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How illness demographics will affect the lab.

Who will be the patient of the future? What dis- eases is he or she likely to contract? Will the health and fitness trend continue? What impact will the new character of disease have on clinical labs?

The answers to these questions are critical in projecting the future dimensions of laboratory medicine. Changing demographics must be considered when forecasting the nature of clinical laboratory testing in the next decades.

That means taking into account the growing number of elderly persons in the general population, the expected dramatic increase in the prevalence of AIDS, more aggressive treatment of infertility, greater interest in exercise and proper nutrition, stronger efforts to combat sub- stance abuse, and the role of self-testing and mass screening. * An aging population. America is graying. A child born in 1776 had a mean life expectancy of 35 years. In fact, the median age of the population at that time was 16 years.

Over the next 100 years, life expectancy rose to 40 years and the median age to 21 years. A child born today can expect to live 75 years, and the median age of our population is 32.3 years.

Considering the growth of the population aged 65 and older from 1900 to 1950, and providing estimates for the years 2000 and 2050. The proportion of Americans 65 and older increased from 4 per cent in 1900 to 8. 1 per cent in 1950. This trend is expected to continue to 13 per cent in 2000 and 21.8 per cent in 2050. While the population as a whole will only double from 1950 to 2050, the number of Americans over 65 will increase fivefold, according to projec-


Predicting life expectancy in the next century is a shaky exercise. The United States Census Bureau places the expected span in the year 2040 at 75 years for men and 83 years for women. Looking ahead to the same year, the National Institute on Aging, a division of the National Institutes of Health, comes up with much higher figures: 86 years for men and 91.5 years for women.

The aging population

trend has considerable impact on utilization of medical resources: Those older than 65 consume up to three times the amount of medical resources consumed by younger individuals. We confirmed this in a 1983 study in the Copenhagen area.

That study found an average of 1,571 hospital bed days consumed annually per 1,000 Danes in the area; for Danes over 65, the rate was three times higher, or 4,980 days per 1,000 inhabitants. Although the total numbers are lower in 1989 than in 1983, people over 65 still consume approximately three times as many bed days as the general population.

The types of diseases found in older people differ from those seen in younger patients. Chronic conditions, such as arthritis and Alzheimer's disease, become more prevalent in an aging population and linger for years rather than causing death quickly. Osteoporosis, prostate cancer, diabetes, and vascular disorders are also commonly considered diseases of aging. In addition, cataracts, decreased hearing in the

higher frequencies, and skin cancer increase proportionately as the population ages.

Let's consider, in greater detail, diabetes, calcium and bone metabolism, kidney function, and immunological disorders in the elderly. * Diabetes. Non-insulin-dependent diabetes mellitus (type 11, NIDDM) is common in elderly patients; it is almost exclusively the type of diabetes found in them. There are marked regional and racial differences worldwide, but most studies show an age-related increase in prevalence. In the United States, the prevalence of NIDDM is 3 to 5 per cent for the 30- to 50-year-old age group, 10 per cent at 60 years, and 16 to 20 per cent at 80 years. While the life span of elderly diabetics is not greatly affected, there is a marked increase in morbidity.

Macro- and microvascular disease-manifested by stroke, coronary heart disease, intermittent claudication, and end-stage renal disease-are found more frequently in late middle-aged and elderly diabetics than in age-matched controls. Age, glycemia, and the duration of diabetes are important determinants, their con-

tribution varying with the clinical condition. It has also been suggested that elderly subjects may have a more limited capacity to cope with chronic hyperglycemia and its metabolic sequelae.

Twenty to 40 per cent of the elderly exhibit abnormal glucose tolerance responses. The frequency is markedly age-related, but there are also significant regional differences. Blood glucose levels at 1 to 2 hours after a meal rise significantly with age, at an average of 4 mg/dl per decade. These findings are consistent with the observation that age has less of an influence on fasting blood glucose than on specimens collected at random during the day.

Deterioration of glucose tolerance with age has long been recognized, and most people over 70 exhibit a diabetic-like curve. This age-related alteration results in a significant correlation between age and the glucose response level.

Regulating blood glucose is less efficient in the elderly than in young adults, as reflected in the greater frequency of glucose intolerance in the former group. Factors contributing to this intolerance include a marked decrease in physical activity and a propor-

tionate increase in adiposity. The age-related decline in renal function, however, is probably the dominant factor in blunting a person's response to hyperglycemia. When a younger person with normal renal function is subjected to hyperglycemia, the response is a marked glycosuria accompanied by polyuria. In contrast, the aged kidney does not elicit as frequent and prompt a response. The osmotic effects of hyperglycemia are initiated at an earlier stage, and the elderly are thus more prone to a hyperglycemic state. Although hyperglycemia occurs in all age groups, most of the patients are either in late middle age or elderly. * Calcium and bone disorders. Metabolic bone loss is also a common problem among the elderly. Laboratory tests are valuable in supporting a diagnosis of conditions that accelerate bone loss, such as renal failure, myeloma, and rheumatoid arthritis. To distinguish among osteoporosis, osteomalacia, and Paget's disease of bone, however, laboratory tests are of limited usefulness.

