An evaluation of physiotherapy-led inhalation testing in chronic respiratory disease at a tertiary centre

Background Inhaled medications improve health outcomes in chronic respiratory patients. Guidelines and pharmaceutical licensing agreements recommend a drug response trial prior to use. Evidence to support this recommendation is of poor quality; adverse events are rare, and the trial process has a considerable impact on physiotherapy clinical time and patient experience. Current literature suggests using percentage predicted forced expiratory volume in 1 second (FEV1) >55% as a predictor of trial success. Aims 1. To identify the failure rate of inhaled therapy trials in the chronic respiratory cohort. 2. To predict risk factors associated with trial outcome to establish those who could avoid a trial due to low risk stratification. Methods An evaluation of service was completed which involved a retrospective review of 204 chronic respiratory participants who completed an inhaled therapy trial between September 2017 and September 2019. Spirometry and other anthropometric measurements were recorded at the time of the drug response trial. Data was analysed using multivariable logistic regression to identify variables linked to passing inhaled therapy trials. Discussion and conclusion FEV1% predicted was significantly less for those that failed (35.5%) compared to those that passed (53.18%) p = 0.012. Those with an FEV1 predicted >55% had a higher likelihood to pass p = 0.005, R² = 0.039. The evaluation identified a low failure rate (4.9%) overall to inhalation therapy trials, with the most significant risk factor for failure being identified as FEV1 predicted