Brett M. Elicker

A Multidimensional Index and Staging System for Idiopathic Pulmonary Fibrosis

BACKGROUND Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with an overall poor prognosis. A simple-to-use staging system for IPF may improve prognostication, help guide management, and facilitate research. OBJECTIVE To develop a multidimensional prognostic staging system for IPF by using commonly measured clinical and physiologic variables. DESIGN A clinical prediction model was developed and validated by using retrospective data from 3 large, geographically distinct cohorts. SETTING Interstitial lung disease referral centers in California, Minnesota, and Italy. PATIENTS 228 patients with IPF at the University of California, San Francisco (derivation cohort), and 330 patients at the Mayo Clinic and Morgagni-Pierantoni Hospital (validation cohort). MEASUREMENTS The primary outcome was mortality, treating transplantation as a competing risk. Model discrimination was assessed by the c-index, and calibration was assessed by comparing predicted and observed cumulative mortality at 1, 2, and 3 years. RESULTS Four variables were included in the final model: gender (G), age (A), and 2 lung physiology variables (P) (FVC and Dlco). A model using continuous predictors (GAP calculator) and a simple point-scoring system (GAP index) performed similarly in derivation (c-index of 70.8 and 69.3, respectively) and validation (c-index of 69.1 and 68.7, respectively). Three stages (stages I, II, and III) were identified based on the GAP index with 1-year mortality of 6%, 16%, and 39%, respectively. The GAP models performed similarly in pooled follow-up visits (c-index ≥71.9). LIMITATION Patients were drawn from academic centers and analyzed retrospectively. CONCLUSION The GAP models use commonly measured clinical and physiologic variables to predict mortality in patients with IPF.

Gastroesophageal Reflux Therapy Is Associated with Longer Survival in Patients with Idiopathic Pulmonary Fibrosis

RATIONALE Gastroesophageal reflux (GER) is highly prevalent in patients with idiopathic pulmonary fibrosis (IPF). Chronic microaspiration secondary to GER may play a role in the pathogenesis and natural history of IPF. OBJECTIVES To investigate the relationship between GER-related variables and survival time in patients with IPF. METHODS Regression analysis was used to investigate the relationship between GER-related variables and survival time in a retrospectively identified cohort of patients with well-characterized IPF from two academic medical centers. MEASUREMENTS AND MAIN RESULTS Two hundred four patients were identified for inclusion. GER-related variables were common in this cohort: reported symptoms of GER (34%), a history of GER disease (45%), reported use of GER medications (47%), and Nissen fundoplication (5%). These GER-related variables were significantly associated with longer survival time on unadjusted analysis. After adjustment, the use of GER medications was an independent predictor of longer survival time. In addition, the use of gastroesophageal reflux medications was associated with a lower radiologic fibrosis score. These findings were present regardless of center. CONCLUSIONS The reported use of GER medications is associated with decreased radiologic fibrosis and is an independent predictor of longer survival time in patients with IPF. These findings further support the hypothesis that GER and chronic microaspiration may play important roles in the pathobiology of IPF.

Usual interstitial pneumonia in rheumatoid arthritis-associated interstitial lung disease

Interstitial lung disease is a common manifestation of rheumatoid arthritis; however, little is known about factors that influence its prognosis. The aim of the present study was to determine whether or not the usual interstitial pneumonia pattern found on high-resolution computed tomography (HRCT) is of prognostic significance in rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Patients with RA-ILD were identified retrospectively (n = 82). The relationship of a definite usual interstitial pneumonia pattern on HRCT to survival was determined and compared to that in a cohort of patients with radiologically diagnosed idiopathic pulmonary fibrosis (n = 51). A definite usual interstitial pneumonia pattern was seen in 20 (24%) out of 82 patients with RA-ILD. These patients showed worse survival than those without this pattern (median survival 3.2 versus 6.6 yrs), and a similar survival to those with idiopathic pulmonary fibrosis. On multivariate analysis, a definite usual interstitial pneumonia pattern on HRCT was associated with worse survival (hazard ratio of 2.3). Analysis of specific HRCT features demonstrated that traction bronchiectasis and honeycomb fibrosis were associated with worse survival (hazard ratio of 2.6 and 2.1, respectively). Female sex (hazard ratio of 0.30) and a higher baseline diffusing capacity of the lung for carbon monoxide (hazard ratio of 0.96) were associated with better survival. A definite usual interstitial pneumonia pattern on HRCT has important prognostic implications in RA-ILD.

