Plasma lactate at admission does not predict mortality and complications in hip fracture patients: a prospective observational study

Figures & data

Figure 1. Flowchart showing number of patients at each stage of the study.

Table 1. Demographics, co-morbidities, laboratory values and vital parameters on admission, choice of anaesthesia, fluid administration and time to operation.

	All	Lactate <2.0 mmol/L	Lactate ≥2.0 mmol/L
Number	690	550	140
Age (years)	84 (77–90)	85 (78–90)	82 (76–89)
Female gender, %	71	72	69
ASA PS1, %	5.5	4.9	7.9
ASA PS2, %	28.1	28.7	25.7
ASA PS3, %	60.9	61.0	60.7
ASA PS4, %	4.2	4.0	5.0
Systolic BP (mmHg)	150 (130–170)	150 (130–170)	150 (130–160)
Heart rate (bpm)	80 (70–90)	80 (70–88)	83 (71–96)
Hemoglobin concentration (g/L)	127 (116–137)	126 (115–136)	132 (121–142)
Plasma creatinine (mmol/L)	79 (64–98)	79 (64–99)	79 (63–96)
Plasma lactate (mmol/L)	1.3 (1.0–1.8)	1.2 (0.9–1.5)	2.3 (2.1–2.9)
Ischemic heart disease, n (%)	139 (20)	114 (20)	25 (18)
Cerebrovascular disease, n (%)	143 (21)	122 (22)	21 (15)
Congestive heart failure, n (%)	96 (14)	75 (14)	21 (15)
COPD, n (%)	56 (8)	40 (7)	16 (11)
Spinal anaesthetic, n (%)	448 (65)	358 (65)	90 (64)
Fluids administered in first 24 h (L)	3.1 (2.2–4.0)	3.1 (2.2–4.0)	3.1 (2.1–4.1)
Admission to operation (h)	17 (10–23)	17 (10–23)	17 (10–23)
More than 36 h to operation, n (%)	39 (6)	30 (5)	9 (6)

Continuous data are presented as median and interquartile range.

COPD: chronic obstructive pulmonary disease; BP: blood pressure; bpm: beats per minute; ASA PS: American Society of Anesthesiologists physical status classification.

Table 2. Outcomes presented by baseline lactate level.

	All n (%)	Lactate <2.0 mmol/L n (%)	Lactate ≥2.0 mmol/L n (%)
Number of patients	690	550	140
30-d mortality	50 (7.2)	39 (7.1)	11 (7.8)
Any complication	311 (45)	248 (45)	63 (45)
Acute kidney injury	22 (3)	18 (3)	4 (3)
Cardiac arrest	2 (0)	2 (0)	0 (0)
Congestive heart failure	47 (7)	40 (7)	7 (5)
Chest infection	50 (7)	37 (7)	13 (9)
Deep venous thrombosis	2 (0)	2 (0)	0 (0)
Gastrointestinal bleeding	11 (2)	9 (2)	2 (1)
Myocardial infarction	15 (2)	11 (2)	4 (3)
Pulmonary embolus	8 (1)	8 (1)	0 (0)
Pyrexia	5 (1)	3 (1)	2 (2)
Urinary retention	57 (8)	43 (8)	14 (10)
Urinary infection	137 (20)	111 (20)	26 (19)
Wound infection	28 (4)	20 (4)	8 (6)
Wound rupture	2 (0)	1 (0)	1 (1)
Arrhythmia	6 (1)	4 (1)	2 (1)
Other infection	28 (4)	24 (4)	4 (3)
Cerebrovascular stroke	7 (1)	6 (1)	1 (1)

Data are presented as absolute numbers and as percentage within parentheses.

Table 3. Demographics of the study cohort compared to study site and nationally during the study period.

	Included patients with lactate level	Lund, eligible not included	Eligible patients included in the national registry during study period*
Number of patients	690	959	48785
Age (years)	84 (77–90)	83 (76–89)	84 (76–89)
Female, %	71	70	68
ASA PS1, %	6	4	6
ASA PS2, %	28	29	37
ASA PS3, %	61	61	48
ASA PS4, %	4	5	7
Cervical fracture, %	53	54	54
Trochanteric fracture, %	41	38	38
Subtrochanteric fracture, %	6	8	8
Admission to operation (h)	17 (10–23)	19 (13–24)	19 (12–25)
30-d mortality, %	7.2	7.5	7.7

Continuous data are presented as median and interquartile range.

ASA PS: American Society of Anaesthesiologists physical status classification.

*Excluding patients from Skåne University Hospital, Lund.

Figure 2. Histogram showing distribution of lactate concentrations for 30-d mortality (A) and the composite of 30-d mortality and complications secondary outcomes (B).

Figure 3. Kaplan–Meier survival curve of patients with lactate concentration< 2.0 mmol/L and ≥2.0 mmol/L. Log rank (Mantel-Cox) significance 0.73. Note that the Y-axis is shortened for clarification.

Table 4. Accuracy and predictive qualities for lactate as a predictor of 30-d mortality or a composite outcome (30-d mortality and complications).

Threshold	Outcome	Sensitivity %	Specificity %	LR+	LR−
2.0 mmol/L	30-d mortality	22	80	1.09	0.98
2.0 mmol/L	Composite outcome	20	80	1.00	1.00
2.2 mmol/L	30-d mortality	28	70	0.93	1.03
2.2 mmol/L	Composite outcome	15	87	1.10	0.99

Threshold 2.2 mmol/L is based on maximizing Youden index for 30-d mortality.

LR+/LR−: positive and negative likelihood ratios, respectively.