RESEARCH - MTX pneumonitis incidence: a prosepctive study

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ACR/ARHP 2008 Scientific Meeting

Session: RA: Comorbidities

Sunday, Oct 26, 2008, 9:00 AM - 6:00 PM

Presentation: 281 - Methotrexate Pneumonitis Incidence: A Prospective Study

Author(s): Navtej Sathi1, Batsirai Chikura2, Viswanath V. Kaushik3,

K. Dawson4. 1ington Hospital, Wigan, United Kingdom;

2Royal Liverpool Hospital, Liverpool, United Kingdom; 3Lincoln County

Hospital, Lincoln, United Kingdom; 4St. Helens and Knowsley NHS Trust,

St. Helens, United Kingdom

Abstract:

Purpose:

Methotrexate (MTX) is currently the most preferred first line agent by

british rheumatologists for the treatment of rheumatoid arthritis. It

also has a license for use in patients with psoriatic arthritis. It

has been proven to control erosive RA. Its onset is relatively quick

and is prescribed with greater overall success than other

non-biological disease-modifying anti-rheumatic drugs (DMARDs).

Low dose methotrexate has been found to have three main pulmonary side

effects. They include: methotrexate pneumonitis (MTX-P);

predisposition to pulmonary infection with opportunistic organisms;

and drug induced asthma. The review of present literature suggests the

prevalence of MTX-P to vary between 3% and 7%.

Methods:

The Null Hypothesis is that the incidence of methotrexate pneumonitis

is the same as published data i.e.: 3-7%.

We have undertaken an ongoing prospective study at St. Helens and

Whiston Hospitals looking at the incidence of MTX-P on patients being

commenced low-dose methotrexate for inflammatory arthropathy.

We recruited patients starting low-dose methotrexate and followed them

up for two years or until development of MTX-P. Initial assessmentwere

done with routine regular reviews as dictated by the patients

condition. Assessment forms would be filled during each visit.

Inclusion Criteria : All patients who are commencing low-dose

methotrexate (oral/IM/SC) , dose range 2.5mg to 30mg.

Exclusion Criteria :- Previous exposure to methotrexate; Patients who

refuse or unable to give consent;

Results:

All 164 patients had an FVC of >1.0L and were started on 10 mg of

Methotrexate. The data is displayed on the table below on the basis of

thier spirometry results, smoking status and gender.

Only one patient developed methotrexate pneumonitis. This would

suggest an incidence of 0.625% in all patients at one year (n=164),

and 0.42% at 2 years (n=120). Hence the null hypothesis is rejected.

Conclusions:

The results of this ongoing prospective trial would suggest that MTX-P

does not occur as often as previously thought. It would also appear

from our data that baseline obstructive and restrictive lung functions

as well as a history of smoking should not prevent initiation of

methotrexate. Hence rheumatologists should not be cautious in using

methotrexate in patients with restrictive or obstructive disease or

smokers, provided their FVC is greater than 1 litre.

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