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American Journal of Speech-Language Pathology logoLink to American Journal of Speech-Language Pathology
. 2021 Sep 7;30(6):2368–2378. doi: 10.1044/2021_AJSLP-20-00402

Assessing Change in Communication Limitations in Primary Progressive Apraxia of Speech and Aphasia: A 1-Year Follow-Up Study

Rene L Utianski a,✉, Peter R Martin b, Joseph R Duffy a, Hugo Botha a, Heather M Clark a, Keith A Josephs a
PMCID: PMC9132068  PMID: 34491800

Abstract

Purpose

Individuals with primary progressive apraxia of speech have apraxia of speech (AOS) as the initial and predominant symptom. Many develop aphasia and/or dysarthria later in the disease course. It was previously demonstrated that patients with neurodegenerative AOS experience reduced participation in communication that is further exacerbated by co-occurring language deficits (Utianski et al., 2020). Measures of disease severity did not necessarily correlate with measures of participation restrictions. The aim of this follow-up study was to describe changes in communication limitations in these patients, again measured by (a) the patient via the Communicative Participation Item Bank (CPIB) and (b) the speech-language pathologist via the American Speech-Language-Hearing Association's (ASHA's) Functional Communication Measures (FCMs) and an adapted motor speech disorder (MSD) severity rating to determine if there are significant changes in these and other objective speech and language measures at follow-up after 1 year.

Method

Of the 24 patients reported in the study of Utianski et al. (2020), 17 (10 men, seven women) returned for a second visit approximately 1 year following the first visit. Identical procedures were utilized; the communication measures collected at each visit were statistically compared. Correlations were calculated between the participation ratings and other clinical assessment measures at the second visit and for the change in scores on those measures between the first and second visits.

Results

There were statistically significant differences in AOS and aphasia severity between visits. There were significant changes in clinical assessments, MSD severity rating, and all ASHA FCMs between visits, but not the CPIB. Correlation analyses suggest the relationships among clinical and participation measures are complex; overall, patients with more severe changes in AOS experienced greater changes in participation restrictions.

Conclusions

The findings of this study support the use of patient-reported outcome measures as they may better reflect the patient experience, including the influence of factors such as ongoing speech therapy and the emergence of neuropsychiatric features, and associated changes in day-to-day functioning, when other measures may simply index the progression of the disease.

Supplemental Material

https://doi.org/10.23641/asha.16528512

Primary progressive apraxia of speech (PPAOS) is the diagnosis given when apraxia of speech (AOS) is gradual in onset, progressive, and the first or only clinical complaint associated with a neurodegenerative disease. Over the last 10 years, the clinical presentation (Duffy et al., 2017; Josephs et al., 2013; Poole et al., 2017), underlying pathophysiology (Botha et al., 2015; Duffy et al., 2015; Josephs et al., 2005, 2010, 2012; Utianski, Duffy, Clark, Strand, Botha, et al., 2018; Utianski, Whitwell, et al., 2018; Whitwell et al., 2013), and evolving neurological picture that is heralded by PPAOS (Josephs et al., 2014; Seckin et al., 2020; Utianski, Duffy, Clark, Strand, Boland, et al., 2018; Whitwell, Duffy, et al., 2017; Whitwell, Weigand, et al., 2017) have been well detailed.

Across etiologies, AOS is somewhat heterogeneous in its clinical features; however, it consistently reflects disruptions of articulation and prosody. What differs, at least in neurodegenerative AOS, is that disruptions in either articulation or prosody can predominate the speech pattern (Josephs et al., 2013; Mailend & Maas, 2020; Takakura et al., 2019; Utianski, Duffy, Clark, Strand, Botha, et al., 2018). Patients are referred to as having phonetic (articulatory) PPAOS if distorted sound substitutions or additions clearly dominate the speech pattern. On the other hand, prosodic PPAOS is used to describe patients in whom syllable segmentation or lengthened intersegment durations between syllables, words, or phrases clearly dominate the speech pattern. When neither phonetic nor prosodic features predominate, due to either mild or profound severity or a lack of clear perceptual predominance between those features, the term mixed PPAOS is applied.

As time goes on for patients with PPAOS, AOS becomes more severe, and other speech, language, neurological, and neuropsychological symptoms typically emerge (Duffy et al., 2020). Verbal output may become limited to a small number of unintelligible words or undifferentiated sounds. This can be further exacerbated by dysarthria when it develops. Patients with PPAOS may also develop agrammatic aphasia during the disease course (referred to here as PAA). In the framework of the current, widely adopted consensus criteria, all patients with PPAOS technically meet criteria for the nonfluent/agrammatic variant of primary progressive aphasia (PPA), even in the absence of aphasia (Gorno-Tempini et al., 2011). This is the case because those criteria consider motor speech as a component of language. However, for a number of reasons, including distinct clinical imaging features (Tetzloff et al., 2019) and differing prognoses (Whitwell et al., 2020), we recognize patients with isolated AOS as having a problem distinct from PPA (i.e., PPAOS). When aphasia develops later, it is the authors' opinion that patients still do not meet the root criteria for PPA, as it stipulates that aphasia should be the most prominent deficit at symptom onset.

