A cohort study of mortality predictors and characteristics of patients with combined pulmonary fibrosis and emphysema

Our plain-English summary of A cohort study of mortality predictors and characteristics of patients with combined pulmonary fibrosis and emphysema, by T. Kishaba, Y. Shimaoka, H. Fukuyama, et al (BMJ Open, 2012).

The study

• Authors: T. Kishaba, Y. Shimaoka, H. Fukuyama, K. Yoshida, M. Tanaka, S. Yamashiro, H. Tamaki
• Journal: BMJ Open
• Published: 2012;2(3)
• Cited by: 47 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Our purpose was to assess the clinical data, predictors of mortality and acute exacerbation (AE) in combined pulmonary fibrosis and emphysema (CPFE) patients.

Design: Single-centre retrospective cohort study.

Setting: Teaching hospital in Japan.

Participants: We identified 93 CPFE patients with high-resolution computed tomographic (HRCT) through multidisciplinary discussion. Patients who had connective tissue disease, drug-associated interstitial lung disease and occupationally related interstitial lung disease, such as asbestosis and silicosis, were excluded.

Interventions: There were no interventions.

Methods: Medical records and HRCT scans from January 2002 through December 2007 were reviewed retrospectively at our hospital. Ninety-three patients had CPFE.

Results: The mean age of CPFE patients was 74 years. Idiopathic pulmonary fibrosis and non-specific interstitial pneumonia were observed as distinct HRCT patterns. Forty-two patients showed finger clubbing. Mean serum Krebs von den Lungen-6 (KL-6) and per cent predicted forced vital capacity (%FVC) were 1089 IU/l, 63.86%, respectively. Twenty-two patients developed AE during observation period. Baseline KL-6 was a strong predictor of AE (OR=1.0016, p=0.009). Finger clubbing (HR=2.2620, p=0.015) and per cent predicted forced expiratory volume in one second/%FVC more than 1.2 (HR=1.9259, p=0.048) were independent predictors of mortality in CPFE.

Conclusions: Baseline serum KL-6 was a useful predictor of AE (cut-off =1050, receiver operator characteristic curve: 0.7720), which occurred in 24% (22/93) of the CPFE patients. Finger clubbing and per cent predicted forced expiratory volume in one second/%FVC more than 1.2 were independent predictors of mortality.

In plain English

This single-hospital retrospective cohort study reviewed records and chest CT scans from Okinawa Chubu Hospital, Japan, from 2002 to 2007 for 93 patients with combined pulmonary fibrosis and emphysema (CPFE), in which lung scarring and emphysema occur together. Patients with occupationally related lung disease, such as asbestosis and silicosis, were excluded, so asbestos exposure was not studied. All patients had smoked. Over a mean follow-up of 30.7 months, 67 patients (72%) died and 22 (24%) had a sudden worsening called acute exacerbation. A higher baseline blood level of the lung marker KL-6 was associated with acute exacerbation (odds ratio 1.0016, 95% CI 1.0003 to 1.0027). Finger clubbing (hazard ratio 2.2620, 95% CI 1.1746 to 4.3560) and a ratio of two breathing-test values (%FEV1 to %FVC) above 1.2 (hazard ratio 1.9259, 95% CI 1.0057 to 3.6883) were independent predictors of death. The authors concluded that KL-6 was a useful predictor of acute exacerbation. They noted limitations including the single-centre retrospective design and that all patients were heavy smokers.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Single-centre retrospective cohort study (review of medical records and HRCT scans)
• Who was studied: 93 patients with combined pulmonary fibrosis and emphysema (CPFE), 76 men and 17 women, mean age 73 years. They were identified from 319 interstitial lung disease patients at Okinawa Chubu Hospital, Okinawa, Japan, between 1 January 2002 and 31 December 2007. Patients with connective tissue disease, drug-associated lung disease or occupationally related lung disease were excluded.
• Exposure: No asbestos exposure was studied. Occupationally related interstitial lung disease such as asbestosis and silicosis was an exclusion criterion. All patients had a smoking history (mean 62 pack-years). The study examined clinical, blood (KL-6), lung function and CT features as predictors of acute exacerbation and death.
• Main results:
  • During the observation period (mean follow-up 30.7 months), 67 of the 93 CPFE patients (72%) died.
  • 22 of the 93 CPFE patients (24%) developed acute exacerbation.
  • In logistic regression, baseline serum KL-6 was the strongest predictor of acute exacerbation in CPFE patients: OR 1.0016 (95% CI 1.0003 to 1.0027), p=0.009.
  • ROC analysis gave a useful KL-6 threshold of 1050 for predicting acute exacerbation (ROC 0.7720).
  • In Cox proportional hazards analysis, finger clubbing was an independent predictor of mortality in CPFE patients: HR 2.2620 (95% CI 1.1746 to 4.3560), p=0.015. 42 patients (45%) had finger clubbing.
  • A ratio of %FEV1 to %FVC greater than 1.2 was an independent predictor of mortality in CPFE patients: HR 1.9259 (95% CI 1.0057 to 3.6883), p=0.048.
  • 68 patients had the IPF (usual interstitial pneumonia) CT pattern and 25 had the NSIP pattern. CT pattern was not an independent prognostic predictor.
  • 12 of the 93 patients (13%) developed lung cancer.
• The authors' conclusion: The authors concluded that CPFE patients showed poor survival in their cohort and often developed acute exacerbation, for which baseline serum KL-6 was a useful predictor. They also concluded that finger clubbing and %FEV1/%FVC more than 1.2 were independent predictors of mortality, and called for a multicentre study.
• Limitations the authors state:
  • The study was a single-centre, uncontrolled, retrospective study, so important data may not have been collected.
  • The exact areas of emphysema and fibrosis were not measured, so the cohort may have been at a different disease stage than in earlier studies.
  • Most patients could not undergo surgical biopsy, so detailed pathology could not be evaluated.
  • Serial (repeated) lung function was not evaluated.
  • All patients were heavy smokers, so CPFE could not be distinguished from smoking-related NSIP.

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study, Pulmonary Fibrosis, Emphysema, High-Resolution CT (HRCT), Interstitial Lung Disease, Silicosis, Idiopathic, Interstitial.

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