works under contract with the Centers for Medicare & Medicaid Services to support quality measurement programs; was a recipient of a research grant, through Yale, from Medtronic and the US Food and Drug Administration to develop methods for postmarket surveillance of medical devices; was a recipient of a research grant with Medtronic and is the recipient of a research grant from Johnson & Johnson, through Yale University, to support clinical trial data sharing; was a recipient of a research agreement, through Yale University, from the Shenzhen Center for Health Information for work to advance intelligent disease prevention and health promotion; collaborates with the National Center for Cardiovascular Diseases in Beijing; receives payment from the Arnold & Porter Law Firm for work related to the Sanofi clopidogrel litigation, from the Martin/Baughman Law Firm for work related to the Cook Celect IVC filter litigation, and from the Siegfried and Jensen Law Firm for work related to Vioxx litigation; chairs a Cardiac Scientific Advisory Board for UnitedHealth; was a participant/participant representative of the IBM Watson Health Life Sciences Board; is a member of the Advisory Board for Element Science, the Advisory Board for Facebook, and the Physician Advisory Board for Aetna; and is the co‐founder of HugoHealth, a personal health information platform, and co‐founder of Refactor Health, an enterprise healthcare AI‐augmented data management company. Dr. Gupta received payment from the Arnold & Porter Law Firm for work related to the Sanofi clopidogrel litigation and from the Ben C. Martin Law Firm for work related to the Cook Celect IVC filter litigation. She is also co‐founder of Heartbeat Health, Inc, a cardiology healthcare platform. The remaining authors have no disclosures to report.

Tables S1–S3

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