While the clinical and neuroimaging characteristics of PPAOS have been well detailed, there is limited information on the day-to-day limitations experienced by this patient population. We previously demonstrated (Utianski et al., 2020) that patients with neurodegenerative AOS experience reduced participation in communication that is further exacerbated by co-occurring language deficits, as indexed by the Communicative Participation Item Bank (CPIB; Baylor et al., 2013). In that study, there were statistically significant correlations between the CPIB and other indices of communicative functioning (American Speech-Language-Hearing Association's [ASHA's] Functional Communication Measures [FCMs] in Motor Speech and Language Expression ratings and the motor speech disorder [MSD] severity rating). The CPIB did not correlate with the ASHA FCM in Language Comprehension or other speech-language measures, such as the Apraxia of Speech Rating Scale (ASRS; Strand et al., 2014) and the Western Aphasia Battery–Aphasia Quotient (WAB-AQ; Kertesz, 2007). The results supported the notion that measures of impairment severity cannot be assumed to correlate with measures of participation restrictions. While that study provided insight into the day-to-day sequela of progressive speech and language disorders, it did not address change over time.

The primary aim of this study was to describe the changes in communication limitations over a 1-year period, as measured by (a) the patient via the CPIB and (b) the examining speech-language pathologist (SLP) via ASHA FCMs and an adapted MSD severity rating. A secondary aim was to examine changes in other speech-language measures and the relationships of these different indices of disease progression.

Method

Participants

The assessment methods are identical to those in the study of Utianski et al. (2020); of the patients originally described in that article, 17 (10 men, seven women) returned for a second visit approximately 1 year following the first visit. Two additional patients were scheduled to return, but one had a stroke between visits and the other was not able to participate in any testing due to severity; they were therefore excluded from participation. Patients were seen between February 2018 and August 2020. They had a median age of 72.5 years (interquartile range: 60.2–74.1) at the first visit, at which time they had a median disease duration of 4.7 years (2.0–5.2). All participants had AOS. Among them, six presented with isolated AOS (i.e., PPAOS, without aphasia) and 11 had a combination of AOS and agrammatic aphasia, referred to as AOS + PAA, at the first visit. All patients were White, not Hispanic, per self-report. This study was approved by the Mayo Clinic Institutional Review Board, and all patients provided written consent to participate.

Clinical Examination

Language and motor speech evaluations were conducted by experienced clinicians (R. L. U., J. R. D., or H. M. C.). Clinical judgments regarding the presence, type, and severity of AOS, aphasia, and dysarthria were made by the examining clinician and subsequently confirmed by consensus agreement among the other nonexamining clinicians. Subjective severity ratings of AOS, aphasia, and dysarthria were made using a 5-point scale (0 = absent, 1 = mild, 2 = moderate, 3 = marked, 4 = severe). The Western Aphasia Battery–Revised (WAB-R; Kertesz, 2007) was administered, and the WAB-AQ served as an additional index of aphasia severity. Clinical judgments regarding language functioning were based on performance on the WAB-R, as well as other formal clinical measures (see Utianski, Duffy, Clark, Strand, Boland, et al., 2018, for full details of the language battery), written and spoken picture descriptions, and conversational interaction. Participants were required to perform below normal on at least two measures of language to establish the presence of aphasia. More specifically, grammatical integrity was assessed in conversational speech and verbal and written picture description tasks, as well as more formal measures of complex comprehension (subtests of the Boston Diagnostic Aphasia Examination, Token Test) and production (Northwestern Anagram Test). A consensus determination was made as to whether a patient qualified as agrammatic based on the performance on these informal and formal measures.

A conversational speech sample and a narrative picture description were collected, and supplementary speech and speechlike tasks (i.e., alternating and sequential motion rates) were elicited. These speech samples were used to make a judgment regarding the presence of AOS and the predominance of phonetic or prosodic speech characteristics, again determined by consensus agreement of two experienced clinicians. Following those gestalt judgments, the speech samples were also utilized to complete the Apraxia of Speech Rating Scale, Version 3 (ASRS-3; Strand et al., 2014; Utianski, Duffy, Clark, Strand, Botha, et al., 2018). The ASRS-3 rates the presence and severity/prominence of the phonetic and prosodic speech deficits. The ASRS-3 score is considered semi-independently of the AOS subtype (i.e., not modified relative to one another), although they are determined by the same examiner. The ASRS-3 score is considered complementary to the gestalt AOS type as the latter is a nominal designation used to study the natural course of these patients to inform prognostication; beyond reflecting that AOS is present/absent, it did not inform diagnosis. The ASRS-3, on the other hand, is a continuous measure used to, first and foremost, describe the prominence of AOS characteristics (informing diagnosis) and index the severity of speech impairment. The ASRS-3 can also be used as an index of change over time.

