Colorectal Cancer Screening of Medicare Beneficiaries in the US
Colorectal Cancer Screening of Medicare Beneficiaries in the US
The data for this study were obtained from the Medicare Current Beneficiary Survey (MCBS) and matched Medicare claims. The design and data collection methods for the MCBS are described in detail previously. In brief, the MCBS is an ongoing annual survey with four-year rotating cohorts of nationally representative samples of Medicare beneficiaries who are interviewed in-person three times a year. We used data on non-institutionalized beneficiaries who were 50–75 years of age at the beginning of 2006, were continuously enrolled in Medicare, participated in the interviews in both 2006 and 2007, and had no personal history of renal disease or CRC in 2006 or 2007. Our study population therefore also included persons 50–64 years of age who were in Medicare as a result of disability. Our upper age cutoff was based on current U.S. Preventive Services Task Force CRC screening guidelines. This study was reviewed by the institutional review board (IRB) of the University of Massachusetts Medical School (Worcester, MA) and was considered exempt from a full IRB review.
Each survey year, the MCBS collects data on participants including age, gender and marital status; residence in metropolitan service areas (MSA); highest level of educational achievement (less than high school vs. others); household income (<$25,000 vs. others); primary language (English vs. all other languages); the type of health insurance coverage (supplemental vs. no supplemental insurance); and delaying medical care due to cost. These factors are known to be associated with use of CRC screening. Additional data collected includes beneficiary employment, history of non-skin cancers and self-rated general health status (which was used as proxy for wellness to undergo screening).
The primary predictor in our analyses was the specialty of PCP that a beneficiary usually sees for medical care (FP vs. internist). During the fall of each year, the MCBS collects information about the "particular medical person or … clinic [a beneficiary] usually goes to when [he/she is]… sick or [for] advice about … health", and the specialty of the particular doctor he/she usually sees. Among the potentially eligible subjects for this study, 1,922 patients reported their usual physician was either an FP or internist. We then used the Unique Physician Identification Numbers from Medicare claims to match 1,354 other patients to an FP or internist. When both specialties were identified for a particular subject (n = 208), the PCP with the greater number of services rendered was assigned: no ties were observed.
In the fall of 2007, MCBS respondents 50 years of age or older, who did not report a history of CRC, were asked whether they had ever had CRC screening test (sigmoidoscopy, colonoscopy, and/or a home FOBT), and if so, the date of the most recent test (as shown in Figure 1.) We defined a nominal screening variable by first considering the receipt of a sigmoidoscopy/colonoscopy within five years of the interview date and then FOBT within one year, in a mutually exclusive manner. We also created a combined outcome of CRC screening defined as receiving colonoscopy or sigmoidoscopy within 5 years and/or FOBT within one year. This approach was based on how questions were asked on the MCBS as described previously. Respondents were also asked if they were ever given an FOBT kit (categorized as yes vs. no), and those who had received an FOBT kit were then asked if they had returned the last kit (categorized as yes vs. no). Patients who had not previously received a kit were asked if they had "ever heard of this home testing kit" (categorized as yes vs. no). In addition to questions on FOBT use, those who had not previously undergone a colonoscopy or sigmoidoscopy were asked if they had "ever heard of" sigmoidoscopy/colonoscopy and if so, whether his/her physician recommended that he/she should have the exam (categorized as yes vs. no). Participants who had previously heard of or received CRC screening were asked: "Before today, did you know that Medicare now helps pay for the cost of screening tests".
(Enlarge Image)
Figure 1.
Design of CRC testing questions on the 2007 Medicare Current Beneficiary Survey with analytic samples (n = 3,276). #Participants who had previously heard of or received a screening by FOBT (fecal occult blood test) or sigmoidoscopy/colonoscopy were asked if they knew that Medicare helps to pay for colon cancer screening, n = 3,130. *Those who have never heard of colonoscopy were considered not to have previously received a recommendation and thus included in the dominator for this analysis.
Two-by-two contingency tables and the Wald chi-square test were used to compare beneficiaries' characteristics, awareness and knowledge of CRC screening according to PCP specialty (FP vs. internist). Specifically, we examined differences in awareness of CRC, colonoscopy/sigmoidoscopy, home FOBT kit, or Medicare's coverage for CRC screening. Analyses on knowledge of Medicare's coverage for CRC screening were stratified according to prior history of colonoscopy/sigmoidoscopy. We also examined for differences in whether or not a beneficiary returned his/her last home FOBT kit.
Multinomial regression models were used to determine whether use of an FOBT alone within one year, or colonoscopy/sigmoidoscopy alone within five years differed according to PCP specialty. We then used logistic regression models to examine the association between PCP specialty and the combined outcome of any CRC screening exam. Further, we examined two additional outcomes that involve direct healthcare provider participation as reported by patients: whether an eligible beneficiary was given an FOBT kit, or received a colonoscopy recommendation. Several subgroup and sensitivity analyses were also performed.
Individual enrollees were the unit of analyses, and we used data on beneficiaries' usual PCP and covariates from the 2006 survey for the analyses. The covariates included in the regression models (as shown in Table 1) were based on previous studies. We used cross-sectional survey weights in all analyses and variance estimation accounted for the complex survey design. The analyses were performed using STATA version 12.
