Introduction

Preventive medicine may be defined as the application of biomedical and epidemiological science to the promotion of health and the elimination or early detection of disease in populations and individuals.

Trends in Health Manpower in the U.S.

According to the Health Resources and Services Administration, the active number of health personnel in 1983 was as follows:

The number of people employed in the health care industry grew by nearly 90% between 1970-1984 from 4.2 million to 7.9 million.

Between 1970 and 1983, the number of registered nurses per 100,000 population increased by 63% from 369-600, compared with a 35% increase in the physician-population ratio during this period (from 143-193).

Substantial regional variation in the supply of health personnel persisted in 1983. Physician supply was greatest in the Northeast (243 per 100,000 population) and lowest in the South (165 per 100,000). Nursing supply was also greatest in the Northeast and lowest in the South (772 vs. 477 per 100,000).

In 1983, 3.1 million full-time equivalent employees worked in community hospitals, and 39% were nurses or ancillary nursing personnel. Registered nurses made up the largest share of hospital employees (698,000) followed by ancillary nursing personnel (294,000) and licensed practical nurses (230,000).

Between 1971-1972 and 1983-1984, total enrollment in schools of allopathic medicine increased 54% and minority enrollment more than tripled. Hispanic enrollment quadrupled; Asian enrollment increased fivefold; American Indians experienced a sixfold increase; and Black enrollment nearly doubled. In 1983-1984, medical school enrollment was 67,327. Black students accounted for 6% of this total; 4% were Hispanic; 5% were Asian; and 0.4% were American Indian.

In the academic year 1983-1984, entering classes in the nation's health professions schools continued to include increasing proportions of women. Females comprised about 50% of first-year classes in pharmacy and veterinary medicine, and between 25% and 33% of new enrollees at schools of denistry, osteopathic medicine, optometry, and allopathic medicine were women.

During 1983-1984, the percent of female students entering medical school was higher among minority students than among white students. Among white entering students, 32% were female compared with 34% of Asian students and 46% of Black students.

Physician Practice Patterns in Preventive Medicine

Internists, general and family practitioners, pediatricians, and obstetrician-gynecologists are the physicians who provide the majority of preventive services in clinical settings. These subspecialties comprised approximately 30% of all professionally active physicians in non-federal office-based practice in 1983:

There are 120 departments of preventive/community medicine in the 127 medical schools in the U.S.

Fewer than 3% of practicing physicians are diplomates of the American Board of Preventive Medicine and Preventive/Community Medicine.

Prevention in Medical Education

In 1945, the Association of American Medical Colleges recommended that every medical school have an independent preventive medicine department and that 7% of the total curricular teaching time be devoted to the field. The average teaching time allocated then was 82 hours; 200 hours in a conventional 4 year curriculum would have been required to meet the standard. Although the AAMC policy persists, the 200 hour goal has never been reached. The average number of hours devoted currently to preventive medicine education is 51.

In 1984-1985, there were 70 preventive medicine residency programs in the United States: 30 in general preventive medicine, 12 in public health, 25 in occupational medicine and 3 in aerospace medicine.

A residency in preventive medicine requires 3 years: a clinical, an academic, and a field year. A fourth year of training, teaching practice and/or research must be completed before the American Board of Preventive Medicine examination may be taken.

A total of 731 residency positions were available in 1984-1984, 60% of which were funded. In terms of enrollment, there was a total of 469 residents in all programs, with an average of 6.7 residents per program.

Approximately 71% of all residency training programs were housed in schools of medicine or public health; others were offered by state and local health departments, Departments of the Army, Navy and Air Force, and the U.S. Public Health Service. The percentage of medical and public health school programs has been on the rise in past years, whereas the percentage of programs offered by the military, health departments and industry has been declining.

Recommendations for Preventive Health Services

Several professional associations, distinguished advisory panels, and federal organizations have issued recommendations concerning the appropriate use of preventive services in clinical practice for age- and sex-specific groups, risks, and conditions. Recommendations have been set forth regarding history and physical assessment (e.g., blood pressure reading, height and weight measurement); immunizations (e.g., diptheria, pertussis, tetanus vaccines, oral polio vaccines); laboratory and screening tests (e.g., serum cholesteral assessment, breast cancer screening); and patient education and counseling (e.g., smoking cessation, exercise initiation and/or maintenance).

Preventive services literature offers contradictions concerning the appropriate age of initiation and discontinuation of particular maneuvers, the efficacy and effectiveness of various interventions and the optimal frequency of their delivery.

The following references represent some of the major recommendations issued to date regarding selected clinical preventive services:

Ad Hoc Advisory Group to the Institute President. Preventive Services for the Well Population. Washington, DC: Institute of Medicine, National Academy of Sciences, 1978.

American Academy of Pediatrics. Guidelines for Health Supervision, 1985. American Academy of Pediatrics, 1985.

American Cancer Society. Guidelines for the cancer-related checkup. Cancer, 1980, 30, 194-240.

American Cancer Society. Mammography guidelines 1983: Background statement and update of cancer-related checkup guidelines for breast cancer detection in asymptomatic women age 40 to 49. Cancer, 1983, 33:255.

