Colon cancer stage

The passage of Medicare in 1965 was accompanied by a confident expectation that covering most of the costs of physicians' and inpatient hospital services would remove the major barriers to health care for the elderly. A lingering concern was the lack of coverage for prevention and early detection of disease. Over time, Medicare was amended to cover pap smears (1990), routine screening mammography (1991), influenza immunizations (1993), colorectal cancer screening (1998), and prostate cancer screening, including the prostate specific antigen (PSA) test (2000).

During the past decade new concerns have been raised by a succession of studies indicating that race and socioeconomic status (SES) continue to influence the use of health care services by the elderly enrolled in Medicare; these studies show three distinct patterns: black beneficiaries and persons less economically and socially advantaged use (1) fewer preventive and cancer screening services, (2) fewer common surgical procedures to improve health and functioning, but (3) more procedures associated with poor outcomes of chronic diseases than white beneficiaries and beneficiaries in higher socioeconomic status (Ayanian et al. 1993; Gornick 2000; Health Care Financing Administration 1995a; Gornick et al. 1996). Disparities in the use of preventive, cancer screening, and other services to maintain health are especially troubling because blacks and disadvantaged persons experience higher rates of morbidity and mortality (National Center for Health Statistics 2002).

Why substantial disparities persist in the use of preventive and cancer screening services, especially among the elderly covered by Medicare, remains a fundamental question. Although it is true that barriers relating to coinsurance requirements for services such as mammography may explain some of the disparities by race and SES, the greatest disparities are found in the use of flu shots, which are "free." Moreover, about 90 percent of the elderly when surveyed respond that they have a usual source of care (Health and Health Care of the Medicare Population 2001).

The Institute of Medicine convened two committees to consider ways of promoting health, particularly among vulnerable subgroups; committee reports were in accord that no single factor can explain disparities in health--given the multitude of complex social and behavioral factors that can influence health outcomes (Smedley and Syme 2000; Committee on Health and Behavior 2001). Smedley and Syme (2000) noted that "behavioral and social interventions ... offer great promise to reduce disease morbidity and mortality, but as yet their potential to improve the public's health has been relatively poorly tapped." The Committee on Health and Behavior (2001) recommended research that "integrates biological, psychological, behavioral, and social variables."

This study integrates into health services research some of the theories and findings from health psychology and the behavioral and social sciences. In this study we concentrate on a health behavior exemplified by a beneficiary's use of an array of covered preventive and cancer screening services (hereafter, described simply as "preventive services"). Health behaviors have been a subject of interest to health psychologists for a long time. Rosenstock (1969, p. 169) defined health behavior as "the activity undertaken by persons who believe themselves to be healthy, for the purpose of preventing or detecting disease in an asymptomatic stage." It is generally believed that health behaviors reflect various beliefs and attitudes, such as an individual's conviction that illness is preventable or controllable--which may translate into behaviors relating to preventive service use. Studies, going as far back as the 1930's, have found a consistency in an individual's health behaviors, although the correlations were often only small or modest (Rosenstock 1969; Norris 1997).

For this study we analyzed health behavior to see if there was some consistency in the use of an array of services that included flu shots, pneumonia immunizations, mammography, pap smears, and prostate and colon cancer screening. It is important to emphasize that use is driven not only by the behavior of beneficiaries themselves, who can initiative services such as flu shots, but also--and very significantly--by the behavior of providers, who may (or may not) recommend patients for services such as mammograms (O'Malley et al. 2001), colonoscopy, and PSA tests.

The consistency of an individual's use of preventive services was illustrated by a study in Massachusetts reporting that women who had a mammogram and men who had a prostate specific antigen test (PSA) were more likely to have colorectal screening than their counterparts without a mammogram or a PSA test (Lemon et al. 2001). Further insight into the consistency of behaviors regarding preventive services was provided by a Medicare study that found women who had a mammogram were six times as likely to have a pap smear as women who did not have a mammogram, and men who had a flu shot were more likely to have a prostate screening test than men who did not have a flu shot; these patterns held across races and income groups (Gornick, Eggers, and Riley 2001).

Additional insight into health behaviors comes from studies showing correlations across a variety of health behaviors, such as the use of preventive services and use of seatbelts, smoking cessation, regular exercise, alcohol consumption, and dietary fat intake (Hofer and Katz 1996; Costakis, Dunnagan, and Haynes 1999; Boutelle et al. 2000; Gornick, Eggers, and Riley 2001). Further insight comes from studies showing a consistency between health behaviors and behaviors that are not exclusively related to health, such as precautionary behaviors regarding crime prevention and hazard preparedness (e.g., having batteries ready for potential hurricanes), albeit, again, some of the correlations were only small or modest (Norris 1997; Weinstein 1993).

We were interested in determining if health behaviors regarding preventive service use were associated with health outcomes--specifically, stage of cancer when first diagnosed. We hypothesized that Medicare beneficiaries who used more of an array of preventive services covered by Medicare would have a lower probability of late stage of cancer at time of diagnosis than others who used fewer of these services. Our rationale was: If the use of preventive services (a) is correlated--as the health psychology literature indicates--with other healthy behaviors (such as exercising, not smoking, controlling weight) and the belief that illness is preventable or controllable and (b) promotes opportunities to discuss signs and symptoms of illness with health care providers--then a greater use of preventive services will be associated with a lower probability of late stage cancer at the time a beneficiary is first diagnosed with cancer. In essence, our hypothesis was that the use of preventive services is consistent with a range of healthy behaviors that promote health and early detection of disease.

We studied eight frequently diagnosed cancers in 1995--breast, colorectal, uterine, and ovarian cancer in women and prostate, colorectal, bladder, and stomach cancer in men, and an array of preventive services: influenza and pneumonia immunization, colonoscopy, sigrnoidoscopy, barium enema, mammography, pap smear, and the PSA test. The time period selected for studying the use of preventive services prior to the diagnosis of cancer was set at two years. However, as described in the Methods section, we used the 24 months ending in the third month prior to diagnosis as our two-year observation period. The health outcome was stage of cancer when first diagnosed.

Four of the eight types of cancers studied have a specific screening procedure associated with it. It is important to stress, however, that the objective of this research was not to analyze whether the use of any particular screening service, such as the PSA test or mammography, was related to stage of prostate or breast cancer when first diagnosed. Such studies require substantially different methods, data, and design than used in this study (Friedman et al. 1995). Rather, the objective was to determine if the health behavior characterized by using available preventive services was associated with stage of cancer at time of diagnosis. That finding would be of particular importance because data from the National Cancer Institute (Ries et al. 1997) show that elderly blacks are more likely to have late stage cancer when first diagnosed--and more likely to have lower five-year survival rates--than their white counterparts.