Reducing the environmental burden of unnecessary investigations

Unnecessary care

The definition of unnecessary care is “care that provides minimal or no benefit, considering the harms, the costs, alternatives and the preferences of the patient.”¹⁰ It is estimated that up to 30% of the investigations and treatments ordered in the health care system are unnecessary and 10% result in direct harm to patients.¹¹ Unnecessary testing can lead to false-positive results, further unnecessary interventions, overdiagnosis, anxiety, and overtreatment. It increases direct and indirect costs for patients and the system, diverting resources away from the provision of higher-value care. It creates additional work for technicians, clerical staff, and physicians responsible for reviewing and following up on results.^12,13 Investigations have direct and indirect costs to patients, the system, and the environment, whether the test is necessary or not. When there is little likelihood of benefit, exposing patients to these risks is unjustified.

Unnecessary care also has an enormous environmental cost, given the energy and resources required to extract, process, manufacture, package, transport, and dispose of materials required for each medication, investigation, or health care visit.¹¹ Reducing unnecessary care is a way primary care providers can reduce our environmental impact without compromising quality of care.¹¹ Medications, which are an important example of overuse in health care and account for 26% of the greenhouse gases produced in the Canadian health care system,⁴ will be discussed in a separate article in this series.

Drivers of overuse

Many systemic-, provider-, and patient-level drivers lead to overuse. Guidelines for specialists promote unrealistic volumes of tests and treatments that do not result in improvements to patient-relevant outcomes.¹⁴ Providers may also experience real or perceived pressures from patients. Training, habit, time limitations, and financial incentives, such as pay-for-performance targets, are additional drivers.¹⁵ Another concern relates to medicolegal risk, as more malpractice lawsuits result from overuse (complications or adverse effects) than underuse (missing a diagnosis by failing to order enough tests).¹⁶ Medicolegal experts advise that the most frequent contributor to litigation is inadequate physician-patient communication.^16,17

Laboratory testing

Tests require resources and energy to produce the supplies needed to collect and process each sample. Medical laboratories are some of the most resource-intensive parts of our system, using 10 times more energy and 4 times more water than offices, and generating billions of pounds of hazardous biological or toxic chemical waste every year.¹⁸ Although the impact of each laboratory test is small—for example, a complete blood count requires the same amount of energy as driving an average gas-powered vehicle 0.8 km¹⁹—they add up. In Canada, more than 1.2 million laboratory tests are performed every day.²⁰ A review of vitamin D testing in Australia found 1 in 6 (4,457,657) people were tested in 2020; 76.5% of these tests were considered unnecessary, at a cost of more than $87,000,000 AUD and a carbon footprint equivalent to driving 160,000 to 230,000 km.²¹ In another Australian study, microbiological tests (cultures) were found to be particularly resource-intensive due to the additional processing and storage required (Figure 1).¹⁹ A study done in Vancouver, BC, evaluated routine postoperative laboratory work in a small sample of 83 patients, and found that 76% of patients underwent unnecessary testing at a total cost of $5235, with 1.1 L of excess total blood drawn and a total environmental cost of 61 kg CO₂ equivalents (same as driving 245 km).²²

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Figure 1.

Climate change impact of laboratory tests

The most effective way to reduce the environmental impact of laboratory testing is to order fewer unnecessary tests.¹¹ While it depends on the study, it has been shown that an estimated 12% to 44% of laboratory tests ordered are not clinically indicated.²³

Medical imaging

The energy used to operate imaging equipment, along with the embodied energy (energy and materials used in the manufacturing of such tools) of the equipment itself, are substantial. In 1 study, medical imaging accounted for 4% of a hospital’s energy use.²⁴ Another study estimated that the operation of 1 computed tomography (CT) scanner for a year was comparable to the annual energy use of 5, 4-person households; and 1 magnetic resonance imaging (MRI) machine was comparable to 26, 4-person households.²⁴ Both CT and MRI machines have large carbon footprints in comparison to plain radiographs and ultrasound scans (Figure 2).²⁵ Imaging is associated with other specific environmental harms, such as disposal of contrast, radioactive materials (nuclear medicine), and physical waste (gowns, materials, cleaners).²⁶ Although there is much the radiology community can do to reduce these impacts,²⁶ avoiding requests for low-value imaging plays an important role in reducing the impact of primary care.