Breslow L. Personal health services. In: Last, J.M. ed. Maxcy-Rosenau Public Health and Preventive Medicine, 12th ed. Norwalk, CT.: Appleton-Century-Crofts, 1986. pp. 1689-1702.

Breslow L., & Somers, A.R. The lifetime health-monitoring program: a practical approach to preventive medicine. New England Journal of Medicine, 1977, 296, 601-608.

Canadian Task Force on Cervical Cancer Screening Programs. Cervical cancer screening programs: Summary of the 1982 Canadian Task Force report. Canadian Medical Association Journal, 1982, 127, 581-589.

Canadian Task Force on the Periodic Health Examination. Task Force report: the periodic health examination. Canadian Medical Association Journal, 1979, 121, 1-45.

Canadian Task Force on the Periodic Health Examination. Task Force report update: the periodic health examination. Canadian Medical Association Journal, 130, 1-6.

Canadian Task Force on the Periodic Health Examination. Task Force report: the periodic health examination. Canadian Medical Association Journal, 1984, 130, 1-6.

Canadian Task Force on the Periodic Health Examination. Task Force report update: the periodic health examination. Canadian Medical Association Journal, 1986, 134, 721-727.

Committee on Immunization. American College of Physicians. Guide for Adult Immunization, 1985. Philadelphia, Pa.: American College of Physicians, 1985.

Council on Scientific Affairs, American Medical Association. Medical evaluation of healthy persons, 1983, 249, 1626-1633.

Frame, P.S., A critical review of adult health maintenance. Journal of Family Practice. In press, 1986.

Frame, P.S., & Carlson, S.J. A Critical review of periodic health screening using specific screening criteria. Journal of Family Practice, 1975, 2, 29-36.

Surveys on the Utilization of Preventive Health Services

[According to the 1985 Health Promotion and Disease Prevention Supplement to the National Health Interview Survey, approximately half of all Americans are receiving Papanicoloau smears, clinical breast examination, and blood pressure testing each year. Younger women are more likely to undergo cervical and breast cancer screening, whereas older adults are more frequently screened for hypertension.]

Papanicoloau Smears

About how long has it been since you had a Pap smear test?

Clinical Breast Examination

About how long has it been since you had a breast examination by a doctor or other health professional?

High Blood Pressure Testing

About how long has it been since you last had your blood pressure taken by a doctor or other health professional?

77% of Americans surveyed claim to seek care from a particular clinic, health center, doctor's office, or other place if they are sick or need advice about health. Females and persons 65 years and over responded affirmatively to this item more often than did males and younger interviewees.

Among persons in families with children under 5 years of age, 47% reported that a doctor or other health professional had discussed the importance of using car safety seats for their children.

Only 5% of respondents had ever been told by a doctor or other health professional that they had high cholesterol.

64% of interviewees claimed that eating proper foods is "rarely or never" discussed when visiting a doctor or other health professional for routine care.

[The results of a Louis Harris and Associates survey to assess the health knowledge, attitudes, and practices of Americans was published in a Rodale Press document, Prevention Index, 1986. A total of 1,256 randomly selected adults across the country were interviewed in November, 1985. Among the questions posed were several concerning periodic medical exams and tests.]

Blood Pressure Reading. 86% of adults reported having a blood pressure reading at least once a year. Groups at higher risk for hypertension such as those aged 65 and over and Blacks were most likely to have had a blood pressure reading even more often than once a year. Socioeconomic status, as measured by income, occupation, or education, was unrelated to frequency of blood pressure assessment.

Blood Cholesterol Testing. Nearly five out of ten adults (48%) claimed to undergo cholesterol testing at least once annually. Groups most likely to respond affirmatively included those over 40 years of age and those in the highest income bracket ($50,000 plus). Respondents who described their health as "fair or poor" were more likely to have received cholesterol testing, suggesting that this intervention may be delivered during a curative medical vist rather than a preventive medical visit.

Pap Smear for Women. More than three-quarters of adult women (78%) said they received a Pap smear testing every one or two years. Groups most likely to respond affirmatively included women under age 50, those with at least some college education, and those whose annual household income totalled $25,000 or more.

Breast Self-Examination for Women. Approximately half (48%) of adult women reported examining their breasts at least once a month to detect cancer symptoms. Women most likely to perform breast self-examination were those aged 40-64 years of age, and those from blue-collar households. This latter finding has appeared in three Annual Prevention Index Surveys, suggesting that when screening tests are easy, inexpensive, and widely publicized, all classes of Americans take advantage of them.

Testicular Self-Examinations for Men. 16% of males reported examining their testicles for cancer symptoms at least once a month; 12% claimed they did so more than once annually. However, 46% of those interviewed claimed to never perform testicular self-examinations. College-educated males and those claiming to "participate a lot" in medical decision-making most frequently responded affirmatively to this item.

Dental Examinations. 74% of adults claimed to visit a dentist at least once a year. Annual dental checkups were most common among those under age 50, those with more years of formal education, those with higher income levels, those in more prestigious occupations, and those with a high level of perceived control over their future health.

