Table 4.

Associations of serum folate higher (≥6 ng/mL) vs. lower (<6 ng/mL) levels with suicidal behavior in patients with depressive disorder.

Suicidal behavior	Folate level	N patient	N (%) presence of suicidal behavior	Odds ratio (95% confidence interval)
				Unadjusted	Adjusteda
Present previous suicidal attempt	Higher	688	42 (6.1)	Ref	Ref
	Lower	406	54 (13.3)	2.36 (1.55–3.60)‡	1.95 (1.21–3.13)†
Higher baseline suicidal severity	Higher	688	203 (29.5)	Ref	Ref
	Lower	406	159 (39.2)	1.54 (1.19–1.99)†	1.50 (1.12–2.02)†
Increased suicidal severity during follow-up	Higher	549	81 (14.8)	Ref	Ref
	Lower	335	74 (22.1)	1.64 (1.16–2.32)†	1.45 (1.00–2.16)*
Fatal/non-fatal suicidal attempt during follow-up	Higher	549	12 (2.2)	Ref	Ref
	Lower	335	26 (7.8)	3.77 (1.87–7.57)‡	2.69 (1.27–5.69)*

Baseline suicidal severity was defined using the brief psychiatric rating scale (BPRS) suicidality item scores, divided into lower [1 (not present) ~ 3 (mild)] and higher [4 (moderate) ~ 7 (extremely severe)]. Increased suicidal severity was defined as any instance in the increase in BPRS suicidality item score during 12-month pharmacotherapy.

^aAdjusted for age, sex, marital state, religious affiliation, monthly income, atypical feature, number of previous depressive episode, use vitamin supplement, and scores on Hospital Anxiety and Depression Scale-anxiety subscale and Alcohol Use Disorders Identification Test for baseline analyses, plus treatment steps over 12-month pharmacotherapy for follow-up analyses.

^* P < 0.05;

^† P < 0.01;

^‡P < 0.001.