Attrition comparison. Comparison of baseline data between those who did and those who did not return for follow-up revealed no significant differences in gender (χ2(1) = 0.01, p = .94), age (t=1.26, p=.21), childhood PEs (χ2(1) = 2.66, p = .10), SES (t=-1.64, p=.10), need for special educational support (χ2(1) = 2.60, p = .11), SDQ borderline/abnormal peer problems (χ2(1) =0.24, p = .63), childhood adversity (χ2(1) =2.16, p = .14) or childhood psychopathology (χ2(1) = 0.44, p = .51).
Sample characteristics. Young adults who attended at follow-up (N=103; 46.9% male, 53.1% female) were aged between 19 and 25 years. Of those, 65.0% (N=67) did not report PEs at either baseline or follow-up. These individuals made up the control group for this study. A further 28.2% (N=29) reported PEs at baseline but not at follow-up. These individuals made up the Transient PE group for the current study (referred to hereafter as the PE group). The remaining 6.8% (N=7) of individuals reported either new onset PEs at follow-up (N=5) or had recurrent PEs (i.e. met criteria at both baseline and follow-up) (N=2). Due to the small numbers of those with either new onset or recurrent PEs, data on these seven individuals were not examined in this study.
No significant differences were found between the PE and control groups in relation to age, SES status, baseline psychopathology, educational or peer problems in childhood. There was, however, a non-significant trend for childhood psychopathology (p=0.06), with those in the PE group found to have higher rates of childhood psychopathology. Significant gender differences were found between groups. Those with PEs had significantly higher rates of childhood adversity (see Table 1).
TABLE 1 Sample characteristics
|
Transient PE Group (N=29)
|
Control Group
(N=67)
|
P value
|
Gender
|
|
|
0.016
|
Male
|
19 (65.5%)
|
38.8% (26)
|
Female
|
10 (34.5%)
|
61.2% (41)
|
Mean age at baseline
|
11.66
|
11.72
|
0.682
|
Mean age at follow-up
|
20.72
|
21.09
|
0.221
|
Mean SESa
|
2.64
|
2.23
|
0.178
|
Met criteria for lifetime DSM-IV mental disorder at baseline
|
14 (48.3%)
|
19 (28.4%)
|
0.059
|
Met criteria for current DSM-V mental disorder at follow-up
|
8 (27.6%)
|
4 (6.0%)
|
0.003
|
Experienced childhood adversityb
|
23 (79.3%)
|
33 (49.3%)
|
0.006
|
Borderline or abnormal score on SDQ peer problems subscale at baseline
|
4 (13.8%)
|
6 (9.0%)
|
0.486
|
Required special educational services at baseline
|
10 (34.5%)
|
13 (19.4%)
|
0.111
|
a N = 93 due to missing SES data
b Defined as any exposure to childhood sexual abuse physical abuse or bullying as reported at baseline
Significant outcomes in bold
Relationship between Transient PEs and self-reported adolescent and young adult interpersonal difficulties
In adolescence, the median number of interpersonal difficulties reported was 1 (range 0-6). There was no significant difference between male and female participants in the number of interpersonal difficulties reported in adolescence (z = 0.35, p =.73). In young adulthood most participants did not report interpersonal difficulties (median = 0, range 0-2). There was no significant difference between male and female participants in the number of interpersonal difficulties reported in young adulthood (z = -0.09, p =.93).
Our main analysis indicated that, when controlling for gender and SES, there was a significant effect of group, indicating that participants with Transient PEs had significantly more interpersonal difficulties than controls (IRR: 1.79, 95%ileCI: 1.06- 3.01, p = .027). There was also a significant main effect of time, indicating a reduction in the number of difficulties reported in young adulthood relative to adolescence (IRR: 0.18, 95%ileCI: 0.09- 0.35, p < .001). Additionally, there was, a significant interaction between group and time (Chi2 = 6.39, p = 0.04). This interaction indicated that participants with Transient PEs reported more interpersonal difficulties than controls in adolescence (IRR: 1.79, 95%ileCI: 1.07- 3.01, p = .03) but not in young adulthood (IRR: 0.48, 95%ileCI: 0.10-2.27, p = .36). The predicted number of events for each group in adolescence and young adulthood (based on the estimated marginal means) are displayed in Table 2.
