Quality of Life and Bronchial Hyper-Responsiveness in Subjects With Bronchiectasis: Validation of the Seattle Obstructive Lung Disease Questionnaire in Bronchiectasis

Study Design

This study included 78 subjects with clinically stable bronchiectasis and 41 healthy controls matched for age and sex. Patients attending the clinic who had been diagnosed with bronchiectasis by high-resolution computed tomography (CT) were approached to take part in the study. All subjects signed informed consent forms, and the study was approved by the local ethics committee.

A detailed history, physical examination, and spirometric measurements were obtained from each subject. Clinical stability was required in all subjects, and it was defined as the absence of clinical worsening beyond normal daily variations with no need for increasing habitual or rescue medication for at least 4 weeks before evaluation.

Exclusion criteria included the presence of cystic fibrosis, cardiac disorder, cognitive impairment, treatment with systemic corticosteroids, or respiratory tract infection in the previous 4 weeks. The etiology of bronchiectasis in the study was not investigated. As a control group, we studied healthy subjects of similar age and sex who had never smoked. No participant suffered from any other chronic disease (COPD, diabetes mellitus, liver cirrhosis, thyroid dysfunction, rheumatoid arthritis, chronic renal failure, and/or psychiatric disorders) or was taking any type of medication.

Quality of Life

The SOLQ is a 29-question instrument developed to measure physical and function, coping skills, and treatment satisfaction. Individual items of the SOLQ are scored on a simple linear scale, with a response of 1 representing the lowest function. Responses to questions on the scale are summed into a raw score and then transformed to a normalized score ranging from 0 to 100. This normalized score is calculated by subtracting the lowest possible score from the raw score and then dividing this by the range of possible scores and multiplying by 100. Each of the 4 scales is scored separately, with a score of 100 representing the highest possible function. Currently, no overall score can be generated.¹⁰ First, the SOLQ was translated into Turkish by a specialist in social psychology and 2 other clinicians in chest disease areas, and the final text was constructed using their common sentences. Second, the test was administered to a small group of 7 subjects with bronchiectasis. After this administration, some words that caused misunderstanding were changed.

The general HRQOL instrument used in this study was the SF-36 (version 1.0). The SF-36 measures the health domains of physical functioning, role limitations due to physical health problems, bodily pain, general health, vitality, social function, role limitations due to emotional problems, and mental health. These domains can be further aggregated into 2 summary scores for physical and mental health.^11,12

Assessment of Psychological Status

Subjects were asked to fill in the self-reported Hospital Anxiety and Depression Scale (HADS) questionnaire. The questionnaire consists of 14 questions, in which the overall severity of anxiety and depression is rated on 4-point scale (0–3). Seven questions are related to anxiety and 7 to depression.¹³

Bronchial Provocation Test

A histamine inhalation test was performed on subjects to determine the level of bronchial hyper-reactivity. Before testing, inhaled and oral bronchodilators were withheld for at least 12 h. Inhaled corticosteroids were not withheld. Histamine solution (diphosphate salt, Sigma, Deisenhofen, Germany) was prepared in sterile isotonic saline. The histamine challenge test was performed according to a standardized procedure.¹⁴ Pulmonary function was measured by a flow-sensing spirometer connected to a computer for data analysis (Jaeger, Würzburg, Germany). Each subject inhaled increasing (doubling) concentrations of histamine (0.03–16 mg/mL) nebulized by a dosimeter with an output of 0.9 ± 0.3 mL/puff (Dosimeter APS Pro, Jaeger) until FEV₁ was reduced by 20% from baseline values. Bronchial response to histamine was expressed as the provocative dose causing a 20% fall in FEV₁ (mg/mL) and calculated using the same computer program (LAB 4.3, Jaeger).

An exacerbation was defined as subjective and persistent (>24 h) deterioration in at least 3 respiratory symptoms, including cough, dyspnea, hemoptysis, and increased sputum purulence or volume. For the purposes of this study, exacerbation frequency was defined as the number of times in the previous year a subject had these symptoms as a result of bronchiectasis.

High-Resolution CT

CT scans of the chest were performed on a Picker SeleCT (Haifa, Israel) in high-resolution mode according to the method of Mayo et al.¹⁵ The matrix size was 512 × 512, and the scanning time was 2.1 s. Subjects were examined while supine during full deep inspiration with their arms held over their heads. Images were recorded at a window width of 1,600 Hounsfield units and at a window level of −600 Hounsfield units. No intravenous contrast medium was administered. Section cuts of 1.5-mm thickness at 10-mm increments were obtained throughout the lungs.

Two observers independently scored each of 6 lobes (the lingula was regarded as a separate lobe) at inspiratory CT scanning. The presence and extent of bronchiectasis, on the basis of established CT criteria, were scored as follows: grade 0 = no disease, grade 1 = localized bronchiectasis affecting one or part of one bronchopulmonary segment (localized), grade 2 = bronchiectasis in more than one bronchopulmonary segment (extensive), and grade 3 = generalized cystic bronchiectasis. The average severity of bronchial dilatation was quantified relative to the adjacent pulmonary arteries as follows: grade 0 = no bronchiectasis, grade 1 = 100–200% arterial diameters, grade 2 = 200–300% arterial diameters, and grade 3 = >300% arterial diameter. Bronchial wall thickness was quantified relative to the adjacent pulmonary arteries as follows: grade 0 = none, grade 1 = <50% arterial diameter, grade 2 = 50–100% arterial diameters, and grade 3 = >100% arterial diameter.^16,17 The CT diagnosis of mosaic perfusion was established according to the area of low attenuation compared with adjacent normal lung parenchyma.

Statistical Analysis

The internal consistency measures the degree of association between the questionnaire items. It was tested to determine the Cronbach α coefficient. A minimum of 0.7 for the Cronbach α coefficient was accepted as the minimum reliability coefficient for group comparison. Test-retest reliability, which measured the ability of the SOLQ to produce consistent scores over a short period of time (at 2 weeks), and the intraclass correlation coefficient were determined. Concurrent validity of the SOLQ was assessed by comparing its component and total scores with the SF-36 and HADS overall scores and the clinical parameters.

The relationship between variables was determined by Pearson rank correlation analysis. Subjects with bronchiectasis were categorized in terms of the presence or absence of bronchial hyper-reactivity. The differences between groups were assessed with the Student t test and Mann-Whitney U test as appropriate. Multiple linear regression analysis was performed with the quality-of-life scores as the dependent variables and the extent of bronchiectasis, HADS scores, percent-of-predicted FEV₁, sex, age, bronchiectasis duration, exacerbation frequency, and presence of bronchial hyper-reactivity as predictor variables. Predictor variables were entered into the multivariate model using a stepwise procedure. Clinical data were expressed as mean ± SD. P < .05 was considered statistically significant.