48 / 60
National Disability Insurance Scheme
94
JCPSLP
Volume 18, Number 2 2016
Journal of Clinical Practice in Speech-Language Pathology
Charn Nang
(top) and Natalie
Ciccone
THIS ARTICLE
HAS BEEN
PEER-
REVIEWED
KEYWORDS
ONSET
PREDICTION
PROGNOSIS
RECOVERY
STUTTERING
TREATMENT
OUTCOMES
based on an integration of the current best evidence,
clinician and client-based factors, and the service setting
(Hoffmann, Bennett, & Del Mar, 2013). An understanding of
which client factors may provide information on the
individual’s prognosis is required to improve client
outcomes and to ultimately inform health policy.
As a broad term,
prognosis
means “foreseeing,
predicting, or estimating the probability or risk of future
conditions” (Moons, Royston, Vergouwe, Grobbee, &
Altman, 2009, p. 1317), and the relevant factors are clinical
or biologic characteristics that are objectively measured.
They include factors such as an individual’s age, gender,
history, symptoms, signs, and diagnostic test results.
A more specific medical definition of a
prognostic factor
is a measurement that is associated with the natural
progression of a disease, independent of therapy (Gordis,
2014). It provides information about the likely course of a
disease or condition in an untreated individual. However,
prognostic factors do not have to be specifically linked to
an illness or presence of a health condition. They can also
be used to predict the future of healthy individuals (Moons
et al., 2009). Therefore, in stuttering the relevant prognostic
factors are ones that can identify (a) subgroups of those
who start to stutter and those who do not; and (b) within
untreated individuals who stutter, subgroups of those who
recover and those whose stutters persist.
On the other hand, a
predictive factor
provides a
measurement of outcome (with response or lack of) that
is associated with a specific therapy (Gordis, 2014). Valid
and reliable predictive factors can be used to select the
therapy with the highest likelihood of efficacy for the
individual patient in order to inform tailor-made treatment.
Accordingly, predictive factors can be used to identify
subpopulations of patients that are most likely to benefit
from a given therapy (Adolfsson & Steineck, 2000).
Regarding stuttering, predictive factors are ones that
can account for subgroups of individuals having different
treatment outcomes, such as individuals who recover
compared to those who persist with stuttering after some
form of treatment, or those who maintain treatment gains
compared to those who relapse.
As both prognostic and predictive factors are related
to the outcome of an individual who develops a disease
or health condition, the two concepts are related.
Nevertheless, the extent of this relationship is unknown
for stuttering. A prognostic factor may or may not also be
predictive of treatment outcomes (Adolfsson & Steineck,
2000).
There is value in understanding the prognostic
indicators of stuttering onset and stuttering
persistence due to the associated negative
life consequences. Stuttering therapy can be
beneficial, but not all individuals respond
equally to therapy. Knowledge of the factors
relevant to treatment success is required to
enhance client outcomes. This review
summarises and compares the prognostic
factors of stuttering, as well factors that
predict treatment outcomes. Prognostic
indicators for stuttering onset include positive
family history, age, and gender; whereas for
persistent stuttering they are gender, age of
onset, time since onset, and family history of
persistence. The most consistent factor for
predicting treatment outcomes is pre-treatment
stuttering rate. However, there is lack of data
for predictive treatment factors. Overall, the
findings of studies of prognostic and predictive
factors of stuttering need replication, but with
improved study design. In the meantime, a
systematic review of existing literature is
recommended to synthesise and quantify the
strength of each factor.
S
tuttering is defined as a disorder of speech
production, specifically in the rhythm of speech
(Bloodstein & Bernstein Ratner, 2008). Speakers
know what they want to say but have difficulty in doing so
due to involuntary disfluencies characterised as repetitions,
prolongations, and cessation of sound. Negative
consequences and feelings associated with stuttering
may begin as early as the preschool years (Yaruss, 2010).
For those with chronic stuttering, difficulty with producing
fluent speech can negatively impact on all domains
of an individual’s life including education attainment
(O’Brian, Jones, Packman, Menzies, & Onslow, 2011) and
employment opportunities (Yaruss, 2010).
Prognostic and predictive factors
The importance of prognosis is emphasised in evidence-
based practice where clinical decisions should be made
Stuttering prognosis
and predictive factors of
treatment outcome:
A review
Charn Nang and Natalie Ciccone