- Journal List
- Prog Rehabil Med
- v.7; 2022
- PMC9470499
As a library, NLM provides access to scientific literature. Inclusion in an NLM database does not imply endorsem*nt of, or agreement with, the contents by NLM or the National Institutes of Health.
Learn more: PMC Disclaimer | PMC Copyright Notice
Prog Rehabil Med. 2022; 7: 20220046.
Published online 2022 Sep 9. doi:10.2490/prm.20220046
PMCID: PMC9470499
PMID: 36160026
Narumi Watanabe, OTR, MS,a,b Yohei Otaka, MD, PhD,a,c Masashi Kumagai, OTR, PhD,a,b Kunitsugu Kondo, MD, PhD,a and Eiji Shimizu, MD, PhDb
Author information Article notes Copyright and License information PMC Disclaimer
ABSTRACT
Objectives:
This study examined whether the reliability of the Nine Hole Peg Test (NHPT) isimproved by a modification (mNHPT) that confines the peg insertion/removal order to oneway to reduce the degree of freedom of spatial strategies.
Methods:
Participants performed the NHPT and mNHPT three times each in two sessions with aninterval of 3–5 days. Healthy adults used their non-dominant hand (n=40), while thosewith hemiparetic stroke used their affected (n=40) or unaffected hand (n=40). The meanvalue of three trials from each session was used for analyses. The reliabilities of theNHPT and mNHPT during the two sessions were assessed via intraclass correlationcoefficients (ICCs) and Bland–Altman analysis.
Results:
The ICCs of the NHPT and mNHPT were 0.49 and 0.66, respectively, in healthyparticipants, and 0.91 and 0.94, respectively, in participants with stroke, regardlessof the hand used. A significant fixed bias between the sessions was observed in bothtests, except for participants with stroke who used their affected hand. Proportionalbiases were noted in the mNHPT results of healthy participants and in the NHPT and mNHPTresults of participants with stroke who used their affected hand. The limits ofa*greement (lower, upper) in the affected hand were −11.0 and 9.5 for the NHPT and −8.0and 6.2 for the mNHPT.
Conclusions:
Reduced degrees of freedom in the spatial strategy improved the relative reliabilityand reduced measurement errors in the NHPT. However, fixed and proportional biases werestill evident.
Keywords: dexterity, fingers, motor skills, outcome assessment, validation study
INTRODUCTION
Finger dexterity is a unique characteristic of human beings and is essential foraccomplishing various tasks in daily life and occupations. Around 60% of patients withmiddle cerebral artery stroke reportedly have some residual impairment in finger dexterity 6months after the onset of the stroke.1) Decreased upper limb function is also reportedly associatedwith a decreased quality of life.2) The assessment of dexterity is necessary when planningrehabilitation and evaluating the efficacy of treatment in individuals with upper extremityimpairments. The Nine Hole Peg Test (NHPT) is widely used to assess finger dexterity inclinical settings because of its simplicity, low cost, and short time toadminister.3) It is one ofthe most frequently used upper limb outcome measures in stroke rehabilitationstudies.4) When a measure isused repeatedly over time in a clinical or research setting, test–retest reliability shouldbe considered. There are two types of test–retest reliability: relative reliability andabsolute reliability. Correlation coefficients and intraclass correlation coefficients(ICCs) are commonly used to examine relative reliability. Absolute reliability is examinedusing the Bland–Altman analysis,5) which systematically assesses biases and errors.
Relative reliability of the NHPT, measured using Pearson’s correlation coefficient, isreportedly relatively high for the right hand (r=0.69) and moderate for the left hand inhealthy adults (r=0.43).3) Therelative reliability of the NHPT in individuals with stroke, measured using ICC, isreportedly high for both the unaffected hand (ICC=0.89) and the affected hand(ICC=0.85).6) Regarding theabsolute reliability of the NHPT, different studies have reported the minimal detectablechange (MDC) percentage in the unaffected and affected hands in stroke patients as 23% and54%,6) and 12% and 24%,respectively,7) indicatingthat the measurement error may be large in some populations. Additionally, the time requiredto complete the NHPT has been shown to be decreased during the retest session compared tothe first session in healthy adults, indicating the existence of bias.3,7,8) Therefore, previous studies suggest that while the relativereliability of the NHPT is acceptable, the absolute reliability is poor in terms of errorsand bias.
