A brief 5-item version of the Neck Disability Index shows good psychometric properties

Abstract

BackgroundThe purpose of this secondary analysis of clinical databases of people with neck pain was to use a mixed unique conceptual and statistical approach to develop a brief version of the Neck Disability Index (NDI).MethodsAn a priori framework of neck-related function based on the International Classification of Functioning, Disability and Health was used to identify items from the original 10-item NDI that do not conceptually fit. Remaining items were subject to Rasch analysis to identify items that did not statistically fit with axioms of quantitative measurement. Finally, approaches drawn from classical test theory were used to compare stability, responsiveness and concurrent validity of the original NDI, the new brief NDI and the linearly-transformed brief NDI.ResultsConceptual analysis identified 3 items that did not fit with the construct of self-reported ability to perform activity: pain intensity, headache, and sleeping. These items were removed, and responses to the remaining 7 items drawn from an assembled database of 316 physiotherapy patients with neck pain were subject to Rasch analysis. Two items were removed due to either considerable differential item functioning (reading) or statistical redundancy (lifting). The remaining items were considered the NDI-5. Test-retest reliability, responsiveness, sensitivity to change, and concurrent validity were all comparable across the original NDI, NDI-5 and linearly-transformed NDI-5. Sensitivity to change over a 1-month period of physiotherapy was the notable exception, where the linearly-transformed NDI-5 showed superiority over the other two forms.ConclusionsA shortened version of the NDI, the NDI-5, has been constructed that is conceptually and statistically sound. Implications for research and clinical practice are discussed. Comparison with the NDI-8 is provided that suggests overall similar function across the forms, although the latter may be more sensitive to change.

Rasch analysis of the Neck Bournemouth Questionnaire to measure disability related to chronic neck pain

“…Furthermore, the PSI of Subscale 1 allows its use for research purpose. Previous studies on the NDI (8,32) reported PSI values similar to the values obtained in this study. Despite the fact that these data are from different samples, our sample was comparable in terms of male/female ratio, mean age and pain intensity.…”

Agreement between Original and Rasch-Approved Neck Disability Index

“…Six studies were then selected for full text review after title and abstract review. Of these, two Rasch solutions that met the study criteria were identi ed from 2 individual studies including a 8-item version NDI (NDI-8) developed by Van Der Velde and colleagues (Van Der Velde et al, 2009) which was based on Rasch criteria, and a 5-item version NDI (NDI-5) developed by Walton and MacDermid (2013) based on conceptual and Rasch criteria (Walton & MacDermid, 2013). This allowed 3 B&A comparisons (NDI-10 vs. NDI-8, NDI-10 vs.NDI-5, and NDI-8 vs. NDI-5).…”

“…We calculated second set of NDI scores according to the 8 item Rasch solution provided by Van Der Velde and collogues (Van Der Velde et al, 2009), where 2 items (headache and lifting) were removed and then, the ordinal scores were transferred to linear score with the maximum value of 50. For third score transformation, two steps were taken to derive the total score as recommended in a study that considered both conceptual issues and Rasch ndings (Walton & MacDermid, 2013). Firstly, 5 functional items regarding person care, concentration, working, driving, and recreation were kept into the total score calculation.…”

“…Rasch analysis based on item response theory (IRT) and Rasch modelling enables examination of unidimensionality and interval level of scaling, and can lead to a transformation strategy to convert an ordinal score to interval scaling, which can validate the use of a total sum score (Cano, Barrett, Zajicek, & Hobart, 2011). Where outcome measures are not developed using Rasch modelling, they can retrospectively be evaluated for t to the Rasch model which often result in suggested modi cations needed to obtain t. Several studies have inspected the NDI-10 using Rasch analysis and found violations of Rasch basic assumptions (Gabel, Cuesta-Vargas, Osborne, Burkett, & Melloh, 2014;Van Der Velde et al, 2009;Walton & MacDermid, 2013). They offered solutions which included exclusion of mis t items and new coding algorithms.…”

Adaptação transcultural para o português-brasileiro, validação e confiabilidade do questionário para avaliação de dor cervical Profile Fitness Mapping Neck

“…Como já mencionado de acordo com o COSMIN, a análise fatorial é parte da validade de construto (DE VET et al, 2011;MOKKINK et al, 2010) WALTON;MACDERMID, 2013;GABEL et al, 2014;HUNG et al, 2015). Possíveis explicações para essas diferenças podem estar relacionadas aos procedimentos estatísticos adotados, bem como características e tamanhos de amostras de pesquisa consideradas (HOGG-JOHNSON et al, 2009).…”