Although science has long relied on animal models to understand human biology, researchers continue to learn that animal models are not fully predictive of what happens in people. At the end of the day, the very best way to understand human biology, health and well-being is by studying humans. A number of “tried and true” research approaches, with a human basis, have stood the test of time and have made significant contributions to our understanding of human health and disease. This section describes some of the traditional research methodologies that are critical for advancing science in a human-relevant fashion.
Autopsy studies and study of postmortem specimens
Autopsies are medical procedures performed by doctors (pathologists) in which an individual’s body is thoroughly examined after death. In addition to acquiring information about the cause and manner of an individual’s death, a great deal of information about disease and injury present can also be collected. During the procedure, doctors can:
- determine the cause of an individual’s death
- learn how a disease progresses
- learn if specific treatments for diseases have been effective
- collect specimens of tissues and body fluids for additional study
- work with government agencies to track and identify diseases and public health hazards.
Physicians and researchers alike recognize how important autopsy and post mortem studies are to advancing science. Dr. Gerald D. Fischbach, a professor emeritus at Columbia, was recently quoted as saying, “There’s just no question that human tissue is the gold standard for research … You absolutely need it to answer some very basic questions.” Dr. Gregory Davis, forensic pathologist at the University of Kentucky College of Medicine agrees: "The autopsy has long been and remains the gold standard for confirming or ruling out diagnoses and plays an integral role in promoting the public health."
Autopsies have been responsible for a number of significant medical breakthroughs, but unfortunately, data has shown that the rate of autopsies performed in the U.S. and abroad is on the decline for a number of reasons. It is thought that some physicians’ attitudes towards autopsy have had a major effect on autopsy rate. Several studies have shown that many physicians do not request permission from the next of kin of the deceased to perform an autopsy because they felt that they had already collected sufficient information from the patient prior to death and because of overreliance on the tools used to make patients’ diagnoses, although in many cases, discrepancies exist between premortem and postmortem diagnoses. Other reasons for the decline include concerns of the physician about litigation, discomfort in asking the next of kin for permission to perform the autopsy, and lack of funding for the procedure, as the cost of an autopsy is generally not covered by health care organizations or by the patient’s insurance. In any case, many opportunities for retrieving valuable, human-relevant information critical for advancing science are being missed.
The following sources provide additional information on how autopsy studies have contributed greatly to our understanding of human health:
- The age of onset of atherosclerosis
-Strong, JP, et al. Prevalence and Extent of Atherosclerosis in Adolescents and Young Adults. Journal of the American Medical Association. 1999; 281(8): 727-735.
- The mechanisms underlying Sudden Infant Death Syndrome (SIDS)
-Blood-Siegfried, J. The Role of Infection and Inflammation in Sudden Infant Death Syndrome. Immunopharmacol Immunotoxicol. 2009; 31(4): 516–523.
- The mechanisms underlying Alzheimer’s Disease
-Joachim, CL, et al. Clinically diagnosed Alzheimer’s disease: autopsy results in 150 cases. Ann Neurol. 1988; 24(1): 50-6.
- The pathologic description of AIDS
-Welch K, et al. Autopsy findings in the acquired immune deficiency syndrome. Journal of the American Medical Association. 1984; 252(9):1152–9.
- Finding diagnostic errors which would have otherwise gone undiscovered
-Goldman L, et al. The value of the autopsy in three medical eras. New England Journal of Medicine. 1983; 308(17): 1000–5.
-Anderson R E, et al. The sensitivity and specificity of clinical diagnostics during five decades. Toward an understanding of necessary fallibility. Journal of the American Medical Association. 1989; 261 (11): 1610–7.
-Veress B, et al. Clinical diagnostic accuracy audited by autopsy in a university hospital in two eras. Qual Assur Health Care. 1993; 5(4):
-Kirch W, et al. Misdiagnosis at a university hospital in 4 medical eras. Medicine (Baltimore). 1996; 75(1): 29–40.
-Sonderegger-Iseli K, et al. Diagnostic errors in three medical eras: a necropsy study. Lancet. 2000; 355 (9220): 2027–31.
Epidemiology is a field of research focused on the study of the incidence, distribution and control of disease in a population, enabling scientists to best understand how, when and where diseases occur. Epidemiologists play an important role in advancing science and improving human health and well-being because their investigations into the causes of disease and other human health issues can prevent the spreading of disease and stop the public health issues from happening again. One of the important jobs of an epidemiologist is to try to determine risk factors (like environmental and lifestyle factors) associated with disease as well as factors that may help protect against disease. Epidemiological studies have demonstrated the relationship between smoking and cancer and have unveiled the association between chemical exposure and disease in the occupational sector, among many other things. Although epidemiological studies do not prove that specific risk factors actually cause the disease under investigation, they do show the correlation of specific risk factors with incidence of disease.
