Overview
We explored aphasia recovery after stroke using eligible data from across the database, as relevant for each analysis. We investigated:
- the natural history of language recovery in participants with no access to SLT
- language recovery over time in participants with access to SLT
- distribution of language scores at study entry
- change in scores from baseline to first follow-up after study access to SLT.
Natural history of language recovery
To meet the criteria for the natural history population, participants had to be enrolled in the primary study within 15 days of their first stroke and allocated to a no-SLT group. For these participants, only one data set reported IPD on overall language ability (n = 61), auditory comprehension (n = 6), naming (n = 6) or functional communication (observer-rated activity and participation, both n = 51), respectively. As we had prespecified that we would not base an analysis on a single data set, there were insufficient data to ascertain the natural history of language recovery in relation to these domains for this population. For the remaining domains (other spoken language, reading comprehension and writing), we identified no eligible IPD for exploring natural history of language recovery.
Language recovery over time in participants with study access to speech and language therapy
We examined the pattern of language recovery over time in each language domain for participants who had access to SLT during the primary study. We also examined language recovery among participants who were allocated to receive no SLT during the primary study. These participants were not considered in our natural history analysis as they were enrolled beyond 15 days of index stroke, and we had clear evidence or reasonable grounds to assume that they had historical access to SLT as part of standard health care before the start of the study. When participants were allocated to receive no therapy intervention in the primary study but were permitted access to SLT after the active comparison period had been completed, we truncated our analysis of follow-up to the first assessment following the study intervention period, thus excluding any impact of later access to SLT in this group.
Trajectory of overall language ability over time
We examined the trajectory of overall language ability over time by looking at scores on aphasia test batteries transformed to the anchor measure [Western Aphasia Battery-Aphasia Quotient (WAB-AQ)], in which higher scores indicated better language performance. We had no data capturing overall language ability over time for participants who had received only historical SLT in the RCT population, meaning we could not conduct comparative analyses with the participants who had SLT during the primary studies on this population. We therefore present the trajectory of overall language ability scores over time for participants allocated to SLT in RCTs (601 IPD; 18 RCTs; Figure 4a) and across all study designs (2345 IPD; 74 data sets; see Figure 4b). In both cohorts, there was a trend towards increased scores on aphasia language batteries over time.
FIGURE 4 Overall language ability scores over time. (a) RCTs; and (b) all study types. (Figure not reproduced here; see the original article.)
Trajectory of auditory comprehension over time
In our database, all participants who were allocated to receive no study-based SLT went on to receive SLT after the study intervention period was over. Due to inadequate longer-term follow-up assessments beyond the study intervention period, we could not describe the trajectory of auditory comprehension scores over longer time periods in those allocated to SLT versus those who received only historical SLT. We examined the trajectory of auditory comprehension scores over time in both the RCT population (536 IPD; 17 data sets; Figure 5a) and using all study designs (2463 IPD; 62 data sets; see Figure 5b). The anchor measure was Token Test from the Aachen Aphasia Test (TT-AAT).
FIGURE 5 Auditory comprehension scores over time. (a) RCTs; (b) all study types; (c) within earlier follow-up times in RCTs; and (d) earlier follow-up times in all study types. (Figure not reproduced here; see the original article.)
Of 536 IPD from 17 RCTs, 521 IPD (17/17 RCTs) were allocated to receive a SLT intervention, whereas 15 IPD (2/17 RCTs) received historical SLT only (see Figure 5a). Those with historical SLT experienced a decline in their auditory comprehension scores over time. In contrast, those who had study access to SLT experienced an increase in auditory comprehension scores over time. We examined this trajectory more closely by plotting follow-up between the two groups up to 90 days (see Figure 5c).
Despite randomisation, we observed slightly higher initial auditory comprehension scores at baseline in the historical SLT group; this declined over time. Across all primary research study designs (2463 IPD; 62 data sets; see Figure 5b), participants allocated to receive SLT demonstrated an increase in auditory comprehension scores over time. Data from participants who received only historical SLT in this population were available at only three time points and were therefore too sparse to make strong inferences (see Figure 5d).
