Are Screening Tests Harmful?

Doctors must go by the principle of Primum non nocere—a dictum that means “First do no harm”. The question remains whether or not screening tests currently performed in today’s time follow that dictum.

A screening test is one that is performed on a person who has no symptoms of a given disease and is thought to be basically healthy. The idea behind the test is to find a disease for which there are no symptoms. Such screening tests include a routine PAP test for cervical cancer, a mammogram for breast cancer and cholesterol screening for heart disease. Screening is done to large groups of people with follow up for those people who screening test is positive or equivocal for disease.

Screening is different from searching for a disease in a person already suspected to have the disease because of early symptoms or signs. This is traditionally how doctors did their medical practice. Such investigation of disease can occur if the person has simply a family history of the disease. X-rays can be done on a smoker with a severe cough; this is considered investigational medicine.

There are a lot of ethical questions around the current practice of screening for diseases. Should there be screening of hoards of asymptomatic people in the absence of scientific proof that this actually saves lives and prevents disease? Are the tests actually beneficial for the population of people who take the tests and does cost play a role in the cost/benefit analysis?

The decision rests on the question of whether or not screening of disease and detecting it in the early stages actually saves lives. Is it better for the patient to detect disease earlier? Some challenge this and say that, in some cases, the answer is no. This means that a disease is just as lethal when diagnosed earlier or that a later diagnosis isn’t as bad as everyone thinks. In some cases, either situation can be true and screening tests might not be as good as they’re made out to be.

The whole idea behind screening is that the screening test isn’t inherently harmful to the patient. But that isn’t actually the case. Some screening tests can be harmful, such as a colonoscopy that can puncture the intestinal lining, leading to complications in the bowel and abdominal cavity. Other screening tests can be safe to take but the secondary effects can be dangerous. For example, if you have had a screening test showing high cholesterol and are on anti-cholesterol medication after that, the medications can show a side effect or harmfulness to the patient.

The real challenge is to determine the risk/benefit ratio of screening tests and to see if the benefit is actually worth the risk.