Department of Rheumatology, Queen Elizabeth Hospital, Gateshead NE9 6SX, UK
Correspondence to: V. Saravanan. E-mail: Saravana_uk{at}yahoo.co.uk
We appreciate the views of Clewes and Dawson on methotrexate pneumonitis (MTX-P). We agree that the meta-analytical method used to summarize the different studies is not without its drawbacks. The studies are not homogeneous and adopt different yardsticks for both interstitial lung disease (ILD) and MTX-P. A prospective study with sufficient power is needed to identify risk factors for MTX-P.
Our suggestion for excluding ILD prior to MTX was borne out of practical considerations of appropriate treatment for ILD associated with RA rather than its possible link with MTX-P. ILD is under-recognized in RA and increases mortality. Although MTX may not worsen ILD, it is not a proven treatment for this rheumatoid manifestation.
The major reason for recommending baseline transfer factor (TLCO) in addition to spirometry was that it would be repeatable in the event of suspected pneumonitis. A change in vital capacity alone is not sensitive for pneumonitis, whereas a decrease in TLCO would point to pneumonitis. Interestingly, in our group's earlier work, a low baseline TLCO (<70% predicted) carried a much higher relative risk for subsequent pneumonitis than did abnormal spirometry or chest X-ray [1].
However, we do understand Clewes and Dawson's reasons for using chest X-ray and spirometry alone to identify patients with significant lung disease. This is better than no screening at all. A survey of British rheumatologists is under way to identify current practice and views on screening for lung disease prior to methotrexate. Hopefully, we will be able to reach a consensus and redraft current guidelines after this.
The authors have declared no conflicts of interest.
References