Table 1.

Characteristics of subjects in included studies.

Author	Country	HF number	HF homocysteine concentration	Controls number	Controls homocysteine concentration	NOS score
Herrmann et al(2005)	Germany	95	17.1 ± 20.0	18	9.6 ± 2.6	6
Gibelin et al (2006)	France	159	15.8 ± 6.9	119	10.9 ± 3.2	8
Raeder et al (2006)	Norway	29	24.1 ± 2.0	85	17.9 ± 1.0	6
May et al (2007)	USA	621	15.6 ± 7.0	2500	14.6 ± 6.5	6
Okuyan et al (2010)	Turkey	68	16.9 ± 5.27	40	10.15 ± 3.49	8
Topcuoglu et al (2010)	Turkey	31	20.2 ± 9.15	38	13.6 ± 7.56	8
Agoston-Coldea et al (2011)	Romania	65	18.9 ± 10.0	79	14.1 ± 5.2	7
Makarewicz-Wujec and Kozlowska-Wojciechowska (2011)	Poland	55	13.6 ± 4.3	55	10.3 ± 2.6	7
Hjelm et al (2014)	Sweden	138	20.13 ± 7.8	564	17.17 ± 6.91	7
Fournier et al (2015)	France	134	18.4 ± 7.83	50	12.8 ± 3.14	7
Strauss et al (2017)	Poland	55	14.9 ± 6.8	348	12.45 ± 5.16	8
El-Amrousy et al (2018)	Egypt	80	11.15 ± 1.96	80	6.69 ± 0.97	8

HF = heart failure, NOS = Newcastle–Ottawa Scale.