Trajectory of naming over time
We transformed all naming scores to the Boston Naming Test (BNT) distribution. There were inadequate naming data at follow-up time points immediately after study intervention comparison periods from historical SLT participants in the primary studies (29 IPD; 3 RCTs). We therefore could not compare the trajectory of naming scores over longer follow-up time periods between participants with study access to SLT and participants with historical access to SLT in the RCT population. Instead, we present the trajectory of naming scores over shorter follow-up times (up to 90 days) for participants in RCTs (623 IPD; 22 RCTs; Figure 6a) and across all study designs (2592 IPD; 68 data sets; see Figure 6b).
FIGURE 6 Naming scores over time. (a) RCTs; (b) all study types; and (c) within earlier follow-up times in RCTs. (Figure not reproduced here; see the original article.)
Historical SLT participants had higher naming scores at baseline than those allocated to receive SLT. Naming scores appeared to decline over time for the historical SLT participants, whereas scores for the SLT group experienced a steady upwards trajectory over time (see Figure 6a–c). Across all study types, there were limited data on naming scores among the historical SLT participants. For those who had study SLT access, naming scores increased with time (2592 IPD; 68 data sets; see Figure 6b).
Trajectory of other spoken language over time
There were no data available on other spoken-language outcomes for participants who received only historical SLT in RCTs. This meant that we could not describe the trajectory of spoken-language scores among this group or make any comparison with the trajectory of spoken-language scores over time among participants allocated to study SLT. We therefore present the trajectory of spoken-language scores over time [transformed to the verbal (1) subtest of the Porch Index of Communicative Ability (PICA)] for participants allocated to SLT in a RCT (172 IPD; 3 RCTs; Figure 7a) and across all study types (353 IPD; 8 data sets; see Figure 7b). The trajectory appeared to be stable over time in both populations.
FIGURE 7 Other spoke language scores over time. (a) RCTs; and (b) all study types. (Figure not reproduced here; see the original article.)
Trajectory of reading comprehension over time
We reviewed the transformed reading comprehension scores [transformed to fit the range of the Comprehensive Aphasia Test (CAT) reading subtest] for historical SLT participants and for those who had access to SLT in the primary studies. All historical SLT participants were permitted access to conventional SLT beyond the active intervention comparison period. Reading comprehension data beyond the immediate study intervention periods were inadequate for comparative meta-analysis. The stable trajectory of available reading comprehension scores over time among participants who had SLT across all primary studies is presented in Figure 8 (650 IPD; 9 data sets).
FIGURE 8 Reading comprehension scores over time for all study types. (Figure not reproduced here; see the original article.)
Trajectory of writing over time
Participants with available writing scores who received only historical SLT during the primary studies were typically given access to SLT immediately after the study intervention comparison period. Thus, writing data from later follow-up time points were insufficient to permit comparative meta-analysis by SLT status over time. We report writing data from SLT participants only. Data from three RCTs (41 IPD; Figure 9a) suggest a slight score decline across time. Across all study types (635 IPD; 10 data sets; see Figure 9b), following transformation to the anchor score (CAT writing subtest), we observed stable writing scores over time.
FIGURE 9 Writing scores over time. (a) RCTs; and (b) all study types. (Figure not reproduced here; see the original article.)
Trajectory of observer-rated functional communication (activity) over time
For functional communication (activity) over time, we examined 828 IPD from 17 RCTs (Figure 10a). The anchor measure for functional communication domain (activity) was the Aachen Aphasia Test-Spontaneous Speech Communication (AAT-SSC). There were inadequate data on participants who received only historical SLT, which did not permit comparison of trajectories with the SLT group; once again, there were few after-intervention data points and people who received only historical SLT during the study were all permitted to receive SLT after the intervention period was complete. In the SLT group, we observed better observer-rated activity scores over time. This was also evident when looking at all study types (1272 IPD; 28 data sets; see Figure 10b). Data on observer-rated participation measures showed the same patterns for better participation scores over time (see Report Supplementary Material 3, figure 1).
FIGURE 10 Observer-rated activity scores over time. (a) RCTs; and (b) all study types. (Figure not reproduced here; see the original article.)
Trajectory of self-rated functional communication (activity) over time
Data were available on self-rated activity scores for 11 IPD (one RCT), and for 43 IPD (two data sets of all study types). The anchor measure for self-rated activity scores was the Assessment for Living with Aphasia (ALA). We observed an increase in self-rated activity scores with time (Figure 11) when using all study designs. Similar observations were seen for self-rated participation scores (see Report Supplementary Material 3, figure 2).
FIGURE 11 Self-rated activities over time in all study types. (Figure not reproduced here; see the original article.)
