Commentary
IVDs for home-use testing: Issues in diagnosis and monitoring
Lon
Crosby
The
potential for home-based clinical testing to make a significant impact on the
IVD market is widely recognized, but industry expectations have yet to be fully
attained. If they had been, there would be many more manufacturers of such products,
and hundreds more home-based products would be on the marketplace today. Presently,
FDA lists only 483 home-based tests on its over-the-counter device list, which
covers 26 test categories. Of these listings, 33% are blood glucose–related
devices, while 32% are related to pregnancy detection or ovulation prediction.
Nevertheless,
the opportunity for home-use diagnostics is indeed vast, and the current demographic
and economic landscape supports the presence of such opportunities. With an
elderly population that is rapidly expanding, people are living longer and are
staying in residential housing as long as possible. These aging baby boomers
have a propensity to be more actively involved in their own healthcare. In addition,
rapidly escalating healthcare costs provide an impetus for consumers and regulators
to change the healthcare system. By taking into account the costs of travel,
time, and expense for healthcare, the costs and the impetus for change are even
greater.1
Clinicians
recognize this need for change and the opportunities that innovative technology
could provide. For example, a pharmaceutical could routinely be prescribed based
on a patient's blood level, but only if a simple, cost-effective test for
establishing blood levels were available. This approach would maximize therapeutic
effectiveness, minimize complications, and allow doctors to directly address
dosing issues associated with age, sex, race, and metabolic state.
Companies in the laboratory diagnostic market have not yet taken full advantage of opportunities to produce certain classes of tests which could be implemented as home-based tests. Many of these tests are important in monitoring athletic performance, body weight, and a number of major diseases. All of these markets are larger than the pregnancy or ovulation-prediction markets, and many are even as large as the diabetic market.2
In order to develop these home-based tests, the industry needs to reevaluate the test platform, test availability, and data utilization. If industry were to take an active approach, a market explosion in this area could very well be the result.
Packages of
Home-Use Tests
Data on disease
incidence from the National Center for Health Statistics (Hyattsville, MD) suggest
that small groups of home-based clinical tests could be useful for the diagnosis
and monitoring of many diseases, disease complications, or therapy complications.3
Several possible basic test packages are described below. While some of these
tests represent established but underdeveloped markets, others are less recognized.
Anemia.
The most common disease in the United States is anemia.2 There are many causes
of this common condition, and a single test does not provide much useful information.
However, a package of tests for iron, hemoglobin, transferrin, ferritin, vitamin
B12, folate, and a simple decision tree can quickly define the problem or evaluate
the efficacy of the prescribed therapy. Individual tests can then be used to
monitor intervention efficacy.
Bone Loss. Postmenopausal bone loss is a fact of life for most women.
Because it is a multifaceted condition, a number of tests are required for an
effective diagnosis or for monitoring an intervention. A package of such tests
might include tests for calcium, phosphorus, vitamin D metabolites, and bone
degradation.
Drug Side-Effect Monitoring. Many common prescription drugs frequently affect kidney or liver function, and hence routine monitoring of renal function (e.g., electrolytes etc.) or liver function is required.
Hyperlipidemia. Even though cholesterol and heart disease get a lot of attention, the diagnosis and treatment of hypercholesteremia is actually much more complicated. For this condition, a patient needs data on several key parameters, including total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, and homocysteine. Moreover, after diagnosis, there is an ongoing need for individual tests for continual follow-up monitoring.
Human Performance.
According to a review of the human performance literature related to ultraendurance
exercise, anorexia nervosa, pregnancy, dieting, and all of the related disease
conditions, the four key indicators of physiological status are glucose, lactic
acid, beta-hydroxybutyrate, and urea.4 Any tests that are developed
for these indicators represent a continuing-use package.
Malnutrition. Malnutrition due to an inadequate intake of calories or protein is the most common problem among nursing-home residents.5 Its diagnosis requires an examination of a long-half-life protein, such as albumin, and at least one short-half-life protein, such as prealbumin, transferrin, or retinol-binding protein.
Micronutrient Status. One of the best-kept secrets in the United States is the health problems that arise from micronutrient deficiencies of vitamins and trace elements. Data from the Health and Nutrition Examination Survey suggest that a normal individual's risk of either having or being at-risk for a micronutrient deficiency is about 5% for each micronutrient, and that these risks are independent and therefore additive.6 Inappropriate micronutrient supplementation can lead to nutrient toxicity and rebound deficiencies if an individual is suddenly forced to alter established practices. Hence, there is a serious need for tests to monitor micronutrient deficiency.
