Abstract
Communication impairments such as aphasia and apraxia can follow brain injury and result in limitation of an individual's participation in social interactions, and capacity to convey needs and desires. Our research group developed a computerized treatment program which is based on neuroscientific principles of speech production (Whiteside and Varley, 1998; Varley and Whiteside, 2001; Varley, 2010) and has been shown to improve communication in people with apraxia and aphasia (Dyson et al., 2009; Varley et al., 2009). Investigations of treatment efficacy have presented challenges in study design, effect measurement, and statistical analysis which are likely to be shared by other researchers in the wider field of cognitive neurorehabilitation evaluation. Several key factors define neurocognitively based therapies, and differentiate them and their evaluation from other forms of medical intervention. These include: (1) inability to “blind” patients to the content of the treatment and control procedures; (2) neurocognitive changes that are more permanent than pharmacological treatments on which many medical study designs are based; and (3) the semi-permanence of therapeutic effects means that new baselines are set throughout the course of a given treatment study, against which comparative interventions or long term retention effects must be measured. This article examines key issues in study design, effect measurement, and data analysis in relation to the rehabilitation of patients undergoing treatment for apraxia of speech. Results from our research support a case for the use of multiperiod, multiphase cross-over design with specific computational adjustments and statistical considerations. The paper provides researchers in the field with a methodologically feasible and statistically viable alternative to other designs used in rehabilitation sciences.
Highlights
In the field of speech and language rehabilitation research, there has been debate regarding the most appropriate design for evaluating the outcomes of treatment
The limited generalization from a single case to the larger population was addressed through the use of case series designs where a number of participants were administered an intervention via a standard protocol (e.g., Robertson et al, 1995)
The purpose of the current paper is to describe how data from therapy experiments can be used, with some key considerations in terms of baselines and some essential transformations of the dependent measures of interest, to allow researchers to harness the power of cross-over designs beyond the level of individual case series comparison
Summary
In the field of speech and language rehabilitation research, there has been debate regarding the most appropriate design for evaluating the outcomes of treatment. The debate has addressed the relative advantages and disadvantages of randomized controlled trials in comparison to single case or case series designs. A second major issue is that participants often did not receive a single standard protocol treatment, but rather individuals were administered interventions that were appropriate to their particular profile of cognitive–behavioral strengths and weaknesses. The limited generalization from a single case to the larger population was addressed through the use of case series designs where a number of participants were administered an intervention via a standard protocol (e.g., Robertson et al, 1995)
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