|Year : 2016 | Volume
| Issue : 4 | Page : 427-429
Diagnostic tests: Doctor's dilemma revisited
Department of Community Medicine, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Dr. D. Y. Patil Vidyapeeth, Pune, Maharashtra, India
|Date of Web Publication||12-Jul-2016|
Department of Community Medicine, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Dr. D. Y. Patil Vidyapeeth, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Banerjee A. Diagnostic tests: Doctor's dilemma revisited. Med J DY Patil Univ 2016;9:427-9
More than a century ago, the British satirist and playwright George Bernard Shaw penned Doctor's Dilemma, a satire on the state of the medical profession as it prevailed in 1903 before the advent of the National Health Service. It was not reasonable, Shaw believed to expect doctors in private practice to be impartial when confronted by strong pecuniary interests (conflict of interest as we call it today). Shaw expressed concern that people had become overly dependent on the spurious cures of doctors. He looked forward to a time when doctors as competitive practitioners in the marketplace would be replaced by a system of care under responsible and effective control failing which the medical profession will remain a conspiracy to exploit “popular credulity and human suffering.” He mocked the confusing jargon of the medical profession and pressed for re-examination by the London School of Economics of untrustworthy medical statistics.
Shaw conveyed the moral dilemmas created by the limited medical resources of his time and the conflicts between the demands of private medicine as a business and a vocation.
What prevailed in Britain over a century ago we are witnessing today. As a result of neglect of the public health services, India is the most highly privatized health economy in the world. The government spends <1% of the GDP on health. Out-of-pocket health expenditure is as much as 85% of the total health care spending.
An appreciable proportion of the expense of medical care is due to diagnostic tests. Expensive newly available tests are increasing the cost of medical treatment. Diagnostic tests, offered to asymptomatic persons may lead to further tests and sometimes costly treatment which may have unacceptable rates of serious complications. Given this scenario, it is the ethical duty of every physician to judiciously use diagnostic tests.
A disturbing trend is the high pressure marketing by commercial companies offering various screening tests, some appropriate, others of dubious benefit. Agencies offering screening services are selling “packages” of screening tests outside the conventional “doctor–patient relationship” often at a discount. These tests are offered at various locations such as housing societies, shopping malls, jogging tracks, often with a local corporate hospital, academic medical center, or physician group as sponsors. Some companies may drag in celebrities, registered medical practitioners, or private corporate companies to endorse the benefits of going for these “screening packages.” These endorsements may generate a false sense of trust in the quality and appropriateness of these tests without being aware of the potential harms of screening.
In the traditional doctor–patient interaction, doctors ought to discuss age-appropriate screening tests in apparently healthy persons before recommending screening tests. Given the time constraints, such discussion may likely be missing in most cases.
A disturbing phenomenon is the evolution of informal alliances between commercial groups, physicians, and consumer groups. To enhance the utilization of screening tests, incentives and kickbacks are offered. Such practices are unpardonable. Accepting commission or kickbacks is a breach of trust that a doctor owes to the patient. A case in point is the “master health check-up” package offered in many corporate hospitals. On the surface, the philosophy of this package appears laudable that of early diagnosis and treatment. However, among the battery of tests included in this package, few have evidence in support for routine screening. The cost of this package is six times as compared to routine tests.
In 2004, the U.S. Preventive Services Task Force found insufficient evidence to recommend thyroid screening. The issue was revisited a decade later to review again the benefits and harms of screening and treating subclinical and undiagnosed overt hypothyroidism and hyperthyroidism in adults without goiter or thyroid nodules. The review of evidence could not identify any study which directly assessed the benefits and harms of screening versus no screening. For subclinical hypothyroidism, one retrospective cohort study found that treatment of subclinical hypothyroidism was associated with decreased risk for coronary heart disease events versus no treatment. However, this benefit was limited to younger age group (40–70 years). In people over 70 years, there was no association between the use of levothyroxine and risk of ischemic heart disease. Potential limitation of this study was lack of adjustment for medications to reduce the risk for cardiovascular disease. No study in this systemic review found that treatment was associated with improved quality of life, cognitive function, blood pressure, or body mass index. Effect of treatment showed potential beneficial effects on lipid levels, but effects were inconsistent and not statistically significant in most studies. Treatment harms were poorly studied and inconsistently reported.
So once again, after a decade of the first extensive review in 2004, the U.S. Preventive Services Task Force on Screening and Treatment of Thyroid Dysfunction found insufficient evidence to recommend thyroid screening. It concluded that more research is needed to determine the clinical benefits, if any, associated with thyroid screening.
Similarly, evidence review for screening and treatment of prostate cancer undertaken for the U.S. Preventive Services Task Force showed modest and conflicting results and also associated harms related to subsequent evaluation and treatments, some of which may be unnecessary. Screening based on prostate-specific antigen (PSA) identified additional cases of prostate cancer, but most trials found no statistically significant effect on prostate cancer-specific mortality. Meta-analysis of randomized trials included in the review identified no beneficial summary effect of screening on prostate cancer-specific mortality., The two largest and highest quality trials reported conflicting results., Schröder et al. reported PSA screening for every 2–7 years to be associated with 20% relative risk reduction in death from prostate cancer in a subgroup of men aged 55–69 years, whereas Andriole et al. found no effect. Screening was also associated with potential adverse effects such as infections or urinary retention in 0.5% of men who underwent prostate biopsy as a result of an abnormal PSA result. False-positive screening results were found in 12–13% of men randomly assigned to PSA-based screening,, with 1 trial reporting no prostate cancers in 75% of screening-triggered biopsies. Screening also resulted in overdiagnosis due to detection of low-risk cancers that would not have caused morbidity or death during a man's lifetime, and overtreatment of such cancers exposed the subjects to avoidable harms.
The review concluded that PSA-based screening results in small or no reduction in prostate cancer specific-mortality and it is associated with harms related to subsequent evaluation and treatment, some of which may be unnecessary. It also concluded that if screening is effective, optimal screening intervals and PSA thresholds remain uncertain.
This brief editorial has only emphasized the darker side of diagnostic tests and only dealt with screening for two disorders, i.e. thyroid disorders and prostate cancer. Idea was to give the present consensus on screening for these two disorders as the present issue of the journal includes a review on thyroid function tests and a short review on PSA.
It may be conceded that there are many situations and different conditions where screening tests are beneficial and save lives as a result of early detection and prompt treatment. However, to optimize the benefits of screening tests, judicious and objective assessment by doctors without any conflict of interest is important.
Doctors and their patients also need to know the following pitfalls in interpreting the results of diagnostic tests. The normal range of test results is calculated so as to include 95% of the readings obtained in a group of healthy people which means that there is a 5% risk that a healthy person will present with an abnormal test result. Extrapolated, if a normal person undergoes 10 different tests, there is a probability that there is a 40% chance of at least one of them being abnormal – if he undergoes 25 different tests (not unusual in package deals), this chance rises to 72%. Hence, all tests have to be evaluated in the context of the history and clinical examination besides the epidemiology of the disease in person, place, and time dimensions.
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