The Serbian version of the King’s Brief Interstitial Lung Disease questionnaire and its validation in patients with idiopathic pulmonary fibrosis / progressive pulmonary fibrosis

Abstract

Introduction The King’s Brief Interstitial Lung Disease (KBILD) is the first health status questionnaire developed for use in patients with interstitial lung diseases (ILD). There is no valid and reliable questionnaire in Serbian to assess the health status of ILD patients. Progressive pulmonary fibrosis (PPF) and idiopathic pulmonary fibrosis (IPF) are ILD diseases with a progressive course and poor prognoses, which have the greatest impact on patients’ quality of life among all ILDs. The aim of the study is to validate the Serbian version of the KBILD questionnaire for use in patients with PPF, including IPF.

Methods The KBILD was translated into Serbian language. A total of 35 patients with IPF or PPF completed a translated version of the KBILD questionnaire at the baseline, and 29 of them after one month. Pulmonary lung function tests as well as St. George’s Respiratory Questionnaire (SGRQ) were completed at the baseline.

Results Internal consistency was high in the total, psychological, and breathlessness and activities domains, and satisfactory for the chest symptoms domain. The test-retest reliability was good for psychological and breathlessness and activities domains and excellent for chest symptoms and total score. All domains correlated strongly and very strongly with SGRQ, however, we found a weak correlation between the KBILD and lung function, and with Charlson comorbidity index.

Conclusions The Serbian version of the KBILD is valid and reliable for use in patients diagnosed with IPF/PPF.

Keywords: interstitial lung disease; idiopathic pulmonary fibrosis; questionnaire; quality of life