Children's Examinations and Immunizations. The 1985 Louis Harris survey conducted for the Rodale Press included questions addressed to 462 adults living in households in which children were present. Data indicated that at least 19 out of 20 children aged 1 year and older had obtained DPT (diphtheria, whooping cough and tetanus) inoculations and polio shots. 9 out of 10 had received a measles vaccine, 74% an annual eye examination and 62% an annual blood pressure reading. More than 8 out of 10 children (85%) had seen a dentist within the past year.

Pregnant Women. 93% of mothers reported having sought prenatal health care during their first trimester of pregnancy. 8 out of 10 mothers claimed to have received health habit advice during pregnancy from their health care provider. 50% changed their health habits upon learning they were pregnant and 17% did so during their first three months of pregnancy.

Participation in Medical Decisions. 44% of adults claimed that they "participate a lot" in decisions about their medical treatment. Individuals with higher participation had higher rates incomes, worked in more prestigious positions, were better educated, were 30-39 years of age and described themselves as possessing "excellent" health.

Preventive Advice from Doctors. 65% of adults interviewed reported that their physicians had not given them advice about improving their health habits; the other 35% reported having received unsolicited advice. Individuals responding affirmatively claimed to be in "fair or poor" health, suggesting that those who are given advice by doctors are already in medical need of it.

Data from the National Health Interview Survey (1982) based on 42,000 household interviews of 111,000 noninstitutionalized civilians revealed the following:

Routine Physical Examinations. 96.4% of respondents under 17 years of age were reported to ever have had a routine physical examination, 65.4% within the year preceding the interview. Only 90.8% of Hispanic children had done so, compared to 97.0% of non-Hispanic children.

Eye Examinations. 86.1% of children 3-16 years of age ever had received an eye examination. 16.7% of children in households earning less than $10,000 annually had never undergone an eye exam, as compared to only 9.1% in households earning $35,000 or more. 96.7% of persons 17 years of age and over were reported "ever" to have received an eye examination, 34.5% within the year preceding the interview. Percentages for this age group were fairly consistent across sex, income, education, and geographic groupings.

Breast Examinations. 90.2% of females 17 years of age and over reported ever having had a breast examination. Women with less than 12 years of education (18.2%) and those with family incomes of less than $10,000 (15.3%) were more likely to never have had a breast examination, as compared to women with 13 or more years of education (4.9%) and those with household incomes of $35,000 or more (6.1%).

Pap Smears. 89.2% of females 17 years of age and over were reported ever to have received a Pap smear, 45.8% within the year preceding the interview. Women with less than 12 years of education (18.7%) and those with family incomes of less than $10,000 (15.9%) were more likely to never have had a Pap smear, as compared to women with 13 or more years of education (6.8%) and those with household incomes of $35,000 or more (7.8%).

Glaucoma Testing. 80.7% of persons 40 years of age and over were reported ever to have received a glaucoma test, 48.8% within the two years preceding the interview. Percentages were higher among older respondents, females, whites, those with higher incomes, and those with more education.

Blood Pressure Readings. 98.8% of persons 17 years of age and over ever had received a blood pressure test, 75.0% within the year preceding the interview. Affirmative responses were remarkably consistent across sociodemographic groupings.

Electrocardiograms. 76.4% of persons 40 years of age and over were reported ever to have received an electrocardiogram.

Chest X-rays. 8.5% of persons 17 years of age and over were reported ever to have received a chest X-ray. The current recommendation is that chest X-rays not be performed as a means of screening for lung cancer.

Evaluation of Preventive Health Services

Periodic health examinations can significantly reduce mortality from potentially postponable causes, based on results from the Multiphasic Health Checkup Evaluation Study. A randomized controlled trial conducted at Kaiser-Permanente. During 16 years the study group experienced a 30% reduction (p higher than 0.05) in deaths from prespecified "potentially postponable" causes largely associated with lower death rates from colorectal cancer and hypertension. This reduction was most pronounced in the early years of the study. The two groups did not differ to a statistically significant degree in mortality from all other causes (84% of total mortality) or in total mortality.

The INSURE/Lifecycle Preventive Health Services Study was designed to establish the feasibility and cost of incorporating preventive health care in the regular practice of primary physicians. The Lifecycle Model combines periodic examinations and X-ray studies with patient education on behavioral risk factors. INSURE introduced this model with 5,000 patients and 74 physicians in 5 private group practice clinics in the United States, using a controlled design. Data from the 3-year feasibility study demonstrated that it had a positive impact on patients and physicians, and that costs were controllable: 17% of cigarette smoking patients quit smoking following their INSURE examination and counselling by their physician; 33% of previously sedentary patients reported to be exercising a year following their INSURE checkup; 43% of patients lost weight; 22% of patients who did not previously use seat belts reported they used them all the time; 53% of women who did not do regular breast self examinations began doing so following their INSURE checkup; and 35% of chronic drinkers reported decreasing their consumption of alcohol.

The average cost (charge) for the INSURE examination was $73 in 1982-1983 and the average utilization by all patients was 38%. More than three-fifths of patients indicated they would be willing to pay up to $60 per year towards the premium for coverage of preventive services, ranking it as preferable to vision, dental and maternity employee benefits.