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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
Cancer Epidemiol Biomarkers Prev. Author manuscript; available in PMC 2014 June 1.
Published in final edited form as:
PMCID: PMC3681887

Gender differences in correlates of colorectal cancer screening among black Medicare beneficiaries in Baltimore

Kathryn A. Martinez, PhD, MPH,1 Craig E. Pollack, MD, MHS, MS,2 Darcy F. Phelan, DrPH, MHS,3 Diane Markakis, MS,3 Lee Bone, MPH, RN,4 Gary Shapiro, MD,5 Jennifer Wenzel, PhD, RN,5,6 Mollie Howerton, PhD, MPH,7 Lawrence Johnson, MD,8 Mary A. Garza, PhD, MPH,9 and Jean G. Ford, MD3



Previous research has demonstrated colorectal cancer (CRC) screening disparities by gender. Little research has focused primarily on gender differences among older black individuals, and reasons for existing gender differences remain poorly understood.


We used baseline data from the Cancer Prevention and Treatment Demonstration Screening Trial. Participants were recruited from November 2006 to March 2010. In-person interviews were used to assess self-reported colorectal cancer screening behavior. Up-to-date colorectal cancer screening was defined as self-reported colonoscopy or sigmoidoscopy in the past 10 years or fecal occult blood testing in the past year. We used multivariable logistic regression to examine the association between gender and self-reported screening, adjusting for covariates. The final model was stratified by gender to examine factors differentially associated with screening outcomes for males and females.


The final sample consisted of 1,552 female and 586 male black Medicare beneficiaries in Baltimore, Maryland. Males were significantly less likely than females to report being up-to-date with screening (77.5% versus 81.6%, p=0.030), and this difference was significant in the fully adjusted model (Odds Ratio: 0.72 95%Confidence Interval: 0.52–0.99). The association between having a usual source of care and receipt of cancer screening was stronger among males compared to females.


While observed differences in CRC screening were small, several factors suggest gender-specific approaches may be used to promote screening adherence among black Medicare beneficiaries.


Given disproportionate colorectal cancer mortality between white and black Medicare beneficiaries, gender-specific interventions aimed at increasing CRC screening may be warranted among older black patients.

Keywords: gender, colorectal cancer, screening, black, Medicare


Colorectal cancer (CRC) is the third leading cause of cancer mortality in the U.S., with over 50,000 deaths projected for the year 2013. (1, 2) Colorectal cancer occurs most frequently in adults over the age of 65 years, the majority of whom are enrolled in Medicare. (2) While CRC affects all racial and ethnic groups, black men and women experience both higher incidence and mortality from this disease compared to whites, (3) and use of screening remains substantially lower among blacks compared to whites. (4, 5)

Though multiple sociodemographic and health-related beliefs have been associated with lower rates of CRC screening among the general population, (6, 7) patient gender has received comparatively less attention in the literature. (813) A number of studies have found differences in screening rates by gender (11, 1416) however, more recent population based studies have not confirmed these gender differences. (1719) Further, little previous research has focused on gender differences in CRC screening in the black population. (20) Prior qualitative work has found that black females maintain more positive attitudes about the benefits of CRC screening than males, with black males also expressing more fears related to CRC screening than females. (8)

The purpose of this study was to examine whether gender differences exist in CRC screening among black Medicare beneficiaries in Baltimore City, Maryland and to explore correlates of CRC screening, defined as self-reported up-to-date screening, by gender.

Materials and Methods

Data for this analysis are from the Baltimore City, Maryland site of the Cancer Prevention Treatment Demonstration (CPTD) Screening Trial, a four-year, six-site national demonstration project of patient navigation, funded by the Centers for Medicare & Medicaid Services (CMS). The study was approved by the Institutional Review Board of the Johns Hopkins Bloomberg School of Public Health.

Between October 2006 and June 2010, black beneficiaries were recruited via mail using the Medicare enrollment roster, as well as in clinical settings and community-based venues, such as senior centers. Individuals were eligible to participate if they were 65 years or older, black, enrolled in Medicare Parts A and B, and had either no known history of cancer or cancer in remission for five years or longer. Exclusion criteria included enrollment in Medicare Part C (Medicare managed care), inability to provide informed consent, and residence in an institutionalized setting. Individuals with diagnoses that influence the frequency of colorectal endoscopy (e.g. irritable bowel disease) were also excluded. Interviews were performed in-person by trained interviewers.

