Background Extra-articular rheumatoid arthritis (ExRA) manifestations are associated with increased comorbidity and premature mortality. While tumour necrosis factor (TNF)-inhibitors efficiently reduce arthritis, their impact on the risk of ExRA is still uncertain.
Objectives To evaluate whether treatment with TNF-inhibitors has any effect on the risk of developing severe ExRA, and to investigate potential predictors of ExRA in baseline questionnaire data obtained at the beginning of the study period.
Methods A community based sample of patients with rheumatoid arthritis (RA) (n=1016), established in 1997, was studied. Clinical records were reviewed from 1 January 2005 to 31 December 2011 and cases with new onset of severe ExRA (i.e. pericarditis, pleuritis, vasculitis, interstitial lung disease, neuropathy, episcleritis/scleritis, Felty’s syndrome and glomerulonephritis), classified according to predefined criteria, were added to cases found in a previous survey 1. Information on exposure to TNF-inhibitors during the study period was obtained from the South Swedish Arthritis Treatment Group (SSATG) register. Exposure to TNF-inhibitors was treated in a time dependent fashion, and person-years at risk (pyr) were appointed to the appropriate category of exposed or unexposed time. The incidence of ExRA in exposed patients was compared to incidence in unexposed patients. In addition, in 1997 all patients received a questionnaire including the Health Assessment Questionnaire (HAQ), visual analogue scales (VAS) for current pain and global health and questions on current and previous pharmacologic treatment. Cox regression analysis models were used to assess the impact of baseline characteristics and baseline disease severity measures on the risk of ExRA.
Results During treatment with TNF-inhibitors there were 9 patients with new onset of ExRA in 1226 pyr [0.73/100 pyr, 95% confidence interval (CI) 0.34-1.4] compared to 72 in 8320 pyr [0.87/100 pyr, 95% CI 0.68-1.1] in patients without TNF-inhibitors. The relative risk comparing those treated to those not treated was 0.85 (95% CI 0.37-1.7). Male gender [age adjusted hazard ratio (HR) 1.88, 95% CI 1.20-2.93], long duration of disease [age and sex adjusted HR (per year) 1.03, 95% CI 1.01-1.05] and greater disability, measured by HAQ [age and sex adjusted HR (per unit) 1.38, 95% CI 1.00-1.90] at baseline were predictors for ExRA.
Conclusions TNF-inhibitors did not have any major effect on the incidence of severe ExRA in this sample. However, the assessment of the impact of treatment on ExRA may be influenced by the association between ExRA and severe, longstanding disease.
Nyhäll-Wåhlin BM, Petersson I, Jacobsson C, Geborek P, Nilsson JA, Nilsson K, Jacobsson L, Turesson C, Extra-articular manifestations in a community-based sample of patients with rheumatoid arthritis: incidence and relationship to treatment with TNF inhibitors. Scand J Rheumatol. 2012; 41: 434-7.
Disclosure of Interest None Declared
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