Table 1.

Characteristics of the studies included in final phase

Author	Country	age	Male	Female	Design	Sample size	Number of Suicide Case	Positive Cases	Number of Control group	Positive controls	Conclusion	Quality score (out of 8)	Reference
Arling (2009)	United states	40±10	90	149	Case-control	234	81	11	153	17	Positive association	8	[18]
Yagmur F (2010)	Turkey	24.3±7.6	82	318	Case-control	400	200	82	200	56	Positive association	7	[31]
Okusaga (2014)	Germany	38.6±11.1	600	350	Case-control	950	351	146	599	226	No association	8	[19]
Pedersen, M. G (2012)	Denmark	Pregnancy ages	–	45,788	prospective cohort study	45,788	N/A	N/A	N/A	N/A	Positive association	6	[29]
Alvarado-Esquivel, C (2013)	Mexico	All ages	88	195	Case-control	283	156	7	127	10	Negative association	7	[22]
Samojlowicz, D (2013)	Poland	19 to 86 years	115	12	Case-control	127	41	26	86	42	No association	6	[30]
Coryell W (2016)	United states	17.5 ± 1.7	30	78	Case-control	108	17	2	91	2	No association	7	[19]
Gale, S. D (2016)	United states	20 to 80 years	2469	3018	Cross-Sectional	5487	NA	NA	NA	NA	No association	7	[27]
Okusaga, O (2016)	United states	40±11.5	518	307	Case-control	825	308	127	517	200	No association	8	[18]
Sugden, K (2016)	United states	3 to 38 years	423	414	prospective cohort study	837	16	8	821	228	No association	8	[20]
Ansari-Lari, M (2017)	Iran	40±10	72	27	Case-control	99	29	8	70	34	No association	7	[5]
Dickerson, F (2017)	United states	38.6±13	88	74	Case-control	162	N/A	N/A	N/A	N/A	Positive association	8	[25]
Bak, J (2018)	South Korea	43.75 ± 16.75	141	149	Case-control	290	155	21	135	8	Positive association	7	[23]
Dickerson, F (2018)	United states	36±12	647	645	prospective cohort study	1292	N/A	NA	N/A	NA	Positive association	8	[24]
Fond, G (2018)	France	32±8.6	184	66	prospective cohort study	250	9	7	241	177	No association	8	[26]
Ling, Vinita	Eurepe	0–75+	–	–	Ecologcal study	–	–	–	–	–	Positive association	7	[32]