Prevalence and impact of airway diseases on clinical outcomes in idiopathic pulmonary fibrosis

Abstract

Background/aims: The prevalence and effects of airway diseases, including asthma, eosinophilic bronchitis (EB), chronic obstructive pulmonary disease (COPD), and asthma-COPD overlap (ACO) have not been thoroughly studied in patients with idiopathic pulmonary fibrosis (IPF). This study aimed to evaluate the prevalence of airway diseases in patients with IPF and to identify the differences in symptoms based on the presence of airway diseases.

Methods: This single-institution prospective cohort study was conducted from June 2017 to September 2018, at the Seoul National University Hospital. Spirometry with bronchodilator, methacholine bronchial provocation test, induced sputum with eosinophil stain, and exhaled nitric oxide were performed to confirm the presence of airway disease. The modified Medical Research Council (mMRC) dyspnea scale, COPD assessment test (CAT), St. George's Respiratory Questionnaire (SGRQ), EuroQol-5 dimension (EQ-5D) index, and cough-specific quality of life questionnaire (CQLQ) data were collected to assess symptom severity.

Results: Total 147 patients with IPF were screened, and 70 patients were analyzed. The prevalence of airway diseases in the participants was as follows: 5.0% had COPD, 1.7% had asthma, 3.3% had ACO, and 1.7% had EB. The mMRC, CAT, SGRQ, EQ-5D, and CQLQ scores did not differ regardless of combined airway disease. After 3 months, the SGRQ (p = 0.028) and CQLQ (p = 0.030) scores were significantly higher in patients with airway disease than in those without.

Conclusion: The prevalence of airway diseases in patients with IPF is low, but when airway diseases are accompanied by IPF, symptom severity and quality of life may worsen rapidly.

Keywords: Asthma; Asthma-chronic obstructive pulmonary disease overlap syndrome; Idiopathic pulmonary fibrosis; Pulmonary disease, chronic obstructive; Respiratory therapy.

Figure 1

Flow chart of the study. IPF, idiopathic pulmonary fibrosis; ILD, interstitial lung disease; COPD, chronic obstructive pulmonary disease; ACO, asthma-COPD overlap; EB, eosinophilic bronchitis.

Figure 2

Changes in the clinical outcomes according to the presence of airway diseases in the groups after propensity score matching with forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). (A) Chronic obstructive pulmonary disease (COPD) assessment test (CAT) score, (B) St. George’s Respiratory Questionnaire (SGRQ) score, (C) modified Medical Research Council (mMRC) dyspnea scale, (D) cough quality of life questionnaire (CQLQ) score, (E) EuroQol-5 dimension (EQ-5D) score, and (F) cough visual analogue scale (VAS) score. The analysis was carried out with 24 patients after excluding 11 patients who were lost to follow-up and matching by propensity score matched analysis with FVC and FEV1. Increasing scores indicate worsening outcomes in CAT, SGRQ, CQLQ, VAS, and mMRC. Decreasing scores indicate worsening outcomes in EQ-5D. Differences between the two groups were tested using repeated measures analysis of variance (RM-ANOVA). Visit 1, baseline; Visit 2, 3-month follow-up. ^ap < 0.05.

Figure 3

Comparison of changes in the clinical outcomes between patients who used inhalers for their airway diseases and those who did not use inhalers due to the absence of airway disease. (A) Chronic obstructive pulmonary disease (COPD) assessment test (CAT) score, (B) St. George’s Respiratory Questionnaire (SGRQ) score, (C) modified Medical Research Council (mMRC) dyspnea scale, (D) cough quality of life questionnaire (CQLQ) score, (E) EuroQol-5 dimension (EQ-5D) score, and (F) cough visual analogue scale (VAS) score. The analysis was carried out with 48 subjects excluding 11 patients who were lost to follow-up and 11 patients who used inhaler improperly. Increasing scores indicate worsening outcome in CAT, SGRQ, CQLQ, VAS, and mMRC. Decreasing scores indicate worsening outcome in EQ-5D. Differences between the two groups were tested using repeated measures analysis of variance (RM-ANOVA). Visit 1, baseline; Visit 2, 3-month follow-up. ^ap < 0.05.

Figure 4

Changes in clinical outcomes depending on the use of inhalers in patients who needed inhalers. (A) Chronic obstructive pulmonary disease (COPD) assessment test (CAT) score, (B) St. George’s Respiratory Questionnaire (SGRQ) score, (C) modified Medical Research Council (mMRC) dyspnea scale, (D) cough quality of life questionnaire (CQLQ) score, (E) EuroQol-5 dimension (EQ-5D) score, and (F) cough visual analogue scale (VAS) score. The analysis was carried out with 21 subjects who had airway diseases, positive result of induced sputum, or a high level of fractional exhaled nitric oxide. Increasing scores indicate worsening outcomes in CAT, SGRQ, CQLQ, VAS, and mMRC. Decreasing scores indicate worsening outcome in EQ-5D. Differences between the two groups were tested using repeated measures analysis of variance (RM-ANOVA). Visit 1, baseline; Visit 2, 3-month follow-up. ^ap < 0.05.