DEVELOPMENT AND VALIDATION OF THE CURTIN BACK SCREENING QUESTIONNAIRE(CBSQ) - A DISCRIMINATIVE DISABILITY MEASURE

Disability accompanying occupational low back pain (LBP) can include a wide range of incapacitating symptoms which, for the practitioner, ca n be time-consuming and difficult to identify systematically. A questi onnaire designed for case-finding and assessment could assist in both the early recognition of disability and in planning management. A suit able questionnaire for clinical use could not be found in the literatu re. The Curtin Back Screening Questionnaire (CBSQ) was developed, ther efore, as a discriminative screening instrument to serve this purpose. The methods and results of the development and validation of the CBSQ are presented herein. Development of the questionnaire followed the p rinciples of Kirschner and Guyatt (1985) employing data from 74 subjec ts with at least moderately severe work-related LBP. The research desi gn for the validation was multiple-group repeated-measures with a stud y population of 150 subjects. The screening function of the questionna ire was developed through selecting 8 questions from the whole questio nnaire using regression analysis. The questionnaire includes 79 items based on the subjects' perceived health status. The response structure of the CBSQ has been adapted from that of the General Health Question naire (GHQ) and some items in the CBSQ have been developed from items in the Sickness Impact Profile (SIP) and GHQ. The questionnaire discri minates effectively between subjects with different degrees of disabil ity, it correlates quite well with the SIP, test-retest reliability fo r the whole questionnaire is 0.98, the receiver-operating characterist ics are more favourable than those for the SIP, and the CBSQ screening score provides an index of severity which correlates with work incapa city. The CBSQ is a self-administered discriminative instrument design ed specifically for subjects with disabling occupational LBP. It can b e used clinically and in surveys by providing a disability severity sc ore for screening purposes, as well as an itemised description of disa bility within 11 categories of functional incapacity.