Distribution of language scores at study entry
We examined the distribution of participants’ language scores for each domain, as measured at study entry. We selected this time point to mitigate any treatment effect due to access to study SLT. Scores gathered using minority measures were transformed to match the distribution of the relevant anchor measure for that language domain. We considered the distribution of language scores across all study entry time points (days since the index stroke for that study), first for RCT data sets, and then across all study designs. When data permitted, we also considered the distribution of scores within what collaborators agreed were clinically applicable time periods for typical enrolment in aphasia studies (0–1000 days since the index stroke).
Overall language ability at study entry
Following transformation of overall language ability scores from minority measures to match the range of the WAB-AQ (anchor measure), we plotted language ability scores at study entry for RCT participants (700 IPD; 19 RCTs), and for all participants across all study designs for which overall language ability data were available (2571 IPD; 78 data sets).
Regression analyses based on data from the RCT population revealed that time since stroke at baseline (in months) was positively associated with better overall language ability (OR 1.010, 95% CI 1.006 to 1.014; p < 0.0001) (see Report Supplementary Material 3, figure 3). We observed similar overall increasing language ability with increasing time since stroke among all participants across all study designs (OR 1.003, 95% CI 1.002 to 1.005; p < 0.0001) (see Report Supplementary Material 3, figure 3).
When examining the distribution of overall language ability scores within more clinically applicable study enrolment time frames since index stroke (0–1000 days; 1780 IPD; 78 data sets), we observed a similar trend towards greater overall language ability with increasing time (in months) since stroke at baseline (OR 1.026, 95% CI 1.017 to 1.035; p < 0.0001). A 1-year increase in time from stroke to study enrolment was associated with an improvement in overall language ability scores (OR 1.36, 95% CI 1.22 to 1.51; p < 0.0001).
Spontaneous recovery (overall language ability)
A further breakdown of overall language ability scores for study entry at 0–15, 15–30, 30–90, 90–180, 180–365 and 365–1095 days can be found in Report Supplementary Material 3; figures 4 (RCTs) and 5 (all study types). Spontaneous recovery within this domain could be most readily examined by looking at study entry between 0 and 90 days post index stroke, in adjunct with natural history data (which were not available). Examination of the distribution of overall language ability scores at study entry within this time period revealed relatively stable distributions as time increased from 0 to 30 days (45–50 points on the WAB-AQ). Scores appeared to plateau beyond 3–6 months (scores of between 60 and 70); however, this appears to be confounded by sparse data in this time period (see Report Supplementary Material 3, figures 4 and 5). Data should also be interpreted with caution, as scores at study entry (particularly beyond 15 days of index stroke) did not account for SLT exposure prior to study entry.
Auditory comprehension at study entry
Auditory comprehension scores were transformed to fit the range of the anchor measure (the TT-AAT). We plotted these transformed scores at study entry for the RCT population (633 IPD; 19 RCTs; see Report Supplementary Material 3, figure 6) and across all study designs (2597 IPD; 67 data sets; see Report Supplementary Material 3, figure 6).
In the RCT population, auditory comprehension scores appeared to be stable with increased time to study entry. We examined whether or not the slope of the regression line was influenced by the small number of baseline data from later time points by examining the distribution within a more clinically applicable enrolment period of up to 1000 days since stroke in RCTs (506 IPD; 19 data sets; see Report Supplementary Material 3, figure 6). We observed a stable trend in auditory comprehension scores as time since stroke increased (see Report Supplementary Material 3, figure 6). This association was not significant when all baseline time to inclusion was considered (OR 1.001, 95% CI 0.996 to 1.005; p = 0.7312) nor when time to inclusion was limited to 1000 days after stroke (OR 0.999, 95% CI 0.980 to 1.019; p = 0.9571).
We then examined the distribution of auditory comprehension scores at increasing time to enrolment in all study types (see Report Supplementary Material 3, figure 6). In contrast to the RCT data set, we observed a slight increase in auditory comprehension scores at baseline with increasing time since stroke (2597 IPD; 67 data sets; see Report Supplementary Material 3, figure 6). Regression analysis showed no significant association between time to enrolment (in months) and auditory comprehension at baseline (OR 1.001, 95% CI 0.999 to 1.002; p = 0.3763). We examined the distribution of baseline auditory comprehension scores further, looking at clinically applicable enrolment periods of 0–1000 days since stroke for all study types (1879 IPD; 66 data sets; see Report Supplementary Material 3, figure 6). There was no association between time since stroke at baseline (months) and auditory comprehension scores for the 0–1000 days since stroke (OR 1.008, 95% CI 0.999 to 1.017; p = 0.0863).
