Relationship between abnormalities on high-resolution CT and pulmonary function in systemic sclerosis

Study objectives: To determine the predictive value of abnormalities on hig h-resolution CT (HRCT) on pulmonary disease in systemic sclerosis. Patients: Fifty-two patients suffering from systemic sclerosis, Design: Pulmonary disease was defined by pulmonary function test abnormalit ies, ic, total lung capacity (TLC) <80% of predicted value and/or diffusion of carbon monoxide (DLCO) <75% of predicted value, without any pulmonary e vent other than systemic sclerosis in the medical history. Patients were di vided in two groups, group A with pulmonary disease (29 patients) and group B without pulmonary disease (23 patients). HRCT abnormalities were scored on whole lungs. A decision matrix was constructed to determine sensitivity, specificity, positive and negative predictive values, and false-positive a nd false-negative rates. A receiver operating characteristic curve was cons tructed to determine the best compromise between sensitivity and specificit y, Results: HRCT total scores were higher in group A (9.0 +/- 4.3) than in gro up B (5.0 +/- 2.8) (P < 0.001) and they correlated with TLC (r = -0.39, p < 0.005) and DLCO (r = -0.50, p < 0.0002), An HRCT score of 7 corresponded t o the best compromise between sensitivity (0.60) and specificity (0.83), wi th a positive predictive value of 0.82 Taking into account a value of 10 fo r the HRCT score increased specificity to 1 but decreased sensitivity to 0. 41. Conclusion: A minimum score of 7 would be required to consider HRCT abnorma lities in systemic sclerosis as predictive of pulmonary disease, An HRCT sc ore of 10 makes it possible to establish the diagnosis of lung involvement severe enough to impair pulmonary function.