Essential Diagnostics for the Use of World Health Organization Essential Medicines

There are numerous barriers to achieving high-quality laboratory diagnostic testing in resource-limited countries. These include inconsistent supply chains, variable quality of diagnostic devices, lack of human and financial resources, the ever-growing list of available tests, and a historical reliance on syndromic treatment algorithms. A list of essential diagnostics based on an accepted standard like the WHO Essential Medicines List (EML) could coordinate stakeholders in the strengthening of laboratory capacity globally.

To aid in the creation of an essential diagnostics list (EDL), we identified laboratory test indications from expert databases for the safe and effective use of WHO EML medicines. In all, 446 EML medicines were included in the study. We identified 279 conditions targeted by these medicines, spanning communicable and noncommunicable diseases (e.g., HIV, diabetes mellitus).

We found 325 unique diagnostic tests, across 2717 indications, associated with the identified conditions or their associated medicines. The indications were divided into 10 categories: toxicity (865), diagnosis (591), monitoring (379), dosing/safety (325), complications (217), pathophysiology (154), differential diagnosis (97), comorbidities (53), drug-susceptibility testing (22), and companion diagnostic testing (14). We also created a sublist of 74 higher-priority tests to help define the core of the EDL.

An EDL such as we describe here could align the global health community to solve the problems impeding equitable access to high-quality diagnostic testing in support of the global health agenda.