Background We aimed to characterise the all-cause mortality rate (MR) and the incidence of cancer in SLE patients receiving biologic and standard of care (SoC) therapies.

Methods Patients recruited to the BILAG-BR 2010–2021 were included. Demographic and clinical data were recorded at recruitment. Mortality and malignancy data were collected from study centres, the UK Office of National Statistics and the National Cancer Register. Cox regression models were used to estimate risk in biologic-treated patients compared to SoC. Mortality models were adjusted for age, gender, co-morbidity, SLICC damage index (SDI) and hydroxychloroquine (HCQ) use.

Results During follow-up, (1463 patients with 5,962 person years [pys]), 32 incident cancers occurred in 31 individuals, a median (IQR) of 1.31 (0.63–3.36) years after registration. Compared to the UK general population, the SIR (95% CI) was 1.21 (0.85–1.72). Using SoC as the comparator, the age and gender adjusted HR was 1.49 (0.57–3.92) for rituximab and 2.47 (0.57–10.58) for belimumab. Across the whole cohort, associated risk factors (table 1), included age at recruitment (HR 1.05 [1.02- 1.08]) and male sex (HR 2.68 [1.13–6.41]).

Following registration, 54 deaths occurred after a median of 1.8 (0.8–3.3) years. The standardised MR was 4.74 (3.63–6.19). The most common causes of death were infection (22, 40.7%), SLE (11, 20.3%) and cancer (6, 11.1%). MR was 3.3 (1.3–8.9) per 1000 py in the SoC, 11.3 (8.5–15.0) in the rituximab and 2.5 (0.4–17.9) in the belimumab group. Risk factors included age at recruitment (HR 1.07 [1.05–1.09]) and SDI (HR 1.34 [1.08–1.67]. HCQ use was protective (HR 0.30 [0.14–0.65]). In multivariate analysis, compared to SoC, risk was similar in rituximab (HR 2.36 [0.69–8.10) and belimumab groups (HR 1.41 [0.14–14.14]).

Conclusions Although overall numbers are low, mortality rate and incidence of cancer appears to be broadly similar in SoC, rituximab and belimumab treated patients.