An articulatory error score (AES) was calculated from the proportion of incorrectly produced words on repeated repetitions of words of increasing length and complexity and single repetitions of sentences; the items included on the AES can be found in the study of Duffy et al. (2015). The AES served as an index of articulation errors, which may result from any combination of AOS, aphasia, or dysarthria. The SLP obtaining, scoring, and interpreting measures for the second visit was blinded to the results from the first visit.

Raw scores from the Montréal Cognitive Assessment (MoCA; Nasreddine et al., 2005) served as a proxy for general cognitive abilities. The Neuropsychiatric Inventory–Questionnaire (NPI-Q; Kaufer et al., 2000) and the Frontal Behavioral Inventory (FBI; Kertesz et al., 1997) served as indices of mood, depressive, and other neuropsychiatric symptoms.

Communication Measures

The communication measures were the same as those collected in the study of Utianski et al. (2020) and include the CPIB, the MSD severity rating, and ASHA FCMs, collected at first and second visits. Briefly, the CPIB short form is a 10-question survey (0–3 points per question, where a score of 30 suggests the condition does not interfere with communication); it is intended to index interference of an unspecified condition on communication participation in a variety of situations (Baylor et al., 2013). The generic nature of items on the CPIB allows for its use across a variety of communication disorders. Patients are instructed to complete this independently, although caregivers may provide input to facilitate their understanding of the written questions. Total raw scores and T scores (Baylor et al., 2013) were recorded, but raw scores are reported here because the primary measure of interest was annualized change.

The examining SLP completed the MSD severity rating (adapted from Hillel et al., 1989; Yorkston et al., 1993), which is a 1–10 rating that indexes the degree to which speech is understood, without regard to specific activities of daily living. This scale is derived from an amyotrophic lateral sclerosis (ALS) severity scale, originally designed and utilized for the judgment of speech symptom severity secondary to ALS (Hillel et al., 1989); here, it is adapted to index speech ability more generically (i.e., for any type of MSD associated with any neurological disease). The ratings reflect a range from normal speech (rating of 10 or 9) through loss of useful speech (rating of 2 or 1).

ASHA's National Outcomes Measurement System scales, referred to as FCMs, are 7-point rating scales (7 = independently successful, 1 = not successful) used to describe a patient's abilities specific to different domains of speech and language functioning. The examining SLP rated the FCMs specific to Motor Speech, Language Expression, and Language Comprehension. Strong interjudge reliability for the above measures was previously reported (Utianski et al., 2020).

Data Analyses

The appropriate parametric t test or nonparametric signed-ranks test was used to assess whether the annualized change for participants was different from zero for the following tests: ASRS-3, WAB, AOS, dysarthria and aphasia severity, and communication limitation measures (CPIB, ASHA FCMs, and MSD severity). Statistical significance was assessed at p < .05. Due to small sample size, correction for multiple comparisons was not imposed. Data were visualized for further qualitative assessment of change.

Spearman rank correlations were calculated among the measures of communication limitations (CPIB, FCMs) and quantitative clinical measures (WAB-AQ, MoCA, ASRS-3, and AES) for data collected at the second visit. Additionally, correlations were computed on the changes in scores on these measures between the first and second visits. Statistical significance was assessed at p < .05, where the reported p value is false discovery rate corrected for multiple comparisons (within each data set) to allow for comparison with previous findings. These correlations were qualitatively compared to those previously reported (Utianski et al., 2020) for data collected at the first visit.

Results

Table 1 summarizes the clinical data for the first and second visits. See Figure 1 for individual data for clinical assessments and Figure 2 for individual data for the communication limitation measures. At the first visit, six patients presented with an isolated AOS, and the remaining 11 also had aphasia; by the second visit, an additional three had developed aphasia. Across all patients, median AOS severity was moderate at the first visit and marked at the second visit; median aphasia and dysarthria severity were mild at both visits. Of note, 13 of 17 dysarthria severity ratings remained stable from Visit 1 to Visit 2; changes included three patients who were judged to have dysarthria at the return visit who were not present at the initial visit. For aphasia severity ratings, 10 of 17 patients remained stable, and seven of 17 worsened between visits. It is therefore not surprising that there were statistically significant differences in AOS and aphasia but not dysarthria severity between visits. One patient whose AOS was initially classified as “phonetic” was classified as “mixed” at the second visit, likely reflecting progression of AOS; there were no other changes in designation of AOS subtype. Additional visualization of all data by AOS subtype is provided in Supplemental Materials S1 and S2.

Table 1.

Clinical data, presented as median (interquartile range).

Variable Visit 1 (N = 17) Visit 2 (N = 17) Mean annualized change (p)
Patient-rated participation measure
 CPIB (/30) 5 (2–11) 9 (1–11) −0.58 (.681 a )
SLP-rated communication measures
 MSD severity score rating (/10) 6 (5–6) 5 (3–6) −1.22 (< .001 a )*
 ASHA FCM Motor Speech (/7) 6 (5–6) 5 (2–5) −1.21 (.001 a )*
 ASHA FCM Language Expression (/7) 6 (6–7) 6 (5–7) −0.88 (.009 a )*
 ASHA FCM Language Comprehension (/7) 7 (6–7) 6 (5–7) −0.54 (.015 a )*
Speech-language clinical measures
 WAB-AQ (/100) 95.8 (92.6–97.6) 91.4 (88.7–96) −6.08 (.021 a )*
 ASRS-3 total (/52) 23 (16–24) 27 (21–30) 5.50 (.002 a )*
 ASRS-3 Phonetic subscore (/16) 8 (6–9) 9 (8–14) 2.11 (.013 a )*
 ASRS-3 Prosodic subscore (/16) 8 (4–10) 9 (5.8–10.5) 1.32 (.013 a )*
 AES 35.7 (17.9–48.1) 58 (26.8–69.9) 15.32 (< .001 a )*
 MoCA 25 (20–26) 20 (18–26) −3.06 (.007 a )*
Neuropsychiatric symptom measures
 FBI 11 (8–21) 18 (13.5–35.5) 7.33 (.004 a )*
 NPI-Q 2 (0–3) 2 (1–6) 1.74 (.054 a )
SLP-rated measures
 Aphasia, present 11 14
 Aphasia severity (/4) 1 (1–2) 1 (1–2) 0.44 (.021 b)*
 Dysarthria, present 6 9
 Dysarthria severity (/4) 1 (1–2) 1 (1–2) 0.27 (.098 b)
 AOS severity (/4) 2 (1.5–2.5) 3 (2–4) 0.78 (< .001 a )*
 AOS subtype, mixed 6 (35%) 7 (41%)
 AOS subtype, phonetic 6 (35%) 5 (29%)
 AOS subtype, prosodic 5 (29%) 5 (29%)
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Note. CPIB = Communicative Participation Item Bank; SLP = speech-language pathologist; MSD = motor speech disorder; ASHA FCM = American Speech-Language-Hearing Association's Functional Communication Measure; WAB-AQ = Western Aphasia Battery–Aphasia Quotient; ASRS-3 = Apraxia of Speech Rating Scale, Version 3; AES = articulatory error score; MoCA = Montréal Cognitive Assessment; FBI = Frontal Behavioral Inventory; NPI-Q = Neuropsychiatric Inventory–Questionnaire; AOS = apraxia of speech.

a

The p value from a paired t test of whether the annualized change within participants is different from zero.

b

The p value from a nonparametric Wilcoxon signed-ranks test of whether the annualized change within participants is different from zero.

*

p < .05.

Figure 1.

Figure 1.

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Individual scores on language and speech measures. Point at 0 years indicates performance at the first visit; individual data point for the second visit is placed at the interval of the second visit (e.g., 11 months or 1 year 1 month). Diagnoses are indicated by colored dots (blue = PPAOS, orange = AOS-PAA); lines are color coded to diagnosis at the first visit. The medians of each group are presented in the thick, overlaid line. WAB-AQ = Western Aphasia Battery–Aphasia Quotient; ASRS-3 = Apraxia of Speech Rating Scale, Version 3; PPAOS = primary progressive apraxia of speech; AOS-PAA = combination of AOS and agrammatic aphasia.

Figure 2.

Figure 2.

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Individual scores on communication measures. Point at 0 years indicates performance at the first visit; individual data point for the second visit is placed at the interval of the second visit (e.g., 11 months or 1 year 1 month). Diagnoses are indicated by colored dots (blue = PPAOS, orange = AOS-PAA); lines are color coded to diagnosis at the first visit. The medians of each group are presented in the thick, overlaid line. CPIB = raw score on Communicative Participation Item Bank short form; MSD = motor speech disorder; ASHA FCM = American Speech-Language-Hearing Association's Functional Communication Measure; PPAOS = primary progressive apraxia of speech; AOS-PAA = combination of AOS and agrammatic aphasia.