The NHPT uses a square board with nine holes, arranged in a 3×3 square pattern, and ninepegs. The time required to place the pegs into the holes and to remove them from the holesusing a single arm is measured. The order of insertion and removal of the pegs is notspecified, and there are more than 360,000 ways to insert the pegs.9) Therefore, it is possible that thetime required to complete the NHPT is influenced by the order selected by the individual. Infact, the strategy of peg insertion has been reported to influence the performance ofhealthy adults and individuals with stroke.9) When different strategies for insertion and removal of thepegs are used in the test and retest sessions, measurement errors may increase. If a moreefficient spatial strategy is used in the retest session, it leads to a bias toward ashorter time to complete the test.
We hypothesized that the test–retest reliability of the NHPT would improve if a modifiedversion (mNHPT) was used with a specific order of insertion and removal of the pegs. Thepurposes of this study were to examine the relative and absolute reliability of the mNHPT inhealthy adults and individuals with hemiparetic stroke, and to compare them with those ofthe NHPT.
MATERIALS AND METHODS
Design and Setting
This study was a test–retest reliability study conducted in a convalescent rehabilitationhospital in Japan.
Participants
A total of 120 individuals participated in this study, including 40 healthy adults (mean[standard deviation, SD] age: 26.0 [2.0] years) and 80 patients with hemiparetic stroke(mean [SD] age: 66.0 [13.3] years). Patients with their first-ever hemiparetic stroke wererecruited from among those who were admitted to the convalescent rehabilitation ward viaconvenience sampling. The following inclusion criteria were used: patient experienced astroke at least 1 month prior to the start of the study; patient was able to sit withoutassistance; patient could understand the instructions for the tasks. The followingexclusion criteria were used: neurological diseases other than stroke; subarachnoidhemorrhage; lesions in the cerebellum; multiple brain lesions. Half the patients withhemiparetic stroke (n=40) performed the tasks with the affected hand (affected handgroup), while the other half (n=40) performed them with the unaffected hand (unaffectedhand group). Participants with hemiparetic stroke who could complete the task within 60seconds were allocated to the affected hand group. Participants with hemiparetic strokewho could not complete the task within 60 seconds were allocated to the unaffected handgroup. Healthy adults with pain and/or neuromuscular disorders in the upper extremities,cognitive deficits, or visual disturbances that affected the performance of the task wereexcluded. The sample size was calculated based on ICCs to ensure that the number ofparticipants in this study was sufficient, considering a statistical power of 80% and asignificance level α of 0.05. The sample size was calculated to be 36 (minimum acceptableICC, 0.85; expected ICC, 0.95; number of repetitions, 2; expected dropout rate, 30%) basedon the Sample Size Calculator (http://wnarifin.github.io) and methodology described by Walter etal.10)
Each participant performed the test with only one arm throughout the study becauseinter-limb skill transfer was reported in the NHPT.9) The healthy adults performed the tasks with theirnon-dominant hand. According to the Edinburgh handedness inventory,11) all but one of the healthyadults were right-handed (mean [SD] laterality quotient: 91.0 [31.9]). The characteristicsof the individuals with hemiparetic stroke, including the Fugl-Meyer Assessment12) and the modified Ashworthscale,13) are presentedin Table 1. This study was conducted inaccordance with the Declaration of Helsinki of 1964, as revised in 2013. The studyprotocol was approved by the Institutional Review Board of Tokyo Bay RehabilitationHospital (approval number 115-2). Written informed consent was obtained from allparticipants included in the study.
Table 1.
Participant characteristics
| Characteristic | Healthy adults (n=40) | Unaffected hand group (n=40) | Affected hand group (n=40) |
| Age, years | 26.0 (2.0) | 63.3 (14.9) | 68.7 (11.0) |
| Sex, female/male | 19/11 | 16/24 | 23/17 |
| Type of stroke, infarction/hemorrhage | - | 21/19 | 14/26 |
| Side of paresis, right/left | - | 19/21 | 26/14 |
| Time since stroke onset, days | - | 104.9 (43.6) | 72.1 (28.3) |
| Edinburgh Handedness Inventory | 91.0 (31.9) | 89.8 (42.0) | 95.7 (9.6) |
| Fugl–Meyer Assessment in the affected arm | - | 18.5 (4–39) | 61.5 (58–63) |
| Modified Ashworth scale in the affected arma | - | 1 (1–2) | 0 (0–0) |
Open in a separate window
Data are given as mean (SD), number, or median (interquartile range).
a 1+ was treated as 2 for the modified Ashworth scale. The scores foranalyses range from 0 to 5.
