Preferences of Community Physicians for Cancer Screening Guidelines

Clinical practice guidelines have received much attention [1-5], especially those for prevention and early detection of heart disease, hypertension, and cancer [6-8]. There is considerable disagreement among guidelines for some early-detection procedures [6-15]. It is important, therefore, to understand the effects of this disagreement on what providers in the community believe to be the appropriate screening intervals for such procedures. Using data from a national survey, we examine 1) the level of consensus among community physicians in four specialties (family practice, general internal medicine, general surgery, and gynecology) about the performance of and appropriate intervals for screening for early detection of cancers of the breast, cervix, colon and rectum, and lung in asymptomatic patients at normal risk [that is, those with no significant symptoms or history of major risk factors]; 2) agreement among these physicians with the American Cancer Society and National Cancer Institute guidelines for specific screening intervals; and 3) variation around the modal preference by specialty and physician and practice characteristics. Early-Detection Guidelines Establishing guidelines for early detection of cancer has been a major activity of both voluntary and government agencies. The American Cancer Society has a long-standing policy of publishing guidelines for cancer-related check-ups; the most recent guidelines were published in 1985 [9]. Following a directive from the Assistant Secretary for Health [10-12], the National Cancer Institute established objectives for reducing mortality caused by cancer. The Early Detection Branch of the Division of Cancer Prevention and Control at the National Cancer Institute developed and disseminated early-detection guidelines in 1987 [12], which paralleled those published by the American Cancer Society. The Canadian Task Force on Periodic Health Examination and the United States Preventive Services Task Force also published guidelines [6, 8, 13], which are generally more conservative than those of the National Cancer Institute and the American Cancer Society. For example, the American Cancer Society and the National Cancer Institute advocate periodic mammography every 1 to 2 years for women aged 40 to 49 years and annual mammography for women older than 50 years. Neither of the task forces currently recommends mammography for women younger than 50 years [9, 12, 16-18]. The National Cancer Institute and the American Cancer Society advocate fecal occult blood tests, flexible sigmoidoscopy for persons older than 50 years, and digital rectal examinations, whereas the task forces make no recommendations on these procedures [8, 9, 12, 13]. Generally speaking, the American College of Physicians and the American Academy of Family Practice use the guidelines established in the Guide to Clinical Preventive Services, the Blue Book [6-8]. The American College of Surgeons and the American College of Gynecologists generally follow the American Cancer Society guidelines [6-9]. However, as shown below, these are not consistent patterns. Methods Study Design Data were collected through a national survey of physicians in four specialties (family practice, internal medicine, general surgery, and gynecology) who did not list oncology or hematology as subspecialties. The survey was conducted as part of the evaluation of the National Cancer Institute's Community Clinical Oncology Program [19]. Two samples of physicians were selected: community physicians who had admitting privileges at hospitals associated with the program (the evaluation sample) and a national sample of community physicians derived from the American Medical Association's listing of physicians in all 50 states and Puerto Rico (the comparison sample). Both samples were disproportionate, stratified, and randomly selected. Interviews were conducted between 2 October 1989 and 31 March 1990. Eligibility was ascertained by telephone, and those eligible were interviewed by mail or by telephone, depending on their preference. After screening, the total number of eligible physicians included 2655 from the evaluation sample and 2451 from the comparison sample. Interviews were completed with 3436 physicians: 1898 (71%) from the evaluation sample and 1538 (63%) from the comparison sample. Completion rates by specialty were 74% for surgeons, 73% for gynecologists, 63% for family practitioners, and 55% for general internists [19]. Defining Preference for Screening Interval For each screening procedure, respondents were asked to select from a list the screening interval they would recommend for patients with no known risk for the relevant cancer. The questions had a common format. The question for clinical breast examination read, How often would you recommend breast palpation by a physician for women who have no known risk factors? Response choices for each question were every 6 months or less, every 7 to 11 months, every 12 months, between 1 to 2 years, every 2 years or more, and other (specify). For each question, consensus was defined as the modal response from all physicians. Because the existing guidelines for mammography specify different screening intervals for patients aged 40 through 49 years than for those 50 years and older, separate questions were asked to establish consensus on the appropriate interval for women in each age category. Factors associated with the modal response were compared with those associated with other screening intervals. Highly unlikely responses (outliers) were deleted (generally 1% to 3% of all responses). In most cases, this procedure resulted in two clearly defined alternatives. However, there were exceptions. The variation from the mode for clinical breast palpation did not cluster, so the comparison was between annual palpation (the mode) and any other preference. For sigmoidoscopy, two comparisons were tested. The mode was every 2 years or less frequently. It was compared with two secondary modal points: annual/between 1 and 2 years and never Physician and Practice Characteristics Two sets of variables were used to examine physician preference: physician specialization and physician and practice characteristics. Surgeons were chosen as the reference category for specialization. Thus, family practice, general internal medicine, and gynecology were compared with surgery. We assessed whether cancer control initiatives in the Community Clinical Oncology Program influenced community physicians to be more sensitive to guidelines for early detection than other community physicians. Because samples were selected from different frames, we combined the two samples and controlled for the sample frame. This simultaneously assessed the question of program influence and controlled for selection bias. It was hypothesized that recent medical school graduates and those not in practice by themselves might have the most access to current information about recommended screening intervals. Preferences among those who graduated from medical school more than 20 years ago were compared with preferences among more recent graduates. Similarly, preferences of those in solo practice were compared with those of physicians in group or other practice settings. A series of questions assessed belief in the effectiveness of screening. Respondents were asked to rate the effectiveness of early detection in improving the likelihood of surviving cancers of the colon, rectum, breast, lung, prostate, bladder, and skin. Respondents were not asked about their assessment of the effectiveness of early detection of gynecologic cancers. Instead, a summary variable of overall assessment of screening effectiveness, based on the physicians' ratings of the other seven items, was used. Logit analysis with maximum-likelihood estimation [20] was used to model the main effects. In each case, the residual chi-square was not significant, suggesting no need to explore interaction effects. Results To assess the recommendations of various professional groups and of the U.S. Preventive Services Task Force, the American Cancer Society, and the National Cancer Institute, the summary provided by Hayward and colleagues [8] was used. The recommendations by the American Cancer Society and the National Cancer Institute are summarized in Table 1. We rate the extent to which other groups agreed with these recommendations, using four categories: high (all specialty groups, including the American Academy of Family Practice, the American College of Physicians, the American College of Surgeons, the American College of Gynecologists, and the U. S. Preventive Services Task Force, agree with the recommendations of the American Cancer Society and the National Cancer Institute), moderate (all agree except the U.S. Preventive Services Task Force), weak (the American College of Physicians, the American College of Gynecologists, the American Cancer Society, and the National Cancer Institute agree); and very weak (only the American Cancer Society and the National Cancer Institute agree). For the Papanicolaou smear, the consensus on interval is rated high, but there are differences regarding the age at which screening is recommended. The American College of Physicians and the U. S. Preventive Services Task Force recommend cessation of screening after the age of 65 years, and the American College of Physicians recommends starting screening at the age of 20 years rather than at the age of 18 years. Table 1. Consensus among Physicians and Physician Agreement with American Cancer Society and National Cancer Institute Recommendations for the Use of Screening Procedures with Patients at Normal Risk All published guidelines are consistent in their recommendation regarding the clinical breast examination, mammography for women aged 50 years and older, the chest roentgenogram (which is not recommended by any group), and the Papanicolaou smear; the guidelines vary in recommendations regar