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ORIGINAL CONTRIBUTION
Reducing child conduct disordered behaviour and improving
parent mental health in disadvantaged families: a 12-month
follow-up and cost analysis of a parenting intervention
Sinead McGilloway •Grainne NiMhaille •Tracey Bywater •Yvonne Leckey •
Paul Kelly •Mairead Furlong •Catherine Comiskey •Donal O’Neill •
Michael Donnelly
Received: 19 April 2013 / Accepted: 17 November 2013 / Published online: 24 January 2014
ÓSpringer-Verlag Berlin Heidelberg 2014
Abstract The effectiveness of the Incredible Years Basic
parent programme (IYBP) in reducing child conduct
problems and improving parent competencies and mental
health was examined in a 12-month follow-up. Pre- to post-
intervention service use and related costs were also ana-
lysed. A total of 103 families and their children (aged
32–88 months), who previously participated in a random-
ised controlled trial of the IYBP, took part in a 12-month
follow-up assessment. Child and parent behaviour and
well-being were measured using psychometric and obser-
vational measures. An intention-to-treat analysis was car-
ried out using a one-way repeated measures ANOVA.
Pairwise comparisons were subsequently conducted to
determine whether treatment outcomes were sustained
1 year post-baseline assessment. Results indicate that post-
intervention improvements in child conduct problems,
parenting behaviour and parental mental health were
maintained. Service use and associated costs continued to
decline. The results indicate that parent-focused interven-
tions, implemented in the early years, can result in
improvements in child and parent behaviour and well-
being 12 months later. A reduced reliance on formal ser-
vices is also indicated.
Keywords Conduct disorder Child development
Parenting Parenting intervention Parent–child
relationships Cost analysis
Introduction
Conduct disordered behaviour is the primary cause of
functional disability in childhood and affects around 10 %
of children in the UK and Ireland [1,2]. Children who
experience social adversity (including socioeconomic dis-
advantage, parental neglect and abuse, parental psychopa-
thology, parental substance abuse and/or criminality) are
particularly vulnerable to conduct disordered behaviour
and/or mental health problems [3]. Numerous studies have
highlighted links between early exposure to inadequate
care in early childhood and negative outcomes for children
[4]. Harsh and inconsistent discipline, inadequate supervi-
sion and low levels of parental warmth and involvement
are some of the most important precursors of early onset
conduct problems. Positive parent–child interactions, on
the other hand, predict good child psychological and
behavioural adjustment in childhood [5].
The negative impact of early childhood conduct disorder
is substantial. Children who display behavioural difficulties
are at increased risk of adverse long-term outcomes,
including poor educational attainment and early school
leaving [6], mental health and social difficulties, substance
S. McGilloway (&)G. NiMhaille Y. Leckey P. Kelly
M. Furlong
Department of Psychology, National University of Ireland
Maynooth, Maynooth, Ireland
e-mail: Sinead.McGilloway@nuim.ie
T. Bywater
Institute for Effective Education, University of York, York, UK
C. Comiskey
School of Nursing and Midwifery, Trinity College Dublin,
Dublin, Ireland
D. O’Neill
Department of Economics, National University of Ireland
Maynooth, Maynooth, Ireland
M. Donnelly
Centre for Public Health, Queen’s University Belfast, Belfast,
Northern Ireland
123
Eur Child Adolesc Psychiatry (2014) 23:783–794
DOI 10.1007/s00787-013-0499-2
abuse [7], poor employment prospects and increased reli-
ance on welfare and social care systems in later life [8]. It
has also been found that the costs of health, special edu-
cational and social welfare services associated with the
treatment of children with conduct disordered behaviour
may be up to ten times higher than in those with no conduct
problems [9]. Economic costs can also accumulate over the
lifespan. Scott et al. [9] reported that welfare payments
until the age of 28 were 1.65 times higher for children with
conduct problems than for those with none. In a recent UK
study, the costs of adverse outcomes associated with poor
adjustment in childhood were estimated to be as high as
£225,000 over an individual’s lifetime [10].
There is now strong evidence to show that parenting
interventions which are based on behavioural and social
cognitive principles and which aim to improve parent–child
relationships, are effective in tackling behavioural disorders
in childhood [11,12]. The Incredible Years Basic parent-
training programme (IYBP) is a brief, group-based inter-
vention that has been considered a ‘‘model’’ programme for
addressing early childhood conduct problems [13,14].
Existing evidence indicates that the IYBP leads to signifi-
cant improvements in child adjustment [3,15], including
improvements in conduct disordered behaviour [16,17],
hyperactivity and oppositional defiant problems [18–20].
Benefits of the IYBP for parenting skills, parent mental
health and sibling adjustment have also been documented
[21–23]. Previous research also supports the effectiveness
of the IYBP for disadvantaged families [24,25].
