Dataset Information

Analysis of internal construct validity of the SRS-24 questionnaire.

ABSTRACT:

Purpose

The SRS-24 questionnaire was originally validated using methods of classical test theory, but internal construct validity has never been shown. Internal construct validity, i.e. unidimensionality and linearity, is a fundamental arithmetic requirement and needs to be shown for a scale for summating any set of Likert-type items. Here, internal construct validity of the SRS-24 questionnaire in adolescent idiopathic scoliosis (AIS) patients is analyzed.

Methods

232 SRS-24 questionnaires distributed to 116 patients with AIS pre-operatively and at postoperative follow-up were analyzed. 103 patients were females; the average age was 16.5 ± 7.1 years. The questionnaires were subjected to Rasch analysis using the RUMM2020 software package.

Results

All seven domains of the SRS-24 showed misfit to the Rasch model, and three of seven were unidimensional. Unidimensionality and linearity could only be achieved for an aggregate score by separating pre- and postoperative items and omitting items which caused model misfit. Reducing the questionnaire to six pre-operative items (p = 0.098; 2.25% t tests) and five postoperative items (p = 0.267; 3.70% t tests) yields model fit and unidimensionality for both summated scores. The person-separation indices (PSI) were 0.67 and 0.69, respectively, for the pre- and postoperative patients.

Conclusions

The SRS-24 score is a non-linear and multidimensional construct. Adding the items into a single value is therefore not supported and invalid in principle. Making profound changes to the questionnaire yields a score which fulfills the properties of internal construct validity and supports its use a change score for outcome measurement.

SUBMITTER: Rothenfluh DA

PROVIDER: S-EPMC3535236 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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Publications

Analysis of internal construct validity of the SRS-24 questionnaire.

Rothenfluh Dominique A DA Neubauer Georg G Klasen Juergen J Min Kan K

European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society 20120801 8

<h4>Purpose</h4>The SRS-24 questionnaire was originally validated using methods of classical test theory, but internal construct validity has never been shown. Internal construct validity, i.e. unidimensionality and linearity, is a fundamental arithmetic requirement and needs to be shown for a scale for summating any set of Likert-type items. Here, internal construct validity of the SRS-24 questionnaire in adolescent idiopathic scoliosis (AIS) patients is analyzed.<h4>Methods</h4>232 SRS-24 ques ...[more]

PMID: 22315036

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Project description:BackgroundThe SRS-22 is a valid instrument for the assessment of the health related quality of life of patients with Idiopathic scoliosis. The SRS-22 questionnaire was developed in USA and has been widely used in the English speaking countries. Recently it has been translated and validated in many other languages. The purpose of this study is to evaluate the reliability and validity of the adapted Greek version of the refined Scoliosis Research Society-22 Questionnaire.MethodsFollowing the steps of cross - cultural adaptation the adapted Greek version of the SRS-22 questionnaire and a validated Greek version of the SF-36 questionnaire were mailed to 68 patients treated surgically for Idiopathic Scoliosis. 51 out of the 68 patients returned the 1st set of questionnaires, while a second set was emailed to 30 randomly selected patients of the first time responders. 20 out of the 30 patients returned the 2nd set. The mean age at the time of operation was 16,2 years and the mean age at the time of evaluation was 21,2 years. Descriptive statistics for content analysis were calculated. Reliability assessment was determined by estimating Cronbach's alpha and intraclass correlation coefficient (ICC) respectively. Concurrent validity was evaluated by comparing SRS-22 domains with relevant domains in the SF-36 questionnaire using Pearson's Correlation Coefficient (r).ResultsThe calculated Cronbach's alpha of internal consistency for three of the corresponding domains (pain 0.85; mental health 0.87; self image 0.83) were very satisfactory and for two domains (function/activity 0.72 and satisfaction 0.67) were good. The ICC of all domains of SRS-22 questionnaire was high (ICC>0.70), demonstrating very satisfactory or excellent test/retest reproducibility. Considering concurrent validity all correlations were found to be statistically significant at the 0.01 level among related domains and generally demonstrated high correlation coefficient.ConclusionThe adapted Greek version of the SRS-22 questionnaire is valid and reliable and can be used for the assessment of the outcome of the treatment of the Greek speaking patients with idiopathic scoliosis.

Project description:BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease that often causes disabling dyspnea. In IPF and other lung diseases, patient-reported outcomes (PROs)-questionnaires designed to gather information from the patient's perspective-can determine whether therapies affect dyspnea or other outcomes meaningful to patients. Before a PRO can be used confidently as an outcome measure in a longitudinal trial, studies must demonstrate the PRO's ability to capture change over time in the target population. Our goal in this study was to examine whether the UCSD Shortness of Breath Questionnaire does so in patients with IPF.MethodsWe used data from the Sildenafil Trial of Exercise Performance in Idiopathic Pulmonary Fibrosis (STEP-IPF) to perform analyses that examined associations between UCSD scores and five external measures (anchors) at baseline and over time. Anchors included the Activity domain from St. George's Respiratory Questionnaire (SGRQ-A), the Physical Functioning domain from the SF-36 (SF36-PF), forced vital capacity (FVC), diffusing capacity of the lung for carbon monoxide (DLCO), and distance walked during a timed walk test (6MWD). Linear regression models were used to examine relationships between UCSD scores and anchors over time.ResultsAt baseline, UCSD scores were weakly correlated with percent predicted FVC (-0.21, p = 0.005) and percent predicted DLCO (-0.20, p = 0.008), moderately correlated with 6MWD (-0.39, p < 0.0001) and strongly correlated with SGRQ-A (0.79, p < 0.0001) and SF36-PF (-0.72, p < 0.0001). Change over time in UCSD scores was associated with change in FVC (estimate = 2.54, standard error [SE] = 1.23, p = 0.04), SGRQ-A (estimate = 7.94, SE = 1.11, p < 0.0001), SF36-PF (estimate = 6.00, SE = 1.13, p < 0.0001), and 6MWD (estimate = 4.23, SE = 1.18, p = 0.0004) but not DLCO (estimate = 0.33, SE = 1.33, p = 0.80).ConclusionsThese results support the validity of the UCSD to assess change in dyspnea over time in patients with IPF.

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Dataset Information

Analysis of internal construct validity of the SRS-24 questionnaire.

Purpose

Methods

Results

Conclusions

Publications

Analysis of internal construct validity of the SRS-24 questionnaire.

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