Urine drug test may improve adherence to blood pressure treatment, UK trial finds

The largest UK trial of a urine-based medication adherence test found that discussing test results with patients improved adherence to blood pressure medicines, although the intervention did not produce a statistically significant reduction in blood pressure.

A urine drug test already used across the UK’s National Health Service (NHS) may help patients take their blood pressure medicines more regularly, according to the largest randomised trial of its kind conducted in the country.

The study, led by researchers at The University of Manchester and Manchester University NHS Foundation Trust (MFT), evaluated a technology known as chemical adherence testing (CAT), which detects whether prescribed blood pressure-lowering medicines are present in a patient’s urine. The findings, published in The Lancet Primary Care on 16 April 2026, suggest the approach could improve medication adherence in people with hypertension, a major risk factor for cardiovascular disease.

Why medication adherence matters

Hypertension, or high blood pressure, is a chronic condition that often requires long-term treatment with medicines. However, many patients do not take their prescribed medicines consistently. According to the researchers, hidden non-adherence affects up to one in three people with high blood pressure and leads to unnecessary investigations and treatments, costing the NHS millions of pounds.

Medication adherence refers to how closely patients follow their prescribed treatment regimen. Poor adherence can make hypertension appear difficult to control, even when effective medicines have been prescribed.

The researchers tested whether sharing CAT results with patients, alongside a personalised discussion about missed doses, could improve adherence and help bring blood pressure under control.

How the OUTREACH study was conducted

The trial, known as the OUTREACH study, brought together 12 recruitment centres across the UK and was funded by the British Heart Foundation.

Researchers enrolled 130 adults with hypertension who were taking at least two blood pressure medicines but were found to be non-adherent based on urine testing using CAT.

Chemical adherence testing uses liquid chromatography-mass spectrometry, a laboratory technique that identifies specific drugs or their metabolites in blood or urine samples. The technology is primarily used in hospital hypertension and renal or cardiology clinics, particularly for patients with resistant hypertension.

Participants were randomly assigned to one of two groups:

• A CAT intervention group that received their test results along with a personalised discussion about reasons for missing medication doses.
• A usual care group that continued standard treatment without the intervention.

Improved adherence, but blood pressure impact remains unclear

After a median follow-up of nearly three months, the study found no statistically significant difference in average systolic blood pressure between the two groups.

Systolic blood pressure is the pressure exerted on artery walls when the heart contracts and pumps blood.

Although adjusted systolic blood pressure was approximately 5 mmHg lower in the intervention group than in the standard care group, the difference did not reach statistical significance.

However, patients who received the CAT-based intervention showed improved adherence to their prescribed blood pressure-lowering medicines three months after the intervention.

The researchers said this was a promising indication that the strategy may help patients take medicines more consistently.

Researchers call for larger trials

Professor Maciej Tomaszewski, Chief Investigator of OUTREACH, Professor of Cardiovascular Medicine at The University of Manchester and Honorary Consultant Physician at Manchester University NHS Foundation Trust, said discussing test results with patients appeared to improve adherence.

“Sharing the results of the CAT with the patients and the discussion for the reasons behind missing their blood pressure lowering medications appears to help in improving adherence,” Tomaszewski said.

He added that although there was a trend towards lower blood pressure among patients with improved adherence, the study did not identify a statistically significant effect on blood pressure outcomes.

“Hidden non-adherence remains a major and costly problem in hypertension care, and our findings underline the need for larger, longer-term trials to understand where CAT-based approaches might still add value,” he said.

Tomaszewski is also Integrative Cardiovascular Medicine Co-Theme Lead at the National Institute for Health and Care Research (NIHR) Manchester Biomedical Research Centre (BRC), which partly supported the research.

Potential role in personalised hypertension care

Study authors also suggest the technology could become part of a personalised approach to managing chronic conditions in which missed medication doses are common.

Professor Bryan Williams, Chief Scientific and Medical Officer at the British Heart Foundation and senior author of the study, said improving adherence remains a critical challenge in cardiovascular care.

“High blood pressure is the leading modifiable risk factor for cardiovascular disease in the UK, where it is associated with 50% of heart attacks and strokes. This means it is crucial that people take medications to treat it as advised by their doctor,” Williams said.

He added that personalised monitoring approaches could help address the many reasons patients do not take medicines as prescribed.

“We hope that this personalised approach to monitoring adherence can help address the many reasons why people may not be taking their medication properly, and support them to do so in future. This study showed signs that this strategy may help improve adherence, but to properly judge its effectiveness, a larger study is needed,” Williams said.