Lower lifetime prevalence of atopy in rheumatoid arthritis

Abstract

There is evidence that the prevalence of atopic disorders may be lower in patients with autoimmune conditions [1]. In the past, five studies have looked into the associations between atopy and rheumatoid arthritis (RA). All have found evidence of a lower prevalence of atopy in RA patients. However, they were either only questionnaire based, without serological confirmation of atopy [2–4], or they did not account for all manifestations of atopy [4–6]. We have set out to assess the lifetime prevalence of clinical and serological manifestations of atopy in RA patients in a case control study. The subjects were recruited between July 2010 and July 2011, from outpatient clinic for rheumatology at the Maxima Medical Center, Eindhoven, and the controls were patients with varicosities from our phlebology outpatient clinic. All subjects provided informed consent, and the study protocol was reviewed by the local Medical Ethical Committee. The diagnosis of RA was made according to the criteria of the American Rheumatism Association. The disease activity and course severity in RA patients were assessed with disease activity score 28 (DAS) and Health Assessment Questionnaire Disability Index, respectively (HAQDI) [7, 8]. Manifestations of atopy were assessed using a questionnaire based on the European Community Respiratory Health Survey [9]. Blood samples were taken from all subjects and levels of total serum IgE, and IgE directed against common aeroallergens were measured using Phadiatop; Phadia AB, Uppsala Sweden, according to the manufacturers protocol. One hundred and thirty-three RA patients and 124 controls were included. Eighty-nine (66 %) of the RA patients were anti-CCP positive and 90 (67 %) were currently treated with methotrexate. The average age at onset of RA was 50 years, standard deviation 13. The average age was higher in RA patients than in controls (62 vs. 54 years, p \ 0.001). There were 48 (36 %) and 53 (42 %) males in RA and control group, respectively (p = 0.278). RA patients reported previous symptoms of dermatitis, itching and flexural rash less often (20 vs. 33 %, p = 0.020) and (9 vs. 19 %, p = 0.037) (Table 1). However, dry skin during last year, a measure of current symptomatology of atopic dermatitis, was reported equally in both groups (44 vs. 44 %, p = 0.896). RA patients also reported having had hay fever less often (11 vs. 20 %, p = 0.032). The percentage of patients diagnosed with asthma was lower in the RA group although the difference did not reach statistical significance (8 vs. 14 %, p = 0.086). Current asthma symptomatology expressed as asthma attacks in the last year and inhalator use were equally distributed across both groups (Table 1). Finally, serological evidence of atopy was less often found in RA patients. Twelve per cent of the RA group had a serum IgE level of more than 100 kU/L, and in controls, this was 21 %, p = 0.053. A smaller percentage of the RA group were sensitized to common aeroallergens than controls (22 vs. 33 %, p = 0.043). Having any atopic feature lowered the odds of having RA by roughly 60 % with OR 0.43; 95 % CI [0.25–0.75]. Adjusted for age and sex this was OR 0.51; 95 % CI [0.28–0.92]. The median HAQDI in sensitized RA patients did not differ from the median in non-sensitized patients (1.0; IQR [0.3–1.6] vs. 1.0; IQR [0.4–1.5], p = 0.375). The DAS28 score was equally distributed in sensitized and non-sensitized RA patients as well (2.6; IQR [2.1–3.9] vs. 3.2; IQR [2.2–4.0], p = 0.343). In conclusion, RA patients had a lower prevalence of clinical and serological atopic features. Atopy had no effect E. Hajdarbegovic (&) B. Thio T. Nijsten Rotterdam, The Netherlands e-mail: e.hajdarbegovic@erasmusmc.nl