Evaluation of clinical diagnostic guidelines for idiopathic pulmonary fibrosis

To analyze the international consensus statement on diagnostic criteria for idiopathic pulmonary fibrosis. All patients diagnosed of any interstitial lung disease by means of open lung biopsy since 1980 were included. The patients' clinical records were examined to determine whether they fulfilled the diagnostic criteria, and their biopsies were reviewed to find those with the usual interstitial pneumonia pattern. We calculated sensitivity, specificity, positive and negative predictive values and likelihood ratios for the diagnostic criteria in the consensus statement. Afterwards, we performed the analyses again using only one of the two conditions for fulfilling the function criterion. Of 39 patients enrolled in the study, 17 had idiopathic pulmonary fibrosis. Specificity and positive predictive value were both 100%, but sensitivity was 41.2% and negative predictive value was 68.7%. The likelihood ratio for a negative result was 0.59. In the second analysis, sensitivity was 64.7% and negative predictive value was 78.5%, while specificity and positive predictive value remained unchanged. The likelihood ratio for a negative result was 0.35. The criteria are sufficiently specific to allow us to diagnose confidently when the criteria are fulfilled. However, a slight change in the function criterion should be considered in order to increase diagnostic yield.