Outcome Measure

The primary dependent variable in this analysis was self-reported CRC screening status (colonoscopy, sigmoidoscopy, or fecal occult blood testing (FOBT)). Following a brief description of colonoscopy and sigmoidoscopy, participants were asked if they had ever had one of these two tests; the time interval of screening was also collected. Similarly, after a description of FOBT, participants were asked whether or not they had been screened by FOBT and, if so, the time interval. Up-to-date CRC screening was defined as receipt of a colonoscopy or sigmoidoscopy in the past 10 years or FOBT in the past year.

Independent Measures

Survey data applied to this analysis included sociodemographic characteristics including gender, age, annual income, educational attainment, and marital status, as well as smoking status. These variables have previously been shown to be related to CRC screening receipt. (6, 7, 17)

Measures of healthcare access and coverage included having a usual source of care (”Is there a place that you usually go to when you are sick or need advice about your health?”), presence of Medicare supplemental insurance (e.g., Medigap), and knowledge of coverage for screening services. Knowledge was assessed by the question “How much do you feel you know about Medicare coverage for cancer screening tests?” Possible responses were “almost none,” “somewhat,” or “just about everything.”

With regards to provider communication, participants were asked how often the following statement reflected their experiences in the health care system: “Health care professionals explain things in an understandable way.”

Cancer knowledge and beliefs were assessed by whether the participant agreed or disagreed with the following statements: “There’s not much a person can do to lower their chances of getting cancer;” and “It seems like everything causes cancer.”

Statistical Analysis

Univariate analyses were conducted to determine the variability and distribution of the data by gender, followed by bivariate analyses. We conducted a multivariable logistic regression to examine the association of gender with self-report of being up-to-date with CRC screening, adjusting for covariates. To assess whether factors were differently associated with CRC screening behavior between men and women, the adjusted model was stratified by gender. In order to account for missing values, the nearest neighbor hotdeck method was used to impute responses for covariates. All variables had less than 2% missingness. The outcome of self-reported screening receipt was not imputed. Two-sided statistical significance was set at the p < 0.05 level, and all analyses were performed using SAS version 9.2.


The study population (N = 2,138) was 73% female; the median age was 71 (range 65–84 years). Table I shows the descriptive baseline characteristics of the study population stratified by gender. Females were older than males, a larger percentage were widowed, divorced, or separated and they reported lower incomes than males. Males reported lower levels of education than females. Relative to males, females reported greater knowledge of Medicare coverage for cancer screening and more reported having a usual source of care. Baseline up-to-date screening for CRC was 81.6% for females and 77.5% for males (p = 0.030).

Table I
Descriptive baseline characteristics and screening status, stratified by gender from the Cancer Prevention Treatment Demonstration (CPTD) Screening Trial in Baltimore City

Table I also shows the distribution of males and females reporting being up-to-date with screening for each category of covariate. A larger percentage of males relative to females reporting being up-to-date with screening were in the youngest age category (75.3% vs. 67.1%). A larger percentage of females (20.9%) than males (12.8%) reporting being up-to-date with screening reported an annual income of $9,999 or less, and a larger percentage of males reporting being a current smoker were up-to-date with screening relative to women reporting that they currently smoked (19.6% versus 11.9%). The association between knowledge of Medicare coverage for cancer screening and being up-to-date with screening was also significantly different for males and females in our sample (p=0.016), with a larger percentage of up-to-date females (12.9%) than up-to-date males (7.9%) reporting they knew “just about everything” about Medicare coverage for cancer screening.

Table II presents the adjusted multivariable logistic model. Males were significantly less likely to be up-to-date with CRC screening than females (OR:0.71 95%CI:0.54–0.92). Higher income (≥$30,000), being a former smoker, having a usual source of care, having Medigap insurance, and having a provider who explained things in an understandable way were all significantly associated with being up-to-date on screening compared to the respective baseline categories. The ‘no opinion’ categories to the cancer health belief questions were also significantly associated with screening.

Table II
Adjusted logistic regression models examining the odds of being up-to-date on colorectal cancer screening among Medicare beneficiaries in Cancer Prevention Treatment Demonstration (CPTD) Screening Trial in Baltimore City, N=2,138; Overall and by gender ...

Table II also presents the fully adjusted model stratified by gender. Three items were significantly associated with screening status among males alone including: having a usual source of care, reporting income of $30,000 or more annually and being a former smoker. In contrast, two factors were only significantly associated with screening among females: having Medigap insurance and reporting that health care professionals usually or always explain things in an understandable way. Though not significant among males, the point estimate for the association between Medigap insurance and being up-to-date was similar to that found among female respondents.


We found a relatively high self-reported rate of being up-to-date with screening among black Medicare beneficiaries of both genders in Baltimore City. In contrast to previous publications that reported either no differences by gender (18) or higher screening rates among males than females, (11, 15, 16) we found that males were significantly less likely to be up-to-date with screening, compared to females. Though the absolute difference in rates of screening between men and women was relatively small—4.1% points in unadjusted analyses—the results suggest that several factors, including access to care and provider-patient communication, may be differently related to screening patterns among men and women in this population.

Consistent with previous publications, we found a significant association between having a usual source of care and positive screening status among males. (15) A similar association was noted among females reporting having Medigap coverage, as well as those reporting good communication with their health care providers. These data suggest that interventions that address these factors may impact screening rates for men and women differently. While not statistically significant, the association between Medigap coverage and being up-to-date with screening showed a positive association for males. Similarly, though again not significant, our results suggest that having a usual source of care may also be an important correlate of screening receipt for females. As a result, strategies aimed at expanding access and supplemental coverage among black Medicare beneficiaries would likely benefit both males and females in this population.

This study has several limitations. First, we relied on self-report of CRC screening. Prior research has suggested that self-report of CRC screening status may be subject to recall bias, considering the long intervals between some screening modalities and the use of multiple screening tests. (21, 22) This may, at least partially, account for the higher-than-expected rates of screening as compared to national averages. (23) Second, our survey instrument did not include measures of attitudes and beliefs specifically related to endoscopic screening, which may differ by gender. Prior work suggests that women may feel reluctance to complete preparation procedures for colonoscopy, (10) while men maintain negative perceptions of sexual connotations of endoscopic screening. (8) Third, we were unable to determine whether patients received colonoscopy versus sigmoidoscopy, which have different recommended screening intervals. Fourth, while a relatively low number of men in our sample reported “no opinion” to questions about cancer knowledge and beliefs, we retained them in our analysis due to uncertainty about the meaning of this response. Finally, our results focus on specifically on Baltimore City, limiting the generalizability of the findings. Conducting this study in Baltimore City, however, where the majority of the population is black, allowed us to accrue a large sample of black Medicare beneficiaries to investigate gender differences in screening.

Our results suggest that focusing on improving access to care may be an important strategy to increase screening overall and to narrow gender differences in this urban, black population. In this target population, interventions that promote effective patient-provider communication may be especially beneficial among females, and those that aim to enhance continuity of care may be especially beneficial to males. Continued study of determinants of gender differences in screening patterns may elucidate pathways toward targeted interventions to reduce the burden of colorectal cancer among black older adults.


The authors wish to thank the CPTD participants, staff, and Community Advisory Committee.

Financial Support: This study was supported by CMS Cooperative Agreement #1A0CMS300066. In addition, Dr. Martinez was supported by AHRQ grant #5T32HS000029-25. Dr. Pollack was supported by NIH grant #5U54CA091409-10, and #K07CA151910. Dr. Garza was supported through NIH grant #K01CA140358. Dr. Wenzel was supported American Cancer Society grant #117902-MRSGT-09-152-01-CPPB and Robert Wood Johnson Foundation grant #ID#64197.

Source of funding for the trial: This work was supported by the Cancer Prevention and Treatment Demonstration for Ethnic and Racial Minorities of the Centers for Medicare & Medicaid Services [Cooperative Agreement #1A0CMS300066]. This research was also supported by the Community Networks Program (Grant U54CA153710) of the National Cancer Institute and by the Maryland Cigarette Restitution Fund.


Conflicts of Interest: The authors have no potential conflicts of interest to disclose.

Date of JHSPH IRB approval: September 6, 2006

Trial registry name and number: This trial is registered at the Protocol Registration System (PRS) as "Partnership for Healthy Seniors" under identifier NCT00379743.


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