both prospective and retrospective studies have shown that hemiplegic stroke patients are 
 at a high risk of fall throughout their post - stroke lifespan1 .
although previous studies have reported varying fall rates among 
 hemiplegic stroke patients , there is a general consensus regarding the higher fall rate in 
 stroke patients compared to the general population of the same age2 , 3 .
falls are a common 
 and serious complication after stroke4 , 
 and approximately one - third of hospital - related falls lead to potentially serious injuries , 
 such as a fracture5 . given that falls in 
 stroke patients
are associated with lower rehabilitation potential and functional 
 recovery6 , prevention of falls is a 
 major rehabilitation goal . although the physical consequences of a fall receive the most attention , the psychosocial 
 effects are also important .
one of these psychosocial effects is the fear of falling . 
 falling and fear of falling form a vicious circle . the experience of falling increases the 
 fear of falling , and the fear of falling decreases physical activity , resulting in 
 deconditioning .
deconditioning leads to decreased physical activity , resulting in lower 
 functioning that increases the incidence of falls in stroke patients7,8,9 .
the negative effect that the fear of falling has on rehabilitation 
 emphasizes the need for physical therapists to be aware of this fear in hemiplegic stroke 
 patients .
assessment is the first step in developing a targeted rehabilitation intervention . choosing 
 an appropriate tool that measures the fear of falling is the foundation for planning an 
 appropriate course of therapy for post - stroke intervention and assessing the effects of an 
 intervention10 . despite a shift that 
 places emphasis on task - oriented evaluation and self - efficacy in rehabilitation assessment 
 and management of chronic disease11 , use 
 of a self - reported scale is insufficient in most environmental contexts .
the falls efficacy 
 scale ( fes ) developed by tinetti et al.12 
 is an instrument based on the theory of self - efficacy .
the fes is designed to measure 
 self - perceived fear of falling during the performance of 10 common activities , including 
 dressing , toileting , and preparing meals .
the authors investigated its reliability in 
 ambulatory individuals aged over 65  years and reported a test - retest reliability of 
 0.7112 .
understanding individual factors such as the level of confidence and the emotional 
 responses of a patient working toward a particular post - stroke goal could help health 
 professionals appreciate the different responses to rehabilitation13 ; therefore the fes , which measures balance confidence , is 
 useful for the physical therapist .
although the fes is used for measuring the fear of 
 falling in hemiplegic stroke patients14 , 
 its psychometric properties have not been fully investigated .
hellstrm et al.15 reported the scaling properties and the 
 test - retest reliability of an extended version of the fes .
responsiveness of the fes was 
 investigated through comparison with the berg balance scale and the fugl - meyer balance 
 subscale .
the results of a previous study suggested that the fes is responsive and useful 
 for measurement of perceived confidence in task performance16 .
after development of the fes , several studies have investigated its use in the general 
 elderly population .
studies that examined the psychometric properties of the fes were 
 conducted on the basis of the classical test theory . when investigating the psychometric 
 properties of the fes in a clinical population , such as in patients with hemiplegic stroke , 
 rasch analysis , which is a specific application of the item response theory that is based on 
 the application of a related mathematical model , is appropriate17 , 18 .
rasch analysis 
 is less sample - dependent and more broadly useful than the classical test theory because it 
 provides a more comprehensive understanding of the latent structure of the test19 .
the purpose of this study was to investigate the psychometric properties of the fes using 
 rasch analysis in patients with hemiplegic stroke . through this investigation
the study sample was chosen from a group of community - dwelling hemiplegic stroke patients 
 visiting a convalescent or rehabilitation center for disabled individuals in south korea . 

inclusion criteria were as follows : ( 1 ) presence of hemiplegia , ( 2 ) score on the korean 
 version of the mini - mental state examination ( mmse - k ) > 21 , and ( 3 ) age > 65  years . 

study approval was received from the ethics review board of our affiliated university , and 
 written informed consent was obtained from all participants .
participants responses to the 
 questionnaire and their measurements were analyzed ; none had missing data .
participants 
 ages ranged from 65 to 89  years , with an average of 70.73  3.06  years .
stroke duration since diagnosis ranged from 6 to 480 months , with an average 
 of 103.87  38.69 months .
participants scores on the mmse - k ranged from 21 to 30 , with a 
 mean of 27.71 .
there were 10 items using a 10-point ordinal scale 
 included in the fes , with a total possible score of 100 points .
the korean fes items were as 
 follows : ( 1 ) take a bath or shower , ( 2 ) reach into the closet , ( 3 ) do  light  housekeeping 
 ( e.g. , clean up your nightstand or dresser ) , ( 4 ) walk around the nursing home , ( 5 ) get in 
 and out of bed , ( 6 ) get up at night to go to the bathroom , ( 7 ) get in and out of a chair , 
 ( 8) get dressed and undressed , ( 9 ) do personal grooming ( e.g. , wash your face , comb your 
 hair ) , and ( 10 ) get on and off the toilet .
the rasch 
 model assumes that an item response is the result of an interaction between the scale item 
 and the respondent s ability .
the strength of rasch analysis lies in its investigation of 
 the construction and validation of health status questionnaires for various patient groups , 
 including stroke patients21,22,23 . in this study
infit and outfit mean square ( mnsq ) statistics were used to confirm unidimensionality . 