Spontaneous recovery (auditory comprehension)
A further breakdown of auditory comprehension scores for study entry at 0–15, 15–30, 30–90, 90–180, 180–365 and 365–1095 days can be found in Report Supplementary Material 3, figures 7 (RCTs) and 8 (all study types). Spontaneous recovery within this domain could be most readily examined by looking at study entry between 0 and 90 days post index stroke, in adjunct with natural history data (which were not available). Examination of the distribution of auditory comprehension scores at study entry within this time period (i.e. 0–90 days post index stroke) revealed higher scores between days 1 and 15 (ranging between 27 and 28 points on the TT-AAT), and diminishing with time up to 3 months (ranging between 15 and 18 points on the TT between 1 and 3 months). However, this observation appears to be confounded by sparse data within this time period (see Report Supplementary Material 3, figure 7) and the fact that data did not account for SLT exposure prior to study entry, particularly for enrolment beyond 15 days of stroke.
Naming scores at study entry
We described the distribution of naming scores at study entry in RCTs (748 IPD; 25 RCTs; see Report Supplementary Material 3, figure 9) and all study designs (2760 IPD; 72 data sets; see Report Supplementary Material 3, figure 9). In the RCT population, naming scores appeared to be stable with increasing time from stroke to study entry (OR 1.00, 95% CI 0.996 to 1.003; p = 0.95). In contrast, for all study designs, an increase in baseline time (in months) was associated with increased naming scores (OR 1.005, 95% CI 1.004 to 1.007; p < 0.0001). A similar trend towards better naming scores with increased time from stroke to study enrolment (months) was observed within a clinically applicable period of 0–1000 days (1836 IPD; 71 data sets; see Report Supplementary Material 3, figures 9–11) (OR 1.031, 95% CI 1.022 to 1.040; p ≤ 0.0001).
Spontaneous recovery (naming)
A further breakdown of naming scores for study entry at 0–15, 15–30, 30–90, 90–180, 180–365 and 365–1095 days can be found in Report Supplementary Material 3, figures 10 (RCTs) and 11 (all study types). Spontaneous recovery within this domain could be most readily examined by looking at study entry between 0 and 90 days post index stroke, in adjunct with natural history data (which were not available). Examination of the distribution of naming scores at study entry within this time period (i.e. 0–90 days post index stroke) revealed higher scores between days 1 and 15 (ranging between 10 and 22 points on the BNT), and diminishing with time after 3 months (ranging between 7 and 12 points on the BNT between 1 and 3 months). However, this observation appears to be confounded by sparse data within this time period (see Report Supplementary Material 3, figures 10 and 11) and the fact that data did not account for SLT exposure prior to study entry.
Other spoken language at study entry
We described the distribution of other spoken-language scores at study entry for participants who were enrolled in a RCT (163 IPD; 2 RCTs; see Report Supplementary Material 3, figure 12) and across all study designs (344 IPD; 7 data sets; see Report Supplementary Material 3, figure 12). We observed relatively stable spoken-language scores among the RCT population as study entry time increased (OR 0.999, 95% CI 0.992 to 1.005; p = 0.69). There appeared to be relatively stable spoken-language scores with increasing time to study enrolment among participants from all study types (OR 1.002, 95% CI 0.998 to 1.007; p = 0.26) (see Report Supplementary Material 3, figure 12). Similar patterns were observed when examining a clinically applicable study enrolment period (0–1000 days; see Report Supplementary Material 3, figure 12).
Reading comprehension at study entry
We plotted the distribution of reading comprehension scores at study entry. These scores were transformed to fit the range of the CAT reading comprehension subtest. Data from the RCT population were available for only 11 IPD from one RCT, and therefore did not meet our prerequisites for analysis. We examined data at study entry from all study types (652 IPD; 9 data sets; see Report Supplementary Material 3, figure 13). We observed stable reading scores over time from stroke to study enrolment (OR 1.001, 95% CI 0.999 to 1.003; p = 0.46). We examined the distribution of scores during a more clinically applicable time span of 0–1000 days (see Report Supplementary Material 3, figure 13). We observed similarly stable reading comprehension scores among participants recruited later after stroke onset (OR 0.996, 95% CI 0.978 to 1.014; p = 0.68).
