Illness perceptions; exploring mediators and/or moderators in disabling persistent low back pain. Multiple baseline single-case experimental design.

INTRODUCTION: Illness Perceptions (IPs) may play a role in the management of persistent low back pain. The mediation and/or moderation effect of IPs on primary outcomes in physiotherapy treatment is unknown. METHODS: A multiple single-case experimental design, using a matched care physiotherapy intervention, with three phases (phases A-B-A') was used including a 3 month follow up (phase A'). Primary outcomes: pain intensity, physical functioning and pain interference in daily life. Analyzes: linear mixed models, adjusted for fear of movement, catastrophizing, avoidance, sombreness and sleep. RESULTS: Nine patients were included by six different primary care physiotherapists. Repeated measures on 196 data points showed that IPs Consequences, Personal control, Identity, Concern and Emotional response had a mediation effect on all three primary outcomes. The IP Personal control acted as a moderator for all primary outcomes, with clinically relevant improvements at 3 month follow up. CONCLUSION: Our study might indicate that some IPs have a mediating or a moderating effect on the outcome of a matched care physiotherapy treatment. Assessing Personal control at baseline, as a relevant moderator for the outcome prognosis of successful physiotherapy management of persistent low back pain, should be further eplored.

Limited predictive value of illness perceptions for short-term poor recovery in musculoskeletal pain. A multi-center longitudinal study.

BACKGROUND: Musculoskeletal pain (MSP) is recognized worldwide as a major cause of increased years lived with disability. In addition to known generic prognostic factors, illness perceptions (IPs) may have predictive value for poor recovery in MSP. We were interested in the added predictive value of baseline IPs, over and above the known generic prognostic factors, on clinical recovery from MSP. Also, it is hypothesized there may be overlap between IPs and domains covered by the Four-Dimensional Symptom Questionnaire (4DSQ), measuring distress, depression, anxiety and somatization. The aim of this study is twofold; 1) to assess the added predictive value of IPs for poor recovery and 2) to assess differences in predictive value for poor recovery between the Brief Illness Perception Questionnaire - Dutch Language Version (Brief IPQ-DLV) and the 4DSQ. METHODS: An eligible sample of 251 patients with musculoskeletal pain attending outpatient physical therapy were included in a multi-center longitudinal cohort study. Pain intensity, physical functioning and Global Perceived Effect were the primary outcomes. Hierarchical logistic regression models were used to assess the added value of baseline IPs for predicting poor recovery. To investigate the performance of the models, the levels of calibration (Hosmer-Lemeshov test) and discrimination (Area under the Curve (AUC)) were assessed. RESULTS: Baseline 'Treatment Control' added little predictive value for poor recovery in pain intensity [Odds Ratio (OR) 0.80 (Confidence Interval (CI) 0.66-0.97), increase in AUC 2%] and global perceived effect [OR 0.78 (CI 0.65-0.93), increase in AUC 3%]. Baseline 'Timeline' added little predictive value for poor recovery in physical functioning [OR 1.16 (CI 1.03-1.30), increase in AUC 2%]. There was a non-significant difference between AUCs in predictive value for poor recovery between the Brief IPQ-DLV and the 4DSQ. CONCLUSIONS: Based on the findings of this explorative study, assessing baseline IPs, over and above the known generic prognostic factors, does not result in a substantial improvement in the prediction of poor recovery. Also, no recommendations can be given for preferring either the 4DSQ or the Brief IPQ-DLV to assess psychological factors.

Illness perceptions associated with patient burden with musculoskeletal pain in outpatient physical therapy practice, a cross-sectional study.

INTRODUCTION: Musculoskeletal pain (MSP) is a burden to patients and to society. In addition to well-known prognostic factors, illness perceptions (IPs) may be associated with pain intensity and physical functioning in MSP but their role is not fully understood. Our research focused on these questions: 1) Do IPs differ between patients with acute, sub-acute and persistent MSP 2) Are IPs, in addition to well-known prognostic factors, associated with pain intensity and with limitations in physical functioning? METHODS: Eligible MSP patients from 29 physical therapy practices were invited to participate in a cross-sectional study. IPs were measured with the Brief IPQ-DLV. We compared IPs between patients with acute, sub-acute and persistent MSP (1-way ANOVA with Tukey post-hoc tests). Secondly, associations between IPs with pain intensity and physical functioning were assessed (multiple linear regression). RESULTS: With 658 participants, most IP dimensions showed small differences between acute, sub-acute or persistent pain. For pain intensity, the IP dimensions Consequences, Identity and Comprehensibility explained an additional 13.3% of the variance. For physical functioning, the dimensions Consequences, Treatment Control, Identity and Concern explained an additional 26.5% of the variance. DISCUSSION/CONCLUSION: Most IP dimensions showed small differences between acute, sub-acute or persistent pain. In addition to some well-known prognostic variables, higher scores on some IP dimensions are associated with higher pain intensity and more limitations in physical functioning in patients with MSP. Longitudinal studies are needed to explore the longitudinal associations.