Therapeutic Drug Levels. Establishing drug dosing schedules and monitoring efficacy would be easier if a drug or metabolite could be monitored. For example, instead of arbitrarily prescribing two pills every four hours, a physician could find an appropriate therapeutic level by testing the patient's blood, saliva, or in some cases, urine. This approach minimizes problems that are associated with age in both children and geriatrics, pregnancy, and chronic drug use where the drug-handling system is elevated.3
Common Platform
The issues regarding the need for a common home-based test platform and the opportunities for creating one have been discussed at length in a previous article.7
One such platform that could be adapted for home-use testing purposes is the personal digital assistant (PDA). A PDA provides a standard upgradable interface and can be connected to other communication and diagnostic devices. PDAs and cell phones are beginning to be combined into single packages that allow simpler data transfer, and Bluetooth wireless interfaces can link a PDA to multiple personal devices. With such options, a simple diode array spectrometer can provide the foundation for a simple universal reader that is capable of analyzing indicator systems in the visible, ultraviolet, and near-IR regions.
The opportunity to use a PDA as a mobile data-collection system and an educational platform appears somewhat untapped. For example, by providing a common interface, a PDA could allow a diabetic to maintain a food diary, create an activity record (through heart-rate monitoring, GPS monitoring, etc.), and store blood pressure readings and blood glucose data. This package of information would enable clinicians to put individual glucose readings in a better context.
In addition, PDAs have sufficient memory and processing power such that they can provide real-time analysis and effective patient feedback. Considering that educators say the best time to teach is when a measurement has been taken, the opportunity to package tests with educational software creates unique market opportunities, brand loyalty, and potentially significant healthcare cost savings.
Interpretation
and Education
With such new objectives, however, IVD manufacturers cannot assume that their role is simply to develop and market tests that generate numbers. The goal should be broadened to include interpretation and education. In other words, companies must create personal modules that include both a knowledge system and an education system.
Knowledge Systems. Knowledge engineers claim that they can create a software program that is 95% as good as the human expert that they clone. With plenty of health experts who can serve as prototypes, creating a knowledge system for a differential diagnosis would be a rather simple task, especially when looking for known complications of a disease or treatment process.
A doctor's
differential diagnosis is only as good as the information that is made available.
Consequently, computers and PDAs are often better than physicians and nurses
at collecting particular information because they can ask the relevant questions,
present questions in a format that is appropriate to the individual, collect
accurate timing information, and are impersonal, nonhuman questioners. In addition,
computers and PDAs can seek information that physicians and nurses are untrained
to collect. An example might be the collection of food consumption data for
the diagnosis and treatment of anemia, weight gain or loss, and so on.
Patient Education. Computers and PDAs can also provide a unique foundation for patient education. Add-on memory can offer interactive educational activities far beyond the one-page tear sheets that are frequently used. With this capacity, programs can be adapted to education level, treatment sophistication, treatment or drug interaction, and patient behavior. Because PDAs can store data and perform data analyses, the educational system can adapt accordingly. For a diabetic, for instance, such a system could adapt to low or high blood sugar levels at a particular point in the day, and adapt to fluctuations in activity. Such adaptive interaction could even be used to make immediate testing recommendations (e.g., from once a day to every four hours).
Computers and PDAs can also provide timing and feedback information. They can remind a patient to take medication, collect diagnostic information via test strips or other nominal procedures, or perform timed inquiries.
Conclusion
Right now, diagnostic tests are primarily blood- or plasma-based. But many small molecules can be easily monitored using saliva, sweat, or tears. Devices are available for collecting all of these fluids. While there is an acute need for specific urine and fecal tests, the healthcare community underestimates what patients are willing to do to help themselves.
From a logistics standpoint, everyone would benefit from the conversion of traditional collection and analytical approaches to home-based testing. The quality of the data would go up, costs would go down, and timeliness would go way up.
References
1. LA Hindus, "The
Tele-Health Model: Saving Lives, Time and Money—With Imaging," Advanced
Imaging 15, no. 11 (2000): 47.
2. "Health Status and Determinants; Determinants and Measures of Health," Health, United States, 2001, with Urban and Rural Health Chartbook (Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics, Div. of Data Services, 2001).
3. Conn's Current Therapy, 2002, ed. RE Rakel and ET Bope (Philadelphia: Saunders, 2002).
4. LO Crosby, "Substrate Utilization, Body Composition and Nutrient Requirements in Endurance Athletes," Annals in Sports Medicine 3, no. 2 (1987): 104–108.
5. "Surgical Nutrition," Surgical Clinics of North America, vol. 61, ed. JL Mullen, LO Crosby, and JL Rombeau (1981).
6. "Perioperative Total Parenteral Nutrition in Surgical Patients: The Veterans Affairs Total Parenteral Nutrition Cooperative Study Group," New England Journal of Medicine 325, no. 8 (1991): 525–532.
7. A Reder, "Taking IVD Test Technology Beyond Human Clinical Diagnostics," IVD Technology 7, no. 5 (2001): 35–44.
Lon Crosby, PhD, is the director of research and development at Numedloc Inc. (Webster City, IA), a technology consulting firm. He can be reached via e-mail at lon.crosby@starband.net.
Copyright ©2002 IVD Technology