Writing at study entry
Randomised controlled trial data on writing scores at study entry were available for only 11 IPD from one RCT, and were therefore not taken forward for further analysis. Data on 673 IPD (11 data sets; see Report Supplementary Material 3, figure 14) were available across all study types. Writing scores appeared to increase slightly with increasing time to study enrolment, but this was not significant (OR 1.000, 95% CI 0.998 to 1.002; p = 0.96), nor was it significant within a more clinically applicable period of 0–1000 days (421 IPD; 11 data sets; see Report Supplementary Material 3, figure 14) (OR 1.003, 95% CI 0.986 to 1.021; p = 0.71).
Observer-rated functional communication (activity) at study entry
Data on observer-rated functional communication (activity) were converted to match the range of the AAT-SSC domain. Data were available for 998 IPD from 18 RCTs. We observed stable activity scores with increasing time to inclusion in RCTs (see Report Supplementary Material 3, figure 15) (OR 0.999, 95% CI 0.994 to 1.003; p = 0.51). We observed increased activity scores with increasing time to enrolment in RCTs when examining a more clinically applicable time period (0–1000 days after stroke; see Report Supplementary Material 3, figure 15) (OR 1.021; 95% CI 1.001 to 1.042; p = 0.036).
Data were available on activity measures for 1437 IPD from 29 data sets across all study types (see Report Supplementary Material 3, figure 15). We observed relatively stable activity scores with increasing time from stroke to study enrolment (OR 1.0; 95% CI 0.997 to 1.003; p = 0.94). Within a clinically meaningful enrolment period (0–1000 days after stroke), we observed similarly stable scores with increasing time to study enrolment (OR 1.005, 95% CI 0.992 to 1.019; p = 0.46) (see Report Supplementary Material 3, figure 15).
Observer-rated participation data were derived from this data set and also demonstrated similar observations across RCTs and all study types (see Report Supplementary Material 3, figure 16). A further breakdown of language ability scores for study entry at 0–15, 15–30, 30–90, 90–180, 180–365 and 365–1095 days can be found in Report Supplementary Material 3, figure 17 (RCTs) and 18 (all study types).
Spontaneous recovery [observer-rated functional communication (activity)]
Spontaneous recovery within this domain could be most readily examined by looking at study entry between 0 and 90 days post index stroke, in adjunct with natural history data (which were not available). Examination of the distribution of observer-rated activity scores at study entry within this time period (i.e. 0–90 days post index stroke) revealed higher scores between days 1 and 30 (ranging between 1.5 and 2.5 points on the AAT-SSC), and stabilising with time after 3 months (ranging between 2 and 2.5 points on the AAT-SSC). However, this observation appears to be confounded by sparse data within this time period (see Report Supplementary Material 3, figures 16 and 17) and the fact that data did not account for SLT exposure prior to study entry.
Observed-rated functional communication (participation) at study entry
Observer-rated participation data were also derived from this data set and also demonstrated similar observations across RCTs and all study types (see Report Supplementary Material 3, figure 18).
Self-rated functional communication at baseline
Data were available for only 11 IPD from one RCT on self-rated activity and participation. Data were therefore examined from all study types (see Report Supplementary Material 3, figure 19). Across all baseline times to study inclusion, self-rated activity scores appeared stable (OR 1.004, 95% CI 0.993 to 1.014; p = 0.48). This was also apparent when examining a more clinically meaningful enrolment period of 0–1000 days (OR 0.991, 95% CI 0.914 to 1.075; p = 0.83). Data on self-rated participation were also generated from these IPD and showed similar distributions (see Report Supplementary Material 3, figure 20).
Language recovery: absolute proportion of change in language scores from baseline to first follow-up after access to speech and language therapy
We examined the median absolute proportion of change observed across each language domain from baseline to the first follow-up after SLT. Chapter 7 details dichotomised sensitivity analyses that take into account recovery in participants relative to their initial language impairment.
The absolute proportion of change was calculated independently from the transformed scores and the maximum possible score on the relevant anchor measure. Data were presented in absolute percentages, so as to compare recovery across each domain. We first considered data extracted from RCTs (Figure 12a) followed by data extracted across all study types, regardless of study design (see Figure 12b). Figures are presented as medians and IQRs.
