Association of HLA-DR4, protease inhibitor phenotypes and keratoconjunctivitis sicca with pulmonary abnormalities in rheumatoid arthritis.

One-hundred rheumatoid arthritis (RA) patients were assessed for the association of HLA-DR4, protease inhibitor (Pi) phenotype and keratoconjunctivitis sicca (KCS) with a variety of clinical features, airflow obstruction and bronchial reactivity. Spirometry, lung volume and gas transfer factor measurements were performed to detect airflow obstruction. Bronchial reactivity to inhaled methacholine was assessed by measuring the provocative dose of methacholine causing a 20% fall in FEV1 from the baseline (PD20). Sixty-two patients were HLA-DR4 positive, 87 had Pi MM and 13 MS phenotypes and 37 had positive Schirmer's tear tests. Patients with KCS had a significantly increased history of wheeze (11/37 vs 7/63, P = 0.03, relative risk (RR) 1.8 [95% CI 1.04, 3.1]), those with HLA-DR4 had a significantly decreased atopy on skin-prick testing [3/62 vs 7/38, were significantly higher in the Pi MS group compared to Pi MM group. There was no significant association of HLA-DR4, Pi phenotype and KCS with bronchial reactivity. We conclude that there is no overall significant association of HLA-DR4, Pi phenotype and KCS with airflow obstruction and bronchial reactivity in RA.