Despite the evidence in support of the effectiveness of
parenting programmes, less is known about their longer-
term impact [26]. Webster-Stratton [3] found that the
effects of the IYBP on child and parent behaviour were
maintained 1 year after parent training and a small number
of other studies have also identified the potential longer-run
benefits of parenting interventions [27,28]. A recent sys-
tematic review (involving eight RCTs) on the long-term
impact of parenting interventions for young children found
that positive child and family outcomes, such as reduced
externalising and internalising problems and improved
social competence, were generally maintained at 1-year
post-intervention [29]. A further study in Norway [30]
demonstrated a maintenance of positive effects from parent
training 5 to 6 years later, whilst Webster-Stratton et al.
[31] also found that children whose parents attended the IY
parenting programme, showed fewer severe conduct
problems (criminal behaviour, delinquency and substance
abuse) than would be expected later in adolescence.
Cost analyses of parent-training programmes typically
focus on short-term outcomes [32]. Group-based parenting
programmes are generally characterised by low costs and
increasing evidence indicates that they may be more cost-
efficient in the longer term than later interventions [10,33,
34]. A recent cost-effectiveness analysis of the IYBP—
based on results from our RCT evaluation—indicated a
substantial decline in service use for the intervention group
when compared to the control group, thereby supporting
the cost-effectiveness of the programme [35], whilst further
research [28] indicates that the intervention can result in
long-term reductions in the utilisation of health and social
care services. However, whilst the longer-term effects of
parenting programmes appear quite promising, a need for
further research is indicated, especially in community-
based settings [36,37].
The study reported here, involved a 12-month follow-up
of families who received the IYBP and who had previously
participated in a RCT evaluation of the programme [25].
The findings from the RCT illustrated significant short-
term benefits of the IYBP for child behaviour, parenting
skills and parental mental health. We subsequently set out
to examine whether these positive effects were maintained
in the longer run, at 12-month post-baseline assessment.
We also examined patterns of service utilisation (health,
social and special educational) and associated costs
amongst intervention children over time.
Our hypotheses were as follows: (a) improvements in
child behaviour would be sustained at 12-month follow-up;
(b) improvements in parenting skills, parenting stress and
depression would also be sustained 12 months later;
(c) there would be positive effects of parent training on
sibling behaviour and marital conflict; and (d) the use of
health, social, and special educational services would
decrease in the longer run.
Method
Study design
The RCT included 149 families who were blindly and
randomly allocated to an IYBP intervention group
(n=103) or a waiting-list control group (n=46). At
baseline, two cohorts of parents were recruited and asses-
sed (cohort 1 =53 parents; cohort 2 =96 parents) (two
cohorts were required as it took much longer than antici-
pated to recruit willing and eligible parents into the trial).
Follow-up assessments were completed 6-month post-
baseline assessment. During this 6-month interval, parents
in the intervention group received the intervention. This
study reports a subsequent 12-month post-baseline assess-
ment which was conducted on intervention group families
only (n=103). For ethical reasons, the participants in the
control group were offered the intervention after the
6-month follow-up assessment. Therefore, it was not pos-
sible to compare the intervention and control groups at the
12-month follow-up.
784 Eur Child Adolesc Psychiatry (2014) 23:783–794
123
Participants and study setting
Families were recruited to the study using existing ser-
vice systems including public health service waiting
lists, local schools, community-based agencies and self-
referral. Written informed consent was provided by
parents and guardians of participating children. Partici-
pants were eligible if the primary caregiver rated their
child (aged 32–88 months) above the clinical cut-off on
either the ‘intensity’ subscale (intensity score C127) or
the ‘problem’ subscale (problem score C11) of the
Eyberg Child Behaviour Inventory (ECBI) [38]. Parents
also had to be willing and able to attend the
programme.
The intervention was delivered in typical community-
based services in Ireland. These services are based in four
urban areas which are designated as ‘disadvantaged’
according to information on demographic profile, social
class composition and labour market situation [39].
Attrition
The flow of participants through the study is shown in
Fig. 1. At 6-month post-baseline assessment, 95 interven-
tion group participants (92 %) were retained in the study.
At 12-month follow-up, 87 participating families (84 %)
completed assessments (see Fig. 1). Five parents withdrew
from the research and 11 could not be contacted despite
vigorous efforts by the research team.
Randomisation and masking
Following baseline assessments, participants were blindly
and randomly allocated to the intervention group using a
computer-generated random number sequence. Research-
ers were originally blind to allocation, but at the 12-month
follow-up, only the intervention group could be assessed.
Therefore, researchers could not be blind to intervention
allocation at this time point.
Parents with children (aged approx 3-7 yrs) referred to research team from local
organisations/health services and self-referral for problem behaviour
Parent interested in participating (n=195)
Parents referred (n=233) Contact unsuccessful (n=10)
Parent declined to take part (n=28)
Eligibility criteria fulfilled (n=149)
2:1 randomisation (n=149)
Allocated to intervention group (n=103) Allocated to waiting list control (n=46)
Follow-up 1 assessment:
42 (91%) completed 6 mth assessments
(2 formally withdrew before intervention,
2 lost to follow-up*)
Control group offered the intervention
programme after 6 mth follow-up
Follow -up 1 assessment:
95 (92%) completed 6 mth assessments
(4 formally withdrew before intervention,
4 lost to follow -up*)
Follow-up 2 assessment:
87 (84%) completed 12 mth follow-up
(5 refused, 11 lost to follow-up*)
Not eligible (n=46)
* Lost to follow-up = no contact made/unable to schedule interviews
Fig. 1 Flow of participants through trial
Eur Child Adolesc Psychiatry (2014) 23:783–794 785
123
The intervention
The IYBP is a manualised, collaborative-based interven-
tion which uses group discussions and role plays in com-
bination with video material to foster positive parent–child
relationships and illustrate positive parenting techniques
and non-aversive discipline strategies. The assumed
mechanism of action is that the intervention improves
positive parenting which, in turn, impacts child behaviour.
The IYBP intervention is based on behavioural and social
learning theory and, at the time of the study, consisted of
14 2-h sessions. Nine intervention groups, each with
approximately 11–12 members, were delivered by two
fully trained facilitators. Both participant cohorts received
the 14-session intervention. However, due to time/resource
limitations, the first cohort of participants received the
intervention over 12 weeks rather than (as in the case of the
second cohort) a 14-week period; the intervention was
identical in both cases. Implementation fidelity was mon-
itored by means of facilitator-completed self-evaluation
checklists. Approximately three-quarters (76 %) of the first
cohort of participants attended seven or more sessions
(mean attendance 10.8 sessions) compared to half (52 %)
of the second cohort (mean attendance 6.6 sessions). In
total, 31 % of participants attended three or fewer sessions.
Procedure and measures
A battery of standardised psychometric measures was
administered at all three time points bymeans of a face-to-face
interview with the main caregiver. The internal consistency of
all scales was calculated on baseline data using Cronbach’s a.
Observations were also used to provide an objective measure
of parent and child behaviour. Demographic and background
information was collected by means of a standardised Per-
sonal and Demographic Information Form.
Child measures
The ECBI was the primary outcome measure and was used
to assess the frequency of child delinquency, temper tan-
trums and aggressive behaviour. This widely used measure
consists of two subscales: an ‘intensity subscale’, which
comprises a seven-point Likert scale and measures the
frequency of 36 problem behaviours (a=0.89); the
‘problem subscale’ elicits a ‘yes–no’ response from parents
on whether or not the parent considers the child’s behav-
iour to be problematic (a=0.87). The ECBI was also
administered to the sibling closest in age to the index child
(where applicable; n=63) to assess possible intervention
effects on other family members.
The Strengths and Difficulties Questionnaire (SDQ) is a
25-item scale which measures emotional symptoms,
conduct problems, peer problems, hyperactivity and pro-
social behaviour; this was used to provide a secondary
measure of child conduct problems [40]. The scores on
each subscale (except for the ‘pro-social’ subscale) are
summed to generate a ‘total difficulties’ score (a=0.77).
The Conners Abbreviated Parent Rating Scale (CPRS)
provided a brief, 10-item measure of child hyperactivity and
inattentive behaviours (a=0.86), including restlessness,
over-activity, emotional reactivity and inattention [41]. The
Social Competence Scale [42] was used to assess child
social functioning including emotional self-regulation and
pro-social behaviours (a=0.86). Typical questions on this
12-item scale are: ‘‘Your child shares things with others’’ or
‘‘Your child can accept things not going his/her way’’.
Parents rate how well the items reflect their child’s behav-
iour on a five-point scale (0 =not at all/4 =very well).
Parent and family well-being measures
Parent stress and mental health were assessed using the
Parenting Stress Index-Short Form (PSI-SF) and the Beck
Depression Inventory (BDI) respectively [43,44]. The PSI-
SF (a=0.93) comprises 36 items which measure the
distress experienced by parents in their parenting role as
well as dysfunctional parent–child interactions, whilst the
BDI (a=0.93) was used to assess the prevalence and
severity of parental depression. The O’Leary–Porter Scale
[45] was also used to assess parents’ overt negative
behaviours and index child exposure to inter-partner hos-
tility (a=0.78). This 10-item scale was administered to all
those parent participants who were partnered (n=62).
Typical items are: ‘‘How often do you and your partner
argue over disciplinary problems in this child’s presence?’’
or ‘‘How often do you complain to your spouse about his/
her personal habits in front of this child?’’. Items are rated
on a five-point scale ranging from ‘‘Never’’ to ‘‘Very
often’’.
Observational measure
Parent report was supplemented by use of the Dyadic
Parent-child Interactive Coding System Revised (DPICS-
R) that provided an independent observational measure of
parent–child interactions and behaviours based on a 30-min
observation period [46]. The coding system comprises 21
parent behaviour categories (e.g., commands, questions,
praise, positive affect and physical behaviours) and 7 child
behaviour categories (e.g., destructive and physically
negative behaviours, smart talk, crying and positive affect).
Coding is continuous and is based on the frequency of a
given behaviour during parent–child interaction. Observa-
tions were conducted at both baseline and follow-up for the
second cohort of parent participants only (n=59). It was
786 Eur Child Adolesc Psychiatry (2014) 23:783–794
123
not possible to conduct observations during the first wave
of participant recruitment due to the need for observational
training for the research team and intervention delivery
timetabling constraints. However, all participants in the
second cohort were included in observations.
All observers were fully trained and reliability checks
were conducted on 20 % of observations at all three
assessment time points. Summary variables of observa-
tional data were created for analysis. ‘Child problem
behaviour’ represents the aggregate of frequency counts for
aversive child behaviours including destructive and
aggressive behaviours (e.g., throwing items or hitting,
shouting, crying, whinging and smart talk). ‘Positive par-
enting’, comprising eight parent behaviour categories,
represents the summed frequency counts for use of praise
and encouragement and positive physical behaviours
towards the child (e.g., displays of affection). ‘Critical
parenting’ comprises three parent behaviour categories
including the use of negative commands, critical state-
ments, and physically negative behaviours (e.g., snatching
an item away from the child). Reliability was measured by
intra-class correlation coefficients (ICCs) for summary
variables. High inter-rater consistency was found (child
problem behaviour 0.95; positive parenting 0.98; critical
parenting 0.89).
Service utilisation
For purposes of the cost analysis, parents were also asked
to complete a Service Utilisation Questionnaire (SUQ), an
adapted version of the Client Service Receipt Inventory
(CSRI) [47] to provide information on their child’s use of
health, social, and special educational services during the
previous 6-month time period. These included: the number
of visits to a GP, nurse and/or community paediatrician;
hospital appointments and/or stays; the frequency of the
child’s use of speech language, psychological and social
work services; and the number of hours the child spent in
receipt of special educational resources (including one-to-
one help such as the allocation of a Special Needs Assistant
and resource teaching hours). All of these services are
considered relevant to childhood conduct problems.
Analysis strategy
A strict intention-to-treat analysis was used whereby all
families for whom data were collected at baseline were
included in the analysis of longer-term outcomes, including
those who were lost to either the 6- or 12-month follow-ups
and those who did not start the intervention or who had poor
treatment adherence. Missing values at follow-up were
replaced using a method of multiple imputation [48] carried
out using IBM SPSS and based on a fully conditional
specification, where imputed values are derived from
observed values and their normal distribution [49]. This
involves imputing several (M) sets of plausible values for the
missing data. Missing data were assumed to be ‘missing at
random’, minimum and maximum values for scores were set
(for each scale) and scores at baseline or 6-month follow-up
were used as predictors for imputing data at follow-up time
points. The goal, therefore, is to ‘‘average over’’ the missing
data by generating multiple substitutions for missing data
(i.e., creating a database with M=10 versions of our
data). In each version of the data, existing or complete data
stay the same. However, multiple substitutions for missing
data are imputed with some variation from one imputation to
another. We then performed analyses on each copy of our
data and finally pooled the results of those repeated analysis.
A one-way repeated measures ANOVA was used to
examine differences in scores within the intervention group
between baseline and 6-month, and between the baseline and
12-month follow-up. Pairwise comparisons (paired ttests)
were used to compare each of the time points (i.e., baseline to
6-month follow-up, baseline to 12-month follow-up and 6- to
12-month follow-up) to indicate any significant differences.
These post hoc tests were used to ascertain whether treatment
outcomes were sustained between follow-up time points. We
hypothesised that there would be no significant differences
between the 6- and 12-month follow-up if the effects of the
intervention had been maintained. This approach has been
used in similar previous research [23,28]. Effect sizes were
calculated to provide an estimate of the size of the effect of the
intervention on child and parent outcomes; a small effect size
is denoted by approx 0.3, 0.5 denotes a medium/moderate
effect size, and 0.7 and above denotes a large effect size [50].
The cost analysis was carried out by obtaining unit cost
data for relevant Irish services (detailed in Table 3). The
Irish government does not publish a detailed description of
unit costs nor are any normative cost data available in Ire-
land. Some costs, such as those related to GP care are well
established whilst others, including those for primary care
and educational services, were derived from a variety of
sources including official annual governmental publications
[51], relevant organisations (e.g., the health service execu-
tive) and official Government pay scales [35]. This approach
to assessing longer-term costs has been used elsewhere [28].
A cost-effectiveness evaluation was not carried out due to the
lack of a control group at 12-month follow-up.
Results
Baseline characteristics
Parents (98 mothers, 5 fathers) were, on average, 33 years
old and approximately 60 % (61/103) had partners. Most
Eur Child Adolesc Psychiatry (2014) 23:783–794 787
123
Table 1 Intention-to-treat analysis of child outcome measures: longer-term outcomes of the IYBP
Mean (SD) intervention (n=103) Estimated mean differences using repeated measures ANOVA
Baseline to 6-month follow-up Baseline to 12-month follow-up 6-month follow-up to 12-month
follow-up
Baseline 6-month
follow-up
12-month
follow-up
Mean difference
(95 % CI), p
Effect size
(95 % CI)
Mean difference
(95 % CI), p
Effect size
(95 % CI)
Mean difference
(95 % CI), p
Effect size
(95 % CI)
ECBI Intensity
subscale (cut off
C127)
156.71 (30.02) 117.27 (42.46) 119.25 (46) 39.44 (32.2 to
46.68), \0.001
1.08 (0.88 to
1.28)
37.45 (30.13 to
44.78), \0.001
0.97 (0.78 to
1.16)
-1.99 (-8.39 to
4.42), 0.538
-0.05 (-0.19 to
0.1)
ECBI Problem
subscale (cut off
C11)
20.3 (6.95) 10.79 (9.01) 11.17 (10.06) 9.51 (7.68 to
11.34), \0.001
1.19 (0.95 to
1.42)
9.13 (7.25 to
11.01), \0.001
1.06 (0.84 to
1.28)
-0.38 (-1.65 to
0.88), 0.554
-0.04 (-0.18 to
0.09)
SDQ ‘total
difficulties’ (cut off
C17)
18.11 (5.75) 13.18 (6.98) 14.06 (8.24) 4.93 (3.85 to
6.01), \0.001
0.77 (0.6 to
0.94)
4.05 (2.65 to
5.45), \0.001
0.57 (0.37 to
0.77)
-0.87 (-2.08 to
0.33), 0.153
-0.12 (-0.28 to
0.04)
Conners (cut off
C15)
28.41 (6.47) 22.23 (8.12) 22.87 (8.66) 6.18 (4.99 to
7.37), \0.001
0.85 (0.68 to
1.01)
5.53 (4.16 to
6.91), \0.001
0.73 (0.54 to
0.91)
-0.65 (-2.01 to
0.72), 0.35
-0.08 (-0.25 to
0.09)
Social competence
a
1.37 (0.68) 2.14 (0.93) 2.09 (0.94) -0.77 (-0.91 to
-0.62), \0.001
-0.95 (-1.13 to
-0.77)
-0.72 (-0.88 to
-0.56), \0.001
-0.88 (-1.08 to
-0.69)
0.05 (-0.09 to
0.19), 0.51
0.05 (-0.1 to
0.2)
Child Problem
Behaviour
b
10.69 (11.43) 6.52 (8.4) 11.58 (20.77) 4.18 (1.03 to
7.33), 0.009
0.42 (0.1 to
0.74)
-0.89 (-5.86 to
4.08), 0.723
-0.05 (-0.36 to
0.25)
-5.07 (-10.46 to
0.32), 0.065
-0.32 (-0.67 to
0.02)
ECBI intensity
(sibling)
c
115.57 (37.68) 99.87 (39.81) 93.92 (31.73) 15.7 (6.01 to
25.39), 0.002
0.41 (0.15 to
0.66)
21.65 (12.56 to
30.75), \0.001
0.63 (0.36 to
0.89)
5.95 (-1.13 to
13.04), 0.1
0.17 (-0.04 to
0.37)
ECBI problem
(sibling)
c
12.83 (8.23) 8.82 (8.34) 7.59 (7.07) 4 (1.6 to
6.41), 0.001
0.49 (0.19 to
0.78)
5.24 (3.12 to
7.36), \0.001
0.69 (0.41 to
0.97)
1.24 (-0.48 to
2.95), 0.157
0.16 (-0.07 to
0.38)
a
Higher scores indicate better social competence
b
Frequency counts in 30 min using the DPICS-R (n=59/103 intervention index children)
c
n=63; 32 girls, 31 boys
788 Eur Child Adolesc Psychiatry (2014) 23:783–794
123
of the families were socioeconomically disadvantaged and
62 % (64/103) were considered to be at risk of poverty.
Child participants were aged, on average, approximately
5 years (Mean 59 months; SD 15.6) and 58 % were boys.
There were no socioeconomic or demographic differences
between those who were lost to follow-up and those who
were retained in the study; neither were there any dif-
ferences on measures of parenting behaviour or well-
being. Children of parents lost to follow-up had signifi-
cantly higher levels of social competence, although no
other significant differences in child characteristics were
found.
12-month follow-up findings
Child behaviour outcomes
Statistical analyses highlighted significant differences in
both child behaviour and adjustment from baseline to
6-month follow-up on both subscales of the primary out-
come measure (the ECBI), as well as on the secondary
outcome measures (the SDQ, CPRS and the Social Com-
petence Scale). As hypothesised, there were no statistically
significant differences between the 6- and 12-month fol-
low-ups. Hence, it may be inferred, albeit in the absence of
a control group, that the post-intervention improvements in
child outcomes observed, were maintained in the longer
term (Table 1). Analysis of the observational data for child
behaviour (n=59) showed a significant improvement at
the 6-month follow-up, although there was a return to
baseline levels at the 12-month time point. Results also
indicated a significant reduction in problem sibling
behaviour (n=63; 32 girls; 31 boys) from baseline to the
12-month follow-up (mean difference 21.65, 12.56–30.75,
p\0.001). Indeed, larger effect sizes at 12-month follow-
up suggest longer-term accumulative benefits with respect
to sibling behaviour (effect size 0.63).
Parent outcomes
The intervention was found to have a statistically signifi-
cant beneficial effect on parental well-being and psycho-
social functioning (as measured by the BDI), whilst parents
also reported feeling less stressed in their role as parents
(measured by the PSI-SF). No change between the 6- and
12-month follow-ups, indicates that improvements in par-
ent mental health were sustained. Similar findings were
evident for the observational data, highlighting longer-term
increases in positive parenting strategies and decreases in
critical parenting. A positive effect of the IYBP was also
found with regard to marital conflict (n=62); significantly
higher mean scores at the 6- and 12-month follow-ups
when compared to baseline were found on the O’Leary–
Table 2 Intention-to-treat analysis of parent outcome measures: longer-term outcomes of the IYBP
Mean (SD) intervention =103 Estimated mean differences using repeated measures ANOVA
Baseline to 6-month follow-up Baseline to 12-month follow-up 6-month follow-up to 12-month
follow-up
Baseline 6-month
follow-up
12-month
follow-up
Mean difference
(95 % CI), p
Effect size
(95 % CI)
Mean difference
(95 % CI), p
Effect size
(95 % CI)
Mean difference
(95 % CI), p
Effect size
(95 % CI)
BDI (cut off
C19)
16.2 (11.65) 12.61 (12.01) 11.94 (11.65) 3.59 (2.07 to
5.11), \0.001
0.31 (0.17 to
0.43)
4.26 (1.98 to
6.54), \0.001
0.37 (0.17 to
0.56)
0.67 (-1.23 to
2.57), 0.489
0.06 (-0.11 to
0.22)
PSI total 102.39 (23.02) 83.6 (26.57) 84.45 (28.62) 18.79 (14.77 to
22.8), \0.001
0.76 (0.59 to
0.92)
17.94 (13.35 to
22.53), \0.001
0.69 (0.51 to
0.87)
-0.85 (-4.71 to
3.01), 0.666
-0.03 (-0.18 to
0.11)
O’Leary–
Porter
a
29.18 (5.6) 31.85 (5.64) 31.66 (4.85) -2.67 (-4.17 to
-1.18), \0.001
-0.48 (-0.75 to
-0.21)
-2.48 (-3.78 to
-1.18), \0.001
-0.48 (-0.73 to
-0.23)
0.2 (-0.85 to
1.24), 0.712
0.04 (-0.17 to
0.24)
Positive
parenting
b
26.98 (20.97) 42.17 (28.26) 41.39 (28.87) -15.18 (-21.75 to
-8.62), \0.001
-0.62 (-0.89 to
-0.35)
-14.4 (-21.21 to
-7.6), \0.001
-0.58 (-0.85 to
-0.3)
0.78 (-5.88 to
7.44), 0.818
0.03 (-0.21 to
0.26)
Critical
parenting
b
14.64 (13.9) 6.5 (7.34) 8.2 (10.64) 8.14 (4.64 to
11.64), \0.001
0.74 (0.42 to
1.06)
6.44 (2.78 to
10.11), 0.001
0.53 (0.22 to
0.82)
-1.7 (-4.35 to
0.95), 0.208
-0.19 (-0.48 to
0.1)
a
Higher scores indicate less inter-partner conflict (n=62/103)
b
Frequency counts in 30 min using the DPICS-R (n=56/103)
Eur Child Adolesc Psychiatry (2014) 23:783–794 789
123
Porter Scale. This suggests that parents were less likely,
12 months later, to report conflict with their spouse with
respect to disciplinary matters, or in the presence of the
child (Table 2).
Costs of service use
Substantial reductions in service use between baseline and
6-month follow-up were found. These reductions were sus-
tained at 12-month follow-up. The fall in service use over the
three waves of data collection is also reflected in the total
costs, which fell from €1,047.91 per child at baseline to
€873.48 at 6 months and then to €626.907 at 12 months.
Thus, the cost of service use amongst the intervention group
was only 60 % of that observed at baseline (Tables 3,4).
Discussion
Our results indicate that an evidence-based parent-training
programme, the IYBP, can result in significant reductions in
child conduct disordered and hyperactive-inattentive
behaviours. At 12-month follow-up, parents continued to
report significantly reduced levels of child socioemotional
and behavioural difficulties, as well as increases in pro-
social behaviour. These findings are in line with the small
pool of previous research in the US [3] and Europe [20,28].
Participation in the IYBP helped to increase parents’ use
of positive parenting strategies and reduce the frequency of
critical disciplinary strategies and these changes were
maintained at 12-month follow-up. Positive parenting
strategies, characterised by high levels of warmth and
appropriate and proactive discipline, can strengthen the
parent–child bond and help to reduce the risk of conduct
disorder [52,53]. Benefits to parental psychosocial func-
tioning were also evident, with parents reporting reductions
in levels of stress and depression at the 12-month follow-
up. Parents also reported lower levels of inter-partner
conflict, suggesting general benefits of the intervention for
overall family and marital adjustment. Existing evidence
suggests that parental psychopathology and family conflict
can negatively affect child behaviour and the quality of
parent–child relationships [54]. Thus, improvements in
parental and family well-being are likely to positively
influence child behavioural and psychosocial outcomes.