unidimensionality examines whether all items contribute adequately to the scale s domain and 
 identifies any misfit items . in this study , if the item or subject was in the range of 0.60 
 to 1.40 or had a z - value between 2.0 and 2.0 for the infit , it was considered to have an 
 appropriate model fit24 . in rasch 

analysis , each item is explained by a chain of threshold parameters that describe the 
 difficulty or probability of the response categories .
rating scale analysis includes average 
 measures , threshold estimates , and category fit . in this study ,
the item rating scale was 
 considered to have an appropriate rating scale if the threshold increased by at least 1.4 
 logits between categories25 .
reliability 
 was verified using the person separation reliability statistic ; the separation index ( si ) 
 must exceed 2 to attain the desired level of separation reliability ( i.e. , a value of 0.80 ) , 
 and exceed 3 to achieve a value of 0.9026 .
there were no misfit persons or items ( table 
 1table 1.item fit statistics : entry orderitemmeasureseinfitoutfitmnsqz - valuemnsqz - value152.941.151.241.01.100.5256.471.191.351.31.110.5354.541.160.780.090.731.1451.381.131.301.21.030.2549.211.130.631.70.641.6649.721.130.661.50.522.3747.791.140.890.41.090.4847.391.150.800.80.780.8944.931.201.090.40.920.21045.641.180.920.20.850.6mnsq : mean square statistic , se : standard error ) .
a summary of the rating scale analysis is presented in table 2table 2.rating scale analysis of the original 10-point scalecategorylevelobservedaverageinfitmnsqoutfitmnsqstructurecalibration127.713.641.21none222.280.740.8536.7037.080.740.593.4042.270.941.085.3751.240.800.630.8062.770.940.821.5574.290.390.260.1988.241.341.294.38915.910.450.5911.451018.511.911.1331.54mnsq : mean square statistic .
the average measures , which indicate the average of the modeled 
 fes for all patients who chose that particular response category , followed the low - to - high 
 expected order and increased with the category value . however , structure calibrations were 
 disordered .
based on the 
 structure calibration and fit statistics , ratings 1 , 2 , 5 , 6 , 7 , 9 , and 10 were combined in 
 a new scale .
a summary of the new 6-point rating scale analysis is presented in table 3table 3.rating scale analysis of the revised 6-point scalecategorylevelobservedaverageinfitmnsqoutfitmnsqstructurecalibration116.201.181.23none210.730.750.8710.8332.991.001.195.9843.120.760.6510.14511.871.301.2410.12624.800.890.9316.83mnsq : mean square statistic .
mnsq : mean square statistic , se : standard error mnsq : mean square statistic mnsq : mean square statistic with this new scale , the threshold increased by more than 1.4 logits between categories . 

thus , the rating scale 
 from 1 to 6 was determined to be appropriate for stroke patients .
the 
 reliability of all items was at an acceptable level for patients with hemiplegic stroke .
the purpose of this study was to use rasch analysis to investigate the psychometric 
 properties of the fes for measuring balance confidence in patients with hemiplegic stroke . 

