Table 9 Comparison of individual item and total scores on the SBQ-R and SBQ-ASC between the autistic, possibly autistic and non-autistic groups

SBQ-R mean item scores

Lifetime suicidality

3.04 (.893)

2.66 (.935)

2.94 (.92)

2.11 (.965)

H(2) = 119.05, p < .001

Frequency of suicidal thoughts in the past year

3.13 (1.59)ⁿ

2.78 (1.5)ⁿ

3.03 (1.57)

1.83 (1.21)

H(2) = 101.35, p < .001

Suicide threat

1.78 (.865)

1.52 (.75)

1.71 (.841)

1.28 (.57)

H(2) = 52.9, p < .001

Likelihood of future suicide attempt

2.85 (1.8)

2.08 (1.71)

2.65 (1.81)

1.06 (1.25)

H(3) = 146.65, p < .001

Total SBQ-R score

10.81 (4.05)

9.04 (3.9)

10.33 (4.08)

6.28 (3.08)

-

 > Psychiatric cut-off

230 (76.7)

48 (57.1)

294 (71.4)

183 (30.9)

X²(2) = 119.27 p < .001, φ = .42

SBQ-ASC visual aids

Yes

117 (38)

35 (31)

152 (36.1)

59 (22)

X²(2) = 17.21 p < .001, φ = .16

SBQ-ASC item 1: lifetime suicidality

Non-suicidal

19 (6.17)

10 (8.85)

29 (6.89)

81 (30.22)

Suicidal ideation—"brief passing thought"

45 (14.61)

40 (35.4)

85 (20.19)

82 (30.6)

Suicidal ideation—"seriously thought about"

41 (13.31)

13 (11.5)

54 (12.83)

40 (14.93)

Suicide plan

90 (29.22)

24 (21.24)

114 (27.08)

42 (15.67)

Suicide attempt

113 (36.69)

26 (23.01)

139 (33.02)

23 (8.58)

Mean item score

2.76 (1.26)

2.14 (1.35)

2.59 (1.31)

1.42 (1.3)

H(2) = 125.98, p < .001

Lifetime suicide attempt subgroup follow-up questions:

I had a plan that I carried out

66 (58.41)

12 (46.15)

78 (56.12)

10 (43.48)

X²(2) = 2.74, p = .254, φ = .131

I had no plan

19 (16.81)

1 (3.85)

20 (14.39)

3 (13.04)

X²(2) = 3, p = .223, φ = .136

I suddenly felt the urge to attempt to end my life (impulsivity)

44 (38.94)

12 (46.15)

56 (40.29)

12 (52.17)

X²(2) = 1.49, p = .474, φ = .096

I happened to have access to the means to end my life

31 (27.43)

9 (34.62)

40 (28.78)

5 (21.74)

X²(2) = 1.02, p = .6, φ = .08

SBQ-ASC item 2: frequency of suicidal thoughts in last 12 months

Never

90 (29.22)

39 (34.51)

129 (30.64)

173 (64.55)

Less than once a month

81 (26.3)

36 (31.86)

117 (27.79)

64 (23.88)

Once a month

29 (9.42)

16 (14.16)

45 (10.69)

13 (4.85)

2–3 times a month

32 (10.39)

8 (7.08)

40 (9.5)

8 (2.99)

Once a week

23 (7.47)

4 (3.54)

27 (6.41)

4 (1.49)

2–6 times a week

33 (10.71)

9 (7.96)

42 (9.98)

5 (1.87)

1 or more times a day

20 (6.49)

1 (0.88)

21 (4.99)

1 (0.37)

Mean item score

1.99 (1.96)ⁿ

1.41 (1.56)ⁿ

1.83 (1.88)

.06 (1.09)

H(2) = 100.25, p < .001

SBQ-ASC item 3: duration of suicidal thoughts

N/A

57 (18.51)

34 (30.09)

91 (21.62)

146 (54.48)

Less than 5 min

38 (12.34)

22 (19.47)

60 (14.25)

46 (17.16)

Less than 1 h

71 (23.05)

22 (19.47)

93 (22.09)

27 (10.07)

1–4 h

73 (23.7)

19 (16.81)

92 (21.85)

30 (11.19)

5–8 h

29 (9.42)

7 (6.19)

36 (8.55)

5 (1.87)

More than 8 h

40 (12.99)