NHPT
The square board used in the NHPT has nine pegs and nine holes arranged in a 3×3 squarepattern, spaced 3.2 cm apart when measured center-to-center (Fig. 1A). Each hole is 1.3 cm deep and is drilled with a 0.71-cmdrill bit. The nine wooden pegs are 0.64 cm in diameter and 3.2 cm in length. Thecontainer was constructed using 0.7-cm plywood. The participants picked up the pegs andinserted them into a hole one by one using one arm until all of the holes were filled. Thepegs were then removed one by one and placed in a container. The participants wereinstructed to perform the task as quickly as possible. The time required to complete thetasks was measured.3) If a pegwas dropped outside the pegboard, the test was stopped and restarted.
Fig. 1.
Nine Hole Peg Test (NHPT) and the modified Nine Hole Peg Test (mNHPT). (A) The NHPTincludes a square board with nine holes arranged in a 3×3 square and nine pegs. (B)The mNHPT confines the order of peg insertion and removal to one way to reduce thedegree of freedom of spatial strategies. In both tests, the time required to place thepegs into the holes and then remove them from the holes using a single upper limb ismeasured.
Modified Version of the NHPT
We designed the mNHPT to decrease the degree of freedom in the spatial strategy for peginsertion and removal. The layout of the holes was designed such that the participantcould intuitively insert or remove the pegs in one way; the layout was changed from a 3×3square pattern to a line, and a specific order of peg insertion and removal was required(Fig. 1B). The spaces between the holes(3.2 cm) and the length of the pegs (3.2 cm) were the same in the NHPT and the mNHPT. ThemNHPT was administered in the same manner as the NHPT, except for the peginsertion/removal order. When the participants used their left hand to complete the mNHPT,the pegs were inserted from the right lower corner to the left lower corner and removedfrom the left lower corner to the right lower corner.
Experimental Procedure
The NHPT and mNHPT were performed three times each during each session, and the meanduration of the three trials was used in the analyses; the second session (retest) wasconducted 3–5 days after the first session.6) The order of administration of the NHPT and mNHPT was equalamong the participants to eliminate order bias. The performances of the NHPT were recordedby video, and the order of insertion and removal of the pegs was examined to evaluate theefficiency of each spatial strategy. One occupational therapist with 11 years of clinicalexperience supervised all tests in a quiet room throughout the study.
ANALYSES
Values for the Tests
The mean duration of the three trials in each session was calculated and used in allanalyses. Differences in the values between the NHPT and the mNHPT in each session wereexamined using the paired t-test. Statistical analyses were conductedusing Modified R Commander (version 4.0.2 software for Windows). P values <0.05 wereconsidered statistically significant.
Relative Reliability
The test–retest reliability between the sessions was assessed using the ICC (1,1). Thestrength of agreement was interpreted as follows: <0.00, slight; 0–0.19, lowcorrelation; 0.20–0.39, moderate correlation; 0.41–0.69, high correlation; 0.70–0.89,substantial; and 0.90–1.00, very high correlation.14)
Absolute Reliability
The absolute reliability of the NHPT and mNHPT was examined using Bland–Altmananalysis5) to check thesystematic bias and estimate the limit of agreement (LOA). Two types of systemic biasesexist: fixed and proportional. The two biases can be statistically confirmed andvisualized using the Bland–Altman scatter plot, in which the Y-axis shows the differencebetween the two paired measurements, and the X-axis represents the mean of thesemeasurements.
The fixed bias was statistically evaluated using the 95% confidence interval (CI) of themean differences between the session 1 and session 2 values ().A fixed bias was present if zero was not within the range of the 95% CI of .The Bland–Altman plot, in which the distribution of d is biased toward positive ornegative, can be used to depict the fixed bias. A proportional bias was present when thevalue of the difference between two sessions (d or |d|) was significantly correlated withthe mean of the two sessions.15) The magnitude of d or |d| changes depending on themagnitude of the mean of the two sessions in the Bland–Altman plot when a proportionalbias is present.
The 95% LOA was calculated as the mean ± 1.96 SD of the differences, and the %LOA wascalculated as the mean %d ± 1.96 SD of %d, where %d = (d/mean of sessions) × 100, usingthe relative differences between sessions. These values are shown as Bland–Altman plots.In addition, the 95% CIs of the upper and lower LOAs were calculated.5) Given that it is recommended thatthe acceptable LOAs be determined prior to the study,16) we determined acceptable LOAs based on those calculatedfrom previous studies conducted on individuals with stroke.6,7) We calculated the LOA from the mean and SD of thedifferences between the sessions,6) or from the mean and 95% CI of the differences between thesessions.7,17) The calculated LOAs (lower andupper) were −7.8 and 8.6 in the unaffected hand, −24.3 and 30.5 in the affectedhand;6) and −3.3 and 1.9in the less affected hand and −13.1 and 6.3 in the more affected hand.7) Based on our hypothesis that mNHPTwould have fewer measurement errors, we determined the acceptable LOAs in this study bycalculating 80% of the mean LOAs in the two previous studies. The priori acceptable LOAsfor the healthy and unaffected hands were calculated as −4.4 and 4.2, and those for theaffected hands were −15.0 and 14.7.