The median ASRS-3 score was 23 (/52) at the first visit and worsened to 27 at the second visit. Median AES was 35.7% at the first visit and 58% at the second visit. Median WAB-AQ dropped from 95.8 at the first visit to 91.4 at the second visit. Mean MoCA was 25 at the first visit and 20 at the second visit. Median MSD severity and ASHA FCMs for Motor Speech and Language Comprehension dropped by 1 point between the first and second visits; average Language Expression was unchanged. Interestingly, the median CPIB increased (improved) from 5 at the first visit to 9 at the second visit, although that change was not statistically significant. There were significant changes in ASRS-3 scores, AES, WAB-AQ, MoCA, FBI, MSD severity rating, and all ASHA FCMs between visits, with borderline significant changes in the NPI-Q.

The correlations among measures of function (i.e., MSD severity rating, ASHA FCMs, and CPIB) and clinical assessment measures (i.e., WAB-AQ, ASRS, and AES) at the second visit are summarized in Table 2. The SLP-rated MSD severity ratings strongly and significantly correlated with the ASRS-3 score (ρ = −.72), the AES (ρ = −.86), and the ASHA FCM Motor Speech rating (ρ = .90) in the direction of greater severity in all measures. The ASHA FCM Motor Speech also strongly correlated with the ASRS-3 (ρ = −.73) and the AES (ρ = −.85). In contrast to a nonsignificant correlation at the first visit, the ASHA FCM Motor Speech rating now significantly correlated with the WAB-AQ (ρ = .64). The ASHA FCM Language Expression remained strongly correlated with the WAB-AQ (ρ = .80) and the MoCA (ρ = .85), as well as the ASHA FCM Language Comprehension (ρ = .83) and ASHA FCM Motor Speech (ρ = .54). Similar to the initial visit, the ASHA FCM Language Comprehension rating showed significant strong, positive correlations with the MoCA (ρ = .81) and the WAB-AQ (ρ = .76).

Table 2.

Spearman's correlations of clinical data.

Measure MoCA WAB-AQ ASRS-3 MSD Sev AES FCM MS FCM LC FMC LE CPIB
Spearman's correlations of clinical data at the second visit
MoCA 1.0
WAB-AQ .64* 1.0
ASRS-3 −.07 .51 1.0
MSD Sev .36 .47 −.72* 1.0
AES −.34 −.60* .72* −.86* 1.0
FCM MS .48 .64* −.73* .90* −.85* 1.0
FCM LC .81* .76* −.09 .28 −.20 .47 1.0
FMC LE .85* .80* −.17 .48 −.36 .54* .83* 1.0
CPIB .31 .52* −.54* .32 −.18 .57* .50* .39 1.0
Spearman's correlations of clinical data at the first visit, as published in the study of Utianski et al. (2020)
MoCA 1.0
WAB-AQ .78* 1.0
ASRS-3 −.06 −.03 1.0
MSD Sev .15 .20 −.88* 1.0
AES −.35 −.38 .71* −.68* 1.0
FCM MS .26 .36 −.81* .91* −.68* 1.0
FCM LC .75* .80* −.27 .32 −.46* .44* 1.0
FMC LE .71* .91* −.03 .16 −.38 .33 .71* 1.0
CPIB .30 .37 −.31 .48* −.30 .53* .33 .40* 1.0
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Note. MoCA = Montréal Cognitive Assessment; WAB-AQ = Western Aphasia Battery–Aphasia Quotient; ASRS-3 = Apraxia of Speech Rating Scale, Version 3; MSD Sev = motor speech disorder severity rating; AES = articulatory error score; FCM = Functional Communication Measure; MS = Motor Speech; LC = Language Comprehension; LE = Language Expression; CPIB = Communicative Participation Item Bank.

*

p < .05.

When comparing the correlations at each visit between the CPIB and other measures, several changes are evident. In the first visit, the CPIB correlated with the MSD severity and ASHA FCM Motor Speech and Language Expression ratings but not with the clinical assessment measures (WAB-AQ or ASRS-3 score; Utianski et al., 2020). At the second visit, the CPIB had moderate, significant correlations with the WAB-AQ (ρ = .52), the ASRS-3 (ρ = −.54), and the ASHA FCM Motor Speech (ρ = .57) and Language Comprehension (ρ = .50) ratings. The correlation between the CPIB and the ASHA FCM Language Expression failed to reach significance at this visit (likely because of the smaller number of patients), but the magnitude of the correlation did not change.

The correlations among difference scores of these measures are reported in Table 3. The CPIB had moderate, significant correlations with the ASRS-3 score (ρ = −.51) and the ASHA FCM in Language Comprehension (ρ = .55; see Figure 3).

