WS15.06Comparison of the Leeds criteria and CFHealthHub criteria for classification of chronic Pseudomonas aeruginosa infection in people with cystic fibrosis in the post-modulator era

Abstract

Objectives

The 2023 UK CF Registry reported a prevalence of chronic Pseudomonas aeruginosa (Pa) in people with CF (PwCF) ≥16y of 14.6%, down from 40.7% in 2019. Since the availability of elexacaftor/tezacaftor/ivacaftor (ETI) in 2020, many PwCF have less sputum, making clinicians increasingly reliant on less-sensitive cough swabs to detect Pa. As a result, classification methods like the Leeds Criteria, which rely solely on sample positivity, may underestimate prevalence. We aimed to compare chronic Pa prevalence across an entire centre cohort using the Leeds criteria and CFHealthHub (CFHH) criteria, which also incorporates Pa serology, strain typing and clinical context.

Methods

All PwCF (≥16 years) at a UK adult CF centre were classified as either “chronic Pa” or “not chronic Pa” based on both Leeds and CFHH criteria. Data were cross-tabulated, and agreement measured using Cohen's kappa.

Results

Among the 240 PwCF, the median age was 30 years (IQR: 23-38), 113 (47.1%) were female and 198 (82.5%) were on a CFTR modulator. Median %FEV1 was 86.7% (IQR 66.6-98.6) and BMI 25.1 (21.9-28.3). The Leeds criteria classified 32 people (13.3%) with chronic Pa infection compared to 107 (44.6%) using the CFHH criteria. Crude agreement was 68.8%, with a kappa coefficient of 0.32 (95% CI: 0.23–0.41).

Conclusions

In this single centre study, more than three times the number of PwCF were classified as having chronic Pa using the multi-component CFHH criteria compared to the Leeds criteria. The apparent reduction in chronic Pa prevalence since 2019 may partly reflect limitations in classification methods relying solely on microbiological samples. In PwCF with low or absent sputum production, additional investigations may be required to more accurately determine Pa status and guide treatment recommendations.