9 (7.96)

49 (11.64)

14 (5.22)

Mean item score

2.32 (1.6)

1.73 (1.58)

2.16 (1.61)

1.04 (1.45)

H(2) = 95.7, p < .001

SBQ-ASC item 4: Likelihood of acting on suicidal thoughts

N/A

43 (13.96)

28 (24.78)

71 (16.86)

127 (47.39)

No chance at all

49 (15.91)

25 (22.12)

74 (17.58)

70 (26.12)

Very unlikely

95 (30.84)

42 (37.17)

137 (32.54)

45 (16.79)

Rather unlikely

90 (29.22)

17 (15.04)

107 (25.42)

25 (9.33)

Rather likely

27 (8.77)

1 (0.88)

28 (6.65)

1 (0.37)

Very likely

4 (1.3)

0 (0)

4 (0.95)

0 (0)

Mean item score

2.07 (1.21)

1.45 (1.05)

1.9 (1.2)

.89 (1.02)

H(2) = 128.38, p < .001

SBQ-ASC item 5: communication of suicidality to others

Suicidal ideation

186 (60.39)

50 (44.25)

236 (56.06)

82 (30.6)

Future suicide attempt

82 (26.62)

19 (16.81)

101 (23.99)

26 (9.7)

Past suicide attempt

110 (35.71)

24 (21.24)

134 (31.83)

26 (9.7)

Mean item score

2.21 (2.25)

1.42 (1.95)

1.99 (2.2)

.79 (1.47)

H(2) = 78.68, p < .001

Overall communication of suicidality

210 (68.2)

57 (50.4)

267 (63.4)

92 (34.3)

5b: Communicated suicidal intent subgroup: person(s) disclosed to

An acquaintance

5 (2.6)

4 (7.4)

9 (3.6)

3 (3.2)

-

A friend

73 (37.2)

19 (35.2)

92 (36.8)

40 (42.6)

X²(2) = 1.03, p = .6, φ = .05

A family member

75 (38.3)

17 (31.5)

92 (36.8)

37 (39.4)

X²(2) = 1.02, p = .6, φ = .05

A health professional (e.g. General Practitioner, family doctor, Psychiatrist, Psychologist)

138 (70.4)

36 (63)

172 (68.8)

56 (62.3)

X²(2) = 3.65, p = .16, φ = .1

Other

25 (12.8)

8 (14.8)

33 (13.2)

15 (16)

X²(2) = .582, p = .75, φ = .04

5c: Non-disclosure subgroup: reasons

I had no one to tell

22 (16.2)

4 (7.1)

26 (13.5)

6 (9)

X²(2) = 3.95, p = .14, φ = .12

I chose not to

38 (27.9)

19 (33.9)

57 (29.7)

31 (46.3)

X²(2) = 6.72, p = .035, φ = .16

I was worried about the effect on others

55 (40.4)

22 (39.3)

77 (40.1)

28 (41.8)

X²(2) = 081, p = .96, φ = .02

I was worried about the consequences for myself

39 (28.7)

19 (33.9)

58 (30.2)

8 (11.9)

X²(2) = 9.3, p = .01, φ = .19

I wasn't sure how to express my thoughts

39 (28.7)

17 (30.4)

56 (29.2)

7 (10.4)

X²(2) = 9.51, p = .009, φ = .19

I was afraid to

27 (19.9)

8 (14.3)

35 (18.2)

5 (7.5)

X²(2) = 5.35, p = .07, φ = .14

I didn't consider telling anyone

19 (14)

15 (26.8)

34 (17.7)

18 (26.9)

X²(2) = 6.65, p = .036, φ = .16

Other (please specify):

17 (12.5)

7 (12.5)

24 (12.5)

4 (6)

X²(2) = 2.2, p = .33, φ = .09

SBQ-ASC item 6 (n = 602)

Lifetime NSSI

160 (62.7)

45 (46.4)

205 (58.2)

66 (26.4)

X²(2) = 67.46, p < .001, φ = .335

SBQ-ASC

Total score

11.34 (6.39)

8.15 (5.85)

10.5 (6.4)

4.75 (5.09)

U = 12,308.5, p < .001*

 >  = SBQ-ASC autism cut-off

138 (44.8)

27 (23.9)

165 (39.2)

28 (10.4)

X²(2) = 85.02 p < .001, φ = .35