Debriefing the Brief: It is Time for the Provision of Informed Consent before Pediatric CT

Introduction

In the welter of controversy surrounding the statistical risk projection models of radiation-induced cancer from medical imaging, two recent seminal studies that used direct epidemiologic data from large cohorts of children have emerged and confirmed that the use of computed tomography (CT) produces a small cancer risk. Such studies leave little doubt that these new data move beyond statistical constellations, bear biologic plausibility, and justify concerns about cancer risk from CT performed in childhood and adolescence. In this article, we provide a fresh perspective about the critical need for signed informed consent to strengthen and codify the practice of shared decision making before performing CT in children. A historic and legal overview of informed consent, with an emphasis on provision before all CT studies, has already been addressed by several of the authors in a previous issue of Radiology (1). In the present discussion, we narrow the scope to concentrate on the ethical responsibility for signed informed consent before performing CT in children, an especially vulnerable population.

In a selection from his best-selling book, It Worked for Me: In Life and Leadership (2), General Colin Powell reflected on lessons learned on the battlefield and in the halls of power. He offers a formula for good decision making in the midst of controversial issues and unpredictable consequences: “Over time I developed for my intelligence staffs a set of four rules to ensure that we saw the process from the same perspective and to take off their shoulders some of the burden of accountability: Tell me what you know, tell me what you don’t know, then tell me what you think, always distinguish which is which.” Although General Powell’s directive is brief, for providers in the setting of health care delivery and risk communication, it is no small prescription. It is an example of right conduct as habit.

What We Know: “Cancer Risks from Diagnostic Radiology: The Impact of New Epidemiologic Data”

With the use of electronic record linkage in large populations over many years, two large epidemiologic analyses in the United Kingdom and Australia showed similar results: a 24% increase in cancer in children and adolescents who were exposed to ionizing radiation from CT (3–6). Further, such estimates of lifetime risk that are based on direct analyses and epidemiologic data gleaned from national health registries are compatible with various lifetime risk estimates that are derived from atomic bomb survivor data (7). According to DJ Brenner (7), “the epidemiologic data from A-bomb survivors exposed to low doses and from direct epidemiological studies of pediatric CT are reasonably consistent, suggesting that we do have a reasonable quantitative understanding of the individual risks—in summary, very small but unlikely to be zero.” In a recent editorial in Radiology, DJ Brenner and EJ Hall (8,9) opined that organ dose and atomic bomb survival data were used to estimate a lifetime leukemia risk of approximately 1 in 10 000 for those who underwent pediatric head CT compared with the 1 in 7500 lifetime risk estimate based on direct epidemiologic data, whereas there is an estimated lifetime brain tumor risk of about 1 in 2000 compared with the 1 in 1000 lifetime estimate based on direct epidemiologic data (4). The authors concluded that “it follows that the standard method of estimating radiologic risks—estimating organ doses and applying atomic bomb survivor data—yields fairly reasonable results at CT-like doses” (9). Most authorities now affirm that there is sufficient evidence linking future cancers to the low-dose range (5–100 mGy) associated with a single CT scan (10,11). Westra (10) observed that “as an emerging moral imperative, it falls upon the medical profession to offer information to all patients and their parents of those risks.”

What We Know: The Vulnerable Population of Children in the Midst of Widespread Dose Variation and Unnecessary CT Scans

Radiation-induced cancer risk is magnified in children and adolescents because there is more time for the malignancy to manifest (usually decades later) and because their cells divide more rapidly, making them more susceptible (12). Between 5 million and 9 million CT examinations are performed annually in children in the United States (13). A recent population-based study of more than 350 000 children across five large health care markets in the United States showed that exposure to ionizing radiation from medical imaging may occur frequently among children and that the average child in this study population will have undergone more than seven diagnostic imaging studies that use low-dose ionizing radiation by the time he or she reaches 18 years of age (14). A 2013 study culled data from a large research network of six major health maintenance organizations in the United States and quantified trends in the use of pediatric CT scanning and the associated radiation exposure and cancer risk (15). The study found that many children received high radiation doses from CT. The authors attribute this finding both to the greater use of higher dose CT, such as of the abdomen and pelvis, and to substantial variability in radiation doses (15,16). For example, in this study, among children enrolled in a health maintenance organization, the doses for abdominal CT in children 1–4 years old was 4.8–137 mSv for a single study (15,17). A study at Children’s Hospital Boston and Harvard Medical School evaluated abdominal-pelvic CT performed in children during trauma evaluations at community hospitals prior to transfer of care (18). The study disclosed that fully one-half of children received radiation doses that were greater than the 75th percentile norm, ranging overall from 0.17 to 5.07 times the norm (18). To utilize the data presented by Brenner and Hall (12), wherein the standard radiation dose (10 mSv) for abdominal CT carries a mortality risk of one in 1400 for a 15-year-old child, one in 1100 for a 5-year-old, and one in 700 for a toddler, it is unfortunate that over one-half of the children received radiation doses that exceeded the standard dose, presumably placing them at even higher risk for radiation-induced cancer mortality. The authors also noted that most of these CT studies failed to reveal any pathologic conditions (18). In light of this finding, it should be acknowledged that, in a number of cases, negative findings also provide useful clinical information. In pediatric patients undergoing abdominal CT, multiphase scanning is still common in the community hospital setting, despite the fact that, rather than increasing the diagnostic yield, radiation dose is substantially increased (usually tripled) (19). As T. Slovis (20) comments in his review following the 2014 Image Gently ALARA (as low as reasonably achievable) CT Summit, “sadly, these results are quite similar to those found back in 2001 by Paterson et al,” a study that underscored unnecessarily and inappropriately high radiation doses in pediatric CT (21).

