Methods of suicide predict the risks and method-switching of subsequent suicide attempts: a community cohort study in Taiwan

Figures & data

Table 1 Characteristics of survivors of nonfatal suicide attempts, by low-lethality methods and by high-lethality methods, in Keelung City, Taiwan, from 2006 to 2010

Characteristics	Total (N=2,070) N (%)	Low-lethalitya (N=1,730) N (%)	High-lethalityb (N=340) N (%)	Significance
Sex				χ^2=57.54, df =1, P<0.001***
Female	1,394 (67.3)	1,225 (70.8)	169 (49.7)
Male	676 (32.7)	505 (29.2)	171 (50.3)
Age at the index attemptc (years)				χ^2=15.13, df =3, P=0.002**
<35	826 (39.9)	715 (41.3)	111 (32.6)
35–49	738 (35.7)	589 (34.0)	149 (43.8)
50–64	324 (15.7)	267 (15.4)	57 (16.8)
>64	181 (8.7)	158 (9.1)	23 (6.8)
Not available	1 (<0.1)	1 (0.1)	0 (0)
Marital status				χ^2=12.60, df =2, P=0.002**
Single	538 (26.0)	446 (25.8)	92 (27.1)
Married	786 (38.0)	684 (39.5)	102 (30.0)
Divorced or widowed	732 (35.4)	588 (34.0)	144 (42.4)
Not available	14 (0.7)	12 (0.7)	2 (0.6)
Amount of education (years)				χ^2=0.31, df =1, P=0.579
≤9	764 (36.9)	634 (36.6)	130 (38.2)
>9	1,306 (63.1)	1,096 (63.4)	210 (61.8)
Subsequent suicide attempt				χ^2=9.92, df =1, P=0.002**
No	1,696 (81.9)	1,397 (80.8)	299 (87.9)
Yes	374 (18.1)	333 (19.2)	41 (12.1)

Notes:

a Including drug overdose and self-cutting;

b including charcoal burning, hanging, jumping from high places, drowning, poisoning by domestically used gas, and other methods;

c the earliest suicide attempt recorded in the database.

** P<0.01;

*** P<0.001.

Table 2 Hazard ratios of subsequent suicide attempts (N=374) after the index attemptc, by different methods, followed to the end of 2011

Time (months)	Total			Low-lethal groupa			High-lethal groupb
	Number of terminal events	Number of patients	Hazard ratio (10^−3)	Number of terminal events	Number exposed to risk	Hazard ratio (10^−3)	Number of terminal events	Number exposed to risk	Hazard ratio (10^−3)
0–6	149	2,061.5	12.50	135	1,725	13.57	14	336.5	7.08
7–12	55	1,904	4.88	50	1,585	5.34	5	319	2.63
13–18	48	1,769.5	4.58	41	1,471	4.71	7	298.5	3.95
19–24	27	1,557	2.92	23	1,300	2.98	4	257	2.61
25–30	21	1,370.5	2.57	19	1,156	2.76	2	214.5	1.56
31–36	22	1,202.5	3.08	19	1,024	3.12	3	178.5	2.82
37–42	17	1,014.5	2.82	14	866	2.72	3	148.5	3.40
43–48	12	839	2.40	11	715.5	2.58	1	123.5	1.36
49–54	6	675	1.49	5	572.5	1.46	1	102.5	1.63
55–60	10	485.5	3.47	10	412	4.10	0	73.5	0
61–66	7	279.5	4.23	6	240.5	4.21	1	39	4.33
67–72	0	86.5	0	0	76	0	0	10.5	0

Notes:

a Including those who attempted suicide through drug overdose and self-cutting;

b including those who attempted suicide through charcoal burning, hanging, jumping from high places, drowning, domestically used gases, and other methods;

c the earliest suicide attempt recorded in the database.

