Infection risk in systemic lupus erythematosus patients: susceptibility factors and preventive strategies

Infection is one of the leading causes of morbidity and mortality in systemic lupus erythematosus (SLE). Bacterial infections are most frequent, followed by viral and fungal infections. The impaired cellular and humoral immune functions seen in patients with SLE are predisposing conditions, whilst disease activity, prednisone doses over 7.5-10 mg/day, high doses of methylprednisolone or cyclophosphamide are well-recognised risk factors for infection. The first six months after rituximab treatment and the use of more than three courses are also associated with an increased susceptibility for infection. It has not been established whether belimumab, azathioprine and mycophenolate mofetil increase the risk of serious infections. Most vaccines are effective and safe in SLE patients, although vaccination should be avoided during periods of active disease. Live virus vaccines are contraindicated for immunosuppressed patients. Influenza and pneumococcal vaccines are universally recommended. Tuberculosis prophylaxis should be considered in selected cases. Therefore, it is advisable not to exceed doses of 5 mg/day of prednisone in chronic treatment. Methylprednisolone and cyclophosphamide should be used in low-dose regimens. Antimalarials have a well-known protective role against infection, in addition to other beneficial properties, thus, hydroxychloroquine is recommended for all SLE patients where no contraindication exists.