FIBTEM clot firmness parameters correlate well with the fibrinogen concentration measured by the Clauss assay in patients and healthy subjects

Figures & data

Table 1. Study group characteristics.

Characteristic	Healthy subjects (n = 75)	Bleeding/trauma (n = 34)	Liver surgery (n = 13)	Cardiac surgery (n = 44)	Other (n = 20)
Age (years)	32.0 [26.0–46.0]	56.0 [33.3–65.0]	52.0 [49.0–66.0]	67.5 [56.3–75.0]	55.0 [42.5–65.5]
Sex (women)	64 (85%)	16 (47%)	6 (46%)	7 (16%)	13 (65%)
PT (s)	11.9 [11.5–12.6]	14.1 [12.3–17.9]	15.1 [12.9–18.0]	15.2 [13.5–16.8]	13.8 [11.7–17.5]
APTT (s)	25.0 [23.0–26.0]	27.5 [24.0–33.3]	30.0 [29.0–33.5]	29.0 [26.0–35.8]	27.0 [23.3–38.3]
Fibrinogen^a (g/L)	2.7 [2.3–3.4]	1.9 [1.5–2.6]	2.4 [1.9–3.3]	1.9 [1.5–2.2]	3.2 [1.7–4.3]
FIBTEM α–angle	69.0 [64.0–74.0]	69.5 [62.8–75.8]	73.0 [71.0–80.0]	71.0 [67.5–76.5]	74.0 [64.0–77.0]
FIBTEM A5 (mm)	ND	11.0 [8.3–13.5]	12.0 [9.0–18.5]	10.5 [7.3–13.0]	14.5 [8.3–19.0]
FIBTEM A10 (mm)	15.0 [12.0–17.0]	11.5 [8.5–14.5]	14.0 [10.0–20.0]	12.0 [9.0–14.0]	15.5 [8.5–22.8]
FIBTEM MCF (mm)	15.0 [12.0–18.0]	12.5 [9.5–16.3]	16.0 [11.0–22.5]	13.0 [9.3–15.0]	17.5 [9.8–24.5]

Data are presented as median [interquartile range] or absolute number (%).

^aPatients with major blood loss or very low levels of fibrinogen might have received fibrinogen concentrate, which could have had an impact on these fibrinogen measurements.

A5: amplitude (clot firmness) at 5 min; A10: amplitude at 10 min; APTT: activated partial thromboplastin time; MCF: maximum clot firmness; ND: not determined; PT: prothrombin time.

Figure 1. Correlation between the maximum clot firmness (MCF) of the FIBTEM assay and early FIBTEM parameters (clot firmness at 5 (A5) or 10 (A10) min).

Table 2. Correlation between fibrinogen level (Clauss assay) or the FIBTEM α–angle and FIBTEM clot firmness parameters.

FIBTEM parameter	Healthy (n = 75)	Bleeding/trauma (n = 34)	Liver surgery (n = 13)	Cardiac surgery (n = 44)	Other (n = 20)
A5 vs Clauss		0.846 [0.683–0.918]	0.939 [0.741–0.999]	0.899 [0.805–0.946]	0.808 [0.518–0.943]
A10 vs Clauss	0.697 [0.527–0.829]	0.839 [0.669–0.917]	0.941 [0.755–0.999]	0.899 [0.800–0.946]	0.803 [0.446–0.948]
MCF vs Clauss	0.657 [0.457–0.802]	0.848 [0.678–0.923]	0.935 [0.750–0.991]	0.892 [0.794–0.939]	0.821 [0.496–0.952]
A5 vs α–angle		0.912 [0.788–0.958]	0.917 [0.630–0.998]	0.850 [0.655–0.947]	0.850 [0.568–0.972]
A10 vs α–angle	0.722 [0.575–0.831]	0.900 [0.759–0.952]	0.938 [0.687–1.000]	0.842 [0.634–0.943]	0.837 [0.502–0.978]
MCF vs α–angle	0.718 [0.564–0.829]	0.841 [0.613–0.937]	0.926 [0.700–1.000]	0.777 [0.528–0.900]	0.819 [0.398–0.900]

Data are presented as r_s [95% confidence interval]. All p-values <.001.

r_s: Spearman’s correlation coefficient; p-values by Spearman’s rank test.

Figure 2. Correlation between fibrinogen concentrations measured by the Clauss assay and maximum clot firmness (MCF) of the FIBTEM assay.

Figure 3. Agreement between classification in low, normal and high levels according to the Clauss assay and FIBTEM parameters clot firmness at 5 (A5) or 10 (A10) min or maximum clot firmness (MCF).

Table 3. Agreement between the Clauss assay and FIBTEM parameters in classification in low, normal or high fibrinogen.

FIBTEM parameter (normal range)	Healthy subjects (n = 75)	Bleeding/trauma (n = 34)	Liver surgery (n = 13)	Cardiac surgery (n = 44)	Other (n = 20)
A5 (4–17 mm)		0.693 [0.452–0.934]	0.350 [–0.107–0.807]	0.138 [–0.066–0.342]	0.381 [0.063–0.699]
A10 (7–23 mm)	0.388 [0.711–0.065]	0.885 [0.730–1.040]	1.000 [1.000–1.000]	0.507 [0.256–0.758]	0.514 [0.204–0.824]
MCF (9–25 mm)	0.085 [–0.140–0.310]	0.822 [0.634–1.010]	0.851 [0.571–1.131]	0.536 [0.287–0.785]	0.528 [0.218–0.838]

Data are presented as kappa statistics with [95% confidence interval] of the agreement in classification in 3 groups according to fibrinogen level measured by the Clauss assay (low: ≤1.5; normal: 1.5–3.5 or high: >3.5 g/L) and FIBTEM parameters (low: below normal range, normal: within normal range, high: above normal range).

Table 4. Optimal cut-off values of FIBTEM parameters for fibrinogen levels ≤1.5 g/L.

FIBTEM parameter	Cut-off value	Sensitivity	Specificity
A5	9.5	96.3%	82.1%
A10	9.5	85.2%	90.5%
MCF	10.5	88.9%	88.1%

Cut-off values of FIBTEM parameters to predict fibrinogen levels below 1.5 g/L. Receiver operating characteristic (ROC) curves were made, after which the optimal cut-off values were determined using the Youden index.