Methods
The data for this study were obtained from the Medicare Current Beneficiary Survey (MCBS) and matched Medicare claims. The design and data collection methods for the MCBS are described in detail previously. In brief, the MCBS is an ongoing annual survey with four-year rotating cohorts of nationally representative samples of Medicare beneficiaries who are interviewed in-person three times a year. We used data on non-institutionalized beneficiaries who were 50–75 years of age at the beginning of 2006, were continuously enrolled in Medicare, participated in the interviews in both 2006 and 2007, and had no personal history of renal disease or CRC in 2006 or 2007. Our study population therefore also included persons 50–64 years of age who were in Medicare as a result of disability. Our upper age cutoff was based on current U.S. Preventive Services Task Force CRC screening guidelines. This study was reviewed by the institutional review board (IRB) of the University of Massachusetts Medical School (Worcester, MA) and was considered exempt from a full IRB review.
Data Elements
Each survey year, the MCBS collects data on participants including age, gender and marital status; residence in metropolitan service areas (MSA); highest level of educational achievement (less than high school vs. others); household income (<$25,000 vs. others); primary language (English vs. all other languages); the type of health insurance coverage (supplemental vs. no supplemental insurance); and delaying medical care due to cost. These factors are known to be associated with use of CRC screening. Additional data collected includes beneficiary employment, history of non-skin cancers and self-rated general health status (which was used as proxy for wellness to undergo screening).
Specialty of the Usual Care Primary Care Physician
The primary predictor in our analyses was the specialty of PCP that a beneficiary usually sees for medical care (FP vs. internist). During the fall of each year, the MCBS collects information about the "particular medical person or … clinic [a beneficiary] usually goes to when [he/she is]… sick or [for] advice about … health", and the specialty of the particular doctor he/she usually sees. Among the potentially eligible subjects for this study, 1,922 patients reported their usual physician was either an FP or internist. We then used the Unique Physician Identification Numbers from Medicare claims to match 1,354 other patients to an FP or internist. When both specialties were identified for a particular subject (n = 208), the PCP with the greater number of services rendered was assigned: no ties were observed.
Measures of Colorectal Cancer Awareness and Screening
In the fall of 2007, MCBS respondents 50 years of age or older, who did not report a history of CRC, were asked whether they had ever had CRC screening test (sigmoidoscopy, colonoscopy, and/or a home FOBT), and if so, the date of the most recent test (as shown in Figure 1.) We defined a nominal screening variable by first considering the receipt of a sigmoidoscopy/colonoscopy within five years of the interview date and then FOBT within one year, in a mutually exclusive manner. We also created a combined outcome of CRC screening defined as receiving colonoscopy or sigmoidoscopy within 5 years and/or FOBT within one year. This approach was based on how questions were asked on the MCBS as described previously. Respondents were also asked if they were ever given an FOBT kit (categorized as yes vs. no), and those who had received an FOBT kit were then asked if they had returned the last kit (categorized as yes vs. no). Patients who had not previously received a kit were asked if they had "ever heard of this home testing kit" (categorized as yes vs. no). In addition to questions on FOBT use, those who had not previously undergone a colonoscopy or sigmoidoscopy were asked if they had "ever heard of" sigmoidoscopy/colonoscopy and if so, whether his/her physician recommended that he/she should have the exam (categorized as yes vs. no). Participants who had previously heard of or received CRC screening were asked: "Before today, did you know that Medicare now helps pay for the cost of screening tests".
(Enlarge Image)
Figure 1.
Design of CRC testing questions on the 2007 Medicare Current Beneficiary Survey with analytic samples (n = 3,276). #Participants who had previously heard of or received a screening by FOBT (fecal occult blood test) or sigmoidoscopy/colonoscopy were asked if they knew that Medicare helps to pay for colon cancer screening, n = 3,130. *Those who have never heard of colonoscopy were considered not to have previously received a recommendation and thus included in the dominator for this analysis.
Data Analyses
Two-by-two contingency tables and the Wald chi-square test were used to compare beneficiaries' characteristics, awareness and knowledge of CRC screening according to PCP specialty (FP vs. internist). Specifically, we examined differences in awareness of CRC, colonoscopy/sigmoidoscopy, home FOBT kit, or Medicare's coverage for CRC screening. Analyses on knowledge of Medicare's coverage for CRC screening were stratified according to prior history of colonoscopy/sigmoidoscopy. We also examined for differences in whether or not a beneficiary returned his/her last home FOBT kit.
Multinomial regression models were used to determine whether use of an FOBT alone within one year, or colonoscopy/sigmoidoscopy alone within five years differed according to PCP specialty. We then used logistic regression models to examine the association between PCP specialty and the combined outcome of any CRC screening exam. Further, we examined two additional outcomes that involve direct healthcare provider participation as reported by patients: whether an eligible beneficiary was given an FOBT kit, or received a colonoscopy recommendation. Several subgroup and sensitivity analyses were also performed.
Individual enrollees were the unit of analyses, and we used data on beneficiaries' usual PCP and covariates from the 2006 survey for the analyses. The covariates included in the regression models (as shown in Table 1) were based on previous studies. We used cross-sectional survey weights in all analyses and variance estimation accounted for the complex survey design. The analyses were performed using STATA version 12.