Previous research has identified positive parenting as a
key mediator of change in child outcomes in parent-train-
ing intervention trials [55]. However, in the current study,
observations of child behaviour did not corroborate parent-
report and observed child problem behaviour had returned
to baseline levels at the 12-month follow-up, despite con-
tinued improvements in positive parenting behaviours.
Likewise, a recent meta-analysis found no effect of
behavioural parent training on attention deficit hyperac-
tivity disorder (ADHD) when the analysis was based on
blinded, third party observations rather than parent report
[56]. However, it should be noted that the observational
data in this study were available for only a reduced sub-
sample (n=59).
Sibling behaviour also improved over time. Our earlier
findings from the 6-month RCT evaluation of the IYBP
indicated that siblings did not fare better than their control
group counterparts at the 6-month follow-up [25]. Never-
theless, our current findings indicate that the benefits of the
IYBP for sibling behaviour may accrue over time (i.e.,
between the 6- and 12-month follow-ups) and may, at least
to some extent, reflect ‘sleeper effects’ whereby the effects
of the intervention may only emerge over a longer period
of time [57].
Service use was substantially reduced at 12-month fol-
low-up; this is also consistent with improved child
behaviour. In some cases, greater reductions in service use
were recorded. For example, the proportion visiting a GP
fell a further 8 % points and, after 12 months, was 40 %
Table 3 Proportion of children using health, social care and special
educational services at baseline and follow-up
Service Intention-to-treat (n=103)
Baseline 6-month
follow-up
12-month
follow-up
GP 65.52 48.84 40.23
Nurse 8.05 4.65 2.23
Speech therapist 24.13 15.29 9.20
Physiotherapist 6.90 2.32 3.45
Social worker 10.35 1.16 2.30
Community paediatrician 4.60 3.48 0
SNA 11.49 10.84 12.79
Casualty department (A and E) 14.94 13.95 11.49
Outpatient consultant
appointment
22.09 14.11 16.27
Overnight stay in hospital 6.90 8.24 5.75
Table 4 Costs of health, social care and special education services
used by children
Service Intention-to-treat (n=103)
Baseline 6-month
follow-up
12-month
follow-up
Primary care 158.55 127.13 68.61
Hospital services 453.50 234.46 166.19
Special education 428.13 511.67 386.36
Social services 7.74 0.22 5.75
Total 1,047.92 873.48 626.91
Figures are mean total cost per child (€)
790 Eur Child Adolesc Psychiatry (2014) 23:783–794
123
when compared to 65 % at baseline. Likewise, there was
an additional decline in the numbers visiting speech ther-
apists. At 12 months, 9 % of the sample reported having
seen a speech therapist during the previous 6 months when
compared to 24 % at baseline. Overall, the cost of service
use at the 12-month follow-up (€626.91) amongst the
intervention group was reduced to 60 % of baseline
expenditure on formal services (€1,047.91). These findings
in relation to cost-savings compare favourably to those
reported in a similar UK-based study [28], which found
that reducing child conduct problems through the IYBP led
to a reduction in service use costs to 83 % (£826.38/
€929.99) of total baseline costs (£995.81/€1,120.66). This
would suggest some level of generalisability of the findings
reported here, although it is difficult to be precise in the
absence of more benchmark cost studies and possible dif-
ferences across jurisdictions. However, if the reduction in
service use and associated costs reported here is maintained
into the future, it is likely that wider economic and societal
benefits will be achieved.
These findings further indicate that positive changes in
child and parenting behaviour reported from the follow-up
study were maintained in the context of reduced support
from primary health care and social care services. This
supports the general utility of the IYBP for tackling child
behaviour problems and improving family well-being
whilst also highlighting the dual social and economic ben-
efits of parenting programmes. Our previous findings have
also shown that group-based parenting programmes, such as
the IYBP, are relatively inexpensive to implement and may
result in significant longer-run benefits for society [35].
Study strengths
This study is one of only a relatively small number that
have examined the maintenance effects of a parenting
intervention for vulnerable, socially disadvantaged fami-
lies. Indeed, follow-up data on treatment RCTs involving
young children are very important in this field. The current
study included a service utilisation and cost analysis to
assess any longer-run impact on costs. High quality prac-
tices were adhered to, including the use of trained field-
workers, psychometrically robust measures and
observational data (where possible) to complement parent-
report measures. Sample attrition was very low, with 84 %
of participants completing assessments at the 12-month
follow-up and an intention-to-treat approach using a mul-
tiple imputation method for missing data was used to
ensure that any effects of the programme under real-world
conditions were not over-estimated [58]. The magnitude of
the effects was also convincing in view of the proportion of
parents (almost one-third) who attended three or fewer
sessions. Lastly, improvements in the behaviour of siblings
closest in age to the index children point toward potential
generalisation effects of parent training to the wider family
context.
Study limitations
For ethical reasons, the control group was offered the
intervention after initial follow-up. Therefore, a compara-
tive analysis between conditions at 12-month follow-up
was not possible and researchers were not blind to the
intervention condition. The absence of a control group is a
limitation which is typical of this kind of research and
future studies which allow for controlled-comparisons of
longer-term outcomes (e.g., against treatment as usual)
should strengthen our understanding of the longer-term
effects of parent-training programmes.