Although it is difficult to imagine modern medicine without CT, there is convincing evidence that a substantial fraction of the approximately 80 million CT studies performed annually in the United States are ordered without sound medical justification. Appropriateness criteria for CT studies are critically important because authoritative sources, including the Radiological Society of North America and the American College of Radiology, suggest that 20%–50% of such studies could be replaced by another type of imaging or not be performed at all (16,22,23).

The volume of CT studies performed in children in nonpediatric-specific emergency departments has increased. As many as 6.8 million pediatric CT studies are performed at nonpediatric-focused facilities (20,24). Two large recent studies that used the National Hospital Ambulatory Medical Care Survey data and 14 major commercial health plans across the United States covering all treatment settings and various physician specialties showed dramatic increases in CT utilization in children with abdominal pain and headache, respectively (25,26). In both studies, the authors observed that such overall increased reliance on CT among children occurred despite a low diagnostic yield and a lack of improved clinical outcomes (25,26).

Such verifiable facts demonstrate that the continued overuse of CT and the substantial variations in radiation dose only serve to exacerbate the preexisting problem of radiation-induced cancer risk in children and should further compel physicians to take the most morally relevant action. Today, there is no law that requires physicians to obtain informed consent before a patient undergoes CT. However, in the special case of performing CT in children, legal requirements may be outweighed by moral dictates. It is the ethical duty of the health care provider to inform parents of a potential health risk that they might regard as important. For instance, in the setting of abdominal or pelvic CT, parents may well consider being informed of a one in 500 chance of developing cancer important (4,27).

From a medical-legal perspective, most hospitals and medical practices routinely recommend obtaining written informed consent before general anesthesia is administered or before common procedures, such as colonoscopy, are performed (29,28). In children and young adults who undergo a single CT study, the risk for developing a fatal malignancy later in life are one in 500 for children younger than 1 year old, one in 1250 for children who are 10 years old, and one in 1600 for those who are 20 years old, a risk that is 20–100 times greater than that after colonoscopy (one in 10 000) and general anesthesia (one in 56 000) (8,28–30). If informed consent is regularly sought before general anesthesia is administered and common procedures, such as colonoscopy, are performed, in the words of de Campo (28), “then it is equally appropriate and consistent to seek informed consent before [obtaining] CT scans in children and young adults. Anything less may not be medico-legally sustainable.”

What Patients, Parents, and Providers Want to Know

Concerns about the health risks of radiation from CT continue to intensify in the public domain, as evidenced by a recent article in The New York Times entitled “We Are Giving Ourselves Cancer” (32). Yet even the most recent surveys in the medical literature disclose that patients still have poor knowledge of radiation risks (33–35). In a recent large cohort prospective survey of parents whose children presented to a tertiary care pediatric emergency department with a head injury, 90% of parents wished to be informed of potential cancer risks from CT (36). Of note in this survey, whereas the median age of the children was only 4.4 years, 12% of children already had a history of CT, and 97% of children had only a minor head injury or concussion (36). Further, before the risk estimate provision, 90% of parents were willing to proceed with CT; however, after the disclosure of risk, willingness decreased to 70%, with 6% refusing CT (36). In a recent study examining patients’ views of CT and informed consent, a large majority (77%) responded that informed consent should be signed by patients before undergoing CT (35).