Table 3.

Spearman's correlations of clinical data difference scores (Visit 2 − Visit 1).

Measure MoCA WAB-AQ ASRS-3 MSD Sev AES FCM MS FCM LC FMC LE CPIB
MoCA 1.0
WAB-AQ .22 1.0
ASRS-3 .07 −.47 1.0
MSD Sev .50* .51 −.15 1.0
AES .40 .13 −.27 .03 1.0
FCM MS .23 .60* −.46 .59* −.31 1.0
FCM LC .35 .55* −.50* .58* −.07 .43 1.0
FMC LE .66* .63* .08 .65* −.11 .51* .39 1.0
CPIB −.12 −.07 −.51* .13 −.14 .23 .55* −.22 1.0
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Note. MoCA = Montréal Cognitive Assessment; WAB-AQ = Western Aphasia Battery–Aphasia Quotient; ASRS-3 = Apraxia of Speech Rating Scale, Version 3; MSD Sev = motor speech disorder severity rating; AES = articulatory error score; FCM = Functional Communication Measure; MS = Motor Speech; LC = Language Comprehension; LE = Language Expression; CPIB = Communicative Participation Item Bank.

*

p < .05.

Figure 3.

Figure 3.

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Scatter plot of difference scores (Visit 2 − Visit 1) for the CPIB against the ASHA FCM LC ratings and ASRS-3 total score (the clinical data with significant Spearman's correlations; see Table 3 for details). Shading reflects a 95% confidence interval. CPIB = Communicative Participation Item Bank; ASRS-3 = Apraxia of Speech Rating Scale, Version 3; ASHA FCM = American Speech-Language-Hearing Association's Functional Communication Measure; LC = Language Comprehension.

Discussion

This study described the changes in communication functioning and associated limitations experienced by patients with progressive AOS over a 1-year period via ratings made by the patient (CPIB) and examining SLP (MSD severity rating and ASHA FCMs). Additional clinical measures were examined, including the WAB-AQ, the ASRS-3 score, the MoCA, and the AES. Correlations among these measures were also calculated.

Data analysis revealed statistically significant differences in AOS and aphasia severity, but not dysarthria severity, between visits. AOS subtype classification changed for one patient, most likely reflecting increased severity of AOS. Given the relatively small sample size, there is insufficient power to conjecture about how changes in AOS, aphasia, and dysarthria, as separate entities, might have influenced changes, or lack thereof, in communication participation over time. Regarding AOS subtypes, past research suggests that patients with phonetic-predominant AOS show faster rates of decline in aphasia and AOS severity, while patients with prosodic-predominant AOS show faster rates of decline in parkinsonism (Whitwell, Weigand, et al., 2017); the influence of these differences warrants exploration in future studies.

The formal clinical measures indexed additional changes in speech and language functioning. There were significant changes in ASRS-3 scores, AES, WAB-AQ, MoCA, FBI, and all ASHA FCMs between visits, but not the CPIB. As shown in Figures 1 and 2, most patients declined as expected (scores increasing or decreasing depending on the scale) or remained stable. For three individuals, there is the appearance of improvement on the ASRS phonetic subscore (scores changed from 14 to 12, from 12 to 8, and from 6 to 4, with similar changes in the prosodic score for two patients and total score for all three patients; see Figure 1). However, these small differences may be within the margin of day-to-day, test–retest, and/or intrajudge variability. It is also possibly reflective of the benefit of speech therapy, as all three of these patients reported participating in formal intervention. Speech therapy was not provided by the authors, nor explicitly monitored, but patients were asked about ongoing intervention regimens. Of 17 patients, six patients reported attending formal speech therapy (frequency ranging from twice per month to 3 times weekly) during the study interval. An additional three patients reported trialing speech therapy prior to the study interval but discontinuing due to patient preference and/or SLP recommendation. Two additional patients reported reading aloud regularly, but without any formal intervention. The remaining six patients did not participate in formal or informal speech therapy. It is unclear how participating in ongoing treatment and the associated motivation to do so may have impacted results. Furthermore, there were statistically significant changes (i.e., deterioration) noted on the FBI, which indexes changes in behavior and personality. It is unknown how these changes (e.g., apathy, irritability, and impulsivity) possibly influenced communicative participation, although a recent study suggests they might (Jin et al., 2021).

While the rate of change on the communication measures (ASHA FCMs and MSD severity rating) differed for individual patients, there were consistent declines across all patients. The heterogeneity of the associated patient-based experience is apparent when looking at the individual data of the CPIB (see Figure 2).