FIGURE 12 Absolute proportion of change (median and IQR) in domain scores between baseline to first follow-up. (a) RCTS; and (b) all study types. (Figure not reproduced here; see the original article.)
We identified suitable data on measures of overall language ability (418 IPD; 11 RCTs), auditory comprehension (508 IPD; 17 RCTs), naming (346 IPD; 14 RCTs), other spoken language (155 IPD; 2 RCTs), reading (11 IPD; 1 RCT), writing (41 IPD; 3 RCTs) and functional communication (activity and participation) (608 IPD; 16 RCTs). For participants who had access to SLT in a RCT, we observed the greatest median percentage changes since baseline in observer-rated activity scores (10%) and overall language ability scores (8.4%), followed by auditory comprehension (8.0%).
We then considered the wider data set, inclusive of participants from all study designs. We identified suitable data on overall language ability (788 IPD; 21 data sets), auditory comprehension (921 IPD; 27 data sets), naming (646 IPD; 24 data sets), spoken language (204 IPD; 5 data sets), reading scores (145 IPD; 3 data sets), writing measures (208 IPD; 7 data sets) and functional communication (observer-rated activity: 802 IPD from 22 data sets; self-rated activity: 43 IPD from 2 datasets; see Figure 12). Participants allocated to SLT had the highest median percentage change since baseline in observer-rated functional communication activity scores (9.5%), followed by overall language ability (6.8%) and auditory comprehension (6%) (see Figure 12).
Change in domain scores stratified by time to enrolment
We explored the role that time since index stroke and study enrolment played on the proportion of recovery observed for each domain score. Time since stroke at inclusion in the primary data set was stratified into the following groupings:
- 0–1 month
- > 1–3 months
- > 3–6 months
- > 6 months following index stroke.
There were no participants in the no-SLT group (those who received only historical SLT) for whom values were available at the first follow-up period (in order to calculate change in language domain scores from baseline). Although data were available at later follow-up time points for this population, in the interim period SLT had been administered. This meant that there was no way to ascertain accurately the impact of no SLT on changes in language domain scores from baseline. Results are therefore presented for participants who had access to SLT, for RCTs (Figure 13) and across all study types (see Report Supplementary Material 3, figure 21). As the distribution of data within each domain were skewed, we presented data on the medians and IQRs for each time point.
FIGURE 13 Proportion of recovery (median and IQR) across all language domains, stratified by time to study entry across RCTs. (a) Overall language ability; (b) auditory comprehension; (c) naming; (d) other spoken language; (e) writing; (f) observer-rated activities; and (g) observer-rated participation. (Figure not reproduced here; see the original article.)
Recovery in the randomised controlled trial population
Overall language ability
In those enrolled within 1 month of stroke, the median change in overall language ability score was 16.7% (207 IPD; 10 data sets). This median change since baseline decreased for those enrolled between > 1 and 3 months of index stroke (median 9.5%; 48 IPD; 6 data sets), those enrolled between > 3 and 6 months of index stroke (median 5%; 20 IPD; 4 data sets) and those enrolled beyond 6 months of stroke (median 4.2%; 143 IPD; 4 data sets). The largest proportion of change in overall language ability scores was seen in those who were enrolled within 1 month of index stroke (see Figure 13a).
Auditory comprehension
For those enrolled within 1 month of stroke, the median change in auditory comprehension score was 12.4% (151 IPD; 10 data sets). This decreased to 8.8% for those who were enrolled between > 1 and 3 months of index stroke (69 IPD; 9 data sets), to 6% for those enrolled between > 3 and 6 months of stroke (69 IPD; 7 data sets) and to 4% for those enrolled after 6 months of index stroke (219 IPD; 9 data sets). The largest proportion of change in auditory comprehension scores was seen in those who were enrolled within 1 month of index stroke (see Figure 13b).
Naming
For those enrolled within 1 month of stroke, the median change in naming score was 16.7% (146 IPD; 8 data sets). For those enrolled between > 1 and 3 months of stroke, the median change was 1.5% (67 IPD; 8 data sets). For participants enrolled between > 3 and 6 months of stroke, the median change in naming score had decreased to 1.1% (71 IPD; 7 data sets); for those enrolled beyond 6 months of index stroke, the median change was 2.1% (62 IPD; 7 data sets). The largest changes in naming scores were seen in those enrolled within the first month of index stroke (see Figure 13c).
