JCPSLP Vol 18 no 2 July 2016

National Disability Insurance Scheme

Stuttering prognosis and predictive factors of treatment outcome:

A review Charn Nang and Natalie Ciccone

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

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).

KEYWORDS ONSET PREDICTION PROGNOSIS RECOVERY STUTTERING TREATMENT OUTCOMES

THIS ARTICLE HAS BEEN PEER- REVIEWED

Charn Nang (top) and Natalie Ciccone

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JCPSLP Volume 18, Number 2 2016

Journal of Clinical Practice in Speech-Language Pathology