A picture paints a thousand words. Seeing inside the body, without recourse to a scalpel, through x-rays, CT scans, MRIs and ultrasounds, has revolutionized patient diagnosis and treatment. Yet the sought for certainty and confirmation of suspected diagnoses is not always conclusive, and may introduce unintended consequences, such as investigation momentum: additional, and potentially excessive and invasive, diagnostic testing.
Awareness of radiation exposure risks associated with some tests, particularly when administered to children, are reflected in the Image Gently campaign that makes ordering such tests contingent on risk-benefit assessments. However, the downstream effects of inconclusive or ambiguous results that spawn investigation momentum may be overlooked.
Using unreliable tests for screening purposes increases the risk of investigation momentum. My colleagues and I examined whether receiving an inconclusive result from a prostate-specific antigen (PSA) screening test, which gave no information on the likelihood of cancer, would propel more men to opt for a prostate biopsy. We found that significantly more men (40 percent) stated they would undergo a biopsy if they received an inconclusive PSA result whereas only 25 percent of men opted for a biopsy when they had no PSA test. These results suggest that the consequences of excessive testing may include, as well as higher costs and patient anxiety, further, often unnecessary, and frequently invasive, procedures.
Routine imaging, for example, has not proven beneficial in investigating low back pain, and can engender an investigation momentum of unneeded additional follow-up tests that generate incidental findings, unnecessary surgery and significant cost. Similarly, whole-body CT screening in healthy people has no demonstrated benefits, but risks potentially harmful effects from radiation exposure and additional followups and tests for benign findings, appropriately termed “incidentalomas.”
The main psychological dynamics that push patients and physicians towards investigation momentum are ambiguity aversion and increased commitment to resolving uncertainty or discovering abnormalities. Patient accommodation and defensive medicine also may play a role, as may the conflicts of interest inherent in a fee-for-service model and self-referrals to scans on physicians’ own equipment, which may bias doctors, albeit perhaps unconsciously, to conduct more tests.
That medical imaging tests are nevertheless increasing, even at HMOs, which have no financial incentive to conduct them, suggests that radiologists may view imaging as part of a new standard of medical care. Cost being a key issue in U.S. healthcare policy, questions about benefits and whether more diseases are actually diagnosed gain importance as access to imaging increases.
Investigation momentum could be curbed by relying more on histories and examinations and less on imaging tests as the standard path to diagnosis. Increased communication regarding risks and benefits may help to reassure some patients, particularly the “worried well,” that imaging may not be in their best interest. Reducing the use of CT scans on symptomless patients or for minor injuries in favor of thoughtful, selective testing based on detailed patient history and examination would improve patient care and reduce cost and investigation momentum. Sometimes it is better to rely on a thousand words than an unclear picture.
About the author: Sunita Sah, MD, MBA, PhD, is an assistant professor of strategy, economics, ethics and public policy at Georgetown University and a research fellow at the Ethics Center at Harvard University. Her research focuses on behavioral business ethics, decision-making and advice—in particular, how professionals who give advice alter their behavior as a result of conflicts of interest and the policies designed to manage them.