Other spoken language
There were inadequate data for a reliable description of median change in other spoken-language score within 1 month of stroke (4 IPD; 1 data set), between > 1 and 3 months of stroke (4 IPD; 1 data set) and between > 3 and 6 months of stroke (8 IPD; 1 data set). For those enrolled beyond 6 months of stroke, the median change was 3.1% (139 IPD; 2 data sets). These data should be interpreted with caution as the IPD at each time point were very small (see Figure 13d).
Reading comprehension
Data on changes in reading comprehension scores were not available for participants enrolled at 0–1 months, > 1–3 months or > 3–6 months after stroke. Data for those enrolled in a study > 6 months after index stroke could not be analysed as they did not meet our prespecified minimum data set requirement for analysis (11 IPD; 1 data set).
Writing
For those enrolled within 1 month of stroke, the median change in writing score was 6% (8 IPD; 2 data sets). For those enrolled between > 1 and 3 months of stroke, the median change was 8.1% (6 IPD; 2 data sets); for enrolment between > 3 and 6 months of stroke, this had decreased to 3.1% (11 IPD; 2 data sets), and in those enrolled beyond 6 months of stroke, the median change was 0% (16 IPD; 3 data sets). There were inadequate data for clinically meaningful analyses (see Figure 13e).
Observer-rated functional communication (activity)
Within an enrolment period of 0–1 months of the index stroke, the median percentage change in observer-rated functional communication (activity) was 18.9% (318 IPD; 9 data sets). At > 1–3 months of enrolment, it was 12.5% (78 IPD; 6 data sets); at > 3–6 months, it was 0% (63 IPD; 6 data sets); and by > 6 months, it was 0.2% (149 IPD; 8 data sets). The highest proportion of change was seen for earlier time points (see Figure 13f).
Observer-rated functional communication (participation)
There were 318 IPD from nine data sets on functional communication (participation) for study entry between 0 and 1 month after index stroke (median change 18.2%). The median change in participation at > 1–3 months was 12.5% (78 IPD; 6 data sets); at > 3–6 months, it was 0% (63 IPD; 6 data sets); and by > 6 months it was 0% (149 IPD; 8 data sets). The highest proportion of change was seen for earlier time points (see Figure 13g).
Self-rated functional communication
Data were available at only > 6 months for self-rated functional communication, thereby precluding any further analyses.
Recovery in all study types
Overall language ability
For those enrolled within 1 month of stroke, the median change in overall language ability score was 16.3% (389 IPD; 15 data sets). This median change since baseline decreased for those enrolled between > 1 and 3 months of index stroke (median 8.6%; 57 IPD; 9 data sets), for those enrolled between > 3 and 6 months of index stroke (median 1.5%; 30 IPD; 7 data sets) and for those enrolled beyond 6 months of stroke (median 2.2%; 312 IPD; 11 data sets). The largest proportion of change in overall language ability scores was seen in those enrolled within 1 month of index stroke (see Report Supplementary Material 3, figure 21).
Auditory comprehension
For those enrolled within 1 month of stroke, the median change in auditory comprehension score was 10% (339 IPD; 14 data sets); this similar to the change for those enrolled between > 1 and 3 months of index stroke (median 8.8%; 80 IPD; 11 data sets). The median change had decreased for those enrolled between > 3 and 6 months of stroke (median 4%; 82 IPD; 10 data sets) and for those enrolled beyond 6 months of stroke (median 2.7%; 420 IPD; 16 data sets). The largest proportion of change in auditory comprehension scores was seen in those enrolled within 1 month of index stroke (see Report Supplementary Material 3, figure 21).
Naming
For those enrolled within 1 month of stroke, the median change in naming score was 8.3% (198 IPD; 10 data sets). For those enrolled between > 1 and 3 months of stroke, the median change was 1.9% (77 IPD; 10 data sets); for participants enrolled between > 3 and 6 months of stroke, this decreased to 0.9% (84 IPD; 10 data sets). For those enrolled beyond 6 months of stroke, the median change in naming scores was 1.9% (287 IPD; 16 data sets). The largest changes in naming scores were seen in those enrolled within 1 month of index stroke (see Report Supplementary Material 3, figure 21).
