Adjuvant Chemotherapy After Resection in Elderly Medicare and Medicaid Patients With Colon Cancer

Article (PDF Available)inArchives of Internal Medicine 168(5):521-9 · April 2008with17 Reads
DOI: 10.1001/archinternmed.2007.82 · Source: PubMed
Abstract
This study investigated the influence of Medicaid enrollment on the receipt and completion of adjuvant chemotherapy and the likelihood of evaluation by an oncologist for those patients who do not initiate chemotherapy. Medicaid and Medicare administrative data were merged with the Michigan Tumor Registry to extract a sample of patients who had resection for a first primary colon tumor diagnosed between January 1, 1997, and December 31, 2000 (n = 4765). We used unadjusted and adjusted logistic regression to assess the relationship between Medicaid enrollment and the outcomes of interest. Relative to Medicare patients, Medicaid patients were less likely to initiate chemotherapy (odds ratio, 0.50; 95% confidence interval, 0.39-0.65) or complete chemotherapy (odds ratio, 0.52; 95% confidence interval, 0.31-0.85). When the sample was restricted to patients with TNM-staged disease, Medicaid patients were less likely to initiate chemotherapy. Older patients and patients with comorbidities were also less likely to initiate or, in some cases, to complete chemotherapy. Medicaid enrollment is associated with disparate colon cancer treatment, which likely compromises the long-term survival of these patients.
ORIGINAL INVESTIGATION
Adjuvant Chemotherapy After Resection in Elderly
Medicare and Medicaid Patients With Colon Cancer
Cathy J. Bradley, PhD; Charles W. Given, PhD; Bassam Dahman, MS; Timothy L. Fitzgerald, MD
Background: This study investigated the influence of
Medicaid enrollment on the receipt and completion of
adjuvant chemotherapy and the likelihood of evalua-
tion by an oncologist for those patients who do not ini-
tiate chemotherapy.
Methods: Medicaid and Medicare administrative data
were merged with the Michigan Tumor Registry to ex-
tract a sample of patients who had resection for a first
primary colon tumor diagnosed between January 1, 1997,
and December 31, 2000 (n=4765). We used unadjusted
and adjusted logistic regression to assess the relation-
ship between Medicaid enrollment and the outcomes of
interest.
Results: Relative to Medicare patients, Medicaid pa-
tients were less likely to initiate chemotherapy (odds ra-
tio, 0.50; 95% confidence interval, 0.39-0.65) or com-
plete chemotherapy (odds ratio, 0.52; 95% confidence
interval, 0.31-0.85). When the sample was restricted to
patients with TNM-staged disease, Medicaid patients were
less likely to initiate chemotherapy. Older patients and
patients with comorbidities were also less likely to ini-
tiate or, in some cases, to complete chemotherapy.
Conclusion: Medicaid enrollment is associated with dis-
parate colon cancer treatment, which likely compro-
mises the long-term survival of these patients.
Arch Intern Med. 2008;168(5):521-529
T
HE SURVIVAL BENEFITS OF
adjuvant chemotherapy for
stage III colon cancer have
been demonstrated,
1-3
even
among elderly patients.
4,5
Once patients initiate adjuvant chemo-
therapy, completion rates have been found
to be as high as 78%.
6
Modest survival ben-
efits have been demonstrated for patients
treated with chemotherapy for stage II co-
lon cancer,
7,8
but the use of chemo-
therapy for treating stage II cancer re-
mains controversial and is recommended
only in high-risk patients.
9
However, che-
motherapy administration across oncol-
ogy practices suggests low levels of aware-
ness of guidelines for chemotherapy,
particularly among rural, community-
based cancer care centers.
10
In addition, patient characteristics such
as female sex,
6,7
comorbidity burden,
11
Afri-
can American race,
6,12-15
low income,
6,14
and
older age
5,6,12,14
appear to be related to low
rates of chemotherapy initiation. Further-
more, many patients are not referred to a
medical oncologist for evaluation,
16
indi-
cating that these patients may not have had
the opportunity to evaluate the benefits
and risks of chemotherapy.
Medicaid-insured patients have poor
colon cancer survival,
17
but whether these
patients receive less treatment than pa-
tients with other health insurance is un-
known. We examined adjuvant chemo-
therapy initiation rates, completion rates,
and evaluation by an oncologist in a sample
of elderly patients who underwent resec-
tion for colon cancer. We were primarily
interested in Medicaid enrollment and if
it influenced chemotherapy initiation and
completion and evaluation by an oncolo-
gist. Medicaid patients are of interest be-
cause they often embody the characteris-
tics (eg, low income or racial or ethnic
minority status) associated with dispari-
ties in the receipt of health care
18
and poor
cancer survivorship.
METHODS
We used statewide Medicaid and Medicare data
merged with the Michigan Tumor Registry to
extract a study sample of patients with a first pri-
mary colon cancer diagnosis. The Michigan Can-
cer Surveillance Program, which maintains the
Michigan Tumor Registry, ascertains more than
95% of all incident cancer cases based on ex-
ternal audit findings. This study was approved
Author Affiliations:
Department of Health
Administration and Massey
Cancer Center (Dr Bradley) and
Division of Quality Health Care,
Department of Internal
Medicine (Mr Dahman),
Virginia Commonwealth
University, Richmond;
Department of Family Practice,
Michigan State University, East
Lansing (Dr Given); and Trinity
Health System and Richard J.