Clinical features and outcomes in combined pulmonary fibrosis and emphysema in idiopathic pulmonary fibrosis

BACKGROUND Combined pulmonary fibrosis and emphysema (CPFE) is increasingly recognized, but its prevalence and prognosis remain unclear. We sought to determine the prevalence, clinical features, and prognosis of CPFE in idiopathic pulmonary fibrosis (IPF), using a standardized and reproducible definition. METHODS Patients with IPF were identified from two ongoing cohorts. Two radiologists scored emphysema and fibrosis severity on high-resolution CT (HRCT) scans. CPFE was defined as ≥10% emphysema on HRCT scan. Clinical characteristics and outcomes of patients with CPFE and IPF and those with non-CPFE IPF were compared with unadjusted analysis and then analysis after adjustment for HRCT fibrosis score. Mortality was compared using competing risks regression to handle lung transplantation. Sensitivity analyses were performed using Cox proportional hazards, including time to death (transplantation censored) and time to death or transplant. RESULTS CPFE criteria were met in 29 of 365 patients with IPF (8%), with high agreement between radiologists (κ=0.74). Patients with CPFE had less fibrosis on HRCT scans and higher FVC, but greater oxygen requirements (P≤.01 for all comparisons). Findings were maintained with adjustment for fibrosis severity. Inhaled therapies for COPD were used by 53% of patients with CPFE. There was no significant difference in mortality comparing patients with CPFE and IPF to those with non-CPFE IPF (hazard ratio, 1.14; 95% CI, 0.61-2.13; P=.69). CONCLUSIONS CPFE was identified in 8% of patients with IPF and is a distinct, clinical phenotype with potential therapies that remain underutilized. Patients with CPFE and IPF and those with non-CPFE IPF have similar mortality.

Bronchoalveolar lavage pepsin in acute exacerbation of idiopathic pulmonary fibrosis

Some patients with idiopathic pulmonary fibrosis experience acute exacerbations in their respiratory status leading to substantial morbidity and mortality. Occult aspiration of gastric contents has been proposed as one possible mechanism leading to these acute exacerbations. We sought to determine whether pepsin, a marker of gastric aspiration, is elevated in bronchoalveolar lavage fluid obtained from patients during acute exacerbation of idiopathic pulmonary fibrosis, compared with that obtained in stable disease. Lavage samples were obtained in a case–control study of well-characterised patients. Acute exacerbation was defined using standard criteria. Levels of lavage pepsin were compared in cases and controls, and were correlated with clinical features and disease course. 24 cases with acute exacerbations and 30 stable controls were identified. There were no significant differences in baseline demographics between the two groups. Pepsin level was an indicator of acute exacerbation status (p=0.04). On average, pepsin appeared higher in patients with acute exacerbations compared with stable controls. This difference was driven by a subgroup of eight patients (33%) with pepsin levels ≥70 ng·mL−1. Pepsin level was not an independent predictor of survival time. These results suggest occult aspiration may play a role in some cases of acute exacerbation of idiopathic pulmonary fibrosis.

Prevalence and prognosis of unclassifiable interstitial lung disease

The aim of this study was to determine the prevalence, characteristics and outcomes of patients with unclassifiable interstitial lung disease (ILD) and to develop a simple method of predicting disease behaviour. Unclassifiable ILD patients were identified from an ongoing longitudinal cohort. Unclassifiable ILD was diagnosed after a multidisciplinary review did not secure a specific ILD diagnosis. Clinical characteristics and outcomes were compared with idiopathic pulmonary fibrosis (IPF) and non-IPF ILDs. Independent predictors of mortality were determined using Cox proportional-hazards analysis to identify subgroups with distinct disease behaviour. Unclassifiable ILD was diagnosed in 10% of the ILD cohort (132 out of 1370 patients). The most common reason for being unclassifiable was missing histopathological assessment due to a high risk of surgical lung biopsy. Demographic and physiological features of unclassifiable ILD were intermediate between IPF and non-IPF disease controls. Unclassifiable ILD had longer survival rates when compared to IPF on adjusted analysis (hazard ratio 0.62, p = 0.04) and similar survival compared to non-IPF ILDs (hazard ratio 1.54, p = 0.12). Independent predictors of survival in unclassifiable ILD included diffusion capacity of the lung for carbon monoxide (p = 0.001) and a radiological fibrosis score (p = 0.02). Unclassifiable ILD represents approximately 10% of ILD cases and has a heterogeneous clinical course, which can be predicted using clinical and radiological variables. Unclassifiable ILD has a heterogeneous clinical course that can be predicted using clinical and radiological variables http://ow.ly/mdjwg

