Should There Be a Worldwide Standard List of Essential Diagnostic Tests?

Like the influential Model List of Essential Medicines (EML) maintained by the World Health Organization, there should be a list of key tests every country should have available, with high quality standards, according to a group of experts writing in the June issue of The New England Journal of Medicine.

EML, the authors note, has guided billions of dollars in spending by government agencies, healthcare organizations, and charities worldwide on more than 300 critical pharmaceuticals. A parallel Model List of Essential Diagnostics could help make healthcare more efficient by improving capacity and quality of testing in developing nations. “You can’t treat what you can’t test,” notes Lee F. Schroeder, MD, PhD, an assistant professor of pathology at the University of Michigan Medical School and lead author of the paper. “The list includes the most critical tests for diagnosing conditions, monitoring drug effects and toxicity, reducing overprescription of antibiotics, and enabling surveillance of infectious threats.”

Diagnostic tests are required to fulfill the healthcare needs of populations and are critical to the management of both communicable and noncommunicable diseases, surveillance of emerging infectious diseases, and the safe and rational use of EML medicines. For example, better access to diagnostic tests has been shown to quadruple the number of cases of HIV detected, to double the rate of adequate blood sugar control, and reduce overtreatment of malaria by 73%.

The paper proposes a list of 147 essential lab tests in 57 categories. Some of the tests could have an important impact on outbreaks that can spread throughout the world quickly, such as Ebola and Zika. As with medicines, some diagnostic tests have utility in more than 1 condition. For example, an elevated white cell count can suggest infection, and it can also indicate leukemia. The list syncs with the EML in that a single diagnostic test can guide the use of many different EML-listed medications. The paper lists 19 test categories that can guide the use of 10 or more medications or medication combinations that appear in the EML. The top test, complete blood count, corresponds with 136 medications on the EML; the second test, liver enzymes, corresponds with 104 medications. The last test listed, calcium, corresponds with 10 EML medications.

The EML is probably the single most important tool in global health, says Schroeder. A similar list of essential diagnostics is long overdue and could amplify the impact of current global health investment, he says, and would be cost-effective in the long run. “We believe the world can no longer wait to have laboratory testing available to all clinicians,” the authors say. “An EDL would clarify priorities for policymakers and encourage setting common goals regarding laboratory testing, paving the way toward improved health care delivery and ultimately better patient outcomes.”

Reference

Schroeder LF, Guarner J, Elbireer A, Castle PE, Amukele TK. Time for a model list of essential diagnostics. N Engl J Med. 2016;374:2511-2514. doi:10.1056/NEJMp1602825.