JCPSLP Vol 18 No. 1Mar 2016

Table 2. Descriptive statistics and relationships between average credibility and expectancy, and participant variables Descriptive statistics Average credibility

Average expectancy




Correlation coefficient

Significance (2-tailed)

Correlation coefficient

Significance (2-tailed)









Diff. mono. dB

6.47 –5.74–15.81






DIP total diff.









70.55 50.50– 87.58






















Stage PD








*p < .05

Results Normality of the independent variables (expectancy and credibility) was investigated and it was confirmed that the data were normally distributed. The mean treatment credibility score for the entire sample was 6.82 (1.40 SD) and the mean participant expectation score was 59.59% (22.19 SD). For the pooled data, the mean group monologue dB level pre-treatment was 70.41 (4.38 SD), while post-treatment the group mean was 76.88 (4.86 SD). Thus, the group mean difference in dB between pre- and post-treatment monologue was 6.47dB (3.78 SD). The mean DIP total score pre-treatment was 148.67 (19.26 SD), while post-treatment the mean was 161.02 (19.78 SD). The mean difference in DIP total score, pre- and post-treatment was 12.35 (12.78 SD). This difference indicated an improvement in quality of life as a result of a reduced impact of dysarthria. A paired t-test revealed a significant difference pre- to post-treatment for dB level in monologue (t = –11.98; p < .001) and DIP total score (t = –6.76; p < .001). Spearman’s rank correlation coefficients found no significant relationship between difference in dB level in monologue and patient expectations (r s = –.066, p = .652) or treatment credibility (r s = .103, p = .483). Analysis revealed a correlation between treatment credibility and DIP total score difference. This finding was statistically significant with a fair positive correlation (r s = .388, p = .006). There was no correlation found between DIP total score difference and patient expectations (r s = .182, p = .211). No significant correlations were identified between any of the independent variables and participant variables; age, time post onset of PD, severity of dysarthria, stage of PD. All correlation coefficients are shown in Table 2. Discussion Treatment credibility and patient expectations have not been explored widely in the rehabilitation disciplines, and are particularly lacking in the field of speech-language pathology. Therefore, this study is an important addition to the literature as it explored how treatment credibility and patient expectations may relate to treatment outcomes for people with PD participating in LSVT ® LOUD. The primary hypothesis of this study was that patient expectations and

treatment credibility would predict treatment outcomes; however, the findings did not support the hypothesis. The study revealed that for LSVT ® LOUD, treatment credibility and patient expectations did not correlate with outcomes. The results also refuted the secondary hypothesis, that there would be a relationship between participant variables and treatment credibility and patient expectations. Research suggests that patient expectations and treatment credibility are more often associated with quality-of-life outcomes measured by self-report (Smeets et al., 2008). This association is reflected in the results of the current study in that treatment credibility ratings were associated to a fair degree with the quality-of-life outcome, but not the clinical acoustic outcome measure. The quality- of-life measure (DIP total score difference) was subjective and based on self-report, whereas the acoustic measure (difference in dB level in monologue) was an objective measure. A possible explanation for this association between self-reported quality-of-life measures and treatment credibility and expectation may be that patients with better coping skills are more optimistic and score themselves well on personal achievement (Carver, Scheier, & Kumari Weintraub, 1989). Although the majority of the research in psychotherapy and rehabilitation has been able to establish some relationship between patient expectations and treatment outcomes (Linde et al., 2007; Smeets et al., 2008), other research has been unable to demonstrate this correlation (Perkins et al., 2009; Sanderson et al., 2012). Sanderson et al. attributed their lack of correlation to the particularly chronic nature of the back pain the study sample suffered from which resulted in a lack of significant outcomes from the treatment. In the current sample, the severity of the condition was not a major factor as the group was comprised predominately of people with mild dysarthria. The three participants in advanced stages of PD, however, did demonstrate significant improvements on both outcome measures. Research has shown that those in the later stages of PD can still make significant gains in outcomes with some adjustment to functional goals in LSVT ® LOUD (Trail et al., 2005). In another study, Perkins and colleagues (2009) attributed their nil correlation between patient expectations


JCPSLP Volume 18, Number 1 2016

Journal of Clinical Practice in Speech-Language Pathology

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