Predicting Survival Across Chronic Interstitial Lung Disease: The ILD-GAP Model

BACKGROUND Risk prediction is challenging in chronic interstitial lung disease (ILD) because of heterogeneity in disease-specific and patient-specific variables. Our objective was to determine whether mortality is accurately predicted in patients with chronic ILD using the GAP model, a clinical prediction model based on sex, age, and lung physiology, that was previously validated in patients with idiopathic pulmonary fibrosis. METHODS Patients with idiopathic pulmonary fibrosis (n=307), chronic hypersensitivity pneumonitis (n=206), connective tissue disease-associated ILD (n=281), idiopathic nonspecific interstitial pneumonia (n=45), or unclassifiable ILD (n=173) were selected from an ongoing database (N=1,012). Performance of the previously validated GAP model was compared with novel prediction models in each ILD subtype and the combined cohort. Patients with follow-up pulmonary function data were used for longitudinal model validation. RESULTS The GAP model had good performance in all ILD subtypes (c-index, 74.6 in the combined cohort), which was maintained at all stages of disease severity and during follow-up evaluation. The GAP model had similar performance compared with alternative prediction models. A modified ILD-GAP Index was developed for application across all ILD subtypes to provide disease-specific survival estimates using a single risk prediction model. This was done by adding a disease subtype variable that accounted for better adjusted survival in connective tissue disease-associated ILD, chronic hypersensitivity pneumonitis, and idiopathic nonspecific interstitial pneumonia. CONCLUSION The GAP model accurately predicts risk of death in chronic ILD. The ILD-GAP model accurately predicts mortality in major chronic ILD subtypes and at all stages of disease.

Relative versus absolute change in forced vital capacity in idiopathic pulmonary fibrosis

Background Decline in forced vital capacity (FVC) over time reliably predicts mortality in patients with idiopathic pulmonary fibrosis. The use of this measure in clinical practice is recommended by current evidence-based guidelines. It is unknown if the method of calculating decline in FVC (relative vs absolute change) impacts its frequency or its ability to predict mortality. Methods Patients with idiopathic pulmonary fibrosis from two prospective cohorts were included if they had a baseline and 12-month follow-up FVC. A ≥10% decline in FVC from baseline was calculated in two ways: a relative decline of 10% (eg, from 60% predicted to 54% predicted) and an absolute decline of 10% (eg, from 60% predicted to 50% predicted). The frequency of a ≥10% decline in FVC and its ability to predict 2-year transplant-free survival were compared between these two methods. Declines in FVC of ≥5% and ≥15% were similarly compared. Analyses were performed unadjusted and adjusted for age, gender, use of oxygen, baseline FVC and baseline diffusion capacity for carbon monoxide. Results The frequency of any given FVC decline was significantly greater using the relative change in FVC method. For ≥10% decline, both methods predicted 2-year transplant-free survival with similar accuracy, and remained significant predictors after adjusting for baseline characteristics. The absolute change method appeared more predictive for ≥5% decline. Conclusions Using the relative change in FVC maximises the chance of identifying a ≥10% decline in FVC without sacrificing prognostic accuracy. This may not hold true for ≥5% decline in FVC. These findings have important implications for clinical practice and the design of clinical trials.