A raised serum alkaline phosphatase, above the expected age-related increase, may indicate a recent osteoporotic-associated fracture. One study found that a raised serum bone alkaline phosphatase may antedate an osteoporotic fracture. This suggests that the isoenzyme could help identify postmenopausal women who may suffer a more rapid course.

A low serum phosphorus in the aluminum-containing antacids commonly used by the elderly may indicate depleted phosphate stores. Abnormal lactose tolerance test results have been ob-

served more frequently in osteoporotic women than in age-matched controls, consistent with poorer calcium absorption.

Measuring 25-(OH)vitamin D may help in assessing vitamin D status. The serum vitamin level is markedly altered in renal disease, osteolytic states, hyperparathyroidism, malabsorption, and liver disease. The level of 25- (OH)D should particularly be considered in the elderly with regard to nutritional status, exposure to sunlight, and the pathogenesis of hip fractures. Irrespective of renal status, the elderly sick have a markedly lower level than healthy older persons. Despite wide variations in individual results, a progressive and marked decline in serum 25-(OH)D levels occurs with age. Thus, an elderly person's level may be only half that of a young adult. * Kidney function. Many of the effects of aging on the kidney, particularly on the renal vasculature, are difficult to distinguish from those caused by disease, especially hypertension. Kidney size and volume shrink after age 40. The number of glomeruli decreases by about 30 per cent by 80 years of age. The length and volume of the tubules also decrease with age; there is no compensatory hypertrophy of the remaining nephrons, and many distal tubules show diverticula.

The surface area of the glomeruli decreases, but the volume of the nephrons declines proportionately. The basement membranes of the glomeruli and tubules show focal thickening and reduplication with age. The surface area of the glomerular capillary basement membrane decreases by about 40 per cent. There is

a progressive reduplication of elastic tissues and thickening of the intima of vessels larger than arterioles, neither of which correlates with hypertension.

Glomerular function rate (GFR) declines by about 1I per cent per year after age 40 because of the decreasing number of glomeruli and the reduced blood flow through the kidney. Creatinine clearance falls about 8 ml/min/1.73 M[.sup.2] per decade after age 30. The fall in creatinine production may mask the rise in plasma creatinine associated with glomerular disease.

The role of hemodialysis and kidney transplantation in older patients with compromised renal function is very controversial. Medical ethicists will debate this issue and similar ones as our population ages faster than our financial resources grow. * Immunological disorders. The higher incidence of cancer and autoimmune phenomena in elderly patients has been attributed to an age-related failure in immunological competence. Evidence of such alterations in the immune system-humoral and cell-mediated-includes:

*A reduced cell-mediated immune response, consistently found in the elderly.

*Diminished circulating antibody response to antigenic challenge, also well established.

*Increased incidence of plasma cell dyscraslas-the highest rate of multiple myeloma, Waldenstrom's macroglobulinemia, and asymptomatic monoclonal gammopathies occurs in the elderly.

*Age-related alterations in selective classes of immunoglobulins, and a progressive decline in

ABO isoagglutinins that occurs with aging.

*A marked increase in the presence of autoantibodies in the elderly, with and without symptomatic disease.

Idiopathic gammopathy is a common finding in the elderly. Its prevalence increases with age in both sexes. The disorder is rare before the age of 30. Prevalence is 0. I to 0. 2 per cent from 25 to 49 years; it reaches 5 per cent or more in the 80-99 age group and 19 per cent among those older than 95 years. Overall, 25 to 50 per cent of all benign monoclonal gammopathies occur in persons 70 years of age or older.

Multiple myeloma, uncommon below the age of 30, exhibits an age-related increase in prevalence from middle age, peaking in the seventh to eighth decades. Twenty to 25 per cent of the patients are at least 70 years old at the time of diagnosis. One study estimated that I per cent of older patients suffer from multiple myeloma.

Rheumatoid arthritis is another common condition in the elderly; 20 to 30 per cent of patients with this disorder are 60 or older. The clinical course in most elderly patients is similar to that seen in a younger age group. In one third of the elderly, however, the arthritis is more benign and tends to affect both sexes equally, in contrast to the classic form that primarily afflicts women.

