Mortality in biopsy verified usual interstitial pneumonia and the relation to computed tomography scores

Rationale: High resolution computed tomography (HRCT) is a crucial investigation for the diagnosis of usual interstitial pneumonia (UIP). Less is known about the predictive value of different HRCT patterns in UIP. Objective: To compare HRCT patterns and biopsy verified UIP as predictors of mortality. Methods: The study included 91 patients with a tentative diagnosis of interstitial lung disease. All underwent clinical investigation, surgical lung biopsy and HRCT. Two independent readers assessed the HRCT images for the extent and pattern of abnormality. On the basis of the biopsy result the patients were categorized in three groups: 1) Usual interstitial pneumonia, 2) Other idiopathic interstitial pneumonias (non-UIP) and 3) Other interstitial lung diseases (non-IIP). The diagnostic value of HRCT was investigated using likelihood ratio to estimate the post-test probability of UIP. Results: Multivariate Cox-regression showed that the hazard ratio between UIP and non-UIP was 2.3 (95 % confidence interval 1.2 – 4.2), whereas the mortality increased with 1.5 (1.2 – 2.9) per tertile increase in reticular pattern score. The augmentation of mortality with increasing CT-score was confined to patients less than 60 years and attenuated thereafter. Conclusion: In patients younger than 60 years there was a strong association between CT-score regarding reticular pattern and mortality. This may be important regarding the timing of lung transplantation.