Effect of telomere length on survival in patients with idiopathic pulmonary fibrosis: an observational cohort study with independent validation

BACKGROUND Short telomere lengths are found in a subset of patients with idiopathic pulmonary fibrosis, but their clinical significance is unknown. Our aim was to investigate whether patients with various blood leucocyte telomere lengths had different overall survival. METHODS In this observational cohort study, we enrolled patients with interstitial lung disease from Dallas, TX (primary cohort), and from Chicago, IL, and San Francisco, CA (replication cohorts). We obtained genomic DNA samples from unrelated healthy controls in Dallas, TX, and spouses of patients were also enrolled as an independent control group. Telomere lengths were measured in genomic DNA samples isolated from peripheral blood obtained at the time of the initial enrolment assessment. The primary endpoint was transplant-free survival (ie, time to death or lung transplantation) in the Dallas cohort. Findings were validated in the two independent idiopathic pulmonary fibrosis cohorts (Chicago and San Francisco). FINDINGS 370 patients were enrolled into the Dallas cohort between June 17, 2003, and Aug 25, 2011. The 149 patients with idiopathic pulmonary fibrosis had shorter telomere lengths than did the 195 healthy controls (mean age-adjusted log-transformed ratio of telomere to single copy gene was -0.16 [SD 0.23] vs 0.00 [0.18]; p<0.0001); however, telomere lengths of the Dallas patients with idiopathic pulmonary fibrosis (1.33 [SD 0.25]) were similar to the 221 patients with other interstitial lung disease diagnoses (1.46 [0.24]) after adjusting for age, sex, and ethnicity (p=0.47). Telomere length was independently associated with transplant-free survival time for patients with idiopathic pulmonary fibrosis (HR 0.22 [95% CI 0.08-0.63]; p=0.0048), but not for patients with interstitial lung disease diagnoses other than idiopathic pulmonary fibrosis (HR 0.73 [0.16-3.41]; p=0.69). The association between telomere length and survival in patients with idiopathic pulmonary fibrosis was independent of age, sex, forced vital capacity, or diffusing capacity of carbon monoxide, and was replicated in the two independent idiopathic pulmonary fibrosis replication cohorts (Chicago cohort, HR 0.11 [0.03-0.39], p=0.00066; San Francisco cohort, HR 0.25 [0.07-0.87], p=0.029). INTERPRETATION Shorter leucocyte telomere lengths are associated with worse survival in idiopathic pulmonary fibrosis. Additional studies will be needed to establish clinically relevant thresholds for telomere length and how this biomarker might affect risk stratification of patients with idiopathic pulmonary fibrosis. FUNDING US National Heart, Lung, and Blood Institute, National Center for Advancing Translational Sciences, Harroun Family Foundation, and Nina Ireland Lung Disease Program.

IV Contrast Administration for CT: A Survey of Practices for the Screening and Prevention of Contrast Nephropathy

OBJECTIVE No widely accepted practice guidelines exist for the screening and prevention of contrast nephropathy in patients receiving iodinated IV contrast agents for CT examinations. Issues include screening to identify at-risk patients, discriminatory levels of renal insufficiency beyond which IV contrast material is contraindicated, and the use of preventive measures. We surveyed radiologists to identify the current practice patterns and to determine those areas in which guidelines are most needed. MATERIALS AND METHODS Surveys were e-mailed to 2,000 radiologists. The survey included questions on the issues just described and respondent demographics. RESULTS The response rate was 21%. Serum creatinine is the most commonly used screening method: 92% of respondents for inpatient examinations and 66% for outpatient examinations. Only 2% use estimated creatinine clearance. The average threshold serum creatinine value used to determine that patients should not receive IV contrast material is 1.5 mg/dL in 35%, 1.7 mg/dL in 27%, and 2.0 mg/dL in 31% (mean, 1.78 mg/dL). Diabetes slightly lowers the threshold creatinine (mean, 1.68 mg/dL). Fewer than 30% of respondents frequently administer IV contrast material to patients with a renal transplant or multiple myeloma. The most commonly used preventive measures include hydration (93%), reduction of contrast dose (77%), and administration of acetylcysteine (39%). Overall, no important differences were found among practice settings or level of specialization. CONCLUSION A wide variation of practice patterns is apparent in the screening and prevention of contrast nephropathy. In some cases, these patterns conflict with recommendations from the literature. The results of this study identify opportunities for further research and areas in need of improved practice guidelines.