Construct validity of instruments measuring impairments in body structures and function in rheumatic disorders: which constructs are selected for validation? A systematic review.

PURPOSE: This paper focuses on the construct validity of instruments measuring impairments in body structures and function in rheumatic disorders. The objective is: 1) to make an inventory of constructs, based on the domains of the International Classification of Functioning, Disabilities and Health problems (ICF), against which instruments measuring impairments in body structures and function were validated; 2) to analyse whether validation against a similar construct resulted in higher correlation coefficients than validation against a dissimilar construct. METHODS: In a systematic review papers were identified in which instruments measuring impairments in body structures and function for patients with rheumatic disorders were validated. The instruments identified were assessed on their methodological properties and the constructs against which they were validated. Subsequently, pooled (interclass) correlations of similar constructs and dissimilar constructs against which was validated were compared. An instrument was decided to have good construct validity, if the correlation coefficient was 0.50 or higher, and the measurement instrument in question is validated against similar constructs. RESULTS: In total 216 papers were identified analysing the validity of 42 different instruments. Only 16% of these instruments were validated against instruments that represent the most similar construct. In general, estimates of construct validity were lower when validated against dissimilar constructs, except for instruments measuring impairments in mental functions. CONCLUSION: There is a trend that validation against a similar construct yields higher correlation coefficients than validation against a dissimilar construct. If an instrument measuring impairments is validated against the most similar construct, and a criterion of r > 0.50 is applied, only 10 out of the 42 identified instruments turned out to be valid.

Reliability, validity and responsiveness of instruments to assess disabilities in personal care in patients with rheumatic disorders. A systematic review.

OBJECTIVES: The first aim was to make an inventory of available instruments and questionnaires for the assessment of disabilities in personal care in patients with rheumatic disorders. The second aim was to investigate which of these instruments have acceptable, methodological quality with regard to reliability, validity and responsiveness. The third aim was to investigate the assumption that convergent validity results in stronger correlations when validated against a more similar construct. METHODS: A computer-aided literature search (1982-2001) in several databases was performed to identify studies focusing on the clinimetric properties of instruments to assess impairments in function in patients with rheumatic disorders. Data were extracted in a standardised way and compared to a priori defined criteria. RESULTS: In total, 19 measurement instruments were included. Five out of these 19 were found to have acceptable reliability, while 12 had acceptable validity. Only three questionnaires met both criteria. Results concerning the responsiveness of these three questionnaires were conflicting. No difference was found in the strength of correlation between validation against the most similar construct versus validation against the least similar construct. CONCLUSION: It is concluded that the Arthritis Impact Measurement Scale (AIMS) is the most suitable instrument for the assessment of disabilities in personal care.

Which are the best instruments for measuring disabilities in gait and gait-related activities in patients with rheumatic disorders.

OBJECTIVES: Our first objective was to make an inventory of available instruments for the assessment of disabilities in gait and related activities in patients with rheumatic disorders. Our second aim was to investigate which of these instruments have acceptable methodological quality with regard to reliability and validity. Our third aim was to investigate the assumption that the evaluation of convergent construct validity results in stronger correlations when validated against a more similar construct. MATERIALS: A computer-aided literature search (1982-2001) of several databases was performed to identify studies focusing on the clinimetric properties of instruments to assess impairments in function in patients with rheumatic disorders. Data on intra-rater reliability, inter-rater reliability and convergent construct validity were extracted in a standardized manner and compared to a priori defined criteria. RESULTS: In total 78 instruments were eligible. Intra-observer reliability was investigated for 28 instruments and only 7 demonstrated good reliability as well as good validity. Surprisingly, the convergent construct validation against a similar construct resulted often in lower correlations than validation against a less similar construct. CONCLUSION: Based on the available information, the Rheumatoid Arthritis Quality of Life Scale and the Health Assessment Questionnaire seem to be the best instruments for assessing disabilities in gait and related activities in patients with rheumatic disorders.

Psychometric properties of the Tampa Scale for kinesiophobia and the fear-avoidance beliefs questionnaire in acute low back pain.

