WS13.04Management of intermediate sweat chloride results and diagnosis of CFTR related disorders in a large tertiary paediatric centre

Objectives

This study aimed to review the management of children and young people who have had a sweat test with a sweat chloride concentration (SCC) in the intermediate range between 30 and 59mmol/L.

Methods

All sweat tests with a result in the intermediate range undertaken at our large tertiary paediatric hospital between 01/01/2019 and 31/12/2023 were identified from laboratory records. Electronic health records were reviewed retrospectively to obtain further patient data. Patients diagnosed with CF or CF SPID following newborn screening were excluded.

Results

A total of 47 patients were identified. The primary indication for performing a sweat test included chronic respiratory concerns (74%), pancreatitis (6%), poor growth (6%), surgical concerns (rectal prolapse, bowel stricture - 4%), gastrointestinal symptoms (4%) and nasal polyps (4%).

A total of 31 patients (66%) underwent genetic testing. Five patients were found to have two CFTR mutations, in each case one known to be CF causing and one variant of varying clinical consequence. Four were heterozygous for one CF causing mutation. Eight patients (17%) had not been seen by a CF physician. Only 14 patients had documented advice on CFTR dysfunction.

Conclusions

In our large paediatric centre we identified a significant number of patients with an intermediate SCC who had not received further genetic investigations. There were also a number in whom documented advice on CFTR dysfunction had not been provided and a group who had not been reviewed by the CF team. In the era of modulator therapies and their potential clinical benefit, accurate diagnosis of CFTR related disorders is increasingly important. This work, along with the 2022 publication ‘ECFS standards of care on CFTR-related disorders: Updated diagnostic criteria’ (Castellani, JCF 2022) will be used to define a new local guideline for referral of all patients with intermediate SCC to clinicians with expertise in CF diagnosis.