Rationale The A Tool to Assess Quality of Life in Idiopathic Pulmonary Fibrosis (ATAQ-IPF) was developed in the USA to assess health-related quality of life in patients with IPF. It is likely that some of the original ATAQ-IPF items perform differently when applied in different countries. This paper reports results of a study conducted to identify the need to refine the content of the ATAQ-IPF to minimise cross-country bias between the USA and the UK.
Methods The ATAQ-IPF and other study measures were completed by patients attending specialist IPF clinics in the USA and UK. Rasch analysis was used to determine which items performed differently across countries (USA vs UK) and refine the original ATAQ-IPF to an instrument without cross-country bias (ATAQ-IPF-cA). Preliminary validation of the modified instrument was examined by assessing correlations between ATAQ-IPF-cA scores and scores from dyspnoea-specific patient-reported outcome (PRO) measures.
Results 139 patients with IPF (USA=74; UK=65) participated in the study. A total of 41 items and 4 domains were removed from the original, 86-item instrument to yield the 43 items and 10 domains of the ATAQ-IPF-cA. Each domain had good fit to the Rasch model, internal consistency was comparable to the corresponding domains for the original ATAQ-IPF, and validity was supported by significant correlations between its scores and scores from dyspnoea-specific PROs.
Conclusions The reliability and validity of the substantially shortened ATAQ-IPF-cA are acceptable and comparable to the original instrument. We recommend use of the ATAQ-IPF-cA in IPF studies in which participants are enrolled from the USA and UK.
- Interstitial Fibrosis
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.