Modelling of Quality Life, Clinical and Physiological Measures in Idiopathic Pulmonary Fibrosis

Overview

As there are no validated tools for assessing patient reported outcomes or health related quality of life in idiopathic pulmonary fibrosis (IPF), different studies have utilised different methods. This means that comparison of the outcomes of studies is difficult or inaccurate. By collecting different quality of life tools and patient reported outcome at the same time, it will be possible to map or model the results of one tool or groups of tools onto another. 250 patients with IPF will be asked to complete the EuroQoL 5D, Kings Brief Interstitial Lung Disease questionnaire, St George's Respiratory Questionnaire, MRC dyspnoea scale, University of California, San Diego shortness of breath questionnaire and the Hospital Anxiety and Depression Scale, along with spirometry every 3 months, and undergo a 6 minute walk test every 6 months, over a 12 month period. Prognostic models will be constructed from all the clinical (questionnaire and function) measures a linear regression model.

There are no validated or accepted tools for assessing health related quality of life (HRQOL) or dyspnoea in patients with idiopathic pulmonary fibrosis (IPF) and there are no accepted or recommended tools for assessing patient reported outcomes in clinical trials of patients with IPF. Assessment of these outcomes is important to patients and may be considered the most crucial outcome measures of an intervention in IPF. With this in mind, the majority of the recently reported randomised clinical studies in IPF have evaluated HRQOL and dyspnoea, most commonly as secondary outcomes, but this has been achieved by different tools. For example the Capacity studies(1) utilised the St George's Respiratory Questionnaire whereas the ASCEND (Efficacy and Safety of Pirfenidone in Patients With Idiopathic Pulmonary Fibrosis) (http://clinicaltrial.gov/ct2/show/NCT01366209) study is currently assessing dyspnoea using the University of California, San Diego shortness of breath questionnaire. As there is no method of directly comparing HRQOL between different clinical evaluations in IPF, there is a desperate need to produce algorithms for relating the different outcome measures in IPF. The St George's Respiratory Questionnaire(2) is the most commonly utilised tool in trials of IPF(3-5). Although it relates to physiological impairment in IPF(6), it was developed in patients with Chronic Obstructive Pulmonary Disease (COPD) and therefore lacks content validity. An abbreviated version (SGRQ-I) containing the questions most relevant to IPF has therefore been developed and validated(7). The Kings Brief Interstitial Lung disease (K-BILD) questionnaire is a recently validated tool for patients with interstitial lung disease not specifically idiopathic pulmonary fibrosis(8) but has not been utilised in multicentre studies to measure treatment interventions in IPF. The EuroQol 5D (EQ5D) is a well-validated global health status instrument designed for use in clinical and health-economic trials(9). This has been validated in chronic respiratory disease and has been used in several studies(4, 5, 10). In terms of assessing dyspnoea, studies have utilised the University of California, San Diego (UCSD) shortness of breath questionnaire (SOBQ)(4, 11), the medicine research council (MRC) dyspnoea score(5), and the transition dyspnoea index(12). The investigators have conducted a brief mapping exercise based on the data from patients randomised to the placebo arm of the Treating idiopathic pulmonary fibrosis with the addition of co-trimoxazole (TIPAC) study(5). The SGRQ data were mapped onto the EQ5D data using pairs of data from individuals at the same time point with the addition demographic and lung function data(unpublished). This mapping exercise produced an equation with greater predictive strength than using data from COPD patients showing that modelling algorithms are disease specific information cannot be shared between different respiratory conditions. The investigators now wish to undertake a larger study to generate more accurate models to approximate the EQ5D and also to explore the relationship between other patient reported outcome measures. It is only by undertaking this work, that the results of individual studies can be compared.