The value of rates of change in forced expiratory volume in 1 s (FEV1) and diffusing capacity of the lung for
carbon monoxide (DLCO) to predict
disease progression, and initiation of mTOR (mechanistic target of
rapamycin) inhibitor
therapy has not been evaluated.In 84 premenopausal
lymphangioleiomyomatosis patients, individual rates of change in FEV1 and DLCO and their 95% confidence intervals were used to derive subsequent lowest values of FEV1 and DLCO that would prompt initiation of
sirolimus therapy. These treatment criteria were compared with a criterion based on FEV1 or DLCO ≤70% predicted. In 12 patients undergoing
sirolimus therapy both methods for determining the optimal point for initiation of
therapy were evaluated.27 and 35 patients who experienced greater than expected rates of change in FEV1 and DLCO, respectively, would have been excluded from
therapy based on an FEV1 or DLCO >70%
pred. 25 of the 84 patients were eventually treated, but only when FEV1 or DLCO were ≤70%
pred. Applying such treatment criteria to 12 patients undergoing
sirolimus therapy would have
delayed treatment for many years.Premenopausal females in whom FEV1 or DLCO are declining at rates above the expected based on their individual rates of decline, should be considered for
sirolimus therapy before the FEV1 or DLCO falls to ≤70%
pred.