Exploring the Contribution of PatientReported and

Authors: Martijn W Heymans Jon J Ford Joan M McMeeken Alexander Chan Henrica C W de Vet Willem van Mechelen

Publish Date: 2007/06/15

Volume: 17, Issue: 3, Pages: 383-397

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Abstract

Retrospective cohort study in 194 patients who were compensated because of chronic low back pain and who were treated by a physiotherapy functional restoration program Patientreported and clinician based prognostic indicators were assessed at baseline before patients entered the functional restoration program We investigated the predictive value of these indicators on work status at 6 months Relationships were studied using logistic regression analysis in a 2step bootstrap modelling approach and a nomogram was developed Discrimination and calibration of the nomogram was evaluated internally and the explained variation of the nomogram calculatedSeventy percent of workers were back to work at 6 months We found that including duration of complaints functional disability disc herniation and fear avoidance beliefs resulted in the “best” prognostic model All these factors delayed work resumption This model was used to construct a nomogram The explained variation of the nomogram was 237 Discrimination was estimated by the area under the receiver operating characteristic curve and was 076 and for calibration we used the slope estimate that was 091 The positive predictive values of the nomogram at different cutoff levels of predicted probability were goodLow back pain LBP is the most common and expensive musculoskeletal disorder in Western countries 1 Although most patients recover from LBP within the first 2 months about 10 will develop chronic LBP 2 The recovery process of persons with chronic LBP is slow and their demands on the health care system are both large and costly Total costs in Australia and the Netherlands were estimated yearly to be 400 million Euro in 1993–1994 and 4 billion Euro in 1991 respectively 3 4 Urgent identification of those patients for whom treatment is warranted is necessary to protect them from prolonged disability sickleave and medical over consumptionStudies evaluating the ability of single or combined criteria to predict change in work status following intervention can be useful in identifying patient subgroups that need more intensive interventions because of their poor prognosis Evidence exists for the predictive value of patientreported LBP indicators such as low back symptom duration severity of pain disability and fear avoidance beliefs on treatment outcome 5 6 7 However in general these prognostic models have only been able to explain a relatively small amount of variance in work status change 8 Other studies have shown that patient examination findings of lumbar segmental mobility lumbar range of motion and hip rotation can predict treatment outcome 9 10 11 It is feasible that the inclusion of both patientreport and examination findings would increase the prognostic ability of existing models and therefore increase their value for clinicians and researchersDisc herniation with associated radiculopathy DHR is a category of LBP that has accepted diagnostic criteria 12 Significant literature exists supporting the validity of criteria particularly regarding response to repeated movements that may be indicative of discogenic pain 13 However mixed results exist concerning the prognostic value of the straight leg raising and Waddell’s nonorganic signs test 14 15 16 There is no study that has evaluated the ability of clinician based pathonatomical subgroups in combination with existing patientreported criteria to predict change in work status in response to conservative treatmentSystematic reviews have concluded that multidisciplinary and physiotherapy functional restoration programs are most effective in improving pain disability and work related outcome measures for chronic LBP 17 18 Identifying subgroups of patients that are more or less responsive to functional restoration can be a successful method of enhancing treatment effects and to guide clinical decisionmaking 19

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