The benign form of rheumatoid arthritis has a characteristically sudden onset. The large joints are most often involved, and the sedimentation rate is markedly elevated. Anemia is common, and a polyclonal gammopathy may be present. The disorder has a clinical course of 12

to 18 months. Then it resolves, leaving minimal residua. * Geriatrics. The specialty of geriatrics may become as important as pediatrics. In fact, in July 1983 the number of Americans over the age of 65 surpassed the number of teenagers. By 2050, those over 65 will greatly outnumber children younger than 10.

The rationale for geriatrics being a separate specialty is not so much related to the growing number of elderly as it is to the different spectrum of diseases they contract. In older patients, treatment of these disease often requires an entirely different approach.

The over-85 group is now the fastest-growing age segment of the population. In 1900, only a few thousand Americans were in that bracket, but today there are 3.3 million, and projections are that there will be close to 20 million by 2050. By 2080, it's estimated that 5 million Americans will be older than I 00!

Now we will turn to a demographic analysis of other illness and wellness issues. * AIDS and other infectious diseases. The Centers for Disease Control and the Public Health Service project that 250,000 new cases of AIDS will be diagnosed in the U'S. in the 1986-91 period. A review of published mortality data suggests that a one-year mean survival for all AIDS cases is a reasonable approximation, although mortality studies from San Francisco and New York City have reported a mean survival of less than one year.

Widespread use of AZT appears to be lengthening the average survival among patients able to tolerate chronic therapy with the drug.

The prevalence of AIDS-related complex (ARC) is unknown. A study at San Francisco General Hospital found approximately one ARC diagnosis for each AIDS diagnosis. Progression rates from ARC to AIDS are very high: 83 per cent for

hairy leukoplakia at 31 months, 81 per cent for oral candidiasis at 48 months, and 46 per cent for herpes zoster at 48 months.

The complications of AIDS include pneumocystis pneumonia, other pneumonias, diarrheas, cytomegalovirus infection, Kaposi's sarcoma, neurologic complications, disseminated Mycobacterium avium, Candida esophagitis, and herpes simplex.

In addition to AIDS, we will see more fungal and parasitic diseases. This trend seems to be related to the growing number of patients on immune therapy. The geriatric population in nursing homes will develop more methicillin-resistant staphylococcal infections and, when admitted to hospitals, pose a threat of nosocomial infection to other patients.

The coming years will witness the development of multiple resistant microorganisms due to increased use of new broad-spectrum antibiotics. We will also see continued change in the pattern of infectious diseases as evidenced over the past 10 years with legionellosis, toxic shock syndrome, and Lyme disease. * Infertility. One couple in seven is considered infertile-that is, unable to conceive after one full year of normal heterosexual intercourse performed at regular intervals without the use of any contraception. The odds are abysmally low that a woman will conceive

without medical assistance when she has failed to do so after a year or two of unprotected intercourse.

According to the National Center for Health Statistics, the rate of in- voluntary infertility has remained constant since 1965. Yet the number of infertile couples increases every year in line with population growth. Three major factors increase the likelihood of infertility: venereal diseases, the biological clock, and the use of therapeutic and recreational drugs.

Venereal diseases. Gonorrhea and other venereal diseases are rampant in the United States. Gonorrhea lodges in a woman's fallopian tubes and often results in severe illness. Unfortunately, it can cause so little physical discomfort that women do not bother to seek treatment. But even a minor gonorrheal infection can damage the fallopian tubes, and many women learn they have had gonorrhea only when they investigate the cause of their infertility.

Chlamydiosis, another infection that blocks the fallopian tubes, is just as prevalent. It is very difficult to diagnose and culture, and it responds well only to certain antibiotics. Finally, syphilis is becoming widespread again in the U.S. It is

easily cured in the early stages, but in the later stages its effects cannot be reversed (though its spread can be halted).

The biological clock. Many women choose to delay motherhood until their 30s. There is a price to pay for this decision: Certain infertility-producing disorders tend to appear during the second half of a woman's reproductive life span. A woman who decides to have children after 35 may discover she is infertile due to hormonal problems, a pelvic disease such as endometriosis, or the development of benign uterine fibroid tumors.

The ability to ovulate and concurrently generate a hormonal environment that can adequately support a pregnancy becomes increasingly difficult with age. Thus many women who plan to become pregnant later in their reproductive lives find they are unable to do so.

Therapeutic and recreational drugs. Alcohol, cigarettes, marijuana, cocaine, and other psychotropic drugs alter the structure of eggs and sperm and so can significantly reduce both male and female fertility. The effect is potentially far more severe and longlasting for women. Because a

woman is born with a lifetime quota of eggs already inside her ovaries, unwise use of medications and other drugs can damage all the eggs her body will ever produce.

