A diagnostic model for chronic hypersensitivity pneumonitis

Abstract

The objective of this study was to develop a diagnostic model that allows for a highly specific diagnosis of chronic hypersensitivity pneumonitis using clinical and radiological variables alone. Chronic hypersensitivity pneumonitis and other interstitial lung disease cases were retrospectively identified from a longitudinal database. High-resolution CT scans were blindly scored for radiographic features (eg, ground-glass opacity, mosaic perfusion) as well as the radiologist's diagnostic impression. Candidate models were developed then evaluated using clinical and radiographic variables and assessed by the cross-validated C-statistic. Forty-four chronic hypersensitivity pneumonitis and eighty other interstitial lung disease cases were identified. Two models were selected based on their statistical performance, clinical applicability and face validity. Key model variables included age, down feather and/or bird exposure, radiographic presence of ground-glass opacity and mosaic perfusion and moderate or high confidence in the radiographic impression of chronic hypersensitivity pneumonitis. Models were internally validated with good performance, and cut-off values were established that resulted in high specificity for a diagnosis of chronic hypersensitivity pneumonitis.

Keywords: Clinical Epidemiology; Hypersensitivity pneumonitis; Interstitial Fibrosis.

Figure 1

Receiver operating characteristic curve for (A) the derivation and validation prediction models incorporating clinical, exposure and individual radiological variables and (B) the derivation and validation prediction models incorporating clinical, exposure and radiologist’s confidence variables. The solid and dashed lines represent the derivation and validation cohorts, respectively. The curve areas to the left of the vertical line indicate diagnostic specificity ≥90%.