Development and validity testing of an IPF-specific version of the St George's Respiratory Questionnaire

Rationale The St George's Respiratory Questionnaire (SGRQ) is often applied to assess health-related quality of life in patients with idiopathic pulmonary fibrosis (IPF). Some SGRQ items will inevitably have weaker measurement properties than others when applied to this population. This study was conducted to develop an IPF-specific version of the SGRQ. Methods Data from a recently completed trial that enrolled subjects with IPF (n=158) who completed the SGRQ and other measures were analysed at baseline and 6 months. There were four phases to the study: (1) removing items with missing responses and using Rasch analysis on retained items to identify fit and refine item response categories; (2) development of a new scoring scheme; (3) testing agreement between original and revised versions and testing construct validity of the revised SGRQ; and (4) rewording to finalise the IPF-specific version (SGRQ-I). Results Items were removed due to missing responses (6 items) and misfit to the Rasch model (10 items); 34 items from the original 50 were retained. For certain items, disordered response thresholds were identified and corrected by collapsing response categories. A scoring algorithm was developed to place SGRQ-I scores on a scale with SGRQ scores. For any given outcome measure (eg, forced vital capacity (% predicted) and lung carbon monoxide transfer factor (% predicted), 6-min walk distance and patient-reported questionnaires), Pearson correlations were similar between pairs that included original SGRQ scores and corresponding pairs that included SGRQ-I scores. Internal reliability (Cronbach α) for each SGRQ-I component was comparable to the original SGRQ (Symptoms 0.62; Activities 0.80; Impacts 0.85). Conclusions The SGRQ-I contains items from the original SGRQ that are the most reliable for measuring health-related quality of life in patients with IPF

Cross-Atlantic modification and validation of the A Tool to assess quality of life in idiopathic pulmonary fibrosis (ATAQ-IPF-cA)

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

An empirical approach to the nucleation of sulfuric acid droplets in the atmosphere

We use quantum mechanical evaluations of the Gibbs free energy of the hydrates of sulfuric acid, H2SO4. nH2O and (H2SO4)2 . nH2O to evaluate an empirical surface tension for sulfuric acid-water clusters containing few molecules. We use this surface tension to evaluate nucleation rates using classical heteromolecular theory. At low temperatures (T 213 K) the nucleation rates obtained with the empirical surface tensions are signifi cantly greater than those using bulk values of the surface tension. At higher temperatures the difference disappears

Clinical use of biomarkers of survival in pulmonary fibrosis

<p>Abstract</p> <p>Background</p> <p>Biologic predictors or biomarkers of survival in pulmonary fibrosis with a worse prognosis, more specifically in idiopathic pulmonary fibrosis would help the clinician in deciding whether or not to treat since treatment carries a potential risk for adverse events. These decisions are made easier if accurate and objective measurements of the patients' clinical status can predict the risk of progression to death.</p> <p>Method</p> <p>A literature review is given on different biomarkers of survival in interstitial lung disease, mainly in IPF, since this disease has the worst prognosis.</p> <p>Conclusion</p> <p>Serum biomarkers, and markers measured by medical imaging as HRCT, pertechnegas, DTPA en FDG-PET are not ready for clinical use to predict mortality in different forms of ILD. A baseline FVC, a change of FVC of more than 10%, and change in 6MWD are clinically helpful predictors of survival.</p