Risk factors of digital gangrene secondary to systemic lupus erythematosus flare: real-world data from 2014 to 2022.

OBJECTIVES

To seek risk factors of gangrene secondary to systemic lupus erythematosus (SLE).

METHODS

We reviewed 31 SLE patients who developed gangrene, following them up for over 2 years. A control group of 93 lupus patients without gangrene matched for SLEDAI-2000 scores was also included. Additionally, 93 age- and sex-matched healthy volunteers were recruited as a healthy control group.

RESULTS

Thirty-one out of 3021 (1.03%) SLE patients with gangrene were recorded. The average age at event was 32.23 ± 18.77 years and the average disease duration was 80.23 ± 260.54 months. Gangrene, as the first manifestation of new onset of SLE, was found in 16 patients. Logistic regression analysis indicated that digital ulceration (OR = 8.56, 95% CI: 2.7 4-26.72), Raynaud's phenomenon (OR = 13.45, 95% CI: 2.4 0-75.40), thrombotic microangiopathy (TMA) (OR = 12.24, 95% CI: 1.0 6-141.90), elevated serum C-reactive protein (CRP) (OR = 1.01, 95% CI: 1.0 0-1.03) and declined natural killer (NK) cells (OR = 0.96, 95% CI: 0.9 4-0.99) (P all <0.011) significantly influenced the occurrence of gangrene. During two-year follow-up, nearly half of the gangrene patients (48.4%) experienced amputation. Subgroup analyses revealed that infections secondary to gangrene significantly increased the risk of amputation (P = 0.046). Regarding the follow-up, only three patients experienced a second or subsequent episode of gangrene.

CONCLUSION

Our study establishes a close connection between declined NK cells and the pathogenesis of gangrene. The presence of digital ulceration and/or Raynaud's phenomenon and TMA, along with elevated serum CRP levels, increases the likelihood of gangrene, potentially serving as gangrene predictors in SLE. Infections secondary to gangrene further elevate the risk of amputation.