Generalization outcomes of Sound Production Treatment (SPT) for acquired apraxia of speech: relationship to treatment dosage

Abstract

ABSTRACT Background Dosage is an important aspect of treatment for acquired apraxia of speech (AOS) that has received little attention. Knowledge concerning the association of dosage to treatment outcomes is crucial for informing clinical practice and treatment research. Dosage metrics, representing the number of treatment sessions and teaching episodes (TEs) required to achieve specific performance milestones with Sound Production Treatment (SPT), have recently been provided for treated items. Aims The current investigation was designed to extend AOS dosage research to untreated items. Methods and Procedures Retrospective analyses were performed using data from a previously reported SPT study (Wambaugh et al., 2017) in which 20 speakers with AOS received two applications of SPT with different practice schedules (i.e., SPT-Random and SPT-Blocked). Probe data were used to determine achievement of the following milestones: 1) change above baseline; 2) clinically relevant improvement; and 3) mastery. Follow-up data were used to examine the relationship between the dosage metrics and maintenance of accuracy. Outcomes and Results On average, change above baseline and clinically relevant improvement was achieved for untreated items following 9–10 and 7–8 treatment sessions, respectively. Mastery of untreated items occurred for 45% of targets, following an average of 16–17 treatment sessions. TEs varied widely for all dosage metrics. No statistically significant differences were found between practice schedules for any of the dosage metrics. Better maintenance was associated with earlier achievement of performance milestones. More treatment sessions and TEs were required to meet performance milestones for untreated items in comparison to treated items. Conclusions This study provides dosage metrics for response generalization outcomes which can be used for planning and guiding treatment for AOS.