The main aim of this study was to develop a more quantitative procedure for scoring the degrees of FF than the semiquantitative methods previously reported. Our scoring method using a CCD camera and analytic software enabled us to accurately measure the %FF, and evaluate the degree of FF as the quantitative %FF scores. Additionally, we found that our quantitative %FF score was an independent prognostic factor in patients with UIP in the Cox proportional hazards regression model. Interestingly, patients with CVD-UIP had a significantly lower %FF score than those with IPF/UIP, which may be related to the better prognosis of CVD-UIP than IPF/UIP.
In the present study, we found the interobserver variations were not small in the semiquantitative scoring methods, especially in the methods that had more categorical scales, such as the Denver (six scales) and the Brompton (seven scales) methods. In contrast, our quantitative scoring method had high interobserver correlation (r = 0.877). Moreover, the intraobserver correlation was also shown to be high (r = 0.898). In addition, our quantitative scoring method basically needs only one pathologist, who does not necessarily need to specialize in pulmonary pathology, and the pathologist could easily calculate the proportion of FF using a CCD camera and the analytic software. other
Taken together, these data suggest that our quantitative scoring method, which does not need two or more of pulmonary pathologists, is more objective and reproducible than the semiquantitative scoring methods. We examined whether the quantitative %FF score defined by our scoring method had clinical significance in UIP. Most notably, we found that this score was an independent predictor of survival in all UIP patients as well as IPF patients in the Cox proportional hazards regression model; higher FF score was associated with poor prognosis. In IPF, conflicting reports using semiquantitative scoring systems exist concerning the significance of FF score for survival in the proportional hazards model. Flaherty et al showed that the Michigan FF score was not a significant predictor of survival, while Nicholson et al demonstrated that the Brompton FF score was independently linked to survival. This may reflect the difference in categorization of FF among the scoring systems. In addition, we found no significant correlation between the quantitative %FF score and FVC or resting Pa02 at surgical biopsy in CVD-UIP or IPF/UIP, indicating that this FF score was not associated with baseline pulmonary function.