• lupus erythematosus
• systemic
• lupus nephritis
• quality indicators
• health care

We thank Zhou et al for their interest in our manuscript and their insightful comments.1 In figure 4 of our manuscript (Diagnostic approach to a patient with suspected systemic lupus erythematosus and the use of classification criteria to aid clinical diagnosis), we propose an algorithm to aid clinical diagnosis, especially in patients not fulfilling the classification criteria.2 As opposed to classification, diagnosis by definition may include the notion of probability (ie, possible systemic lupus erythematosus (SLE)). Moreover, as with any set of criteria, this algorithm presupposes that alternative or competing diagnoses have been ruled out prior to SLE diagnosis. In our experience, inflammatory arthritis is not a typical manifestation of the antiphospholipid syndrome, therefore a patient with arthritis, positive antinuclear antibodies (ANA) and antiphospholipid antibodies is closer to a diagnosis of SLE. Regarding the second case scenario, lymphoproliferative disorders are well-known lupus mimics and their exclusion is mandatory prior to consideration of a diagnosis. Once this exclusion is secured, a diagnosis of lupus could be presumed in patients with inflammatory manifestations from two organ systems per EULAR/ACR 2019 criteria, when accompanied by evidence of serological autoimmunity other than ANA. In all circumstances, we agree with the authors that careful consideration is necessary, including re-evaluation of the accuracy of the diagnosis over time.

In terms of treatment options for SLE, in view of the newer, less toxic agents that have shown efficacy in both renal and extra-renal disease (mycophenolate mofetil, belimumab, calcineurin inhibitors), we believe that cyclophosphamide—at least in high doses—should be reserved for severe, organ-threatening disease, especially recalcitrant to first-line treatments. We do agree on the indispensable value of kidney biopsy to guide therapeutic decisions, as well as the choice of rituximab (RTX) for refractory lupus nephritis. Although these parts were omitted from the text for reasons of brevity, RTX was included as an option for the treatment of refractory disease in figure 5.