Model 2. Additional adjustment for baseline psychopathology and childhood adversity did not alter the interpretation of findings from the main effects analysis (Group: IRR: 1.89, 95%ileCI: 1.11- 3.21, p = .019; Time: IRR: 0.18, 95%ileCI: 0.09- 0.36, p < .001), interaction (Chi2 = 6.99, p = 0.03) or simple effects analysis (adolescence: IRR: 1.88, 95%ileCI: 1.11- 3.21, p = .02; young adulthood: IRR: 0.51, 95%ileCI: 0.11-2.40, p = .39).
Model 3. Further adjustment for childhood peer problems and childhood educational problems again did not alter our interpretation of the findings from the main effect analysis (Group: IRR: 1.83, 95%ileCI: 1.10- 3.02, p = .019; Time: IRR: 0.18, 95%ileCI: 0.09-0.36, p< .001), interaction (Chi2 = 6.89, p= 0.03) or simple effects analysis (IRR: 1.83, 95%ileCI: 1.10- 3.02, p = .02; young adulthood: IRR: 0.49, 95%ileCI: 0.10-2.30, p = .37).
TABLE 2 Estimated marginal mean self-reported interpersonal difficulties scores in adolescence and adulthood in Transient PEs and control groups
Measure
|
Group
|
Model 1 (SE)a
|
Model 2 (SE) b
|
Model 3 (SE) c
|
|
|
|
|
|
Adolescence
|
Transient PEs
|
1.52 (0.31)*
|
1.57 (0.33)*
|
1.55 (0.30)*
|
|
Control
|
0.85 (0.13)*
|
0.83 (0.13)*
|
0.85 (0.13)*
|
|
|
|
|
|
Young Adulthood
|
Transient PEs
|
0.07 (0.05)
|
0.07 (0.06)
|
0.08 (0.05)
|
|
Control
|
0.15 (0.05)
|
0.15 (0.05)
|
0.15 (0.05)
|
N = 94 due to missing SLES data for one participant
aAdjusted for gender and SES; bAdjusted for gender, SES, baseline psychopathology and childhood adversity; cAdjusted for gender, SES, baseline psychopathology, childhood adversity, childhood peer problems and childhood educational problems.
*p<0.05; **p<0.01; ***p<0.001
Relationship between Transient PEs and self-reported adolescent and young adult educational/vocational difficulties
In adolescence and young adulthood, most participants did not report educational/vocational difficulties (adolescent median: 0, range 0-5; young adulthood median: 0, range 0-2). Male participants reported significantly more educational/vocational difficulties than female participants did in adolescence (z = 4.04, p <.001) but not in young adulthood (z = 1.55, p = .122).
Our main analysis indicated that, when controlling for gender and SES, there was a significant effect of Group indicating that participants with Transient PEs had significant more educational/vocational difficulties than controls (IRR: 1.99, 95%ileCI: 1.26- 3.14, p = .003). There was also a significant main effect of time indicating a reduction in the number of difficulties reported in young adulthood relative to adolescence (IRR: 0.43, 95%ileCI: 0.24- 0.78, p = .005). Additionally, there was, a significant interaction between group and time (Chi2 = 8.84 p = 0.01). This interaction indicated that participants with Transient PEs reported more educational/vocational difficulties than controls in adolescence (IRR: 1.98, 95%ileCI: 1.25- 3.14, p = .003) but not in young adulthood (IRR: 0.87, 95%ileCI: 0.37-2.06, p = .76). The predicted number of events for each group in adolescence and young adulthood (based on the estimated marginal means) are displayed in Table 3.
Model 2. Additional adjustment for baseline psychopathology and childhood adversity did not alter the interpretation of the findings from the main effects analysis (Group: IRR: 2.35, 95%ileCI: 1.47- 3.75, p < .001; Time: IRR: 0.46, 95%ileCI: 0.26- 0.82, p = .008), interaction (Chi2 = 13.15, p = 0.001) or simple effects analysis (adolescence: IRR: 2.35, 95%ileCI: 1.48- 3.75, p < .001; young adulthood: IRR: 0.91, 95%ileCI: 0.39-2.14, p = .83).
Model 3. Further adjustment for childhood peer problems and childhood educational problems again did not alter our interpretation of the findings from the main effect analysis (Group: IRR: 2.28, 95%ileCI: 1.43- 3.64, p < .001; Time: IRR: 0.46, 95%ileCI: 0.26-0.82, p = .008), interaction (Chi2 = 12.19, p=.002) or simple effects analysis (adolescence: IRR: 2.28, 95%ileCI: 1.43- 3.64, p = .001; young adulthood: IRR: 0.88, 95%ileCI: 0.37-2.08, p = .77).
TABLE 3 Estimated marginal mean self-reported educational/vocational difficulties scores in adolescence and adulthood in Transient PEs and control groups