Pulmonary involvement in sle.

Sir, Grennan et al.1 recently reported in 22 patients with systemic lupus erythematosus (5 with respiratory symptoms), a restrictive ventilatory defect or reduction in diffusing capacity for CO. Their paper is interesting but we should like to make a few comments: (a) Only 3 tests of lung function were employed: VC, FEVi%/FVC, and transfer factor. (b) Most patients were receiving corticosteroids at the time of assessment. (c) Transfer factor was considered to be reduced if it was less than 80% of the mean predicted. One patient (case 12) with a reduced diffusing capacity of 78% had a transfer factor of 7.1 mmol/min/KPa under the predicted normal level (7-410.8 mmol/min/ KPa) and 2 patients (cases 9 and 10) with a similar mean predicted reduction of diffusing capacity (79 %) had normal transfer factor values. In this sense patients 6 and 8 Nvere considered affected, although their transfer factor levels fit into predicted normal values. (d) Statistical methodology should have been described in order to show that there were no significant differences between patients with and without reduced transfer factor with regard to mean DNA binding capacity, mean C3 and C4 levels, or a positive test for rheumatoid factor. At the XlVth International Congress on Internal Medicine (Rome, October 1978) we communicated a study of pulmonary function in 22 lupus patients without respiratory symptoms compared to 30 normal persons. Our analysis included assessment of static and dynamic lung volumes, lung mechanics, and CO diffusing capacity Viewpoint 297