In addition, the MDC score at a confidence level of 95% (MDC95) was calculatedusing the standard error of measurement (SEM) to quantify the measurement errors:MDC95 = 1.96 SEM ×; [MDC95% =(MDC95 / mean of sessions) × 100].6,18)
Strategies for Peg Insertion and Removal in the NHPT
To investigate whether the better spatial strategy improved the measurement time, wereviewed the video recordings of the NHPT trials to evaluate the efficiency of the spatialstrategies of peg insertion and removal used in each trial. An efficient method of peginsertion or removal was defined as the absence of pegs that may have spatially disturbedthe insertion or removal of other pegs. When the test was performed on the left arm, apoint was given for inserting or removing a peg when there was no peg in the holes of allthe area on the left, lower, or lower left sides of the hole where the peg was inserted orremoved (Fig. 2). The possible score ranged from2 to 18 points for each trial, with higher scores indicating a more efficient spatialstrategy. To examine whether the strategy improved during the retest, the mean score ofthe three trials in session 1 was compared with that of session 2 using the pairedt-test. Pearson’s correlation coefficient was used to examine thecorrelation between the improvement rate in the mean spatial strategy score [(session2 −session1) / mean of sessions] and that in the time required to complete the NHPT.
Fig. 2.
Scoring the spatial peg strategy of the NHPT. The spatial strategies used by theparticipants to insert and remove the pegs during the NHPT were scored for efficiency.For example, when the left hand was used, the order of peg insertion/removal ofCBAFEDIHG/GHIDEFABC is one of the most efficient strategies, resulting in a full scorefor efficiency (18 points), whereas the order of peg insertion/removal ofGHIDEFABC/CBAFEDIHG is one of the least efficient strategies, resulting in the minimumscore for efficiency (2 points).
RESULTS
NHPT and MNHPT Values
Sessions 1 and 2 were conducted at a mean (SD) of 4.2 (0.7) days apart. The values foreach session are presented in Table 2. TheNHPT took significantly longer to complete than the mNHPT in each group (all P<0.001).
Table 2.
Time required to complete the Nine Hole Peg Test (NHPT) and the modified NineHole Peg Test (mNHPT)
| Healthy adults Non-dominant hand (n=40) | Participants with stroke | ||||||
| Unaffected hand (n=40) | Affected hand (n=40) | ||||||
| Session 1 | Session 2 | Session 1 | Session 2 | Session 1 | Session 2 | ||
| NHPT | Time, s | 17.6 (1.7) | 16.7 (1.4) | 24.2 (6.1) | 23.1 (5.9) | 34.7 (12.9) | 33.9 (12.2) |
| Strategy score | 12.2 (3.7) | 12.7 (3.4) | 11.1 (3.6) | 11.3 (3.5) | 12.4 (3.3) | 12.5 (3.5) | |
| mNHPT | Time, s | 16.5 (1.7) | 15.8 (1.4) | 22.4 (6.0) | 21.5 (5.7) | 31.6 (11.2) | 30.7 (10.4) |
| P value (time of NHPT vs. time ofmNHPT) | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | |
Open in a separate window
Data given as mean (SD).
Relative Reliability
The test–retest reliability (ICC [1,1]) of the NHPT sessions was moderate in healthyadults (ICC=0.49) and very high in participants with stroke (ICC=0.91). The test–retestreliability (ICC [1,1]) of the mNHPT session was moderate in healthy adults (ICC=0.66) andvery high in participants with stroke (ICC=0.94) (Table 3). The ICCs tended to be better for mNHPT than for NHPT. For both theNHPT and the mNHPT, the 95% CIs of ICCs did not overlap between the healthy adults andparticipants with stroke, indicating that ICCs were significantly lower in healthy adultsthan in participants with stroke.
Table 3.
