Background Several studies have shown an increased risk for infections in patients with rheumatoid arthritis (RA), including risk for hospitalization for infectious disease and an increased risk for certain types of infections such as pneumonia and herpes zoster. Lately, case reports have described reactivation of hepatitis B in RA patients treated with biological drugs, but it is not known whether the risk of hepatitis B is increased in RA patients in general.
Objectives To assess if the risk of hepatitis B is increased in RA patients compared to the general population.
Methods Risk of hepatitis B up until diagnosis of RA was estimated in a cohort of incident RA patients identified in the Swedish Rheumatology Quality Register (SRQ) 1999-2009. For each patient five general-population comparators were matched for sex, age and county of residence. Occurrence of hepatitis B in these cohorts was identified by linkage with the nationwide Swedish Patient Register (hospitalizations and outpatients visits in non-primary care) up until date of RA diagnosis.
Risk for hepatitis B in patients diagnosed with RA was assessed using two RA populations (the above mentioned inception cohort from SRQ and a prevalent RA cohort identified on the basis of outpatient visits listing RA) 1999-2009. For each subject, five population-comparators were matched, and hepatitis B was identified as mentioned above. Relative risks were calculated using conditional logistic regression (OR) and Cox regression (HR), respectively.
Results By the time of RA diagnosis 6 out of 7570 RA patients had an identified history of hepatitis B, compared to 52 cases among the 36778 general population comparators, OR=0.6; 95% CI 0.2-1.3.Counting from RA diagnosis in this cohort, 5 cases of hepatitis B were identified, compared to 12 cases among the controls HR=1.7; 95% CI 0.6-5.0.During follow-up of the prevalent RA cohort (n=46852,280000 person-years),22 patients were identified with hepatitis B,compared to 94 among the controls (n=215424,1903597,person-years), HR=1,4;95%CI 0,9-2,2.
Conclusions We found no significantly increased occurrence of hepatitis B in RA patients in Sweden, neither before nor after RA diagnosis, compared to the general population.
Disclosure of Interest None Declared
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