A New Tool to Assess Quality of Life in Patients with Idiopathic Pulmonary Fibrosis or Non-specific Interstitial Pneumonia.

ABSTRACT

BACKGROUND: Quality of life (QoL) is significantly impaired in patients with pulmonary fibrosis, however reliable tools to assess QoL issues specific for this group of patients are still missing. We thus aimed to develop a new questionnaire called "Quality of life in patients with idiopathic pulmonary fibrosis" (QPF) to measure QoL in patients with fibrotic idiopathic interstitial pneumonias (IIP). METHODS: An item pool was created on the basis of a German expert group with support of patients suffering from pulmonary fibrosis. In a 1st step, this version of the questionnaire was completed by 52 patients with idiopathic pulmonary fibrosis (IPF) or non-specific interstitial pneumonia (NSIP). Following this, an item- and an exploratory factor analysis was carried out and a 2nd version created. In a multicenter validation study in a one-group pre-post design, the questionnaire was filled in by 200 patients with IIP (IPF = 190, iNSIP = 10) at 2 time points with an interval of 6 months. Cross-validation was carried out with the St. Georges Respiratory Questionnaire (SGRQ). RESULTS: The mean age of the patients was 71.0 years (50-90 years), 82.5 % were male. Item analysis revealed that most of Cronbach alpha and selectivity values of QPF-scales could be considered as sufficient (e. g. QPF-scale "condition" [alpha = 0.827], "impairment" [alpha = 0.882]). At scale level, there were significant differences in terms of a deterioration or improvement in the QPF-condition and QPF-breathlessness scales and also in the SGRQ-activity scale. Analysis of construct validation of QPF and SGRQ showed moderate correlations between both questionnaires. A deterioration in health status from the patient's and doctor's perspective was seen in the scales "impairment", "shortness of breath" and "health status" of the QPF. The QPF was able to detect a change in the patient's mood ("condition" scale) in the course of treatment. CONCLUSION: This newly developed questionnaire maps the special needs of the patients well. The QPF is suitable for screening of quality of life as well as for supplementing the medical history and for monitoring the course of disease in fibrotic IIPs.