Table 3 HRs of subsequent suicide attempts (n=374) after the index attemptd for related variables by Cox proportional hazards modeling

Variables	Subsequent suicide attemptsa n/N (%)	Unadjusted HR		Adjusted HR
		HR (95% CI)	P-value	HR (95% CI)	P-value
Sex
Male	101/676 (14.9)	1		1
Female	273/1,394 (19.6)	1.32 (1.05–1.66)	0.014*	1.26 (0.99–1.59)	0.059
Age (years)
<35	137/826 (16.6)	1		1
35–49	164/738 (22.2)	1.38 (1.10–1.74)	0.005**	1.48 (1.15–1.91)	0.003**
50–64	55/324 (17.0)	1.07 (0.78–1.46)	0.688	1.19 (0.83–1.69)	0.347
>64	18/181 (9.9)	0.58 (0.36–0.95)	0.032*	0.65 (0.38–1.12)	0.118
Marital status
Single	94/538 (17.5)	1		1
Married	126/786 (16.0)	0.91 (0.69–1.18)	0.486	0.80 (0.60–1.08)	0.143
Divorced or widowed	151/732 (20.6)	1.17 (0.90–1.51)	0.237	1.03 (0.77–1.39)	0.833
Amount of education (years)
≤9	126/764 (16.5)	1		1
>9	248/1,306 (19.0)	1.15 (0.93–1.43)	0.196	1.06 (0.84–1.35)	0.608
Method of the index attempt
Low-lethalb	333/1,730 (19.2)	1		1
High-lethalc	41/340 (12.1)	0.63 (0.46–0.88)	0.006**	0.62 (0.45–0.86)	0.005**

Notes:

a Individuals with missing data were excluded in the analyses;

b including drug overdose and self-cutting;

c including charcoal burning, hanging, jumping from high places, drowning, poisoning by domestically used gases, and other methods;

d the earliest suicide attempt recorded in the database.

* P<0.05;

** P<0.01.

Abbreviations: CI, confidence interval; HR, hazard ratio; n, number of individuals who had a second suicide attempt; N, number of total subjects.

Table 4 ORs of changing methods of suicide (n=71) in individuals who had a second suicide attempt after the index attemptc (N=374) by logistic regression analysis

Variables	Change of suicide methoda n/N (%)	Unadjusted OR		Adjusted OR
		OR (95% CI)	P-value	OR (95% CI)	P-value
Sex
Male	28/101 (27.7)	1		1
Female	43/273 (15.8)	0.49 (0.28–0.84)	0.010**	0.62 (0.34–1.13)	0.119
Age (years)
<35	22/137 (16.1)	1		1
35–49	27/164 (16.5)	1.03 (0.56–1.91)	0.924	0.96 (0.45–2.06)	0.921
50–64	15/55 (27.3)	1.96 (0.93–4.14)	0.078	2.50 (1.01–6.17)	0.047*
>64	7/18 (38.9)	3.33 (1.16–9.52)	0.025*	3.77 (1.03–13.80)	0.045*
Marital status
Single	17/94 (18.1)	1		1
Married	17/126 (13.5)	0.71 (0.34–1.47)	0.353	0.64 (0.26–1.54)	0.318
Divorced or widowed	37/151 (24.5)	1.47 (0.77–2.80)	0.240	1.42 (0.64–3.16)	0.393
Amount of education (years)
≤9	24/126 (19.0)	1		1
>9	47/248 (19.0)	0.99 (0.58–1.72)	0.982	1.30 (0.68–2.50)	0.433
Method of the index attempt
Low-lethalb	56/333 (16.8)	1		1
High-lethalc	15/41 (36.6)	2.85 (1.42–5.73)	0.003**	2.64 (1.26–5.55)	0.010*

a Individuals with missing data were excluded in the analyses;

b including drug overdose and self-cutting;

c including charcoal burning, hanging, jumping from high places, drowning, poisoning by domestically used gases, and other methods;

c the earliest suicide attempt recorded in the database.

* P<0.05;

** P<0.01.

Abbreviations: CI, confidence interval; n, number of individuals who changed methods of suicide; N, number of individuals who had a second suicide attempt; OR, odds ratio.