HRV indices: SDNN: 57.93 ± 16.99 ms, SDANN: 47.33 ± 16.69 ms, SDNNidx: 31.83 ± 11.00 ms, rMSSD: 19.87 ± 4.39 ms, pNN50: 3.67 ± 2.88%, the parameters acquired from case group were lower than those of control group with statistical difference (p < 0.0001).