Lacks Cancer Center at Saint
Mary’s Health Care, Grand
Rapids, Michigan
(Dr Fitzgerald).
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by institutional review boards at the Michigan Department of
Community Health (Lansing), Michigan State University, and
Virginia Commonwealth University.
Patients were matched to the Michigan state segment of the
Medicare denominator file for the period from January 1, 1997,
through December 31, 2000, using the patient’s Social Security
number. We extracted, from statewide Medicare files, all claims
for inpatient, outpatient, and physician services during the study
period for all patients who were correctly matched to the Michi-
gan state segment of the Medicare denominator file (approxi-
mately 89% of patients) and were enrolled in Parts A and B. Michi-
gan proved to be an ideal state for merging cancer registry and
Medicare data because less than 3% of Michigan Medicare ben-
eficiaries were enrolled in managed care. The process for link-
ing the Michigan Tumor Registry, Medicare, and Medicaid data
sets is described more fully elsewhere.
19
We also used the unique
physician identifying numbers listed in the claim files and linked
with the Medicare Physician Identification and Eligibility Reg-
istry file to extract physician specialty information. To the linked
Michigan Tumor Registry, Medicare, and Medicaid files, we added
data from the 2000 Census Summary File using patient address
information recorded in the Michigan Tumor Registry.
From this sample, we excluded patients who resided in a nurs-
ing home (Medicaid only, n=228). Patients in private pay nurs-
ing homes remained in the Medicare sample because we could
not identify them in the data set. Their presence increased the
illness severity in the overall Medicare sample. We identified 8043
patients with colon cancer who were 66 years and older and who
had undergone resection (International Classification of Diseases,
Ninth Revision [ICD-9] codes 45.71-45.79, 45.8, 48.41-48.49, 48.50,
and 48.61-48.69).
20
We excluded all patients with less than 9
months of data after the month of diagnosis (n=695) and those
whose conditions were diagnosed in 1996 because they had less
than 12 months of data before the month of diagnosis (n=2291).
We also excluded patients with invasive but unknown stage dis-
ease (n=292); the remaining sample size was 4765, of which 458
were insured by Medicaid in addition to Medicare.
We used Medicare claims files to assess the outcomes of in-
terest for the full sample and a sample restricted to patients with
a TNM stage. We used this approach because the TNM stage was
missing for 50% of the patients, but a Surveillance, Epidemiol-
ogy, and End Results (SEER) summary stage was available for all
patients.
Although TNM stage is more informative than the SEER sum-
mary stage, the National Program of Cancer Registries does not
require state registries to report TNM stage. Michigan began
requiring TNM stage in 1997 from facilities that had registries
but excluded smaller facilities that did not have a registry (as
may be the case in rural and underserved areas) from this re-
quirement. Among patients for whom both SEER summary stage
and TNM stage were known, there was a 90% or greater cor-
respondence between TNM stage I and local stage, TNM stage
III and regional stage, and TNM stage IV and distant stage. How-
ever, TNM stage II cancers were split between local (40%) and
regional (57%) stages, making it difficult to infer TNM stage
from a summary stage of regional or local. A TNM stage II tu-
mor that has penetrated nonperitonealized pericolonic tissue
is considered regional even in the absence of positive lymph
nodes. We report findings from the sample with a TNM stage
because it is more precise with regard to stage but also report
findings from the entire sample so as not to exclude patients
treated in small, rural, and/or underserved regions of the state.
OUTCOMES
Chemotherapy initiation was identified by at least 1 claim in-
dicating the administration of chemotherapy within 6 months
after diagnosis (Current Procedural Terminology codes 96400-
96599; Health Care Common Procedural Codes Q0083-
Q0085, J8510, J8520, J8521, J8530-J8999, J9000-J9999, and
J0640; and ICD-9 codes E0781, E9331, and V58.1). Hersh-
manetal
21
found that 91% of elderly patients with colon can-
cer initiate chemotherapy within 3 months of diagnosis but that
older patients and patients with comorbid conditions were more
likely to start chemotherapy 3 or more months after diagnosis.
We defined a complete course of adjuvant chemotherapy
as 5 consecutive months of chemotherapy with 1 claim day in
a month. To avoid misclassifying chemotherapy for cancer re-
currences, we counted claims that ended (1) with the claim date
after which there were 3 months without any type of colon can-
cer treatment, (2) with a cancer recurrence, or (3) 9 months
after diagnosis, whichever came first. Recurrent cancer was iden-
tified by the following codes: ICD-9 codes 50.20 to 50.22, 50.29,
50.3, or 50.4; ICD-9 code 197.7; or Current Procedural Ter-
minology codes 36246, 36247, 47120, 47122, 47125, 47130,
47370, 47371, 47380, 47381, 47382, 76362, 76394, 76490,
36260, or 47100. Secondary malignancies were identified by
the following ICD-9 codes: 197.0, 197.1, 197.2 197.3, 197.8,
198.3 to 198.5, 198.41, 198.45, 198.48, 198.51, 197.04, or
197.08. This method for counting complete chemotherapy ad-
ministration has been validated by a prior nationwide study that
examined practice patterns during our study period.
