Demographic and disease-related predictors of abnormal lung function in patients with established inflammatory polyarthritis and a comparison with the general population.
OBJECTIVE
To identify demographic and clinical predictors of obstructive lung disease (OLD) and restrictive lung disease (RLD) in patients with established inflammatory polyarthritis (IP) and to compare the prevalence of respiratory symptoms in patients with IP and the general population.


METHODS
A total of 421 patients with IP underwent a spirometry test 15 years after inclusion in the Norfolk Arthritis Register (NOAR). Logistic regression analyses were performed to assess the predictive ability of demographic and clinical characteristics obtained at inclusion in NOAR and to assess their association with OLD or RLD at 15 years (age- and gender-adjusted). In addition, the prevalence of OLD and RLD was compared with a matched population (1:4) of people participating in the European Prospective Investigation of Cancer-Norfolk, a representative sample of the general population in Norfolk, UK.


RESULTS
In this IP population, current smoking was the strongest predictor for OLD and functional disability for RLD. In the comparison study, 11.6% had OLD in the IP population and 4.9% in the general population (adjOR 2.01, 95% CI 1.26 to 3.22). The prevalence of RLD was not statistically different between the IP population and the general population (14.6% vs 17.5%; adjOR 0.76, 95% CI 0.53 to 1.10).


CONCLUSIONS
OLD, but not RLD, is more prevalent in the IP population than in the general population. Functional disability is especially associated with RLD whereas smoking is associated with OLD. The latter finding, and the known association between smoking and a poor disease prognosis, underlines the importance of smoking cessation in patients with IP.
Arthritis Research UK Epidemiology Unit, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK. Suzanne.Verstappen@manchester.ac.uk
Suzanne M M
SM
Verstappen
Mark
M
Lunt
Robert N
RN
Luben
Jackie
J
Chipping
Tarnya
T
Marshall
Kay-Tee
KT
Khaw
Nick
N
Wareham
William G
WG
Dixon
Ian N
IN
Bruce
Deborah P M
DP
Symmons
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D015897:Comorbidity; D003710:Demography; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology* / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D012042:Registries; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology