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JCPSLP Volume 18, Number 2 2016 97
1441). Jones et al. investigated factors including age, time
since stuttering onset, gender, and stuttering severity in 261
children that could predict treatment duration for the first
stage of the LP. They found that stuttering severity at the
first treatment session was the only factor that related to
the how long it took for children to enter the second
(maintenance) stage of the program. Children with more
severe stuttering required more time.
There have since been more studies of factors predicting
outcomes on the LP for early stuttering, with several
studies consistently reporting that treatment takes longer
for children who stutter more frequently or more severely
pre-treatment (Jones et al., 2000; Kingston, Huber, Onslow,
Jones, & Packman, 2003; Koushik, Hewat, Shenker,
Jones, & Onslow, 2011). A follow-up investigation of the
same children from Jones et al. (2000) found that majority
of children treated with LP maintained their fluency gains
(below 1% syllables stuttered) 5 years post-treatment
(Jones et al., 2008). A minority of the children relapsed, but
the authors stated that it was unknown if there were any
predictors of long-term relapse after treatment with the LP
as their analyses did not yield useful results regarding this.
More recently, a replication and re-analysis of the data
from children treated by the LP (independent of the LP
developers) was conducted by Guitar and colleagues
(2015). The authors combined the data from two sets
of children who had been treated with the LP (n = 29) to
investigate predictors of long-term outcomes of treatment
with the LP. They tested pre-treatment stuttering %SS and
gender as factors, and found that both were significant
predictors. They found that females had better long-
term outcomes as measured by %SS and that this was
independent of their pre-treatment %SS. For males, long-
term outcome in %SS was positively correlated with their
pre-treatment %SS.
Older children and adolescents
For older children and adolescents, pre-treatment stuttering
severity has been found to be a predictive factor for
treatment outcome (Cook, Howell, & Donlan, 2013;
Hancock & Craig, 1998). Hancock and Craig (1998) (n =
77) found that trait anxiety post-treatment could also
predict stuttering frequency 1-year post-treatment.
Psychosocial measures and a language measure of lexical
diversity did not predict stuttering severity following
treatment (Cook et al., 2013).
Interpreting predictive factors
The most reliable factor in predicting treatment outcome is
pre-treatment stuttering severity in AWS. To date, this
seems to also be the case for children who stutter, although
data is limited and has been reported mainly for the LP.
Other client factors could be useful for predicting treatment
outcomes, and more studies are required with improved
research design and replication of results. Replication of
results is also necessary across different sites independent
of the original location and the program developers, for
example, for programs like the LP (Guitar et al., 2015;
Jones et al., 2000; Kingston et al., 2003; Koushik et al.,
2011).
Conclusions and future directions
At present, the most consistent prognostic factors
associated with stuttering onset – that is, factors to predict
who is likely to start stuttering – are a positive familial history
of stuttering, age, and gender (being male). The prognostic
factors related to natural recovery – that is, who is likely to
characteristics. The most consistent predictor of relapse or
regression is pre-treatment stuttering severity, usually
measured as percentage of syllables stuttered (%SS). This
has been found in earlier studies as well as more recent
ones of predictive factors of treatment outcomes in AWS
(Block, Onslow, Packman, & Dacakis, 2006; Craig, 1998;
Guitar, 1976; Huinck et al., 2006; Ladouceur, Caron, &
Caron, 1989).
Of the more recent studies, Huinck et al. (2006)
investigated subtypes of AWS (n = 25) based on pre-
treatment scores of stuttering severity (mild or severe)
and severity of negative emotions and negative cognitive
thoughts (mild or severe). Only stuttering severity was
found to be a predictor of treatment outcomes; people with
severe stuttering demonstrated the largest gains in therapy
but they also experienced more relapse as measured by
%SS (Huinck et al., 2006).
Block and colleagues (2006) conducted a prospective
investigation of predictive factors for treatment outcomes
with short- and long-term (up to 5 years post-treatment)
follow-up periods. Consistent with previous findings, pre-
treatment stuttering rate (%SS) was found to be a predictor
of short-term treatment outcome (n = 78). That is, AWS
with mild stuttering achieved better treatment outcomes, as
measured by %SS, at the 1-year follow-up and were less
likely to relapse than adults with a severe stutter. In turn,
the only predictor of long-term treatment outcome was the
short-term stuttering rate at 3 months post-treatment.
Additional factors
Caution is required when interpreting the research literature,
given that studies of factors to predict relapse other than
stuttering severity have yielded inconsistent results, are
based on single studies, and/or are based on weak
evidence. As such, their ability to predict treatment success
is currently questionable and the findings need replication.
These factors requiring further investigation include those
related to communication attitudes, locus of control (internal
or external), social anxiety, personality profiles (Iverach et
al., 2010), mental health disorders (Iverach et al., 2009),
and resilience, which are the processes and mechanisms
by which an individual deals with adversity in life (Craig,
Blumgart, & Tran, 2011). Craig et al. reported that AWS
who were more resilient had lower levels of health risk, were
able to manage their stress levels better, had fewer physical
as well as social limitations, and had more vitality and social
support.
Factors found not to predict treatment outcomes
Factors that have been examined but not found to predict
treatment outcome include the following: age, gender social
status, neuroticism, extroversion, avoidance, reaction (e.g.,
negative reactions to stuttering), self-help activities, formal
practice (booster/maintenance sessions), real-life
assignment (practice of techniques in a functional setting),
post-treatment speech naturalness, number of first-degree
relatives who stutter, and whether or not previous treatment
had been received (Block et al., 2006; Craig, 1998).
Children who stutter
Early stuttering
It is a surprise and a concern that very little data are
available to provide information on the prediction of
treatment outcomes for early stuttering. In 2000, Jones et
al. stated that “almost nothing is known … about factors
that predict the responsiveness of early stuttering to
treatment” (Jones, Onslow, Harrison, & Packman, 2000, p.