External validation and updating of prognostic models for predicting recovery of disability in people with (sub)acute neck pain was successful: broad external validation in a new prospective cohort.

QUESTION: Can existing post-treatment prognostic models for predicting neck pain recovery (primarily in terms of disability and secondarily in terms of pain intensity and perceived improvement) be externally validated and updated at the end of the treatment period and at 6 and 12 weeks of follow-up in a new Dutch cohort of people with neck pain treated with guideline-based usual care physiotherapy? DESIGN: External validation and model updating in a new prospective cohort of three previously developed prognostic models. PARTICIPANTS: People with (sub)acute neck pain and registered for primary care physiotherapy treatment. OUTCOME MEASURES: Recovery of disability, pain intensity, and perceived recovery at 6 and 12 weeks and at the end of the treatment period. RESULTS: Discriminative performance (c-statistic) of the disability model at 6 weeks was 0.73 (95% CI 0.69 to 0.77) and reasonably well calibrated after intercept recalibration. The disability model at 12 weeks and at the end of the treatment period showed discriminative c-statistic performance values of 0.69 (95% CI 0.64 to 0.73) and 0.68 (95% CI 0.63 to 0.72), respectively, and was well calibrated. Pain models and perceived recovery models did not reach acceptable performance. Cervical mobility added value to the disability models and pain catastrophising to the disability and pain models at 6 weeks. DISCUSSION: Broad external validation of the disability model was successful in people with (sub)acute neck pain and clinicians may use this model in clinical practice with reasonable accuracy. Further research is required to assess the disability model's clinical impact and generalisability, and to identify additional valuable model predictors. REGISTRATION: https://osf.io/a6r3k/.

Illness perceptions as an independent predictor of chronic low back pain and pain-related disability: a prospective cohort study.

OBJECTIVES: To investigate whether illness perceptions, measured with the Brief Illness Perception Questionnaire, are an independent predictor of chronic low back pain and pain-related disability at 12 weeks. DESIGN: A prospective, observational cohort study. SETTING: 26 outpatient primary care physiotherapy practices throughout the Netherlands. PARTICIPANTS: Acute nonspecific low back pain patients between the age of 18 and 60 years, with or without radiating pain, and a pain-free episode of at least three months before onset. INTERVENTIONS: Standard physiotherapy care according to Dutch clinical practice guidelines. OUTCOME MEASURE: Chronic low back pain defined as pain ≥3/10 on the Numeric Pain Rating Scale and as pain-related disability ≥19/70 on the Pain Disability Index measured after 12 weeks. RESULTS: Two hundred and four people with acute nonspecific low back pain completed both assessments. In the multivariable analyses, adjusted for pain intensity, disability, duration, radiating pain, depressed mood, associations of illness perceptions were OR 1.04 (95% CI: 1.01 to 1.08) for pain and 1.04 (95% CI: 0.99 to 1.09) for pain-related disability. CONCLUSIONS: Illness perceptions independently predicted chronic low back pain but not pain-related disability at 12 weeks. The added predictive value of illness perceptions was relatively low.

State anxiety improves prediction of pain and pain-related disability after 12 weeks in patients with acute low back pain: a cohort study.

QUESTION: Do measures of state anxiety and trait anxiety in people with acute low back pain (ALBP) improve prediction of chronic low back pain (CLBP), defined as pain or pain-related disability at 12 weeks? DESIGN: Observational multi-centre prospective cohort study in primary physiotherapy care with measurements at baseline and at 12 weeks of state and trait anxiety, as well as other established prognostic factors for CLBP. PARTICIPANTS: People with nonspecific ALBP, aged 18 to 60 years, who had been pain free for ≥ 3 months before their current ALBP, and who were being treated according the Dutch clinical guidelines. OUTCOME MEASURES AND ANALYSIS: CLBP was defined as a pain score ≥ 3/10 on the Numerical Pain Rating Scale (primary outcome), and as a pain-related disability score ≥ 19/70 on the Pain Disability Inventory. Univariate and multivariate logistic regression analyses estimated how the risk of CLBP differed with state and trait anxiety and other established prognostic factors. RESULTS: Most (204 of 225) participants completed both assessments. State anxiety was an independent predictor of CLBP, whether defined as pain or pain-related disability at 12 weeks, in contrast to trait anxiety. State anxiety improved the predictive performance of the model, with area under the curve (AUC) increasing from 0.64 (95% CI 0.56 to 0.71) to 0.75 (95% CI 0.68 to 0.82) and Nagelkerke's R2 increasing from 0.08 to 0.24 for the primary outcome measure, pain. For the secondary outcome measure, pain-related disability: AUC 0.63 (95% CI 0.54 to 0.72) improved to 0.73 (95% CI 0.65 to 0.82) and Nagelkerke's R2 increased from 0.05 to 0.16. Adding trait anxiety to the prognostic model for pain improved the AUC from 0.64 (95% CI 0.56 to 0.71) to 0.70 (95% CI 0.62 to 0.77) and Nagelkerke's R2 from 0.08 to 0.15. CONCLUSION: State anxiety in patients with ALBP improved prediction of CLBP, defined as pain and pain-related disability at 12 weeks.