Validity and Reliability of the Persian Versions of National Institute of Health Stroke Scale and Modified National Institute of Health Stroke Scale in Hospitalized Patients

Background: National Institute of Health Stroke Scale (NIHSS) and Modified National Institute of Health Stroke Scale (mNIHSS) are two valid and reliable questionnaires that assess stroke severity. This study aimed to examine and compare the validity and reliability of Persian versions of NIHSS and mNIHSS in hospitalized patients. Materials and Methods: The English versions of NIHSS and mNIHSS were translated to Persian (forward and backward), and three neurologists examined the face and content validity of both questionnaires. The Persian versions of NIHSS and mNIHSS were used in 75 hospitalized stroke patients (hemorrhagic and obstructive) admitted to Namazi teaching hospital, Shiraz, Iran. The reliability and validity of the Persian versions were examined by Cronbach’s alpha coefficient and convergent validity. Results: The values of Cronbach’s alpha for Persian versions of NIHSS and mNIHSS were 0.81 and 0.86, respectively. The scaling success of convergent validity in NIHSS and mNIHSS were 80% and 100%, respectively. Conclusion: The Persian versions of NIHSS and mNIHSS were reliable and valid. However, mNIHSS was more valid and reliable than NIHSS. Persian version of mNIHSS can be suggested to be used for assessing stroke severity in hospitalized stroke patients by neurologists and researchers.


Introduction
N ational Institute of Health Stroke Scale (NIHSS) is a ubiquitous, valid, and reliable clinical questionnaire predicting the severity of stroke.This questionnaire is useful for making medical and nursing decisions and is routinely being used in clinical trials [1][2][3][4][5].It has 15 items including the level of consciousness (LOC), LOC questions, LOC commands, best gaze, visual, facial palsy, motor arm, motor leg, limb ataxia, sensory, best language, dysarthria, extinction, and inattention.Higher scores on the scale is an indicator of more severe neurological deficits [2].In spite of its reliability, validity and widespread use, the NIHSS has been scrutinized for some redundant items including the OLC, facial palsy, limb ataxia, and dysarthria.These items have caused complexity for NIHSS implementation, prolongation of the questionnaire response time, tiredness of the person filling out the questionnaire and also deviance in its ultimate results.These limitations of NIHSS questionnaire have led to a reduced tendency for implementing and reporting NIHSS in emergency and stroke wards [6,7], while an initial estimation of stroke severity is essential for the appraisal of the treatment and rehabilitation programs.Modified National Institute of Health Stroke Scale (mNIHSS) is a succeeding questionnaire in which the redundant items have been removed.Such changes have brought several advantages for mNIHSS over NIHSS including simpler grading scale, more accessible to administration, more precise results, and shorter time to perform.These advantages have made the mNIHSS more valid, reliable and acceptable among clinicians and researchers [6,8].Stroke is the main cause for physical disability and the second cause of mortality worldwide [9].Two-thirds of all strokes occur in developing countries including Iran [9,10].The incidence of stroke in Iran is about 750-800 individuals in 100000 population per year, which is much higher than worldwide [11,12].Thus, having a valid and reliable questionnaire for evaluating the severity of stroke in stroke and emergency wards and clinical trials is an essential need.English version of NIHSS has been routinely used as a reliable and valid questionnaire in Iran.However, since misinterpretation/misunderstanding of the English version might lead to a deviation in the ultimate results, developing a Persian version of NIHSS seems necessary.There is only one previous study assessing the reliability and validity of the Persian version of NI-HSS [13].However, there were some limitations in the preceding study such as evaluation of validity and reliability of the questionnaire in non-hospitalized subjects; inclusion of only ischemic stroke patients; and exclusion of patients who have sever consciousness deficit, severe hearing or vision impairments [13].Since this questionnaire has been developed to assess the severity of stroke at the time of evaluation in all stroke patients (ischemic or hemorrhagic) regardless of patients' conditions (such as vision and hearing abilities of patients).Therefore, for assessing the validity of Persian version of the questionnaire all stroke patients has to be included in the study in order to generalize its applicability.Also, the evaluation of the severity of the stroke is needed at the time of admission to hospital in order to follow the improvement of patients' complications during drug therapy and rehabilitation programs.Thus, it is also necessary to validate this questionnaire in hospitalized stroke patients.Furthermore, considering the advantages of mNIHSS over NIHSS, it is valuable and worthwhile to validate a Persian version of mNIHSS as well.The availability of a Persian version of this easier and less time-consuming questionnaire will encourage medical staffs to use it more frequently at the emergency and stroke wards.Therefore, this study aimed to examine and compare the validity and reliability of Persian versions of NIHSS and mNIHSS in hospitalized stroke patients.

Materials and Methods
This study was part of a comprehensive research approved by the local Ethics Committee and research council of Shiraz University of Medical Sciences (approval code: 10400).Patients were only enrolled after giving written informed consent.In the case that the patients couldn't fill the informed consent, their legal guardians signed the consent forms.All GMJ.2018;7:e1188 www.gmj.irprocedures were followed in accordance with the guidance and approval of the Institutional Medical Ethics Committee.

