Experts Warn Diagnostic Tests Crucial for Effective Medicine

New analysis from UCSF highlights the overlooked importance of diagnostics in healthcare innovation and patient outcomes.

Apr. 10, 2026 at 9:02am by Ben Kaplan

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A ghostly, translucent X-ray photograph revealing the intricate internal components of a medical diagnostic device, highlighting its essential function in guiding effective treatment.An X-ray view of the complex inner workings of a medical diagnostic device, underscoring the crucial yet often overlooked role of testing in effective healthcare.San Francisco Today

A new analysis from researchers at the University of California, San Francisco (UCSF) argues that diagnostic medical tests, which help match patients to the appropriate treatments, are being undervalued and underinvested in both in the United States and globally. The authors say this is slowing progress against major diseases, despite rapid advances in targeted therapies and precision health.

Why it matters

Diagnostic tests are essential for guiding medical decisions and ensuring patients receive the most effective treatments, but they often receive less funding, research, and insurance coverage than new drugs or therapies. This misalignment can leave powerful diagnostic tools underutilized and prevent doctors from making fully informed decisions about patient care.

The details

The UCSF analysis found that nearly half the world's population lacks adequate access to diagnostic tests. These tests receive less investment for research and development, as well as lower insurance reimbursement than drugs, creating barriers to innovation. For example, many people do not respond to GLP-1 drugs for obesity and diabetes, but few tests exist yet to predict which patients will benefit. Similarly, new Alzheimer's drugs exist to slow disease progression, but the blood tests that could match patients to the most beneficial drugs are costly and rarely covered by insurance.

  • The study was published in the journal Science on April 9, 2026.

The players

Kathryn Phillips

A professor of Health Economics in the School of Pharmacy at UC San Francisco and the lead author of the study.

Robert M. Califf

The former commissioner of the U.S. Food and Drug Administration and a co-author of the paper.

UCSF

The University of California, San Francisco, which is exclusively focused on the health sciences and dedicated to promoting health worldwide through advanced biomedical research, graduate-level education, and excellence in patient care.

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What they’re saying

“Most people can easily understand how a new drug or surgery might help a patient. But the tests that guide medical decisions are just as critical.”

— Kathryn Phillips, Professor of Health Economics, UCSF School of Pharmacy

“Regulatory and payment policy should evolve in tandem with scientific and technological advances. The current misalignment between how we evaluate diagnostics for consideration of allowing marketing and the system for reimbursement decisions about diagnostics versus drugs leaves powerful tools on the shelf and provides inadequate data to make good decisions about which diagnostic tools should be eschewed for lack of benefit in the real world.”

— Robert M. Califf, Former FDA Commissioner

What’s next

The authors say there are clear steps policymakers can take to fix these gaps, including reviewing tests and treatments together, streamlining approvals for tests, and improving how diagnostics are evaluated and paid for.

The takeaway

This case highlights the critical but often overlooked role of diagnostic tests in guiding effective medical treatment and ensuring patients receive the most appropriate care. Addressing the systemic underinvestment and undervaluing of diagnostics could unlock significant progress against major diseases.