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The development and validation of the King's Brief Interstitial Lung Disease (K-BILD) health status questionnaire
  1. Amit S Patel1,
  2. Richard J Siegert2,
  3. Katherine Brignall1,
  4. Patrick Gordon3,
  5. Sophia Steer3,
  6. Sujal R Desai4,
  7. Toby M Maher5,
  8. Elisabetta A Renzoni5,
  9. Athol U Wells5,
  10. Irene J Higginson2,
  11. Surinder S Birring1
  1. 1Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
  2. 2Department of Palliative Care, Policy and Rehabilitation, King's College London, Cicely Saunders Institute, London, UK
  3. 3Department of Rheumatology, King's College Hospital, London, UK
  4. 4Department of Radiology, King's College Hospital, London, UK
  5. 5Interstitial Lung Disease Unit, Royal Brompton Hospital, London, UK
  1. Correspondence to Dr Surinder S Birring, Division of Asthma, Allergy and Lung Biology, King's College London, Denmark Hill, London SE5 9RS, UK; surinder.birring{at}


Rationale Health status is impaired in patients with interstitial lung disease (ILD). There is a paucity of tools that assess health status in ILD. The objective of this study was to develop and validate the King's Brief Interstitial Lung Disease questionnaire (K-BILD), a new health status measure for patients with ILD.

Methods Patients with ILD were recruited from outpatient clinics. The development of the questionnaire consisted of three phases: item generation; item reduction, allocation to domains by factor analysis, Rasch analysis to create unidimensional scales and validation; and repeatability testing.

Results 173 patients with ILD (49 with idiopathic pulmonary fibrosis) completed a preliminary 71-item questionnaire. 56 items were removed due to redundancy, low factor loadings or poor fit to the Rasch model. The final version of the K-BILD questionnaire consisted of 15 items and three domains (breathlessness and activities, chest symptoms and psychological). Internal consistency assessed with Cronbach's α coefficient was 0.94 for the K-BILD total score. Concurrent validity of the K-BILD questionnaire was high compared with St George's Respiratory Questionnaire (r=0.90) and moderate with lung function (vital capacity, r=0.50). The K-BILD questionnaire was repeatable over 2 weeks (n=44), with intraclass correlation coefficients for domains and total score 0.86–0.94. The K-BILD construct validity for patients with idiopathic pulmonary fibrosis was similar to that of other ILDs.

Conclusion The K-BILD questionnaire is a brief, valid, self-completed health status measure for ILD. It could be used in the clinic to assess ILD from the patients' perspective.

  • Quality of life
  • interstitial lung disease
  • idiopathic pulmonary fibrosis
  • connective tissue disease
  • NSIP
  • health status
  • interstitial fibrosis
  • sarcoidosis
  • non-invasive ventilation
  • COPD mechanisms
  • ANCA related vasculitides
  • systemic disease and lungs
  • lung transplantation
  • α1 antitrypsin deficiency
  • cystic fibrosis
  • respiratory measurement
  • lung physiology
  • bronchiectasis
  • airway epithelium
  • drug-induced lung disease
  • rare lung diseases
  • allergic alveolitis
  • ANCA-related vasculitides
  • asbestos-induced lung disease
  • pulmonary eosinophilia
  • pulmonary vasculitis
  • cough/mechanisms/pharmacology

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  • Funding King's College Hospital Charity. AW, TM and ER are supported by the NIHR Respiratory Disease Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London.

  • Competing interests None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.

  • Ethics approval The ethics approval was provided by London—Surrey Borders Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement All data are published in this article.

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