Relative reliability of the NHPT and the mNHPT
| ICC [1, 1] | 95% CI | ||
| NHPT | Healthy adults | 0.49 | 0.22, 0.69 |
| Stroke (unaffected) | 0.91 | 0.83, 0.95 | |
| Stroke (affected) | 0.91 | 0.84, 0.95 | |
| mNHPT | Healthy adults | 0.66 | 0.44, 0.80 |
| Stroke (unaffected) | 0.94 | 0.90, 0.97 | |
| Stroke (affected) | 0.94 | 0.89, 0.97 |
Open in a separate window
Absolute Reliability
The Bland–Altman plots are shown in Figs. 3andand 4, 4, and the data are presented in Tables 4 andand5.5. In all three groups, the mean time required for the NHPT and mNHPT was shorterin session 2 than in session 1. The difference between each session was statisticallysignificant in the healthy adults and the study participants with stroke who used theirunaffected hand for the NHPT and the mNHPT. Therefore, a significant fixed bias wasdetected. In the group that used the affected hand, the differences between sessions 1 and2 were not statistically significant for the NHPT and the mNHPT, although session 2 tendedto be shorter than session 1. Proportional bias was detected in healthy adults for themNHPT and in participants with stroke who used the affected hand for the NHPT and themNHPT (Table 3). Greater differences weredetected when the time to complete the task was longer.
Fig. 3.
Bland–Altman plots for the NHPT (A, C, E) and mNHPT (B, D, F). (A, B) Data of thetrials of healthy adults using their non-dominant hands. (C, D) Data of the trials ofparticipants with stroke using the unaffected hand. (E, F) Data of the trials ofparticipants with stroke using the affected hands. Solid lines represent the mean anddotted lines represent the LOAs. The shaded areas represent the 95% confidenceintervals for the mean and LOAs.
Fig. 4.
Bland–Altman plots for the NHPT (A, C, E) and mNHPT (B, D, F) using the relativedifference between the sessions. (A, B) Data of the trials of healthy adults usingtheir non-dominant hands. (C, D) Data of the trials of participants with stroke usingthe unaffected hand. (E, F) Data of the trials of participants with stroke using theaffected hands. Solid lines represent the %mean and dotted lines represent the %LOAs.Shaded areas represent 95% confidence intervals for the %mean and %LOAs.
Table 4.
Absolute reliability of the NHPT and the mNHPT with Bland–Altmananalysis
| Fixed bias | Proportional bias | ||||||||||
| 95% CI | Lower LOA | 95% CI | Upper LOA | 95% CI | d vs mean | |d| vs mean | |||||
| r | P | r | P | ||||||||
| NHPT | Healthy adults | −0.9 | −1.37, −0.52 | −3.6 | −4.28, −2.82 | 1.7 | 0.94, 2.40 | −0.21 | 0.200 | 0.19 | 0.229 |
| Stroke (unaffected) | −1.1 | −1.86, −0.32 | −5.8 | −7.16, −4.49 | 3.6 | 2.30, 4.97 | −0.11 | 0.498 | 0.14 | 0.240 | |
| Stroke (affected) | −0.8 | −2.45, 0.89 | −11.0 | −13.90, −8.12 | 9.5 | 6.56, 12.34 | −0.15 | 0.367 | 0.49 | 0.001 | |
| mNHPT | Healthy adults | −0.7 | −1.05, −0.33 | −2.9 | −3.55, −2.29 | 1.5 | 0.91, 2.17 | −0.31 | 0.049 | 0.38 | 0.014 |
| Stroke (unaffected) | −1.0 | −1.50, −0.40 | −4.3 | −5.27, −3.37 | 2.4 | 1.46, 3.36 | −0.16 | 0.327 | 0.15 | 0.231 | |
| Stroke (affected) | −1.0 | −2.07, 0.24 | −8.0 | −9.99, −5.99 | 6.2 | 4.17, 8.17 | −0.22 | 0.179 | 0.47 | 0.002 | |
Open in a separate window
Table 5.