While there have not been other studies of changes in participation in PPAOS or PPA, we can look to other longitudinal studies of communication disorders to provide context for these findings. Similar to the findings presented here, one study of patients with multiple sclerosis demonstrated little change in participation, per the CPIB, over 2 years (Baylor et al., 2012); one caveat is that the study explored multiple sclerosis more broadly and not all patients had dysarthria; therefore, communication was not expected to be primarily impacted.

Other studies have examined changes in communication limitations relative to treatment. For instance, Bryans et al. (2021) showed that the CPIB was sensitive to improvements in functioning after intensive loudness therapy for patients with dysarthria associated with Parkinson's disease. Bislick (2020) showed mixed results in a study of treatment for stroke-related AOS in two patients, with one showing decline in participation following treatment and another showing stable participation, per the CPIB. Another study demonstrated that the CPIB was sensitive to positive changes experienced by patients with spasmodic dysphonia after Botox treatment (Yiu et al., 2020), although another study showed no difference in participation following Botox injections (Engelhoven et al., 2020). Preliminary results from a retrospective study of patients with hearing loss suggested the CPIB may be sensitive to changes in participation relative to hearing loss treatment (Miller et al., 2017). For patients with progressive disorders, absence of or slowing of decline may be considered a positive treatment effect, but it remains important to demonstrate this in controlled studies of patients who do and do not receive therapy.

In the first-visit study (Utianski et al., 2020), we reported the relationships among clinical and participation measures. While some relationships were strong (namely, among those that offered concurrent validity of measures of motor speech functioning), the analyses overall suggested that measures of impairment severity do not clearly correlate with measures of participation restrictions. Given that only some of the participation measures changed over time, reexamining the correlations at the second visit allowed us to evaluate whether the relationships among variables also changed. It was hypothesized that if all measures changed in a linear way and to the same degree, the original relationships would be maintained at similar magnitudes. However, at the group level, all measures except the CPIB changed over time, suggesting this is not the case. It is therefore not surprising that the significance of correlations changed more for the CPIB than any other variable. While some differences may be attributable to difference in sample size between visits, an alternative explanation is that there is a threshold of impairment severity that begins to strongly influence participation, but this relationship is unlikely linear. This is akin to findings for patients with ALS who, as their dysarthria worsens, maintain good intelligibility until their impairment reaches a level that speech intelligibility becomes notably reduced (Rong et al., 2016). Further longitudinal study should explore the course of change in individual variables and relationships among them. This longitudinal information could have substantial value for patient counseling about the point at which their impairment might be expected to change their current communication participation.

With particular attention to the correlation of difference scores, the data support the notion that the relationships among clinical assessments, measures of impairment, and associated reductions in participation are complex. Changes in clinical measures (i.e., severity of AOS and auditory comprehension deficits) are correlated with changes in participation restrictions (as indexed by the CPIB), even though at the group level, the CPIB scores did not significantly change over a 1-year interval. The latter is likely attributable to the individual variability in how patients respond to their disease and/or how it affects their life participation. Despite this individual variability, patients with the greatest declines in AOS severity (ASRS-3 total score) and auditory comprehension (ASHA FCM in Language Comprehension) also showed greater participation restrictions (CPIB; see Figure 3). It is of interest to identify the strongest predictors of declining communication measures (e.g., conduct regression analyses) to subsequently estimate the expected experience of individual patients across disease progression.

The growing corpus of research, including this study, supports the use of patient-reported outcome measures because they may better reflect the patient experience and practical benefits of treatment. This is particularly critical for degenerative diseases when other measures might simply show progression of the disorder.

Limitations and Future Directions

There are limitations to this study. While the sample size is large for this relatively rare disorder, the sample size did not permit stratification of the sample into subgroups for statistical analyses (e.g., dysarthria status and AOS subtype). Additional time points over longer intervals will allow for further insight into the trajectory of changes over time. Furthermore, given the small sample size, there was no statistical correction imposed for multiple comparisons for the tests of differences between visits; this was supplemented by visualization of the data, but it will be important to determine if the relationships hold in future, larger studies. Correlation analyses were replicated to allow for comparison of relationships among variables over time; in the future, higher level statistical modeling should be considered. Additionally, assistance provided from caregivers to complete the CPIB was not monitored; this should be addressed in future studies, especially as patients may require increased support or guidance to respond as symptoms progress. It is possible that the lack of change and heterogeneity in the CPIB reflects a “floor” effect, but the visualization of the data and changes in some scores, for example, from 0 to 10, suggests this does not fully account for the finding. Finally, it is important to recognize that, with all its strengths, the CPIB is an unmonitored, subjective tool and, as such, carries inherent measurement variability. Patient-reported outcomes, such as the CPIB, may be influenced not only by external features (e.g., speech therapy) but also by an individual's mood at the time of completion or neuropsychiatric state in general (i.e., parameters indexed by the FBI and the NPI-Q) or by the impression or influence of the person who might be helping to complete it.