Many different methods are used to conduct epidemiological investigations. Distribution of health-related states or events, like disease, can be monitored by surveillance and descriptive studies, and analytical studies are conducted to understand the determinants of disease. Epidemiological investigations can also be divided in another way, based on whether events have already happened (a retrospective study) or whether they might occur in the future (a prospective study).
The sources below provide additional information on how epidemiological studies have contributed greatly to our understanding of human health:
- Association between smoking and lung cancer
-Doll R, et al. The mortality of doctors in relation to their smoking habits: a preliminary report. British Medical Journal. 1954; 1: 1451-5.
- The Framingham Heart Study for identification of risk factors associated with cardiovascular disease
-Ho, KKL, et al. The epidemiology of heart disease: The Framingham Study. Journal of the American College of Cardiology. 1993; 22(4):
- The multi-step nature of cancer formation
-Armitage, P, et al. The age distribution of cancer and a multi-stage theory of carcinogenesis. British Journal of Cancer. 1954; 8(1): 1-12.
- The link between air pollution levels and public health
-Ransom MR, et al. Elementary school absences and PM10 pollution in Utah Valley. Environmental Research. 1992; 58(2): 204-19.
- The link between sub-clinical lead exposure and poor school performance and neurobehavioral function
-Needleman HL, et al. Deficits in psychological and classroom performance of children with elevated dentine lead levels. New England Journal of Medicine. 1979; 300(13): 689-95.
Clinical studies, also known as clinical trials, are biomedical or health-related research studies involving human volunteers. They are designed to answer specific questions about the safety and effectiveness of new therapies, devices, or ways of using known treatments.
Clinical studies collect human-relevant data and contribute significantly to medical research. In addition, those eligible individuals that participate in clinical trials have the opportunity to have a more active role in their own health care and have access to new treatments before they become available to the public. Participants are made aware of the risks involved in clinical trial participation, including side effects of the experimental treatment, the fact that the treatment may or may not be effective for the participant, and that the clinical trial protocol may take up more time and attention than a non-protocol treatment. However, individuals participating in clinical trials are taken care of by medical experts at leading health care facilities while they are participating in the trial.
Clinical studies are conducted after a drug has completed laboratory and animal testing and are also conducted under strict ethical and legal guidelines to protect the rights of the people involved. Individuals who are considering entering a clinical trial receive informed consent documents that provide important facts about the clinical trial to help the patient decide whether or not to participate. The informed consent document explains details about the study and why the research is being conducted, what will be done during the trial, how long the trial will last, and the risks and potential benefits of participating. Individuals may withdraw from clinical trials at any time if they so choose.
Clinical trials continue to provide valuable, human-relevant data that moves science forward. After all, in order to understand exactly how humans will respond to new therapies or devices, we need to test them in people. There is no shortage of human clinical trials available or individuals willing to participate. In fact, in 2012, the clinical trial webpage sponsored by the National Institutes of Health indicated that there are currently 133,741 trials available with locations in 180 countries.
To learn more about just a few of the ways that clinical studies have contributed greatly to our understanding of human health, see the following articles:
References: American Medican NewsClinicalTrials.govMedscape - Reason fort the Decline in Autopsy Rates Medscape - Physician Attitudes Toward AutopsyNational Center for Biotechnology Information - EpidemiologyNew York Times - Brain Banks for Autism Face DearthWebMD - AutopsyWorld Health Organization
- The Salk Polio Vaccine Trials
-Salk, JE, et al. Studies in human subjects on active immunization against poliomyelitis. Am J Public Health Nations Health. 1954; 44(8): 994-1009.
- Post Menopausal Estrogen Therapy for Reduction of Coronary Heart Disease Risk
-Hulley, S. et al. Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Journal of the American Medical Association. 1998; 290(7): 605-613.
- Lumpectomy vs. Mastectomy Trial for Early Stage Breast Cancer
-Fisher, B. et al. Five-year results of a randomized clinical trial comparing total mastectomy and segmental mastectomy with or without radiation in the treatment of breast cancer. New England Journal of Medicine. 1985; 312(11): 665-73.
- The use of statins in prevention of cardiovascular disease
MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20 536 high-risk individuals: a randomised placebo controlled trial. The Lancet. 2002; 360(9326): 7-22.