Absolute reliability of the NHPT and the mNHPT with Bland–Altman analysis usingthe percentage of difference
| Fixed bias | |||||||
| %Mean difference | 95% CI | Lower %LOA | 95% CI | Upper %LOA | 95% CI | ||
| NHPT | Healthy adults | −5.4 | −5.83, −4.98 | −20.6 | −24.82, −16.27 | 9.7 | 5.47, 14.01 |
| Stroke (unaffected) | −4.5 | −7.59, −1.46 | −23.3 | −28.62, −18.01 | 14.3 | 8.96, 19.57 | |
| Stroke (affected) | −2.0 | −5.74, 1.70 | −25.0 | −31.4, −18.47 | 20.9 | 14.43, 27.36 | |
| mNHPT | Healthy adults | −4.1 | −4.49, −3.76 | −17.1 | −20.80, −13.45 | 8.9 | 5.21, 12.55 |
| Stroke (unaffected) | −4.3 | −6.72, −1.84 | −19.3 | −23.48, −15.03 | 10.7 | 6.46, 14.91 | |
| Stroke (affected) | −2.7 | −5.90, 0.51 | −22.4 | −27.89, −16.80 | 17.0 | 11.41, 22.51 | |
Open in a separate window
In healthy adults, the LOAs were −3.6 and 1.7 for NHPT and −2.9 and 1.5 for mNHPT. Inparticipants with stroke who used the unaffected hand, the LOAs were −5.8 and 3.6 for NHPTand −4.3 and 2.4 for mNHPT. In participants with stroke who used the affected hand, theLOAs were −11.0 and 9.5 for NHPT and −8.0 and 6.2 for mNHPT. All LOAs except for the lowerlimit of the unaffected hand among the participants with stroke in NHPT were within theLOAs determined prior to the study. The LOA cannot be evaluated accurately in the presenceof a proportional bias.19) Inthis study, the LOAs of the smaller values tended to be overestimated, whereas those ofthe larger values tended to be underestimated in healthy adults for the mNHPT and inparticipants with stroke who used the affected hand in the NHPT and the mNHPT.
In healthy adults, the MDC% values of NHPT and mNHPT were 15.2% and 13.8%, respectively.In participants with stroke who used the unaffected hand, the MDC% values of NHPT andmNHPT were 20.0% and 15.3%, respectively. In the participants with stroke who used theaffected hand, the MDC% values of NHPT and mNHPT were 29.9% and 22.8%, respectively (Table 6).
Table 6.
Minimal detectable changes (MDC) for the NHPT and the mNHPT
| SEM | MDC95 | MDC95% | ||
| NHPT | Healthy adults | 0.94 | 2.6 | 15.2 |
| Stroke (unaffected) | 1.71 | 4.7 | 20.0 | |
| Stroke (affected) | 3.69 | 10.2 | 29.9 | |
| mNHPT | Healthy adults | 0.80 | 2.2 | 13.8 |
| Stroke (unaffected) | 1.21 | 3.4 | 15.3 | |
| Stroke (affected) | 2.56 | 7.1 | 22.8 |
Open in a separate window
Strategies for Peg Insertion and Removal During the NHPT
No participants used the same peg strategy throughout the six trials during two sessionsexcept for one participant with stroke who used the affected hand. The strategy scoresincreased slightly in the second session; however, the differences were not significant inany group (all P >0.05) (Table 2). Foreither group, the rate of change in the spatial strategy score was not significantlycorrelated with that of the NHPT (all P >0.05).
DISCUSSION
We systematically examined the relative and absolute reliability of the NHPT in healthyadults and participants with hemiparetic stroke and examined whether the reliability wasimproved by modifying the test to require a specific order of peg insertion and removal,which reduces the degree of freedom of the spatial strategies. In terms of relativereliability, the ICCs in the mNHPT were better than those in the NHPT in all groups.Therefore, reducing the degree of freedom in the spatial strategy of the test improved therelative reliability. Regarding the difference between healthy adults and those with stroke,the ICCs of both NHPTs in the participants with stroke were very high (ICC, 0.91–0.94) andsignificantly better than those in healthy adults (ICC, 0.49–0.66). This difference betweenthe healthy adults and those with stroke might have been caused by the difference in therange (variability) of values in the samples, because a larger ICC is obtained in a samplewith a larger range. The range of values in the affected and unaffected hands in theparticipants with stroke was markedly larger than that in healthy adults; therefore, theICCs might have been larger in participants with stroke than in healthy adults.
Regarding absolute reliability, the range of the upper and lower LOA in the mNHPT wasnarrower than that in the NHPT in all groups. Additionally, the LOA of the NHPT in theunaffected hand group was outside of the priori determined acceptable limits. Furthermore,the MDC% values were smaller in the mNHPT than in the NHPT for all groups. The MDC% in themNHPT in this study was 22.8%, which was smaller than the MDC% in the NHPT in the affectedhand in previous studies, which have been reported to be 24%7) and 54%.6) This suggests that the mNHPT has a smaller measurementerror.
