Continuous renal replacement therapy in COVID-19—associated AKI: adding heparin to citrate to extend filter life—a retrospective cohort study

Table 4 Multivariate Cox regression models for first continuous renal replacement therapy circuit clotting in 72 h

Factor	Model 1		Model 2*		Model 3^†
Factor	HR (95% CI)	p	HR (95% CI)	p	HR (95% CI)	p
Anticoagulation (ACD-A + UH vs. ACD-A only)	0.28 (0.18–0.43)	< 0.001	0.25 (0.16–0.39)	< 0.001	0.28 (0.18–0.43)	< 0.001
Adjustment covariate
COVID-19 diagnosis	2.02 (0.96–4.24)	0.063	2.15 (0.99–4.68)	0.053
ACD-A dose (4–5 mmol/L vs. 2–3 mmol/L)	0.88 (0.46–1.69)	0.699	0.72 (0.36–1.42)	0.344
Hemoglobin level (per 1 g/dl increase)	1.13 (1.05–1.22)	0.001	1.18 (1.08–1.28)	< 0.001
Platelet count (per 100,000 increase)	1.00 (1.00–1.00)	0.015	1.00 (1.00–1.00)	0.070
Age (per year increase)			1.01 (1.00–1.03)	0.115
Male sex			0.91 (0.57–1.44)	0.677
BUN (per unit increase)			1.00 (0.99–1.00)	0.379
ACD-A dose (4 mmol/L vs. 3 mmol/L)			0.72 (0.36–1.42)	0.344
Median D-dimer level^‡ (≥ 5990 ng/ml vs. < 5990 ng/ml)					1.94 (1.25–3.01)	0.003

HR, hazard ratio; ACD-A, anticoagulant citrate dextrose solution formula A; UH, unfractionated heparin; COVID-19, coronavirus disease 2019; BUN, blood urea nitrogen
*Also adjusted for CRRT modality strata; ^†analysis restricted to the 180 patients for whom D-dimer values were available; ^‡value obtained closest to the initiation of renal replacement therapy (median 5990 ng/ml)

ISSN: 1364-8535