6
In the as-
sessment of chemotherapy completion, we excluded patients
diagnosed as having distant stage disease or TNM stage IV dis-
ease, depending on the sample, because a complete course of
chemotherapy was not defined for these patients.
We assessed whether patients who did not initiate chemo-
therapy were evaluated by an oncologist. Our process for iden-
tifying oncologists was as follows. First, we examined the phy-
sician specialty codes listed in the Medicare Physician
Identification and Eligibility Registry file that coincided with
the date of any chemotherapy administration, regardless of can-
cer site. Most chemotherapy claims (68%) were submitted by
either a medical oncologist (specialty code 90) or hematologist/
oncologist (specialty code 83). The remaining claims were coded
as either internal medicine or clinic or group practice. Second,
we designated all physicians’ unique physician identifying num-
bers that were ever associated with an oncology specialty or
the administration of chemotherapy as an “oncology special-
ist,” using all claims (including those from cancer sites other
than colon) in the Michigan state segments of the carrier file
for 1996 through 2000. Our method overestimates the num-
ber of oncologists, which reduces the chance of observing a sta-
tistically significant result. For example, among patients who
did not initiate chemotherapy, 84% had been evaluated by an
oncologist.
CONTROL VARIABLES
Data on patient age, race, and sex were obtained from the Michi-
gan Tumor Registry. Age was grouped into the following cat-
egories: 66 to 69 years, 70 to 74 years, 75 to 79 years, and 80
years and older. Race was categorized as white or other, al-
though most of these latter patients were African American
(86%). In addition to these variables, we included informa-
tion on patients’ census tract median household income. The
income categories were less than $25 000, $25 001 to $35 000,
$35 001 to $45 000, and more than $45 000. We also included
variables that indicated whether the patient lived in a metro-
politan area, urban area adjacent to a metropolitan area, urban
area not adjacent to a metropolitan area, rural area adjacent to
a metropolitan area, or an isolated rural area. Address infor-
mation was not available for 5% of the patients. Therefore, we
used the monotone multiple imputations method with logis-
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tured by comorbidity measures, lead to low chemo-
therapy initiation rates. Nevertheless, evidence suggests
that patients with colon cancer and chronic conditions
such as heart failure, diabetes mellitus, and chronic ob-
structive pulmonary disease benefit from chemo-
therapy.
30
Once chemotherapy is initiated, only the old-
est patients discontinue chemotherapy prematurely
relative to their younger counterparts.
The study has 3 main limitations. First, the study is
specific to Michigan, so it may not be generalizable to
other states or regions. However, the only way to iden-
tify Medicaid-insured patients at this time is at the state
level. The state buy-in variable, which is in the Medi-
care denominator file, does not adequately identify Med-
icaid patients. Second, Medicare nursing home patients
could not be identified. Had we been able to identify them,
Table 3. Unadjusted Analysis of Adjuvant Chemotherapy Initiation and Completion in Patients With TNM Staged Disease
Explanatory Variables
Adjuvant Chemotherapy Initiation,
No. (%) (n=2371)
Chemotherapy Completion,
No. (%) (n=598)
Oncology Evaluation,
No. (%) (n=1591)
Insurance status
Medicaid 55 (25.9) 22 (51.2) 134 (85.4)
Medicare only 725 (33.6) 337 (60.7) 1240 (86.5)
P value
a
.02 .22 .70
Age, y
66-69 208 (53.2) 99 (66.9) 155 (84.7)
70-74 263 (45.1) 124 (59.9) 277 (86.6)
75-79 199 (33.7) 95 (59.8) 342 (87.5)
80 110 (13.6) 41 (48.8) 600 (86.1)
P value
a
.001 .06 .83
Race
White 690 (33.4) 317 (59.7) 1189 (86.2)
African American or other 90 (29.8) 42 (62.7) 185 (87.3)
P value
a
.22 .64 .68
Sex
Male 365 (36.4) 178 (64.3) 550 (86.2)
Female 415 (30.3) 181 (56.4) 824 (86.5)
P value
a
.002 .05 .88
Comorbidity score
0 557 (36.2) 264 (62.6) 837 (85.3)
1 143 (27.4) 67 (58.8) 322 (85.0)
2 80 (25.7) 28 (45.2) 215 (93.1)
P value
a
.001 .03 .003
Hospital readmission
No 698 (32.6) 315 (59.0) 1240 (85.9)
Yes 82 (35.8) 44 (68.8) 134 (91.2)
P value
a
.33 .13 .06
Teaching status
No 263 (36.1) 110 (53.4) 381 (81.8)
Yes 517 (31.5) 249 (63.5) 993 (88.3)
P value
a
.03 .02 .001
Census tract median income, $
25 000 165 (29.4) 76 (58.9) 317 (79.9)
25 001-35 000 222 (31.9) 89 (54.3) 423 (89.4)
35 001-45 000 222 (35.2) 109 (65.3) 362 (88.7)
45 001 137 (36.0) 67 (60.4) 221 (91.0)
Missing 34 (32.7) 18 (66.7) 51 (72.9)
P value
a
.15 .31 .001
Urban or rural
Metropolitan 619 (32.7) 290 (61.6) 1142 (89.8)
Rural, adjacent to metropolitan 7 (46.7) 4 (66.7) 5 (62.5)
Isolated rural 12 (25.5) 4 (66.7) 19 (54.3)
Urban, not adjacent to metropolitan 46 (29.1) 17 (50.0) 75 (67.0)
Urban, adjacent to metropolitan 68 (40.2) 27 (47.4) 85 (84.2)
Missing 28 (30.8) 17 (70.8) 48 (76.2)
P value
a
.18 .22 .001
TNM stage
0
3 (5.2) 2 (66.7) 51 (92.7)
I 37 (6.7) 10 (27.0) 427 (82.9)
II 225 (24.6) 115 (51.1) 613 (89.0)
III 333 (68.7) 232 (69.7) 133 (87.5)
IV 182 (50.3) NA 150 (83.3)
P value
a
.001 .001 .01
Abbreviation: NA, not applicable.
a
Statistical significance was determined by the 2-sided
2
test.
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area. Regardless of these differences, the findings were
remarkably similar. This study did not examine the ap-
propriateness of cancer treatment (for example, the pro-
portion of patients with TNM stage III disease who re-
ceived chemotherapy) but instead predicted treatment
patterns for all patients with resected colon cancer, re-
gardless of stage. The evidence suggests that chemo-
therapy is not confined to TNM stage III disease and that
perhaps some patients are treated inappropriately.
The main finding of this study is that Medicaid insur-
ance is associated with a low likelihood of chemo-
therapy initiation and completion, and there is conflict-
ing evidence regarding Medicaid patients’ likelihood of
being evaluated by an oncologist. Several explanations
for these observations are plausible. First, Medicaid-
insured patients may have poorer health status than Medi-
care patients. However, Medicaid patients residing in nurs-
ing homes were removed from the sample, which should
have eliminated cases of greater dependence. Second, Med-
icaid-insured patients may have fewer support services
(eg, transportation or caregivers) to help them get to phy-
sicians’ offices and to care for them after treatment. Fi-
Table 1. Sample Characteristics of the Michigan Patients With Colon Cancer
Characteristic
No. (%) of All Patients
(n= 4765)
P Value
a
No. (%) of Patients With
TNM-Staged Disease
(n= 2371)
P Value
a
Medicaid
(n= 458)
Medicare
(n= 4307)
Medicaid
(n= 212)
Medicare
(n= 2159)
Age, y .43 .42
66-69 74 (16.2) 714 (16.6) 34 (16.0) 357 (16.5)
70-74 123 (26.9) 1062 (24.7) 59 (27.8) 524 (24.3)
75-79 100 (21.8) 1076 (25.0) 44 (20.8) 546 (25.3)
80 161 (35.2) 1455 (33.8) 75 (35.4) 732 (33.9)
Race .001 .001
White 310 (67.7) 3882 (90.1) 144 (67.9) 1925 (89.2)
African American or other 148 (32.3) 425 (9.9) 68 (32.1) 234 (10.8)
Sex .001 .001
Male 134 (29.3) 1922 (44.6) 60 (28.3) 943 (43.7)
Female 324 (70.7) 2385 (55.4) 152 (71.7) 1216 (56.3)
Comorbidity score .001
0 265 (57.9) 2871 (66.7) 129 (60.8) 1409 (65.3) .28
1 114 (24.9) 908 (21.1) 56 (26.4) 466 (21.6)
2 79 (17.3) 528 (12.3) 27 (12.7) 284 (13.2)
Hospital readmission .03 .54
No 398 (86.9) 3882 (90.1) 189 (89.2) 1953 (90.5)
Yes 60 (13.1) 425 (9.9) 23 (10.9) 206 (9.5)
Teaching hospital .15 .98
No 180 (40.4) 1553 (36.8) 65 (30.7) 644 (30.8)
Yes 266 (59.6) 2663 (63.2) 147 (69.3) 1495 (69.3)
Census tract median annual income, $ .001 .001
25 000 233 (50.9) 1063 (24.7) 107 (50.5) 455 (21.1)
25 001-35 000 136 (29.7) 1337 (31.0) 58 (27.4) 637 (29.5)
35 001-45 000 41 (9.0) 1092 (25.4) 23 (10.9) 607 (28.1)
45 001 22 (4.8) 620 (14.4) 16 (7.6) 364 (16.9)
Missing 26 (5.7) 195 (4.5) 8 (3.8) 96 (4.4)
Urban or rural .07 .13
Metropolitan 335 (73.1) 3249 (75.4) 162 (76.4) 1729 (80.1)
Rural, adjacent to metropolitan 4 (0.9) 29 (0.7) 2 (0.9) 13 (0.6)
Isolated rural 8 (1.8) 89 (2.1) 5 (2.4) 42 (2.0)
Urban, not adjacent to metropolitan 55 (12.0) 382 (8.9) 24 (11.3) 134 (6.2)
Urban, adjacent to metropolitan 30 (6.6) 381 (8.9) 11 (5.2) 158 (7.3)
Missing 26 (5.7) 177 (4.1) 8 (8.8) 83 (3.8)
Cancer stage .11 .002
In situ 9 (2.0) 111 (2.6) NA NA
Local 175 (38.2) 1847 (42.9) NA NA
Regional 205 (44.8) 1688 (39.2) NA NA
Distant 69 (15.1) 661 (15.4) NA NA
TNM stage
0 NA NA 2 (0.9) 56 (2.6)
I NA NA 30 (14.2) 522 (24.2)
II NA NA 88 (41.5) 826 (38.3)
III NA NA 54 (25.5) 431 (20.0)
IV NA NA 38 (17.9) 324 (15.0)
Abbreviation: NA, not applicable.
a
Statistical significance was determined by the 2-sided
2
test.
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nally, Medicaid-insured patients may have a lower ac-
ceptance rate of chemotherapy.
Another important finding of the study is that older
patients are less likely to initiate chemotherapy. Several
other published studies
5,29
have found treatment dispari-
ties between older and younger adults. These studies con-
clude that cancer survival and time to recurrences could
be improved for these patients with the administration
of chemotherapy.
5,29
We speculate that conservative prac-
tice patterns, poor physician-patient communication about
the benefits and risks of chemotherapy, and/or differ-
ences in baseline functional status, which may not be cap-
Table 2. Unadjusted Analysis of Adjuvant Chemotherapy Initiation, Completion, and Evaluation by an Oncology Specialist
for All Patients With Colon Cancer
Explanatory Variables
Adjuvant Chemotherapy Initiation,
No. (%) (n=4765)
Chemotherapy Completion, No. (%)
(n= 1210)
a
Oncology Evaluation, No. (%)
(n= 3208)
Insurance status
Medicaid 104 (22.7) 38 (48.1) 285 (80.5)
Medicare only 1453 (33.7) 696 (61.5) 2412 (84.5)
P value
b
.001 .02 .05
Age, y
66-69 390 (49.5) 196 (66.4) 331 (83.2)
70-74 527 (44.5) 253 (61.7) 548 (83.3)
75-79 389 (33.1) 184 (59.7) 680 (86.4)
80 251 (15.5) 101 (51.3) 1138 (83.4)
P value
b
.001 .009 .24
Race
White 1387 (33.1) 664 (60.8) 2348 (83.7)
African American or other 170 (29.7) 70 (59.3) 349 (86.6)
P value
b
.10 .75 .14
Sex
Male 736 (35.8) 341 (60.6) 1097 (83.1)
Female 821 (30.3) 393 (60.7) 1600 (84.8)
P value
b
.001 .95 .21
Comorbidity score
0 1120 (35.7) 537 (62.2) 1661 (82.4)
1 299 (29.3) 145 (62.5) 620 (85.8)
2 138 (22.7) 52 (45.6) 416 (88.7)
P value
b
.001 .003 .001
Hospital readmission
No 1385 (32.4) 648 (60.5) 2417 (83.5)
Yes 172 (35.5) 86 (62.3) 280 (89.5)
P value
b
.17 .67 .006
Teaching status
No 629 (34.3) 291 (56.7) 971 (80.5)
Yes 928 (31.7) 443 (63.6) 1726 (86.3)
P value
b
.07 .02 .001
Census tract median annual income, $
25 000 404 (31.2) 189 (60.4) 705 (79.0)
25 001-35 000 462 (31.4) 189 (55.1) 852 (84.3)
35 001-45 000 406 (35.8) 207 (64.1) 647 (89.0)
45 001 216 (33.6) 112 (64.7) 383 (89.9)
Missing 69 (31.2) 37 (63.8) 110 (72.4)
P value
b
.09 .11 .001
Urban or rural
Metropolitan 1170 (32.7) 561 (62.3) 2110 (87.4)
Rural, adjacent to metropolitan 12 (36.4) 9 (81.8) 16 (76.2)
Isolated rural 28 (28.9) 13 (65.0) 40 (58.0)
Urban, not adjacent to metropolitan 147 (33.6) 65 (56.0) 208 (71.7)
Urban, adjacent to metropolitan 140 (34.1) 52 (47.3) 218 (80.4)
Missing 60 (29.6) 34 (64.2) 105 (73.4)
P value
b
.81 .02 .001
Cancer stage
In situ 10 (8.3) 4 (40.0) 90 (81.8)
Local 286 (14.1) 126 (44.1) 1443 (83.1)
Regional 919 (48.6) 604 (66.1) 850 (87.3)
Distant 342 (46.9) NA 314 (80.9)
P value
b
.001 .001 .008
Abbreviation: NA, not applicable.
a
Excludes patients with distant stage disease.
b
Statistical significance was determined by the 2-sided
2
test.
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tured by comorbidity measures, lead to low chemo-
therapy initiation rates. Nevertheless, evidence suggests
that patients with colon cancer and chronic conditions
such as heart failure, diabetes mellitus, and chronic ob-
structive pulmonary disease benefit from chemo-
therapy.
30
Once chemotherapy is initiated, only the old-
est patients discontinue chemotherapy prematurely
relative to their younger counterparts.
The study has 3 main limitations. First, the study is
specific to Michigan, so it may not be generalizable to
other states or regions. However, the only way to iden-
tify Medicaid-insured patients at this time is at the state
level. The state buy-in variable, which is in the Medi-
care denominator file, does not adequately identify Med-
icaid patients. Second, Medicare nursing home patients
could not be identified. Had we been able to identify them,
Table 3. Unadjusted Analysis of Adjuvant Chemotherapy Initiation and Completion in Patients With TNM Staged Disease
Explanatory Variables
Adjuvant Chemotherapy Initiation,
No. (%) (n=2371)
Chemotherapy Completion,
No. (%) (n=598)
Oncology Evaluation,
No. (%) (n=1591)
Insurance status
Medicaid 55 (25.9) 22 (51.2) 134 (85.4)
Medicare only 725 (33.6) 337 (60.7) 1240 (86.5)
P value
a
.02 .22 .70
Age, y
66-69 208 (53.2) 99 (66.9) 155 (84.7)
70-74 263 (45.1) 124 (59.9) 277 (86.6)
75-79 199 (33.7) 95 (59.8) 342 (87.5)
80 110 (13.6) 41 (48.8) 600 (86.1)
P value
a
.001 .06 .83
Race
White 690 (33.4) 317 (59.7) 1189 (86.2)
African American or other 90 (29.8) 42 (62.7) 185 (87.3)
P value
a
.22 .64 .68
Sex
Male 365 (36.4) 178 (64.3) 550 (86.2)
Female 415 (30.3) 181 (56.4) 824 (86.5)
P value
a
.002 .05 .88
Comorbidity score
0 557 (36.2) 264 (62.6) 837 (85.3)
1 143 (27.4) 67 (58.8) 322 (85.0)
2 80 (25.7) 28 (45.2) 215 (93.1)
P value
a
.001 .03 .003
Hospital readmission
No 698 (32.6) 315 (59.0) 1240 (85.9)
Yes 82 (35.8) 44 (68.8) 134 (91.2)
P value
a
.33 .13 .06
Teaching status
No 263 (36.1) 110 (53.4) 381 (81.8)
Yes 517 (31.5) 249 (63.5) 993 (88.3)
P value
a
.03 .02 .001
Census tract median income, $
25 000 165 (29.4) 76 (58.9) 317 (79.9)
25 001-35 000 222 (31.9) 89 (54.3) 423 (89.4)
35 001-45 000 222 (35.2) 109 (65.3) 362 (88.7)
45 001 137 (36.0) 67 (60.4) 221 (91.0)
Missing 34 (32.7) 18 (66.7) 51 (72.9)
P value
a
.15 .31 .001
Urban or rural
Metropolitan 619 (32.7) 290 (61.6) 1142 (89.8)
Rural, adjacent to metropolitan 7 (46.7) 4 (66.7) 5 (62.5)
Isolated rural 12 (25.5) 4 (66.7) 19 (54.3)
Urban, not adjacent to metropolitan 46 (29.1) 17 (50.0) 75 (67.0)
Urban, adjacent to metropolitan 68 (40.2) 27 (47.4) 85 (84.2)
Missing 28 (30.8) 17 (70.8) 48 (76.2)
P value
a
.18 .22 .001
TNM stage
0
3 (5.2) 2 (66.7) 51 (92.7)
I 37 (6.7) 10 (27.0) 427 (82.9)
II 225 (24.6) 115 (51.1) 613 (89.0)
III 333 (68.7) 232 (69.7) 133 (87.5)
IV 182 (50.3) NA 150 (83.3)
P value
a
.001 .001 .01
Abbreviation: NA, not applicable.
a
Statistical significance was determined by the 2-sided
2
test.
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we may have observed greater differences between Med-
icaid and Medicare patients in the outcomes we studied.
Finally, published estimates indicate that only half of el-
derly Medicare beneficiaries with incomes at or below
the poverty level enroll in Medicaid.
31
The inclusion of
elderly patients who qualify but are not enrolled in Med-
icaid would diminish the relationship between Medic-
aid and the outcomes we studied.
This study found that Medicaid-insured patients, rela-
tive to Medicare-insured patients, are less likely to ini-
tiate and complete chemotherapy. These patients may have
poorer health status, but they may also have inadequate
financial and social support to help get and continue che-
motherapy. Furthermore, physicians may need to spend
extra time with these patients explaining the benefits and
risks of treatment. Clearly, further research is needed to
understand the underlying causes for poor chemo-
therapy initiation. Nevertheless, as Medicaid adminis-
trators across the nation move toward a managed care
model of care delivery, they need to be cognizant of dif-
ferential treatment of their patients for cancer and in-
clude initiatives that increase adherence to cancer treat-
ment regimens. Progress toward increasing compliance
also needs to be measured. As long as these substan-
tially large groups of patients (Medicaid-insured and el-
derly patients) have disparate treatment uptake and com-
pliance, the nation as a whole will have difficulty reaching
its goals for reduced cancer mortality.
Table 4. Adjusted Logistic Regression Models of Adjuvant Chemotherapy Initiation, Chemotherapy Completion,
and Evaluation by a Specialist for All Michigan Patients With Colon Cancer
a
Explanatory Variables
Odds Ratio (95% Confidence Interval)
Adjuvant Chemotherapy
Initiation, All Patients
(n= 4765)
Chemotherapy
Completion
(n= 1210)
b
Oncology
Evaluation
(n= 3208)
Medicare only 1 [Reference] 1 [Reference] 1 [Reference]
Medicaid 0.50 (0.39-0.65)
c
0.52 (0.31-0.85)
c
0.72 (0.53-0.97)
c
Age, y
66-69 1 [Reference] 1 [Reference] 1 [Reference]
70-74 0.78 (0.63-0.95)
c
0.80 (0.57-1.11) 0.97 (0.69-1.35)
75-79 0.44 (0.36-0.55)
c
0.72 (0.51-1.01) 1.14 (0.81-1.61)
80 0.15 (0.12-0.18)
c
0.51 (0.34-0.75)
c
0.87 (0.63-1.18)
Race
White 1 [Reference] 1 [Reference] 1 [Reference]
African American or other 0.83 (0.65-1.06) 0.76 (0.48-1.22) 1.22 (0.89-1.73)
Sex
Male 1 [Reference] 1 [Reference] 1 [Reference]
Female 0.90 (0.78-1.04) 0.99 (0.78-1.27) 1.21 (0.99-1.47)
Comorbidity score
0 1 [Reference] 1 [Reference] 1 [Reference]
1 0.83 (0.70-0.99)
c
1.06 (0.77-1.44) 1.25 (0.98-1.59)
2 0.62 (0.49-0.78)
c
0.58 (0.38-0.87)
c
1.61 (1.17-2.20)
c
Hospital readmission
No 1 [Reference] 1 [Reference] 1 [Reference]
Yes 1.28 (1.02-1.61)
c
1.12 (0.76-1.65) 1.46 (0.99-2.14)
Teaching status
No 1 [Reference] 1 [Reference] 1 [Reference]
Yes 0.71 (0.61-0.82)
c
1.25 (0.96-1.62) 1.12 (0.90-1.39)
Census tract median annual income, $
25 000 0.96 (0.74-1.26) 1.20 (0.73-1.97) 0.62 (0.41-0.92)
c
25 001-35 000 0.96 (0.76-1.21) 0.86 (0.57-1.30) 0.70 (0.49-1.00)
35 001-45 000 1.20 (0.95-1.53) 1.04 (0.70-1.55) 0.92 (0.63-1.34)
45 001 1 [Reference] 1 [Reference] 1 [Reference]
Urban or rural
Metropolitan 1 [Reference] 1 [Reference] 1 [Reference]
Rural, adjacent to metropolitan 1.01 (0.43-2.38) 2.75 (0.55-13.71) 0.69 (0.24-1.97)
Isolated rural 0.63 (0.38-1.05) 0.91 (0.33-2.47) 0.25 (0.15-0.44)
c
Urban, not adjacent to metropolitan 0.97 (0.73-1.29) 0.76 (0.47-1.23) 0.50 (0.35-0.69)
c
Urban, adjacent to metropolitan 0.89 (0.69-1.15) 0.56 (0.37-0.87)
c
0.66 (0.46-0.93)
c
Cancer stage
In situ 0.06 (0.03-0.12)
c
0.37 (0.10-1.37) 0.60 (0.35-1.04)
Local 0.14 (0.12-0.17)
c
0.41 (0.31-0.54)
c
0.67 (0.53-0.85)
c
Regional 1 [Reference] 1 [Reference] 1 [Reference]
Distant 0.87 (0.72-1.05) NA 0.57 (0.41-0.79)
c
Abbreviation: NA, not applicable.
a
All variables shown in the table are included in the adjusted logistic regression.
b
Excludes patients with distant stage disease.
c
Statistically significant at P .05.
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Accepted for Publication: September 26, 2007.
Correspondence: Cathy J. Bradley, PhD, Department of
Health Administration and Massey Cancer Center, Vir-
ginia Commonwealth University, Grant House, 1008 Clay
St, PO Box 980203, Richmond, VA 23298-0203 (cjbradley
@vcu.edu).
Author Contributions: Study concept and design: Bradley
and Dahman. Acquisition of data: Bradley, Given, and Dah-
man. Analysis and interpretation of data: Bradley, Given,
Dahman, and Fitzgerald. Drafting of the manuscript: Bra-
dley, Given, and Fitzgerald. Critical revision of the manu-
script for important intellectual content: Bradley and Dah-
man. Statistical analysis: Bradley and Dahman. Obtained
funding: Bradley and Given. Administrative, technical, and
material support: Bradley. Study supervision: Bradley.
Financial Disclosure: None reported.
Funding/Support: This research was supported by Na-
tional Cancer Institute grant R01-CA101835-01, “In-
Depth Examination of Disparities in Cancer Outcomes”
(Dr Bradley).
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Table 5. Adjusted Logistic Regression Models of Adjuvant Chemotherapy Initiation, Chemotherapy Completion, and Evaluation by a
Specialist for Patients With TNM-Staged Disease
a
Explanatory Variables
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b
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0
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0.78 (0.06-9.99) 1.79 (0.75-2.29)
I 0.02 (0.02-0.04)
b
0.17 (0.08-0.38)
b
0.72 (0.41-1.26)
II 0.14 (0.11-0.18)
b
0.44 (0.31-0.64)
b
1.31 (0.75-2.29)
III 1 [Reference] 1 [Reference] 1 [Reference]
IV 0.65 (0.29-0.55)
b
NA 0.79 (0.41-1.52)
Abbreviation: NA, not applicable.
a
All variables shown in the table are included in the adjusted logistic regression.
b
Statistically significant at P .05.
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    • "As comorbidities alter both the risk and benefit from cancer treatments, they can impact the risk/benefit balance of many treatment decisions. This may be why patients with comorbidities are less likely to receive adjuvant chemotherapy31323334. In a study using SEER-Medicare database, older adults with resected stage III colorectal cancer with comorbidities were less likely to be referred to a medical oncologist for consideration of adjuvant chemotherapy and less likely to be given chemotherapy when seen by an oncologist [33]. "
    [Show abstract] [Hide abstract] ABSTRACT: Comorbidity is an issue of growing importance due to changing demographics and the increasing number of adults over the age of 65 with cancer. The best approach to the clinical management and decision-making in older adults with comorbid conditions remains unclear. In May 2015, the Cancer and Aging Research Group, in collaboration with the National Cancer Institute and the National Institute on Aging, met to discuss the design and implementation of intervention studies in older adults with cancer. A presentation and discussion on comorbidity measurement, interventions, and future research was included. In this article, we discuss the relevance of comorbidities in cancer, examine the commonly used tools to measure comorbidity, and discuss the future direction of comorbidity research. Incorporating standardized comorbidity measurement, relaxing clinical trial eligibility criteria, and utilizing novel trial designs are critical to developing a larger and more generalizable evidence base to guide the management of these patients. Creating or adapting comorbidity management strategies for use in older adults with cancer is necessary to define optimal care for this growing population.
    Full-text · Article · Dec 2015
    • "Patients with pCR were excluded from analysis because the pCR status was not well supported by the SEER-medicare database. Fourth, this study retrospectively examined the use of chemotherapy as identified through the Medicare claims data using a " one-claim " algorithm [36,37] . This created a heterogeneous population in which some patients received a substandard duration of therapy. "
    [Show abstract] [Hide abstract] ABSTRACT: There is no general agreement about whether patients who have already received neoadjuvant chemoradiotherapy need further postoperative chemotherapy based on 5-fluorouracil(5-FU) or 5-FU plus oxaliplatin. Medicare beneficiaries from 1992 to 2008 with Union for International Cancer Control ypStages I to III primary carcinoma of the rectum who underwent 5-FU-based neoadjuvant chemoradiotherapy and surgery for curative intent were identified through the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database. A Cox proportional hazards model and propensity score-matched techniques were used to evaluate the effect of treatment on survival. For patients with resected rectal cancer who have already received 5-FU-based neoadjuvant chemoradiotherapy, postoperative 5-FU-based chemotherapy did not prolong cancer-specific survival (CSS) in ypStage I (P = 0.960) and ypStage II (P = 0.134); however, it significantly improved the CSS in ypStage III (hazard ratio = 1.547, 95% CI = 1.101-2.173, P = 0.012). No significant differences in survival between the 5-FU group and oxaliplatin group were observed. For patients with resected rectal cancer who have already received 5-FU-based neoadjuvant chemoradiotherapy, postoperative 5-FU-based chemotherapy prolongs the CSS of groups in ypStage III. Adding oxaliplatin to fluoropyrimidines in the postoperative chemotherapy did not improve the CSS for patients who received neoadjuvant chemoradiotherapy.
    Full-text · Article · Nov 2014
    • "By doing so, chemotherapy wouldn't be misclassified for cancer recurrence. This algorithm was developed and validated using SEER–Medicare databases [16] and used by other Medicare studies171819. The chemo agent was 5-FU based. "
    [Show abstract] [Hide abstract] ABSTRACT: Background Delayed chemotherapy is associated with inferior survival in stage III colon and stage II/III rectal cancer patients, but similar studies have not been performed in stage II colon cancer patients. We investigate the association between delayed and incomplete chemotherapy, and the association of delayed chemotherapy with survival in stage II colon cancer patients. Patients and Methods Patients (age ≥66) diagnosed as stage II colon cancer and received chemotherapy from 1992 to 2005 were identified from the linked SEER–Medicare database. The association between delayed and incomplete chemotherapy was assessed using unconditional and conditional logistic regressions. Survival outcomes were assessed using stratified Cox regression based on propensity score matched samples. Results 4,209 stage II colon cancer patients were included, of whom 73.0% had chemotherapy initiated timely (≤2 months after surgery), 14.7% had chemotherapy initiated with moderate delay (2–3 months), and 12.3% had delayed chemotherapy (≥3 months). Delayed chemotherapy was associated with not completing chemotherapy (adjusted odds ratio (OR): 1.33 (95% confidence interval: 1.11, 1.59) for moderately delayed group, adjusted OR: 2.60 (2.09, 3.24) for delayed group). Delayed chemotherapy was associated with worse survival outcomes (hazard ratio (HR): 1.75 (1.29, 2.37) for overall survival; HR: 4.23 (2.19, 8.20) for cancer-specific survival). Conclusion Although the benefit of chemotherapy is unclear in stage II colon cancer patients, delay in initiation of chemotherapy is associated with an incomplete chemotherapy course and poorer survival, especially cancer-specific survival. Causal inference in the association between delayed initiation of chemotherapy and inferior survival requires further investigation.
    Full-text · Article · Sep 2014
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