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Thorax. 2017 May;72(5):424-429. doi: 10.1136/thoraxjnl-2016-209671. Epub 2017 Jan 12.

The use of pretest probability increases the value of high-resolution CT in diagnosing usual interstitial pneumonia.

Author information

1
Department of Medicine, University of California San Francisco, San Francisco, California, USA.
2
Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA.
3
Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
4
Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
5
Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA.
6
Department of Pathology, University of California San Francisco, San Francisco, California, USA.
7
Respiratory Diseases Department, Pontifical Catholic University, Santiago, Chile.
8
Department of Medicine, University of Calgary, Calgary, Canada.

Abstract

BACKGROUND:

Recent studies have suggested that non-definitive patterns on high-resolution CT (HRCT) scan provide sufficient diagnostic specificity to forgo surgical lung biopsy in the diagnosis of idiopathic pulmonary fibrosis (IPF). The objective of this study was to determine test characteristics of non-definitive HRCT patterns for identifying histopathological usual interstitial pneumonia (UIP).

METHODS:

Patients with biopsy-proven interstitial lung disease (ILD) and non-definitive HRCT scans were identified from two academic ILD centres. Test characteristics for HRCT patterns as predictors of UIP on surgical lung biopsy were derived and validated in independent cohorts.

RESULTS:

In the derivation cohort, 64/385 (17%) had possible UIP pattern on HRCT; 321/385 (83%) had inconsistent with UIP pattern. 113/385 (29%) patients had histopathological UIP pattern in the derivation cohort. Possible UIP pattern had a specificity of 91.2% (95% CI 87.2% to 94.3%) and a positive predictive value (PPV) of 62.5% (95% CI 49.5% to 74.3%) for UIP pattern on surgical lung biopsy. The addition of age, sex and total traction bronchiectasis score improved the PPV. Inconsistent with UIP pattern demonstrated poor PPV (22.7%, 95% CI 18.3% to 27.7%). HRCT pattern specificity was nearly identical in the validation cohort (92.7%, 95% CI 82.4% to 98.0%). The substantially higher prevalence of UIP pattern in the validation cohort improved the PPV of HRCT patterns.

CONCLUSIONS:

A possible UIP pattern on HRCT has high specificity for UIP on surgical lung biopsy, but PPV is highly dependent on underlying prevalence. Adding clinical and radiographic features to possible UIP pattern on HRCT may provide sufficient probability of histopathological UIP across prevalence ranges to change clinical decision-making.

KEYWORDS:

Histology/Cytology; Idiopathic pulmonary fibrosis; Interstitial Fibrosis; Thoracic Surgery

PMID:
28082530
PMCID:
PMC5555580
DOI:
10.1136/thoraxjnl-2016-209671
[Indexed for MEDLINE]
Free PMC Article

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