A Systematic Review of Speech-Language Pathology Interventions for Presbyphonia Using the Rehabilitation Treatment Specification System

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BackgroundThe prevalence of voice disorders for people over the age of 65 is 4× higher than for the population at large. The most common cause of dysphonia in this group is presbyphonia, the preferred first-line treatment for which is voice therapy with a speech-language pathologist. This systematic review seeks to identify how voice therapy affects multidimensional voice outcomes in people with presbyphonia. MethodsA systematic search of CINAHL, Embase, Emcare, MEDLINE and Google Scholar was undertaken in March 2023. Comparative and non-comparative studies of voice therapy in participants over 50 years with presbyphonia were considered for inclusion. No limitations were placed on date or language of publication. Study quality and risk of bias were assessed with the Cochrane Risk of Bias 2 (RoB 2) tool and the Methodological Index for Non-Randomized Studies (MINORS). Subgroup analysis was used to compare studies based on participant sex, intervention duration, study design and intervention content. Interventions were specified using the Rehabilitation Treatment Specification System (RTSS) employing a consensus methodology among reviewers. Results were synthesized utilizing metanalysis when outcomes were adequately specified, and narrative analysis when they were not. Results23 studies were included with 1,050 subjects (mean age: 72.5 ± 8.6; 51% female). The most reported intervention was Vocal Function Exercises (VFEs). Per the RTSS, 14 interventions employed a predominantly Organ Functions approach and the 14 remaining interventions employed a Skills & Habits approach. Metanalysis confirmed post-therapy improvement in patient-related outcome measures (PROMs) of 0.93 standard mean difference (p<0.00001, 95% CI: 0.70-1.17); studies with predominantly males and with longer treatment periods were associated with larger improvements, while RCTs reported more modest improvements. Metanalysis also identified a mean post-therapy increase in maximum phonation time (MPT) of 5.37 seconds (p<0.00001, 95% CI: 3.52-7.22). Treatments with an Organ Functions focus resulted in greater gains in MPT than those with a Skills & Habits focus (7.52 s vs. 2.90 s). Finally, metanalysis identified reductions in acoustic perturbation measures (jitter: 0.62%, p<0.001, 95% CI: 0.26-0.97%; shimmer 1.05%, p<0.00001, 95% CI: 0.67-1.44%). Narrative synthesis further identified improvement in auditory-perceptual voice quality in all active treatment groups as well as improved glottal function in most studies which reported this. ConclusionsDespite the uncertainty around internal validity introduced by the inclusion of a wide range of study designs, there is convincing evidence that voice therapy for presbyphonia results in significant improvement in patient-reported, aerodynamic, acoustic, and expert-rated voice outcomes. Treatments with an Organ Functions focus may better address the underlying physiological deficits of presbyphonia, although future comparative studies with multidimensional voice assessment are warranted.