we investigated its unidimensionality through item fit , reliability , and appropriateness of 
 the rating scale .
the fes was found to be reliable , there were no misfit persons or items , 
 and it showed unidimensionality . however , the rating scale required modification for 
 application in patients with hemiplegic stroke .
item fit is a tool for determining unidimensionality of a psychometric measure , 
 specifically for showing how each item fits in a single dimension27 .
the fit statistics of the 10 items support the proposed 
 unidimensionality of the fes .
a high mnsq value for an item indicates that the item is not 
 homogenous with the other items , whereas a low mnsq value indicates that the item is a 
 duplicate of another .
the ideal mnsq value is 124 . in this study , we selected a range of 0.601.40 for the infit mnsq 
 values and a z - value of > 2.0 to determine whether the scale items were a misfit .
infit 
 value is more sensitive to the pattern of responses to items targeted on the person , whereas 
 outfit value is more sensitive to the responses to items with difficulty far from the 
 person .
the infit mnsq value is a residual that is sensitive to the estimated person s 
 abilities , whereas the outfit mnsq value is sensitive to unexpected outliers for either 
 person or item parameters .
outfit mnsq values are influenced by outliers and are easy to 
 diagnose and remedy ; therefore , they pose a lesser threat to measurement .
however , infit 
 mnsq values are influenced by response patterns and are usually hard to diagnose and remedy , 
 and therefore they are a greater threat to measurement24 .
two items , namely ,  reach into the closet  and  walk around the nursing home  were the 
 closest to being misfits , having an inordinately high infit mnsq value .
the possibility of 
 the different dimensions of  reach into a closet  and  walk around the nursing home  were 
 reported in a previous study investigating the validity of the fes20 .
the value for  reach into a closet  in this study was reported to be 0.56 , 
 while that for  walk around the nursing home  was 0.62 .
a low item - total correlation value indicates the 
 possibility of a different construct . 
get in and out of bed  and  get up at night to go to 
 the bathroom
 showed a low infit mnsq value ; a low infit mnsq value indicates the 
 possibility of duplication with other items .
although 4 items of the fes had a close misfit 
 value , they did not exceed the border .
in addition , although the fit indices of these 4 
 items were acceptable , further investigation is needed .
psychometric properties of the fes in stroke patients have been examined using the 
 classical test theory .
hellstrm et al.15 
 reported the reliability of the extended fes in 30 stroke patients .
a 13-activity 
 questionnaire was used , and the overall test - retest reliability was high ( intraclass 
 correlation coefficient [ icc ] = 0.97 ) .
the iccs for personal activities of daily living and 
 instrumental activities of daily living were also high .
the authors suggested that the fes 
 was a useful instrument for assessing balance confidence in those patients with hemiplegic 
 stroke who are at risk for falls .
the results of the rating scale analysis in this study showed the need for modifying the 
 original 10-point scale .
the adequacy of the rating scale was judged based on the order and 
 the differences between the items . on the basis of the judgment criteria , ratings of 1 , 2 , 
 5 , 6 , 7 , 9 , and 10
after rescoring , the fit statistics of the 
 rating scale were improved and appropriate .
the order was increased in structure 
 calibration , and the threshold of the differences between items was at least 1.4 logits25 .
these criteria include at 
 least 10 cases per category and monotonically increase the average measures across a 
 category ; a category outfit is indicated by a square value of < 228 .
the modified 6-point ordinal scale was appropriate based 
 on the guidelines for scale adequacy .
person separation in the rasch model is equivalent to 
 cronbach s . in this study , the person separation value indicated how well the measure 
 could differentiate patients in terms of their balance confidence .
the present study had a person separation value of 0.90 . despite the clinical significance of
falls in stroke patients , studies on falls and fall 
 self - efficacy are insufficient1 . the 
 psychosocial aspect of falls , in particular , should be emphasized because fear of falling is 
 related to balance and gait deficits .
new studies have been initiated to identify a 
 validated tool for assessing fall self - efficacy in stroke patients .
validation of this 
 measure of balance confidence in stroke patients is needed to achieve the goals of reducing 
 the fear of falling , developing an appropriate intervention , and assessing the effect of the 
 intervention .
this was the first study to investigate the psychometric properties of the fes 
 using rasch analysis .
the results of this study suggest that the 6-point fes is an 
 appropriate tool for measuring self - perceived fear of falling in patients with hemiplegic 
 stroke .
 [ purpose ] the purpose of this study was to investigate the psychometric properties of the 
 falls efficacy scale using rasch analysis in patients with hemiplegic stroke . 
 [ subjects ] 
 fifty - five community - dwelling hemiplegic stroke patients were selected as participants . 
 
 [ methods ] data were analyzed using the winsteps program ( version 3.62 ) with the rasch 
 model to confirm the unidimensionality through item fit , reliability , and appropriateness 
 of the rating scale . 
 [ results ] there were no misfit persons or items . 
 furthermore , infit 
 and outfit statistics appeared adjacent . 
 the person separation value was 3.07 , and the 
 reliability coefficient was 0.90 . 
 the reliability of all items was at an acceptable level 
 for patients with hemiplegic stroke . 
 [ conclusion ] this was the first study to investigate 
 the psychometric properties of the falls efficacy scale using rasch analysis . 
 the results 
 of this study suggest that the 6-point falls efficacy scale is an appropriate tool for 
 measuring the self - perceived fear of falling in patients with hemiplegic stroke . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION