32 Acta Orthopaedica 2012; 83 (1): 31–35 Table 1. Characteristics of the cohort and blood sample values at the time of admission Hip fracture patients Number of Survived study patients period Number Age, mean (SD) Women Men Sex, n (%) Women Men Blood hemoglobin (mmol/L), mean (SD). Reference interval: women: 7.3–9.5 mmol/L, men: 8.5–10.3 mmol/L Women Men Plasma creatinine (μmol/L), median (range). Ref. int.: women: 50–90 μmol/L, men: 60–105 μmol/L Women Men Plasma sodium (mmol/L), mean (SD). Ref. int.: 137–144 mmol/L Women Men Plasma potassium (mmol/L), mean (SD). Ref. int.: 3.5–4.6 mmol/L Women Men Plasma glucose (mmol/L), mean (SD). Ref. int.: 4.2–7.2 mmol/L Women Men Plasma albumin (g/L), mean (SD). Ref. int.: 34–45 g/L Women Men Plasma CRP (mg/L), median (range). Ref. int.: < 10 mg/L Women Men Leukocyte count (× 109/L), mean (SD). Ref. int.: 3.5–8.8 × 109/L Women Men Platelet count (× 109/L), mean (SD). Ref. int.: 145–390 × 109/L Women Men 792 591 201 591 201 590 201 585 200 587 201 587 201 556 185 515 174 458 170 590 201 590 201 Blood was analyzed for hematology and chemistry using Sysmex (Sysmex Corporation, Kobe City, Japan) and Vitros 5.1 FS (Ortho-Clinical Diagnostics, Pisataway, NJ) respectively, using standardized routine labora- tory methods. Results 232 of 792 patients (29%) died during the study period (Table 1), at median 44 (1–582) days. 57 died between 1 and 66 days, while still in hospital. 106 died after leaving hospital but within 3 months, and 69 died some time after 3 months. Based on the ROC curves (Figure 1), the cutoff values were set at 7 mmol/L in both sexes for hemoglobin and above 50 mg/L for C-reactive protein (CRP). The ROC curves for most other laboratory tests did not indicate any optimal cutoff value (the number of correctly classified patients was the same for a large variety of values) (Table 2). We therefore decided to use the upper or lower limits of normal laboratory reference intervals as cutoff values. In the univariate analysis (Table 3), high age, high plasma creatinine (Figure 2), low plasma albumin, high plasma potas- sium, and low blood hemoglobin led to increased mortality. Patient mortality was not related to gender, blood platelet 68 (33–445) 82 (39–419) 82 (36–615) 106 (50–699) 560 83 (9) 78 (9) 425 (76%) 135 (24%) 7.5 (1.1) 8.0 (1.2) 137 (4.1) 138 (4.3) 3.8 (0.49) 4.0 (0.49) 6.8 (2.1) 6.6 (2.3) 39 (4.4) 39 (4.7) 67 (82) 66 (70) 11.0 (4.0) 11.5 (5.6) 249 (86) 229 (79) Died during study period 232 87 (8) 83 (9) 166 (72%) 66 (28%) 7.3 (1.0) 7.2 (1.2) 137 (5.1) 138 (4.6) 4.0 (0.67) 4.1 (0.59) 6.5 (1.7) 6.8 (2.1) 37 (5.4) 36 (5.6) 71 (73) 81 (86) 10.8 (4.1) 10.5 (4.3) 270 (80) 240 (90) p-value < 0.001 < 0.001 0.2 0.02 < 0.001 < 0.001 < 0.001 < 0.001 0.003 0.4 0.5 0.002 0.2 0.1 0.5 0.05 0.2 0.7 0.1 0.007 0.4