The improved relative reliability and reduced measurement error observed in the mNHPT mighthave been caused by the reduced variability of task performance for each participant becauseof the requirement of a specific spatial strategy. In fact, only one participant out of 120(0.8%) performed the NHPT with the same order of insertions and removals throughout thetrials. Therefore, it is reasonable to assume that the difference in the order of pegsbetween the trials increased the variability of the NHPT. Considering that there was nocorrelation between the spatial strategy score and the time required for the NHPT, thevariability in the time required for the cognitive process for identifying spatialstrategies, rather than the variability in the spatial barriers of the pegs, might beresponsible for the reduced reliability of the NHPT. We believe that by uniquely determiningthe order of pegs as in mNHPT, we may reduce not only the variability in spatial strategies,but also the variability in the time required for completion of the cognitive process foridentifying the spatial strategy.
Contrary to our expectations, the reduction in the degree of freedom of the spatialstrategies did not eliminate the fixed biases observed in the healthy adults andparticipants with stroke who used the unaffected hand. The values in the second session weresignificantly smaller than those in the first session. Furthermore, there was no significantrelationship between the spatial peg strategies and the time required to complete the NHPT,although various peg strategies were used by the participants. This finding suggests thatthe main cause of the fixed bias observed in the NHPT was not the improvement of spatialstrategy but the learning effect of peg manipulation itself. A statistically significantfixed bias was not observed in the affected hand of participants with stroke, although therewas a tendency towards this bias. This may have been caused by the fact that the learningeffects were obscured by the variability of task performance, or that the learning abilitywas impaired in the affected hand of the participants with stroke.
Proportional bias was detected in the healthy adults in the mNHPT and in the participantswith stroke who used the affected hand in the NHPT and the mNHPT. This bias might have beensimply caused by the variability in performances between the sessions. As the time requiredfor the test increased, the variability between the sessions might have increased. Regardingthe relative and absolute reliability, similar findings were reported in the Purdue PegboardTest (PPT), which is known as a test for finger dexterity. The PPT was reported to havealmost perfect test–retest reliability (ICCs >0.8 for each subtest in healthyadults).20) However,systemic bias was present, and a significantly more favorable result was observed in thesecond test compared to the first test in some subtests of the PPT in individuals withschizophrenia.21)
In terms of clinical implications that can be drawn from this study, the mNHPT can be usedwith better relative and absolute reliability in terms of reducing the measurement errorcompared to that of the NHPT when assessing finger dexterity in healthy adults and thosewith stroke. However, the fixed bias caused by the learning effect when the test is usedrepeatedly cannot be overlooked. Furthermore, clinicians should consider that the test hassome measurement error, even though the LOAs are acceptable, and that these errors becomegreater because of proportion bias when the test is used in individuals with severeimpairment who require more time to complete the test. Importantly, the measurement timediffered between the NHPT and the mNHPT, which might be caused by the differences in teststructures, indicating the risk involved in using the values obtained using the NHPT indirect comparison with those obtained using the mNHPT.
The limitations of the study include the small sample size and the lack of age-matchedcontrols. Therefore, the results may not be generalizable to individuals with stroke withdifferent degrees of hemiparesis. In addition, it could not be determined whether thecharacteristics observed in the unaffected hand were stroke-specific or because of aging,although the learning effect was evident even in participants with stroke who used theunaffected hand.
CONCLUSION
The mNHPT has better absolute and relative reliability in terms of reducing the measurementerror than the NHPT in healthy adults and individuals with stroke. However, fixed bias,proportional bias, and measurement errors cannot be ignored.
Footnotes
CONFLICTS OF INTEREST: The authors have no conflicts of interest to declare.