A large survey canvassing Children’s Healthcare of Atlanta tertiary care hospitals revealed that most physicians (71.3%) agreed that informed consent should be obtained before CT to communicate the risk for cancer from radiation exposure and that most physicians (55%) felt that radiology departments should provide information about the risk for radiation-induced cancer in those who undergo CT (37). Interestingly, in this same study, most physicians did not know whether the radiology department actually informed patients about such a risk. The impetus for this study was based on the authors’ assertion that “risk communication is a critical part of medical ethics and public health” (37).

Intelligence Gathering

In the arena of CT scanning and health risks, the process of shared decision making, although celebrated in principle, is challenging in practice. A very recent qualitative analysis with focus groups in the emergency department disclosed that both providers and patients believe that radiation risks should be discussed. Yet providers and patients alike lacked knowledge of radiation risk estimates for CT and had divergent perceptions of the extent and quality of conversations involving radiation risk (34). Such small group interviews can provide rich insights into communication barriers, as the only physician in the survey who knew the correct doses of all three CT protocols retorted, “I think the only reason I knew the answers to your survey is because the electronic medical record at my hospital makes me review the x-ray exposure doses before I sign the order” (34). Specific emergency department provider quotes included: “I can’t even understand a one in 1600 risk that might be delayed 50 years. How is a patient going to?,” “sometimes it’s faster and easier to just get the scan,” and “I’d rather talk with patients about more important things [than a small radiation risk].”

Movement in the communication of health risks associated with CT has been sluggish. Despite a decade of reports, a lack of general knowledge of radiation risk persists among clinicians (34,38). In the past, 95% of patients were not informed of any risk (39). Most current studies show that only 22%–24% of patients are informed of the health risks of CT (33,35).

What We do not Know

Although the radiology community proselytizes the precept of ALARA, if 10 radiologists and 10 physicists were asked what dose a patient should receive for a routine head or abdominal CT study, there would be wide variability in their responses (40,41). If the same experts were asked what doses such patients typically receive, there would be even larger variability (40,41). An apt description of this uncertainty is as follows:

This description also entails the concept of cumulative dose. What is important to consider: cumulative dose over 1 year? A lifetime? Many experts consider that cumulative radiation dose received over a lifetime may be the more correct measure of risk (43). Yet another obstacle to knowing risk is that a radiogenic tumor is clinically and pathologically indistinguishable from cancer resulting from other causes (44). Until a definitive “fingerprint” of a radiation-induced tumor is found, for each individual patient who undergoes CT, radiation-induced cancer risk remains unknowable.

Santa and Lipman (45) and Firestein (46) suggest that we may understand more by appreciating the ignorance that good science creates rather than focusing only on the knowledge, and Firestein says, “but there is another, less pejorative sense of ignorance that describes a particular condition of knowledge: the absence of fact, understanding, insight, or clarity about something. It is not an individual lack of information, but a communal gap in knowledge…this is knowledgeable ignorance, perceptive ignorance, insightful ignorance. It leads us to frame better questions, the first step in getting better answers” (46).

What We Think

We believe that a standardized “radiation consent” form should be given to parents or caregivers, which they would be required to read and sign before every pediatric CT study. The word “consent” derives from the Latin phrase “con sentire,” which means to feel together (47). Such etymologic insight promotes the understanding and practice of consent as arriving at agreement, as opposed to solely granting permission. The informed consent process is not intended to be a substitute for the entire decision-making process; instead, it is designed to solder shared decision making. Without the critical element of a formal, standardized, reproducible document, the evidence for risk communication remains circumstantial. For instance, during the episode of care before performing CT, it is easy to infer that the provider’s implicit concern for patient safety has been made explicit through an explanation of radiation risk. However, only a durable document in the medical record reflecting the duty of the provider to investigate the health and protect the safety of the patient, as well as the duty of the parent to promote the welfare of his or her child, would codify this important dialogue and provide a verifiable evidentiary base.

In conclusion, if we assume that there are radiation risks when there are none, we will be expending effort and resources to minimize those risks; however, if there truly are radiation risks that we choose to ignore, we will have subjected our children to long-term detrimental consequences (48). The danger to the radiology community in not taking the morally relevant stance of requiring informed consent before every CT study performed in a child is that we stand the real chance of having regulations imposed upon us, as is already the case in Europe (22). That the medical profession in general and radiologists in particular should defer to the government or legal system to solve the dilemma of whether and how to discuss radiation risks with patients may compromise patient trust (49). In addition to fulfilling health care providers’ duty to communicate and codify risks, this initiative holds promise to help reduce the substantial number of studies that are not clinically indicated and accelerate efforts to reduce CT radiation dose (36,49). In the modern age of medicine, we should all strive to protect our greatest natural resource: the health and well-being of our children.