Baseline characteristics and outcomes
We initially enrolled 1851 patients with a diagnosis of atrial fibrillation who met the inclusion criteria. 35 patients were excluded because of incomplete SII data and 48 patients were excluded because they were lost to follow-up. Finally, a total of 1768 patients were selected to this study.
During a mean follow-up of 22.35 months, 155 cases of death from all causes occurred and 105 patients died from cardiovascular diseases. The baseline demographic characteristics and clinical data two groups are shown in Table 1. Patients in high SII group were older and more likely to have diabetes mellitus than patients in low SII group. Significant differences were detected in heart rate on admission, WBC, Hb, PLT, albumin, BUN, UA, Cr, HDL, eGFR, D-dimer, CRP, ESR, LAD and LVEF (allp <0.05). Besides, the incidence of death from all causes in high SII group is 97 (14.3%) and in low SII group, it is 58 (5.3%) which is significantly different (p <0.001). The incidence of death from cardiovascular diseases between the two groups also showed a significant difference (9.3% vs. 3.8%,p <0.001). For the secondary endpoints, we did not find any difference in the incidence of major bleeding events and stroke (p = 0.094 and p = 0.623, respectively).
Kaplan-Meier survival curves for SII level and adverse outcomes are shown in Figure 1 and Figure 2. Compared with patients in low SII group, patients in high SII group showed a significantly increased risk of death from all causes and death from cardiovascular diseases (log rankp < 0.001 and p = 0.001).
After adjusting for potential cofounders, including age, diabetes mellitus, WBC, Hb, PLT, albumin, BUN, UA, Cr, HDL, eGFR, D-dimer, CRP, ESR and LAD, multivariable Cox regression analyses were performed to evaluate the prognostic value of SII and adverse outcomes. The risk of death from all causes and death from cardiovascular diseases increased by 77.6% (95% CI: 1.109-3.065, p = 0.018) and 51.2% (95% CI: 1.011-3.742, p = 0.025) in high SII group compared to that in low SII group, during the long-term follow-up (Table 2 and 3).