REFERENCES
1. Kwakkel G,Kollen BJ,van derGrond J,Prevo AJ:Probability of regaining dexterity in the flaccid upper limb: impact ofseverity of paresis and time since onset in acute stroke.Stroke2003;34:2181–2186. 10.1161/01.STR.0000087172.16305.CD [PubMed] [CrossRef] [Google Scholar]
2. Franceschini M,LaPorta F,Agosti M,Massucci M:Is health-related quality of life of stroke patients influenced byneurological impairments at one year after stroke?Eur J Phys Rehabil Med2010;46:389–399. [PubMed] [Google Scholar]
3. Mathiowetz V,Weber K,Kashman N,Volland G:Adult norms for the Nine Hole Peg Test of fingerdexterity. Occup Ther J Res1985;5:24–38. 10.1177/153944928500500102 [CrossRef] [Google Scholar]
4. Santisteban L,Térémetz M,Bleton JP,Baron JC,Maier MA,Lindberg PG:Upper limb outcome measures used in stroke rehabilitation studies: asystematic literature review. PLoS One2016;11:e0154792. 10.1371/journal.pone.0154792 [PMC free article] [PubMed] [CrossRef] [Google Scholar]
5. Bland JM,Altman DG:Statistical methods for assessing agreement between two methods ofclinical measurement. Lancet1986;327:307–310. 10.1016/S0140-6736(86)90837-8 [PubMed] [CrossRef] [Google Scholar]
6. Chen HM,Chen CC,Hsueh IP,Huang SL,Hsieh CL:Test–retest reproducibility and smallest real difference of 5 handfunction tests in patients with stroke. Neurorehabil NeuralRepair2009;23:435–440. 10.1177/1545968308331146 [PubMed] [CrossRef] [Google Scholar]
7. Ekstrand E,Lexell J,Brogårdh C:Test–retest reliability and convergent validity of three manual dexteritymeasures in persons with chronic stroke. PM R2016;8:935–943. 10.1016/j.pmrj.2016.02.014 [PubMed] [CrossRef] [Google Scholar]
8. OxfordGrice K,Vogel KA,Le V,Mitchell A,Muniz S,Vollmer MA:Adult norms for a commercially available Nine Hole Peg Test for fingerdexterity. Am J Occup Ther2003;57:570–573. 10.5014/ajot.57.5.570 [PubMed] [CrossRef] [Google Scholar]
9. Iosa M,Morone G,Ragaglini MR,Fusco A,Paolucci S:Motor strategies and bilateral transfer in sensorimotor learning ofpatients with subacute stroke and healthy subjects. A randomized controlledtrial. Eur J Phys Rehabil Med2013;49:291–299. [PubMed] [Google Scholar]
10. Walter SD,Eliasziw M,Donner A:Sample size and optimal designs for reliability studies.Stat Med1998;17:101–110. 10.1002/(SICI)1097-0258(19980115)17:1<101::AID-SIM727>3.0.CO;2-E [PubMed] [CrossRef] [Google Scholar]
11. Oldfield RC:The assessment and analysis of handedness: the Edinburghinventory. Neuropsychologia1971;9:97–113. 10.1016/0028-3932(71)90067-4 [PubMed] [CrossRef] [Google Scholar]
12. Fugl-Meyer AR,Jääskö L,Leyman I,Olsson S,Steglind S:The post-stroke hemiplegic patient. 1. A method for evaluation ofphysical performance. Scand J Rehabil Med1975;7:13–31. [PubMed] [Google Scholar]
13. Bohannon RW,Smith MB:Interrater reliability of a modified Ashworth scale of musclespasticity. Phys Ther1987;67:206–207. 10.1093/ptj/67.2.206 [PubMed] [CrossRef] [Google Scholar]
14. Guilford JP:Fundamental statistics in psychology and education. McGraw-Hill, New York and London,1942. [Google Scholar]
15. Altman DG,Bland JM:Measurement in medicine: the analysis of method comparisonstudies. Statistician1983;32:307–317. 10.2307/2987937 [CrossRef] [Google Scholar]
16. Abu-Arafeh A,Jordan H,Drummond G:Reporting of method comparison studies: a review of advice, an assessmentof current practice, and specific suggestions for future reports.Br J Anaesth2016;117:569–575. 10.1093/bja/aew320 [PubMed] [CrossRef] [Google Scholar]
17. Bland M: Anintroduction to medical statistics. Oxford University Press, Oxford,2015. [Google Scholar]
18. Faber MJ,Bosscher RJ,vanWieringen PC:Clinimetric properties of the performance-oriented mobilityassessment. Phys Ther2006;86:944–954. 10.1093/ptj/86.7.944 [PubMed] [CrossRef] [Google Scholar]
19. Ludbrook J:Statistical techniques for comparing measurers and methods ofmeasurement: a critical review. Clin Exp PharmacolPhysiol2002;29:527–536. 10.1046/j.1440-1681.2002.03686.x [PubMed] [CrossRef] [Google Scholar]
20. Buddenberg LA,Davis C:Test–retest reliability of the Purdue Pegboard Test.Am J Occup Ther2000;54:555–558. 10.5014/ajot.54.5.555 [PubMed] [CrossRef] [Google Scholar]
21. Lee P,Liu CH,Fan CW,Lu CP,Lu WS,Hsieh CL:The test–retest reliability and the minimal detectable change of thePurdue Pegboard Test in schizophrenia. J Formos MedAssoc2013;112:332–337. 10.1016/j.jfma.2012.02.023 [PubMed] [CrossRef] [Google Scholar]
Articles from Progress in Rehabilitation Medicine are provided here courtesy of Japanese Association of Rehabilitation Medicine
