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Abstract
Objective Several drugs have been implicated in the development of de novo systemic lupus erythematosus (SLE), unmasking of quiescent SLE or causing an exacerbation of previously diagnosed SLE. Our aim is to describe the causative drugs, clinical and serological features of patients diagnosed of Drug-Induced lupus (DIL) in our Rheumatology Department.
Methods A total of 445 patients diagnosed with SLE treated in our Rheumatology Department from 2012 to 2023 were retrospectively screened for the fulfilment of DIL criteria through the search of medical electronic records. Demographic, clinical and laboratory data were summarised using descriptive statistics.
Results We identified 18 patients diagnosed with DIL, representing a prevalence of 4% among all SLE patients in our Department. There was a female preponderance and a young age at disease onset. Patients’ clinical and serological characteristics are shown in table 1. Only three drugs (infliximab, adalimumab and sulfasalazine) were identified as causative agents of DIL, anti-TNF being the most common. Most patients were treated for a condition different from a rheumatic disease, mainly inflammatory bowel disease (IBD). Median time to symptom onset after drug initiation ranged from 3 to 194 weeks (median 50.4). Peripheral arthritis and skin rash were the most frequent symptoms, with 4 patients (22%) presenting both at onset. Serologically, only 2 patients were ANA negative, but tested positive for anti-dsDNA. After drug withdrawal, ANA titre showed a slow decreasing trend over time, as well as anti-dsDNA antibodies. However, only 2 patients lost ANA-positivity through follow-up. Remarkably, more than half of the patients tested positive for antiphospholipid antibodies.
Conclusion DIL showed a prevalence of 4% in our Rheumatology Department. Anti-TNF agents were the most common drugs causing DIL. ANA tend to decrease over time, but only become undetectable in a few patients. Antiphospholipid antibodies are common in our DIL patients. Age at onset is earlier than previously reported, probably because causative drugs are being used in younger populations.
Patients’ clinical and serological characteristics
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