The transition from acute to chronic low back pain (LBP) is influenced by many interacting factors. Pain-related fear, as measured by the Tampa Scale for Kinesiophobia (TSK) and the Fear-Avoidance Beliefs Questionnaire (FABQ), is one of these factors. The objectives of this study were to investigate, in a population with acute LBP, the reliability of TSK and FABQ through evaluation of the internal consistency, the test-retest reliability, and the concurrent validity between TSK and FABQ. One hundred and Seventy-Six patients suffering LBP for no longer than 4 weeks completed a Visual Analogue Scale for pain (VAS), the TSK, the FABQ, and a socio-demographic questionnaire. Each patient completed the VAS, TSK, and FABQ twice within 24 h. Internal consistency of TSK and FABQ scores range from alpha=0.70 to 0.83. Test-retest reliability ranges from r(s)=0.64 to 0.80 (P<0.01). Concurrent validity is moderate, ranging from r(s) =0.33 to 0.59 (P<0.01). It may be concluded that in a population with acute LBP, both the TSK and the FABQ are reliable measures of pain-related fear. In the clinical setting they may provide the practitioner a means of identifying pain-related fear in a patient with acute LBP.

Upper cervical instability: are clinical tests reliable?

SUMMARY. The aim of this preliminary study was to investigate the reliability of a selection of manual tests used for the examination of instability of the upper cervical region. Eleven children with Down's syndrome were examined by four independent examiners with different levels of experience in manual therapy. Three tests as described by Van der El (1992) were used: the lateral displacement test, the Sharp-Purser test, and the upper cervical flexion test. Scores of tests and retests were statistically analysed by calculating the percentage of agreement, and Brennan and Prediger's modified kappa, and with the binomial test. The results showed a significant agreement between test and retest for the upper cervical flexion test in three out of four investigators. Agreement between investigators was significant in four out of six combinations between two investigators, and near to significant for this test (P(bin) =.07) in the two remaining combinations. The other two investigated tests and the total score showed no tendancy towards a consistent level of significant intra- or interobserver reliability. Copyright 1997 Harcourt Publishers Ltd.

Upper cervical instability: fact or fiction?

OBJECTIVES: The purpose of this review is to examine the internal validity of the standardized clinical stability tests for the upper cervical spine in relation to symptomatology. Whether radiology can confirm the clinical diagnosis is also examined. The importance of radiology in this situation, the pathogenesis and the prevalence of atlanto-axial hypermobility and the clinical symptomatology are discussed. DATA SOURCES: A literature search from January 1984 to March 1995. We consulted the CD-ROM Medline with the keywords "atlanto-axial instability," "atlanto-axial dislocation," "hypermobility," "cervical spine" and "atlanto-axial joint." Ninety-six Dutch, French, German, and English publications were selected. The Documentation Centre of the Institute for Research and Postgraduate Education Physiotherapy (SWSF) was consulted with the keywords: atlanto-axial joint, upper cervical spine, segmental examination, interobserver-reliability, intraobserver-reliability, interobserver variation, intraobserver variation, manual therapy, examination, diagnostics. Finally, recent developments and views published during this study were added. RESULTS: There seems to be no correlation between the amount of hypermobility or subluxation and the presence of clinical signs or neurological signs. The clinical signs can vary from relatively diffuse complaints, no symptoms and signs to serious ones. Radiology does not seem to be a reliable diagnostic mechanism in relation to upper-cervical instability. Conventional X-rays fail to give adequate information about atlanto-axial stability. CT-scan and MRI can visualize much more because of the direct sagittal projection but neither is an absolute standard. Furthermore, in relation to upper-cervical hypermobility, the validity of radiology is under debate. CONCLUSION: There is no correlation between the measure of hypermobility and the presence of clinical symptoms. Also, the validity of the upper-cervical stability tests is questionable. In diagnostics, every radiological examination measures anatomical and morphological variables, not functional variables. Despite this, CT and MRI should be preferred in diagnostics over conventional functional radiology.