**3. Results**

#### *3.1. Patient Characteristics*

Of the 1881 participants with hip fractures between January 2015 and September 2019, 48 patients were excluded from this study due to missing HCT data at admission. A total of 1840 patients met the study criteria and were enrolled in our study. A flowchart is shown in Figure 2. Hematocrit levels were divided into five groups. The average admission hematocrit of all patients was 34.44 ± 5.64 vol% (Q1 group: 25.35 ± 2.96 vol%, Q2 group: 30.62 ± 1.08 vol%, Q3 group: 33.75 ± 0.83 vol%, Q4 group: 36.61 ± 0.88 vol%, and Q5 group: 41.29 ± 2.67 vol%). A total of 587 patients (32%) had preoperative DVT ((Q1 group: 95 (33.69%); Q2 group: 120 (36.70%); Q3 group: 135 (37.92%); Q4 group: 125 (30.19%); and Q5 group: 112 (24.30%)). Eight patients had pulmonary embolism, and two died after the operation due to coronary heart disease (CHD).

**Figure 2.** Study flow diagram.

Table 1 lists the demographic and clinical characteristics of all 1840 patients, including comorbidities, factors associated with injuries, and hematocrit levels at admission.


**Table 1.** The demographic and clinical characteristics of the patients (N = 1840).

Mean ± SD/N (%)*. p*-value \*: For continuous variables, we used the Kruskal–Wallis rank-sum test, and Fisher's exact probability test was used for count variables with a theoretical number <10.
