Table 3 Subgroup analysis estimating the association between the postoperative fifth day systemic immune-inflammation index and one-year mortality based on different stratified groups

Age

< 80 years

3.73 (1.47–9.47)

0.006

≥ 80 years

2.29 (1.40–3.74)

0.001

Gender

Female

2.94 (1.65–5.23)

< 0.001

Male

2.42 (1.25–4.68)

0.009

CCI

CCI = 0

1.07 (1.03–1.12)

0.223

CCI = 1

3.37 (1.22–9.29)

0.019

CCI ≥ 2

2.36 (1.44–3.85)

0.001

Albumin

Hypoalbuminemia

3.26 (1.82–5.85)

< 0.001

Normal albumin

2.22 (1.15–4.29)

0.018

Fracture type

Intertrochanteric

3.07 (1.78–5.31)

< 0.001

Neck

2.35 (1.15–4.79)

0.019

Surgery type

Arthroplasty

2.71 (1.68–4.38)

< 0.001

Internal fixation

3.01 (1.07–8.47)

0.034

Delay to surgery

> 48 h

2.22 (1.35–3.66)

0.002

≤ 48 h

5.37 (2.13–13.54)

< 0.001

Hemoglobin

Anemia

2.78 (1.17–6.66)

0.021

Normal hemoglobin

2.72 (1.64–4.49)

< 0.001