Due to factors beyond our control, observations were
conducted only for a reduced sub-sample of participants.
Furthermore, intervention fidelity was monitored through
facilitator self-report, but there was no independent veri-
fication of treatment adherence (e.g., by clinicians or raters/
observers). The relatively low rate of programme atten-
dance, particularly amongst the second cohort of parents,
was an additional weakness despite the local delivery of the
programme. Previous research has indicated that families
who experience high levels of social adversity and who can
potentially benefit the most from parenting interventions,
can be difficult to engage and poor attendance may,
therefore, be associated with poorer outcomes [59]. The
attendance rates in the current study may have been neg-
atively impacted by the large proportion of participants
who were experiencing significant socioeconomic disad-
vantage, especially the second cohort which included par-
ents from a particularly highly disadvantaged inner-city
area. Post hoc independent sample t-tests were carried out
to examine if there were any effects of cohort on inter-
vention outcomes. No differences were found on measures
of child outcomes or parent well-being at 12-month follow-
up for the intention-to-treat sample, despite a lower rate of
attendance amongst parents in the second cohort. Never-
theless, the rates of attendance are lower than those
reported elsewhere [3,16] and this may have implications
for family recruitment and programme implementation in
these kinds of studies more generally. For example, the
process of recruitment and implementation would need to
be undertaken mindful of the challenges associated with
working with particularly chaotic groups of parents.
Indeed, we have explored some of these issues in more
detail in a separate qualitative sub-study reported else-
where [60].
Although this study reports on a 12-month follow-up of
the outcomes of a parent-training intervention, it should be
noted that this reflects a comparatively brief follow-up time
Eur Child Adolesc Psychiatry (2014) 23:783–794 791
123
frame in the context of child development. As indicated
earlier, recent research has demonstrated the positive
effects of parent training on child behaviour 5–6 years later
and into adolescence [29,30]. However, further longitu-
dinal follow-ups are needed to fully understand the effec-
tiveness of parent-training over time.
Study implications and directions for future research
Our results indicate that a group-based parenting pro-
gramme—the IYBP—offers an effective means of reduc-
ing the risks associated with conduct and psychosocial
difficulties in early childhood, whilst also possibly
improving parental and family well-being in the longer
term and reducing child contact with formal health, edu-
cational and social services. The growing number of chil-
dren who experience adjustment difficulties [61], coupled
with an increasing need for better value for money in
public spending, highlight the need for effective and cost-
efficient child-focused services. Thus, these findings are
important in guiding and informing future policy and
practice decisions relating to identifying, resourcing and
implementing appropriate evidence-based interventions for
children with conduct problems and ‘at risk’ families in
disadvantaged communities.
Almost three-quarters (71 %) of children in the current
study showed at least modest change in conduct disor-
dered behaviour at 1-year post-intervention, whilst 40 %
showed a very large change. However, observations of
child behaviour indicated a return to baseline levels of
conduct problems, whilst scores on the ECBI problem
scale and SDQ ‘total difficulties’ scale reflected milder,
but ongoing levels of borderline, behavioural problems.
Thus, whilst parent training may be successful in reducing
overall behavioural problems, additional supports, such as
child social skills training, may also be needed in some
cases to further support any improvements in child psy-
chological adjustment. It should also be noted that a small,
but significant proportion of child participants (29 %)
showed diminished benefit (\0.3 SD) in response to the
intervention at the 12-month follow-up. Previous research
has found that almost one-third of children display per-
sistent behavioural difficulties in spite of parent-training
intervention, whilst some also respond better than others
[24]. High levels of family adversity, including lower
socioeconomic status, increased family disruption and
conflict, single parenthood, teen parenthood, maternal
psychopathology, and parental substance abuse, all predict
less change in child behaviour in response to parent
training [58]. Thus, further research is needed to explore
the moderating effects of longer-term parent-training out-
comes to address the critical question of what interven-
tions work best, for whom and under what circumstances.
Future research should also examine the longitudinal
impact of parent-training and track developmental out-
comes into late childhood and adolescence.
Acknowledgments This research was funded by the Atlantic Phi-
lanthropies, with some small additional support from the Dormant
Accounts Fund in Ireland. We would like to extend a sincere thanks to
Archways (http://www.Archways.ie) for their support and facilitation
of this research and to all of the families who participated in this
research. We would also like to thank all of the community-based
organisations and the parent group facilitators for their co-operation
and support throughout the research process. We also acknowledge
with thanks, the invaluable and continuing support and advice that we
have received from the Expert Advisory committee which included:
Dr Mark Dynarski; Dr Paul Downes; Dr Tony Crooks; Ms Catherine
Byrne; and Professor Judy Hutchings. We also acknowledge with
gratitude, the help provided by Dr Yvonne Barnes-Holmes during the
observational element of this study.
Ethical standard This study was granted ethical approval from the
Ethics Committee of the National University of Ireland Maynooth.
Conflict of interest None.
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