# Eliciting required and desired diagnostic test characteristics to develop patient-focused target product profiles (TPPs) for diagnosing infection and exacerbations in cystic fibrosis

## TL;DR

This study identifies unmet needs in diagnosing lung infections in cystic fibrosis patients and outlines desired features for new diagnostic tests to improve patient care.

## Contribution

The paper presents stakeholder-driven target product profiles for improved diagnostics in cystic fibrosis.

## Key findings

- Current diagnostics are unreliable, invasive, and slow, leading to uncertainty in treatment decisions.
- Stakeholders prioritize accuracy, faster results, and patient-friendly sampling methods for new tests.
- Improved diagnostics could reduce lung damage and antimicrobial resistance through early detection.

## Abstract

In addition to new antimicrobials for people with Cystic Fibrosis (pwCF), new diagnostics are needed to detect and diagnose infections, guide clinical care, and inform decision making. To determine the unmet needs in pulmonary infection diagnostics in Cystic Fibrosis (CF), the required diagnostic test characteristics and priorities of different stakeholders involved in the care of pwCF were collected and analysed.

Three focus groups (two clinical and one pwCF) were conducted and contributed to a wider project to deliver a suite of target product profiles (TPPs) for CF lung microbiological diagnostics. Thematic analysis was performed on the recordings, transcripts, and notes taken during the interviews.

Participants described their experience of the current practices and existing diagnostics for detection, diagnosis and management of infection and exacerbations in CF in the UK NHS.

Unmet needs included: monitoring modalities and testing for treatment efficacy; the lack of samples with good clinical utility; more acceptable methods for sampling; faster microbiology and culture testing. Greater communication between the laboratory and clinical teams, and equity of care across UK CF centres was also highlighted.

TPP characteristics of importance to pwCF and clinical representatives included ‘accuracy’, ‘time to results’, and ‘patient acceptability’. Participants across all groups highlighted the need for suitable alternatives to sputum and emphasised the need for novel biomarkers for the early detection and diagnosis of infection and exacerbation. Amongst clinical representatives, test accuracy was largely valued over the time to results for a clinical test in a non-acute setting.

These focus groups offered rich and detailed insights into the opinions of clinical staff and pwCF alike on the current landscape of diagnosis and management of pulmonary infection and exacerbations in CF. Early and rapid detection would likely have a positive impact on clinical care and inform earlier clinical decision making.

The overall health of people with cystic fibrosis is prone to rapid decline with the onset of each new or recurring lung infection they develop. Being able to diagnose a lung infection before symptoms persist, identify the strain and treat accurately and effectively with the right antibiotics provides the best opportunity to limit structural lung damage, irreversible decline, over medicalisation and speedier return to their normal routine, reducing impact on education, work or family commitments.

A focus group discussion with people living with CF and their carers heard why existing diagnostics do not meet their needs. Tests are unreliable, difficult to replicate, uncomfortably invasive, slow to give accurate results and leave clinicians uncertain about the appropriate course of treatment. This has a negative impact on the confidence of people with CF and increases anxiety. Focus groups with clinicians found the same concerns, identifying the need for new and improved methods of diagnosing lung infections to enable accurate clinical judgement when committing patients to a course of treatment with an ongoing consideration of limiting future treatment options through the development of antimicrobial resistance.

These findings were used as part of a wider project including questionnaire surveys and a symposium event to develop a suite of target product profiles (TPPs) (the ideal characteristics a test should have) for new diagnostic tests. The surveys and symposium included pwCF as well as healthcare professionals and developers of tests to ensure all views were heard.