Background Respiratory disease is the second commonest cause of death after cardiovascular disease in patients with inflammatory polyarthritis (IP) and its subset rheumatoid arthritis (RA). However, limited data are available on predictors of both respiratory morbidity and mortality.
Objectives To identify predictors associated with respiratory morbidity and mortality in early IP.
Methods 942 IP cases with symptom duration <2 years recruited to the Norfolk Arthritis Register (NOAR) between January 1st 2000 and December 31st 2008 were included in this study. At baseline, demographic, clinical and disease activity markers (Table) were collected. Hospital admissions were retrieved from the Hospital Episode Statistics database. Primary and secondary diagnoses of a respiratory event were included and categorized into: i) lung cancer ii) Chronic Lung Disease [CLD] with lung infection iii) CLD without lung infection and iv) others. CLD comprised of COPD, asthma, interstitial lung disease (ILD) and bronchiectasis. Death certificates were provided by the Office of National Statistics. Separate survival analyses were performed for respiratory morbidity and mortality. Patients were followed until their first hospital admission for a respiratory event or death, embarkation date, June 2012 (morbidity analysis) or June 2013 (mortality analysis). The association between baseline predictors and respiratory morbidity or mortality was assessed using Cox proportional regression analysis (HR, 95%CI).
Results The mean age was 57.8±14.8 years and 57% fulfilled the 2010 EULAR/ACR criteria for RA at baseline. Respiratory morbidity and mortality rates were 28.8 and 4.59 per 1000 person year respectively during 6569 and 8065 person-years follow-up. There were 189 respiratory admissions which included cancer (6.9%), CLD with infection (5.8%), CLD without infection (55.6%), and others (31.7%), comprising mainly of infections without underlying lung disease. There were 37 deaths due to pulmonary causes: lung cancer (43%), COPD (22%), lung infection (16%), ILD (8%), bronchiectasis (3%) and others (8%).Men, smoking status and increased functional disability were significant predictors of both morbidity and mortality. Positive RF and ACPA and high DAS28 score were associated with morbidity with a similar trend in mortality but was not significant due to the low death numbers. Low BMI predicted mortality.
Conclusions Although traditional risk factors contributed to respiratory morbidity and deaths, markers of disease severity also significantly predicted respiratory morbidity in early IP.
Disclosure of Interest None declared