Due to the natural population growth in the U.S., the number of couples whose last option for pregnancy is one of the new high-tech procedures is skyrocketing. Recent advances in the evolution of procedures to evaluate and treat infertility offer the hope of pregnancy in once hopeless cases.

Treatment of infertility is headed by the novel alternative of in vitro fertilization (IVF) and embryo transfer (ET). The first baby conceived by IVF-ET was born in 1978. Her birth culminated more than 10 years of research by Drs. Robert Edwards and Patrick Steptoe in England. It started a new era in the treatment of infertility. Women previously considered sterile because of absent or irreparably damaged fallopian tubes might now conceive.

IVF-ET has gained worldwide acceptance. More than 5,000 IVF-ET children have been born with no apparent increased risk to mother or child, compared with other procedures used to correct infertility. The United States alone has more than 100 IVF-ET programs.

Future advances in IVF-ET and similar procedures will increase the need for laboratory testing. Monitoring the menstural cycle and confirming pregnancy will become critical. Assays for human follicle stimulating hormone, luteinizing hormone, estradiol, progsterone, and HCG will be ordered more and more in coming years, and various assays for

sperm motility and viability will undoubtedly be developed. * Health and Fitness. With individuals in good health likely to live up to 10 decades, interest in health and fitness programs will increase. Exercise in the form of both aerobic workouts and flexibility-enhancing programs will be more popular, and exercise physiologists will be consulted about optimal exercise regimens. There will be a search for new laboratory tests to demonstrate the benefits of physical activity.

Increased physical exercise programs will spur more sports-related injuries and disorders. The specialty of sports medicine will grow in importance. Physicians, physiologists, physical therapists, and others will design personal exercise programs and treat injuries resulting from physical activity. The challenge for the clinical laboratory is to develop appropriate tests for this market.

Another component of the health and fitness movement is an increased emphasis on proper diet and nutrition. Interest in diets high in fiber and low in cholesterol and saturated fats will change the way America's food processors prepare their products. Consumers will demand to know whether coconut oil or other saturated fatty acids are present in the food they eat. More work will be done in treating such eating disorders as anorexia and compulsive overeating.

The laboratory will also play an important role in nutrition assessment. Cholesterol testing-e.g., HDL cholesterol and apolipoproteins-will become an expected part of the patient evaluation. We will learn more about the hormon-

al relationship to obesity and anorexia, and various psychological and pharmaceutical interventions will be developed to correct these problems. Moreover, the laboratory will monitor any endocrine imbalance as a cause of eating disorders.

Substance abuse represents a challenge to us all. The public will no longer tolerate rampant drug abuse. The war against drugs will be fought on many fronts, including education to decrease demand, early detection of drug users, screening and confirmation of usage, and monitoring of treatment. We will see more mass screenings for drugs of abuse in the future, along with sophisticated tests for acute and chronic alcohol ingestion.

Medical science will also attack mental illness, which costs our country $36 billion a year in direct care expenses. Ten million persons suffer from mental illness. Depression leads to 16,000 adolescent suicides each year. Up to 40 per cent of long-ten-n hospital beds are occupied by schizophrenics.

Many neurochemical abnormalities associated with psychological problems will be identified and measured in the laboratory, providing biological markers for diagnostic and therapeutic decision making. The various neuroendocrine hormones that cause or are associated with mental illness will be identified and used as disease markers, and we will come to understand more about their diurnal variation. These laboratory tests will be used with various brain imaging methodologies, such as positive emission tomography (PET), magnetic resonance

imaging (MRI), and brain electrical activity mapping (BEAM). * The new health care team. With the growing popularity of self-testing, the patient will work with care-givers on his or her own behalf. Diabetics will monitor their glucose levels, infertile couples will track ovulation, couples will test for pregnancy, and patients on anticoagulant therapy will perform prothrombin tests at home.

As home test kits become available to monitor health and fitness, persons who follow a diet and exercise regimen will be able to assess their performance. There will also be home tests for infectious diseases, especially in the pediatric population.

Mass screening of different types will become available. Testing for cholesterol, AIDS, and drugs of abuse will be done at work and in shopping malls as well as in the lab. Health care will become more oriented toward public health and preventive medicine.

The future of health and of efforts against disease is very exciting. As America ages, the types of disease will change. Concern for health and well-being will become very important. And the clinical laboratory will be an important player on the health care team.
COPYRIGHT 1989 Nelson Publishing
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Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Title Annotation:medical laboratories
Author:Statland, Bernard E.
Publication:Medical Laboratory Observer
Date:Jul 1, 1989
Previous Article:Automation: trends in instrumentation, robotics, computers.
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