Possible UIP pattern on high-resolution computed tomography is associated with better survival than definite UIP in IPF patients

Abstract

Background Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing lung disease of unknown etiology. Inter-society consensus guidelines on IPF diagnosis and management outline radiologic patterns including definite usual interstitial pneumonia (UIP), possible UIP, and inconsistent with UIP. We evaluate these diagnostic categories as prognostic markers among patients with IPF. Methods Included subjects had biopsy-proven UIP, a multidisciplinary team diagnosis of IPF, and a baseline high-resolution computed tomography (HRCT). Thoracic radiologists assigned the radiologic pattern and documented the presence and extent of specific radiologic findings. The outcome of interest was lung transplant-free survival. Results IPF patients with a possible UIP pattern on HRCT had significantly longer Kaplan-Meier event-free survival compared to those with definite UIP pattern (5.21 and 3.57 years, respectively, p=0.002). In a multivariable Cox proportional hazards model adjusted for baseline age, gender, %-predicted FVC, and %-predicted DLCO via the GAP Stage, extent of fibrosis (via the traction bronchiectasis score) and ever-smoker status, possible UIP pattern on HRCT (versus definite UIP) was associated with reduced hazard of death or lung transplant (HR=0.42, CI 95% 0.23–0.78, p=0.006). Conclusions Radiologic diagnosis categories outlined by inter-society consensus guidelines is a widely-reported and potentially useful prognostic marker in IPF patients, with possible UIP pattern on HRCT associated with a favorable prognosis compared to definite UIP pattern, after adjusting for relevant covariates.

Evolution of diagnostic UIP computed tomography patterns in idiopathic pulmonary fibrosis: Disease spectrum and implications for survival

“…Those with 'possible' or 'inconsistent' UIP CT pattern with minimal honeycombing have also been reported to have improved survival. Salisbury and colleagues noted better survival in those with 'possible' or 'inconsistent' UIP pattern at presentation in a single-center cohort of IPF patients [3]. Our group recently showed better survival as well in those with initial 'possible' UIP pattern on presentation when stratified by CT pattern alone, but such survival advantage was attenuated after correction for additional parameters of age, sex, and FVC% [2].…”

“…Depending on when a patient presents, specific findings such as honeycombing may have not yet developed and cause uncertainty with IPF diagnosis, particularly if biopsy is not available. Recent reports suggest 'possible' UIP patterns may be more frequent or common in IPF than previously recognized [2,3,9]. A recent multicenter treatment trial noted 41% of patients at enrollment had 'possible' or 'inconsistent' UIP CT pattern without honeycombing, but similar FVC and DLCO response to anti-fibrotic therapy [10].…”

“…Anecdotally, radiologists and clinicians have referred to cases of IPF with 'possible' or 'inconsistent' UIP CT patterns as 'early' or 'atypical' UIP, suggesting potential or developing disease with expected transition to more 'consistent' or typical findings over time. Recent studies demonstrate 'possible' UIP CT pattern may occur at presentation in 25-50% of patients [2][3][4]. 'Possible' UIP CT pattern was shown to dominate in a series of consecutive IPF patients without correlation to severity of pulmonary function findings [2].…”

“…'Possible' UIP CT pattern was shown to dominate in a series of consecutive IPF patients without correlation to severity of pulmonary function findings [2]. Such patterns have also shown prognostic implication in terms of predicting better survival [3]. It is not well known whether current 2011 international radiologic criteria represent different stages of the same fibrotic process, or unique radiologic phenotypes mostly unaltered over time with specific outcomes and natural histories.…”

Baseline clinical characteristics, comorbidities and prescribed medication in a real-world population of patients with idiopathic pulmonary fibrosis: the PROOF registry

“… 26–28 The high biopsy rate observed in the PROOF registry may be partially explained by evidence suggesting that patients with less advanced IPF are less likely to demonstrate definite UIP on HRCT at the time of diagnosis. 29 The potential relationship between less advanced disease and the likelihood of definite UIP on HRCT is relevant because many patients in the PROOF registry had relatively preserved lung function, with 39% of patients in GAP stage I and mean per cent predicted FVC of 80.6% at baseline. Another factor to be considered, which may partially explain the high biopsy rate observed in the PROOF registry, is the time period at which patients were enrolled compared with other IPF registries.…”