Other spoken language
There were inadequate data for a reliable description of median change in other spoken-language score for those enrolled within 1 month of stroke (6 IPD; 2 data sets), and for those enrolled between > 1 and 3 months of stroke (7 IPD; 2 data sets). For those enrolled within between > 3 and 6 months of stroke, the median change was 1.9% (13 IPD; 2 data sets), and for those enrolled beyond 6 months of stroke, the median change was 2.4% (178 IPD; 5 data sets). Proportion of change in other spoken-language scores increased very slightly from > 3–6 months to beyond 6 months. However, these data should be interpreted with caution as the IPD available at each time point were very small (see Report Supplementary Material 3, figure 21).
Reading comprehension
Data on reading comprehension were not available for participants enrolled between 0 and 1 month of stroke; for those who were enrolled in a study between > 1–3 months and > 3–6 months of stroke, only six IPD were available. By > 6 months of index stroke, the median change in scores at final follow-up was 0% (133 IPD; 3 data sets).
Writing
For those enrolled within 1 month of stroke, the median change in writing score was 9.1 (10 IPD; 3 data sets). For those enrolled between > 1 and 3 months of stroke, the median change was 3.9% (13 IPD; 4 data sets); for those enrolled between > 3 and 6 months of stroke, this decreased to 2.1% (21 IPD; 4 data sets), and for those enrolled beyond 6 months of stroke, it was 0% (164 IPD; 7 data sets). Larger changes in writing scores were seen in those enrolled within 0–1 month after index stroke (see Report Supplementary Material 3, figure 21).
Observer-rated functional communication (activity)
Within an enrolment period of 0–1 month after the index stroke, the median percentage change for observer-rated functional communication (activity) was 16.2% (442 IPD; 11 data sets). The median change in activity for those enrolled within > 1–3 months of stroke was 12.5% (80 IPD; 7 data sets); for those enrolled within > 3–6 months, it was 0% (64 IPD; 7 data sets), and for those enrolled beyond 6 months, it was 1.1% (216 IPD; 12 data sets). The highest proportion of change was seen for earlier time points (see Report Supplementary Material 3, figure 21).
Observer-rated functional communication (participation)
There were 397 IPD from 10 data sets on observer-rated functional communication (participation) for study entry within 0–1 month after index stroke (median change 16.3%). The median change in activity for those enrolled between > 1 and 3 months of stroke was 12.5% (78 IPD; 6 data sets); for those enrolled between > 3 and 6 months, it was 0% (64 IPD; 7 data sets), and for those enrolled beyond 6 months, it was 0.6% (216 IPD; 12 data sets). The highest proportion of change was seen for earlier time points (see Report Supplementary Material 3, figure 21).
Self-rated functional communication
Data were available at only > 6 months for self-rated functional communication, thereby precluding any further analyses.
Summary
There were insufficient data with which to ascertain the natural history of language impairment progression following aphasia due to stroke. Many data sets in which participants were allocated to the no-SLT group (historical SLT only) were permitted to receive SLT following completion of the study intervention period. Coupled with sparse post-intervention assessment time points, this limited the data available for the natural history analyses.
Similarly, we could not compare the trajectory of language scores over time for historical SLT with that for SLT-treated populations. Data in the historical comparison group were either available at baseline only, did not have a corresponding post-intervention follow-up value or did not meet our minimum eligibility criteria for the analysis. For those who had access to SLT, we observed an improvement in scores over time. This was less pronounced for ‘other spoken-language production.’
Examining the scores for each language domain at study entry for all study types suggested better scores with increased time to study enrolment. However, these were only significant for overall language ability and naming.
The median proportion of change was selected to describe the change since baseline across all domains, as it was a more accurate reflection of the distribution of the skewed populations across each language domain. The greatest proportion of change was seen in the domains of observer-rated functional communication (10.0%) and overall language ability (8.4%), followed by auditory comprehension (8.0%), although the CIs were wide for each of these domains, and overlapped. For each of our analyses, similar results were observed whether examining the RCT population alone or all study types. The proportion of change in each domain score since baseline appeared to decrease with increasing time since index stroke. Although many of these differences since baseline did not appear to be significantly different across different domains (e.g. the 95% CIs overlapped), the proportions were notable from a clinical standpoint for some domains (e.g. 16.7% change on the WAB-AQ from baseline for overall language ability; 18.9% change in AAT-SSC for observer-rated activities), and were therefore presented.