Instruments and Participants
After obtaining permission from the National Institute of Neurological Disorders and Stroke (https://www.ninds.nih.gov),both questionnaires were translated to Persian by a single professional translator (forward translation) and then the translated questionnaires were translated into English (backward translation) by another single native English translator.Three neurologists examined the face and content validity of both translations.The final translated versions were finalized after the agreement of translators and neurologists on items that were difficult to be easily perceived.Seventy-five patients (39 men and 36 females) aged 27 to 65 years were randomly and sequentially entered the study in order of their admission time to the stroke ward of Namazi teaching hospital, Shiraz, Iran from April 2017 through July 2017.An inclusion criterion was clinical diagnosis of stroke (hemorrhagic or obstructive) by computed tomography scan or magnetic resonance imaging.Patients with previous neurological disorders such as Alzheimer disease, Parkinson or seizure were excluded from the study.Sample size was calculated according to rule of thumb stating that the required number of subjects for testing validity and reliability of a questionnaire equals to at least 5-10 times of number of questions (items) in a questionnaire (i.e., 15 questions in the NIHSS× 5 = 75 subjects is needed for testing validity and reliability of NIHSS questionnaire) [14,15].For each patient, both NI-HSS and mNIHSS were performed by a single trained researcher.Both NIHSS and mNIHSS questionnaires have multiple Likert-type scale questions.The Likert-type scale questions in both NIHSS and mNIHSS may have three, four or five options that the implementer must choose an answer among the choices for each question.The Likert-type scale questions in both questionnaires determine the patient's condition in several domains (Table -1).These questionnaires have some differences as well.NIHSS has 15 questions while mNIHSS has 11 questions.In mNIHSS, the LOC, facial palsy, limb ataxia, and dysarthria items have been deleted.Also, question 8 (sensory item), which was a three-option question in NIHSS has been changed to a two-option question in mNIHSS.

Data Analysis
The collected data from patients were inserted in the SPSS (version 16, IBM USA) and were analyzed for reliability and validity.Reliability and validity of the two questionnaires were assessed by calculating Cronbach's alpha coefficient and convergent validity of each questionnaire; respectively.Cronbach's alpha coefficient measures the internal consistency (reliability) and ranges from 0 to 1.The values >0.65 are acceptable [16].The higher grades (>0.65) indicates more reliable the questionnaire.Convergent validity is a subtype of construct validity.For calculating the convergent validity, the Pearson correlation coefficient was used.A value of a correlation coefficient of greater than 0.40 between an item and total score is regarded as adequate evidence of convergent validity [17].Also, the scaling success of convergent validity for each questionnaire was calculated by dividing the number of correlations above 0.40 by the total number of correlations ×100 (Table -2).

Results
Face and content validity are subjective measures.If specialists approve the face and content validity, the questionnaire was applicable for assessing the desired goals.In this study, the face and content validities of Persian versions of NIHSS and mNIHSS questionnaires were approved by three neurologists.Cronbach's alpha coefficient is the most frequent measure for assessing reliability (internal consistency).It is mostly used when there are multiple Likert-type scale questions in a questionnaire (such as the NIHSS questionnaire) that form a scale, and one wants to specify if the scale is reliable.In this study, Cronbach's alpha coefficients were 0.81 for NIHSS and 0.86 for mNIHSS (Table -

Discussion
The results of the current study confirmed the reliability and validity of Persian versions of NIHSS and mNIHSS in hospitalized stroke patients.Also, the findings of this study indi-cated that the Persian version of mNIHSS was more valid and reliable than the Persian version of NIHSS.English version of NIHSS is a valid and reliable questionnaire, which is routinely used to assess the severity of the stroke.
In the present study, the Persian version of NIHSS showed an excellent Cronbach's alpha coefficient confirming its reliability to predict the severity of stroke in hospitalized stroke (ischemic and hemorrhagic) patients.There was only one previous study evaluating the reliability of the Persian version of NIHSS in non-hospitalized ischemic stroke patients  LOC: Level of consciousness [13].In line with our finding, the Cronbach's alpha coefficient of the previous study (0.89) also indicated the reliability of Persian version of NIHSS in non-hospitalized stroke patients.Also, the finding of a scaling success of 80% in the present study demonstrated the validity of Persian version NIHSS.This is inconsonant with the results of the previous study using a different method for validity assessment of Persian version NIHSS [13].plicable questionnaire to assess the severity of stroke in stroke and emergency wards as well as clinical trials.Replacing NIHSS with mNI-HSS in stroke and emergency wards may increase the tendency for reporting the severity of stroke, which is necessary for clinical and nursing decisions as well as in treatment and rehabilitation programs.The limitation of this study was not able to implement the questionnaires with more than one researcher that prevented the calculation of the kappa coefficient (inter-rater agreement).Hence, future study should address this issue.

Conclusion
Persian versions of NIHSS and mNIHSS were reliable and valid questionnaires.However, the mNIHSS was more valid and reliable questionnaire than NIHSS.With regards to superiorities of mNIHSS vs. NIHSS, replacing NIHSS with mNIHSS in stroke and emergency wards and clinical trials may be an appropriate move.

Table 1 .
Details of NIHSS and mNIHSS Alert.1= Not alert 2 = Not alert 3= Responds only with reflex motor or autonomic effects or totally unresponsive, flaccid, and are flexic.

Table 2 .
Cronbach's Alpha and Convergent Validity for Persian Version of NIHSS and mNIHSS Minimum and maximum of correlation between each item and total score.b The number of correlations above 0.40/the total number of correlations. a