About Study

Research Questions

Primary Research Question

1. Data on current practice patterns for IIPs diagnosis

   Describe the frequency of surgical lung biopsy, bronchoalveolar lavage, lung function tests, 6-minuite walk test and chest CT.

2. Prevalence of each categorized IIPs

   Investigate the prevalence of each categorized IIPs by using the recent and future guidelines.

3. Natural history of each categorized IIPs

   Describe the natural history of each categorized IIPs, CT findings, FVC changes, medications, and causes of death.

Our reports will be produced twice, one year after registration and at the end of the study.

Secondary Outcome Measures

1. Progression-free survival by category of IIPs

Overall survival time and progression-free survival will be investigated by considering IIPs category; however, the observation will be finished after three years from the last registration. An additional analysis by FVC will be conducted to investigate the absolute and relative FVC changes (>10% decrease, >10% increase, change within 10%) from baseline. Deterioration is defined as a decrease of >10%, a decrease in distance by 50 m or more in a 6-minute walk test, and the onset of acute exacerbation. The log rank test will be used to analyze these results.

2. Hospital admission for acute exacerbations of IIPs

To evaluate incidences, therapy and prognosis of acute respiratory deterioration in patients with IPF (based on the revised definition of acute exacerbation of IPF) and other IIPs will be recorded.

3. Mean change of patient-reported outcome (Total Saint George Respiratory Questionnaire Score, COPD assessment test, Dyspnoea-12) every12 months from baseline

One of the study objectives is to assess patient-reported outcomes, such as health-related quality of life (HRQoL). In particular, it is planned to determine whether low HRQoL scores correlate with more severe clinical parameters, such as serum biomarkers, pulmonary function tests, exercise tests, HRCT findings, and staging systems in patients with IPF and other IIPs.

4. Quantitative evaluation of HRCT findings

Radiologists will estimate the fibrotic score using CT images of the patients, which will also be analyzed by a custom-developed computer-system, the Gaussian Histogram Normalized Correlation (GHNC) system. We will compare the estimates determined by the radiologists and the GHNC system with pulmonary function tests and will use Cox regression analysis to examine the relationship between the volumes and patient survival. Furthermore, we will determine whether the GHNC results are different compared to IPF and other IIPs using ANOVA.

5. Validation of second multidisciplinary discussion

MDD became necessary at the time of diagnosis after the ATS/ERS/JRS/ALAT IPF guideline in 2011. There is no regulation to keep the use of MDD in the second after the diagnosis. However, diagnosis sometimes changes to connective tissue diseases associated interstitial lung disease several years after being diagnosed as idiopathic NSIP. In another case, it is reported a patient with idiopathic NSIP has changed to IPF after the second surgical lung biopsy. In this study, MDD held by independent central reviewers will be conducted twice at the time of registration and final observation using questionnaire. Concordance rate for diagnosis and disease behavior in each case between the time of registration and final observation will be evaluated.

6. IIPs staging systems

To evaluate the predictability of two new models regarding mortality risk in a large cohort of Japanese patients with IPF: the revised Japanese disease severity classification and the revised GAP model. The Kaplan–Meier survival curves will be used for each stage of each model and will be compared by using the log-rank test. The discriminative performance of these two models will be evaluated using the C-statistic.

7. Prognosis and complication of CPFE

The patients with CPFE will be evaluated for FVC changes, as well as incidence of pulmonary hypertension, lung cancer, and acute exacerbation. Cluster analysis will be used, and CPFE will be divided into groups.

8. Background and prognosis of Unclassifiable IIPs

Unclassifiable IIPs is one of the major classifications and has thus become a more common diagnosis than ever before. There are reports that about 15% of IIPs are unclassifiable; hence, this study will investigate the reasons for this diagnosis, as well as patient background and prognosis. Both Unclassifiable IIPs by facility diagnosis and by central reveiw will be investigated. Cluster analysis will be used, and Unclassifiable IIPs will be divided into groups.

9. Validation of new guideline

If there are changes in IIPs diagnostic guidelines or severity classification during this study, these changes will be verified.