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Figure 2.

Energy use of diagnostic imaging modalities

A 2022 report by the Canadian Institute for Health Information and Choosing Wisely Canada²⁷ reported that 24% to 31% of patients with lower back pain and no red flags continue to undergo imaging. Of children presenting to the emergency department with uncomplicated asthma or bronchiolitis, 30% have chest radiographs that are not recommended, and 33% of children with minor head injuries have CT scans despite not meeting validated head CT scan rules. Other studies have found similar rates of unnecessary imaging.²⁸

Imaging carries specific risks: The amount of radiation in a typical chest CT scan is equivalent to 3 years of normal background radiation. The 4 million pediatric CT scans done annually in the United States are projected to cause 4870 future cancers.²⁹ People in regions of the United States with high CT scanning rates have a higher risk of nephrectomy for incidentally detected renal masses.³⁰ A 2018 umbrella review of 20 systematic reviews reported incidental findings in 45% of chest CT scans, 38% of CT colonographs, and 22% of brain and spine MRI scans.³¹ These findings can lead to patient anxiety, follow-up investigations, and interventional procedures that provide no benefit to patients.³¹ Overuse of imaging contributes to increased use and longer wait times, leading to a perceived need for more machines.¹³

Tips to avoid unnecessary investigations

Choosing Wisely Canada is an organization that identifies and educates clinicians about frequently overused tests and treatments unsupported by scientific evidence. Recommendations relevant to investigations in family practice are summarized in Box 1 and Table 1.³² To minimize unnecessary testing, providers can regularly review orders to ensure requisitions include only required and evidence-informed tests at appropriate intervals without duplication. Stepwise investigation is an important approach to consider: Most laboratories will hold samples for a week and perform additional testing if needed.¹⁵ Full panels are often unnecessary. For hepatic screening, for example, alanine transaminase and alkaline phosphatase tests alone are generally adequate.³³ Follow-up testing for values just outside the normal ranges in healthy patients with no signs of illness is not recommended since 5% of normal healthy patients will have “abnormal” results.¹³ Standard testing recommendations from guidelines for chronic diseases should be tailored to individual clinical needs and patient preferences.¹⁴ Patients with well-controlled diabetes who are on stable treatment, for example, may not need to have their hemoglobin A_1c levels checked as frequently as those who are newly diagnosed.³⁴ The PEER (Patients, Experience, Evidence, Research) simplified lipid guidelines suggest screening for lipids every 5 or 10 years after age 40 for men or 50 for women, and not using lipoprotein A or apolipoprotein B levels to determine risk. The guidelines also advise against repeat lipid testing for patients already undergoing treatment.³⁵

Optimizing teamwork and communication can help avoid unnecessary care, improve safety, and provide a better patient experience.³⁶ Primary care providers should ensure recent results are shared with other team members to avoid duplication. Radiologists and pathologists are important partners who can advise on the most appropriate types of testing and help interpret findings and recommendations for follow-up.

Patients tend to overestimate the benefits and underestimate the risks of testing and may request inappropriate imaging or laboratory investigations.³⁷ Providing information about the risks and benefits of testing and using shared decision making can help both patients and providers choose more appropriate investigations. For example, in 1 study, after being given an infographic about head CT scans for minor head trauma, 87% of participants stated they better understood when a CT scan is appropriate, 93% believed they better understood the risks, and 76% understood their doctor can often rule out serious illness without a CT scan.²⁷

Conclusion

Resources within our health care system and on our planet are finite and need to be distributed equitably. Family physicians have a professional and ethical responsibility to consider individual and population health, as well as the health of the planet and future generations.³⁶ Adhering to the principles of environmentally sustainable health care, including avoiding unnecessary investigations, can help primary care providers reduce environmental harms while simultaneously improving patient care, reducing costs, decreasing burdens on health care providers and patients, and creating a more sustainable and resilient health care system.