Thrombosis-free survival of the vascular access in hemodialysis patients according to TGF-β1 production haplotype and stratified by PAI-1 polymorphism. Black lines denote patients with homozygous 5G/5G or heterozygous 4G/5G PAI-1 genotypes; red lines, patients with homozygous 4G/4G PAI-1 genotype; dashed lines, low TGF-β1 production haplotype; solid lines, intermediate TGF-β1 production haplotype; dotted lines, high TGF-β1 production haplotype.