Moving forward, it is worthwhile to more systematically examine factors such as mood/depressive symptoms, as well as ongoing speech-language treatment, to explore their impact on communication participation to then direct efforts to minimize or leverage them, as appropriate. The impact of timing of introduction and use of augmentative and alternative means of communication should also be considered. Of particular interest is exploring other measures of intelligibility (beyond the MSD severity rating, which is, in some ways, an index of intelligibility), which could serve as an intermediary metric between clinician ratings and FCMs. Other factors such as social support and cognitive challenges have previously been highlighted as contributors to participation restrictions (Baylor et al., 2012), as have differences related to age and even country of origin (McAuliffe et al., 2017). While outside the scope of this study, specific CPIB item analyses may offer insight to the contexts that may be differentially impacted. Exploration of other patient-reported outcome measures is warranted, including direct comparison to the CPIB given the requisite language skills and the possible “noisiness” of the data that may have influenced the results of this study.

Conclusions

This is the first study to detail changes in patient- and examiner-judged communication limitations in patients with progressive AOS. Overall, there was progression of disease-related impairment, supported by statistically significant differences in AOS and aphasia severity, clinical assessments (ASRS-3, AES, WAB-AQ, and MoCA), and all ASHA FCMs between visits. Changes in participation restrictions were more heterogeneous, reflected in lack of group-level change in the CPIB. Despite this variability in change on the CPIB, patients with the greatest declines in AOS severity and auditory comprehension also showed greater changes in participation restrictions. The findings support the use of patient-reported outcome measures as they may better reflect the totality of the patient experience and associated changes in day-to-day functioning when other measures may simply index the progression of the disease. However, given that patient-reported outcome measures may be influenced by numerous negative and positive factors (e.g., progression of the primary impairment; emergence of aphasic, neuropsychiatric, behavioral, and other cognitive deficits; psychosocial changes; and speech therapy), further research is necessary to identify the most relevant variables and their relative contributions to the patient experience regarding communication participation.

Supplementary Material

Supplemental Material S1. Individual scores on language and speech measures. Point at 0 years indicates performance at the first visit; individual data point for second visit is placed at interval of second visit. AOS subtype is indicated by colored dots; lines are color coded to diagnosis at the first visit. The medians of each group are presented in the thick, overlaid line. WABAQ = Western Aphasia Battery-Revised Aphasia Quotient; ASRS-3 = Apraxia of Speech Rating Scale - Version 3.
Click here for additional data file. (669.4KB, jpg)
Supplemental Material S2. Individual scores on communication measures. Point at 0 years indicates performance at the first visit; individual data point for second visit is placed at interval of second visit. AOS subtype is indicated by colored dots; lines are color coded to diagnosis at the first visit. The medians of each group are presented in the thick, overlaid line. CPIB = raw score on Communicative Participation Item Bank short form; MSD = Motor Speech Disorder; FCM = Functional Communication Measure.
Click here for additional data file. (800.7KB, jpg)

Acknowledgments

We extend our gratitude to these patients and their families for their time and dedication to our research program. This study was funded by National Institute on Deafness and Other Communication Disorders Grants R01 DC014942 Principal Investigator [PI]: K. A. Josephs) and R01 DC012519 (PI: J. L. Whitwell). The first author extends appreciation to the writing group “The Write Stuff” for providing a regularly scheduled, dedicated, and encouraging writing environment.

Funding Statement

We extend our gratitude to these patients and their families for their time and dedication to our research program. This study was funded by National Institute on Deafness and Other Communication Disorders Grants R01 DC014942 Principal Investigator [PI]: K. A. Josephs) and R01 DC012519 (PI: J. L. Whitwell).

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplemental Material S1. Individual scores on language and speech measures. Point at 0 years indicates performance at the first visit; individual data point for second visit is placed at interval of second visit. AOS subtype is indicated by colored dots; lines are color coded to diagnosis at the first visit. The medians of each group are presented in the thick, overlaid line. WABAQ = Western Aphasia Battery-Revised Aphasia Quotient; ASRS-3 = Apraxia of Speech Rating Scale - Version 3.
Click here for additional data file. (669.4KB, jpg)
Supplemental Material S2. Individual scores on communication measures. Point at 0 years indicates performance at the first visit; individual data point for second visit is placed at interval of second visit. AOS subtype is indicated by colored dots; lines are color coded to diagnosis at the first visit. The medians of each group are presented in the thick, overlaid line. CPIB = raw score on Communicative Participation Item Bank short form; MSD = Motor Speech Disorder; FCM = Functional Communication Measure.
Click here for additional data file. (800.7KB, jpg)

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