Anti-PF4/heparin antibodies associated with repeated hemofiltration-filter clotting: a retrospective study

Table 2 Laboratory and continuous veno-venous hemofiltration (CVVH) parameters

	PF4⁺ (n = 7)	PF4^- (n = 21)	P value
Creatinine before first CVVH, μmol/L	600 (247–742)	403 (312–441)	0.34
Urea before first CVVH, mmol/L	17 (10–25)	15 (12–24)	0.91
Number of CVVH sessions	5 (4–11)	5 (3–9)	0.65
Mean CVVH duration^a, hours	10.4 (9.6–18–4)	22.7 (15.7–22.3)	0.03
Mean urea reduction ratios^a, percentage	17 (10–37)	44 (30–52)	0.04
Platelet nadir, 10⁹/L	40 (24–46)	35 (17–43)	0.54
Maximum platelet count, 10⁹/L	324 (238–366)	286 (182–403)	0.81
PF4 platelet count variation (D₀-D_PF4), percentage	59 (35–73)	56 (35–73)	0.98
Maximum platelet count variation (D₀-D_nadir), percentage	77 (49–81)	79 (55–87)	0.81
Mean minimum aPTT ratios^b	1.20 (1.12–1.22)	1.35 (1.10–1.56)	0.35
Mean maximum aPTT ratios^b	1.85 (1.65–2.12)	2.19 (1.51–2.93)	0.35

Platelet count variations were calculated as follows: [(platelet D₀ – platelet D_x)/platelet D₀] × 100, where platelet D₀ is the platelet count on admission and platelet D_x is the platelet count on the day of anti-PF4/heparin antibody assay (D_PF4) or the minimal platelet count (D_nadir). Results are expressed as median (first quartile to third quartile). ^aFor PF4⁺ patients, mean duration and efficiency of CVVH sessions before replacement of unfractionated heparin by danaparoid; ^bmeans of minimum and maximum aPTT ratios observed during all the CVVH sessions before D_PF4. aPTT, activated partial thromboplastin time (on heparin therapy during all continuous veno-venous hemofiltration sessions); PF4^-, anti-PF4/heparin antibody-negative; PF4⁺, anti-PF4/heparin antibody-positive.

ISSN: 1364-8535