Clinimetric Properties of Outcome Measures in Bronchiectasis in the UK
Condition: Bronchiectasis
MeSH terms: Bronchiectasis
Study type: Observational

Summary: 
      There is an increasing demand for researchers and regulatory bodies to use robust outcome
      measures in clinical trials which have evidence of validity, reliability, and responsiveness.
      There is currently little agreement on the core clinical endpoints that should be used in
      bronchiectasis. The importance of improving endpoint outcome measurement is well recognised
      and groups in other conditions have focused on activities to achieve consensus on a core set
      of outcomes for clinical trials. The Bronch-UK collaboration has explored the current
      evidence for clinimetric properties of commonly used outcome measures in bronchiectasis (e.g.
      forced expiratory volume in one second [FEV1], health related quality of life [HRQoL], and
      pulmonary exacerbations). The results of this extensive rigorous literature review of 68
      papers clearly demonstrate that whilst there was good evidence for validity for key outcome
      measures in bronchiectasis there is little information available on their reliability (during
      periods of clinical stability) or response to treatment (effect sizes).

      The aim of this study is to explore the clinimetric properties of a range of outcome
      measures, in order to make recommendations for their use in clinical trials in
      bronchiectasis.
    

Detailed description: 
      Bronchiectasis is a persistent or progressive condition characterised by dilated thick-walled
      bronchi. The recent guidelines stipulate that high resolution computerised tomography scan
      (HRCT) is the radiological investigation of choice to establish the diagnosis of
      bronchiectasis. The key radiological features of bronchiectasis include bronchial wall
      dilation (internal lumen diameter greater than accompanying pulmonary artery) which is the
      characteristic feature of bronchiectasis.

      Prevalence of bronchiectasis in most populations is largely inaccurate due to lack of recent
      studies. United Kingdom (UK) figures indicate prevalence figures of 100/100,000 based on
      studies undertaken in the 1950's but these did not involve use of high resolution
      computerised tomography scan for diagnosis. This number is five to ten times higher in people
      over 55 years of age. The mean age of death is 72 years.

      The aetiology for bronchiectasis is variable, however, current data suggests that the most
      common causes are: post infectious; immunological; congenital; with a proportion also
      idiopathic.

      Bronchiectasis is increasingly being recognised as a major cause of pulmonary morbidity. The
      signs and symptoms of bronchiectasis include chronic sputum production, shortness of breath
      and fatigue; all of which contribute to increased morbidity and may progress to respiratory
      failure and cor pulmonale.

      The management of bronchiectasis incorporates an intense regime of prevention and treatment.
      These often include daily intake of inhaled and nebulised medications, antibiotic therapy,
      airway clearance, visits to GP and/or respiratory clinics and hospitalisation. The burden of
      treatment associated with bronchiectasis is therefore significant and is provided at a huge
      economic cost to the health service. Many of these treatments are provided in the absence of
      a sound evidence base and so there is a clear need to develop assessment tools for use both
      in clinical trials and in clinical practice.

      There is an increasing demand for researchers and regulatory bodies to use robust outcome
      measures in clinical trials which have evidence of validity, reliability, and responsiveness.
      There is currently little agreement on the core clinical endpoints that should be used in
      bronchiectasis. The importance of improving endpoint outcome measurement is well recognised
      and groups in other conditions have focused on activities to achieve consensus on a core set
      of outcomes for clinical trials. The Bronch-UK collaboration has explored the current
      evidence for clinimetric properties of commonly used outcome measures in bronchiectasis (e.g.
      forced expiratory volume in one second [FEV1], health related quality of life [HRQoL], and
      pulmonary exacerbations). The results of this extensive rigorous literature review of 68
      papers clearly demonstrate that whilst there was good evidence for validity for key outcome
      measures in bronchiectasis there is little information available on their reliability (during
      periods of clinical stability) or response to treatment (effect sizes).

      Spirometry is a method of assessing lung function by measuring the volume of air that the
      patient is able to expel from the lungs after a maximal inspiration. Spirometry is a method
      for measuring the speed and volume of airflow and is seen as the "gold standard" of testing
      lung function. Forced expiratory volume in one second (FEV1) in healthy individuals and those
      with early disease mostly reflects proximal airways, however, the annual rate of change in
      FEV1 in bronchiectasis is very small and FEV1 is not very responsive to many treatments
      especially in mild disease. In recent years other measures of lung function are emerging as
      potential outcome measures in bronchiectasis. The pathological changes in bronchiectasis
      involve the small airways. Forced expiratory flow between 25 and 75% (FEF25-75) of forced
      vital capacity (FVC) has been proposed as a sensitive measure of early airways dysfunction.
      The major barriers to the use of this are that FEF25-75 is very dependent on patient effort,
      is less reproducible than FEV1 and has poorly defined normal ranges in different age groups.
      Lung clearance index measured by multiple breath washout (MBW) is a measure of ventilation
      inhomogeneity and is considered to reflect abnormalities of the smaller airways. Small airway
      disease caused by inflammation and obstruction leads to ventilation heterogeneity. This will
      therefore cause an increased number of breaths to remove a tracer gas due to uneven gas
      mixing and subsequently an increased lung clearance index.

      To date, the majority of studies using the lung clearance index have been conducted in cystic
      fibrosis. These studies have shown that lung clearance index is more sensitive than
      spirometry at detecting early lung pathology and that it is a sensitive and repeatable
      clinical endpoint. It has been used as a secondary end-point in the UK cystic fibrosis gene
      therapy multidose study; Invacaftor study; hypertonic saline study; and, DNase study.

      The investigators have conducted some preliminary studies to explore the use of lung
      clearance index in bronchiectasis and have shown that lung clearance index is repeatable over
      short periods of time and a more sensitive indicator of computed tomography (CT) scan
      abnormalities than spirometry in bronchiectasis. Further research is needed to provide data
      on long term repeatability during periods of stability (noise) and also establish its
      responsiveness to change (effect size).

      Multiple questionnaires including the St Georges Respiratory Questionnaire (SGRQ); Quality of
      Life - Bronchiectasis (QOL-B) Questionnaire; and, EuroQol 5 Dimension (EQ-5D) have been used
      to capture the impact of health related quality of life (HRQoL)/patient reported symptoms in
      bronchiectasis. There is no comparative data to direct choice of the most appropriate
      questionnaire for use in clinical trials. With respect to individual questionnaires there is
      also the need to provide data on long term repeatability and reliability.

      Aims:

      The aim of this study is to explore the clinimetric properties of a range of outcome
      measures, in order to make recommendations for their use in clinical trials in
      bronchiectasis. These measures include: lung function (spirometry, lung clearance index);
      health related quality of life (HRQoL) assessment [St Georges Respiratory Questionnaire
      (SGRQ); Quality of Life - Bronchiectasis (QOL-B) Questionnaire; EuroQol 5 Dimension (EQ-5D)];
      and, blood (white cell count, c-reactive protein) and sputum (microbiology, inflammatory
      markers) processing.

      Specific Objectives:

        -  To ascertain the relative stability (least noise) of these potential outcome measures in
           bronchiectasis over a one year timeframe.

        -  To ascertain the relative effect size of these outcome measures over a pulmonary
           exacerbation signal interval (greatest signal-to-noise ratio).

        -  To compare clinimetric properties (reliability, validity and responsiveness to change)
           of the health related quality of life (HRQoL) questionnaires.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with bronchiectasis
      
Biospecimen description: 
      Blood plasma and sputum specimens
    
Keywords: Clinimetrics; Lung function; Lung clearance index