The clinical course of acute, subacute and persistent low back pain: a systematic review and meta-analysis.

BACKGROUND: Understanding the clinical course of low back pain is essential to informing treatment recommendations and patient stratification. Our aim was to update our previous systematic review and meta-analysis to gain a better understanding of the clinical course of acute, subacute and persistent low back pain. METHODS: To update our 2012 systematic review and meta-analysis, we searched the Embase, MEDLINE and CINAHL databases from 2011 until January 2023, using our previous search strategy. We included prospective inception cohort studies if they reported on participants with acute (< 6 wk), subacute (6 to less than 12 wk) or persistent (12 to less than 52 wk) nonspecific low back pain at study entry. Primary outcome measures included pain and disability (0-100 scale). We assessed risk of bias of included studies using a modified tool and assessed the level of confidence in pooled estimates using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool. We used a mixed model design to calculate pooled estimates (mean, 95% confidence interval [CI]) of pain and disability at 0, 6, 12, 26 and 52 weeks. We treated time in 2 ways: time since study entry (inception time uncorrected) and time since pain onset (inception time corrected). We transformed the latter by adding the mean inception time to the time of study entry. RESULTS: We included 95 studies, with 60 separate cohorts in the systematic review (n = 17 974) and 47 cohorts (n = 9224) in the meta-analysis. Risk of bias of included studies was variable, with poor study attrition and follow-up, and most studies did not select participants as consecutive cases. For the acute pain cohort, the estimated mean pain score with inception time uncorrected was 56 (95% CI 49-62) at baseline, 26 (95% CI 21-31) at 6 weeks, 22 (95% CI 18-26) at 26 weeks and 21 (95% CI 17-25) at 52 weeks (moderate-certainty evidence). For the subacute pain cohort, the mean pain score was 63 (95% CI 55-71) at baseline, 29 (95% CI 22-37) at 6 weeks, 29 (95% CI 22-36) at 26 weeks and 31 (95% 23-39) at 52 weeks (moderate-certainty evidence). For the persistent pain cohort, the mean pain score was 56 (95% CI 37-74) at baseline, 48 (95% CI 32-64) at 6 weeks, 43 (95% CI 29-57) at 26 weeks and 40 (95% CI 27-54) at 52 weeks (very low-certainty evidence). The clinical course of disability was slightly more favourable than the clinical course of pain. INTERPRETATION: Participants with acute and subacute low back pain had substantial improvements in levels of pain and disability within the first 6 weeks ( moderate-certainty evidence); however, participants with persistent low back pain had high levels of pain and disability with minimal improvements over time (very low-certainty evidence). Identifying and escalating care in individuals with subacute low back pain who are recovering slowly could be a focus of intervention to reduce the likelihood of transition into persistent low back pain. PROTOCOL REGISTRATION: PROSPERO - CRD42020207442.

Does fear of movement mediate the relationship between pain intensity and disability in patients following whiplash injury? A prospective longitudinal study.

The aim of this study was to test the capacity of the Fear Avoidance Model to explain the relationship between pain and disability in patients with whiplash-associated disorders. Using the method of Baron and Kenny, we assessed the mediating effect of fear of movement on the cross-sectional and longitudinal relationships between pain and disability. Two hundred and five subjects with neck pain due to a motor vehicle accident provided pain intensity (0 to 10 numerical rating scale), fear of movement (Tampa Scale of Kinesiophobia and Pictorial Fear of Activity Scale) and disability (Neck Disability Index) scores within 4 weeks of their accident, after 3 months, and after 6 months. The analyses were consistent with the Fear Avoidance Model mediating approximately 20% to 40% of the relationship between pain and disability. Contrary to our initial hypothesis, the proportion of the total effect of pain on disability that was mediated by fear of movement did not substantially change as increasing time elapsed after the accident. The proportion mediated was slightly higher when fear of movement was measured by Tampa Scale of Kinesiophobia as compared with Pictorial Fear of Activity Scale. The findings of this study suggest that the Fear Avoidance Model plays a role in explaining a moderate proportion of the relationship between pain and disability after whiplash injury.

The Brazilian-Portuguese versions of the McGill Pain Questionnaire were reproducible, valid, and responsive in patients with musculoskeletal pain.

OBJECTIVE: To cross-culturally adapt the Short Form of the McGill Pain Questionnaire (SF-MPQ) into Brazilian-Portuguese and test the clinimetric properties of the newly developed SF-MPQ and the previously cross-culturally adapted Brazilian-Portuguese Long Form of the McGill Pain Questionnaire (LF-MPQ). STUDY DESIGN AND SETTING: The SF-MPQ was translated and adapted into Brazilian-Portuguese following recommendations from current guidelines. Both SF-MPQ and LF-MPQ were administered in a prospective longitudinal design to 203 patients with a range of musculoskeletal conditions to evaluate their clinimetric properties. RESULTS: Both questionnaires demonstrated high levels of internal consistency (Cronbach α range=0.70-0.79), reliability (intraclass correlation coefficient(2,1) range=0.69-0.85), and agreement (standard error of the measurement range=0.80-6.92). We observed positive and moderate-to-high correlations among the SF-MPQ, the LF-MPQ, and the Numerical Rating Scale (Pearson r ranging from 0.49 to 0.68). No ceiling or floor effects were detected. Both versions demonstrated acceptable levels of responsiveness (effect size range=0.30-0.60; correlations range=0.23-0.51; and area under the curve range=0.56-0.76). CONCLUSIONS: The Brazilian-Portuguese versions of the MPQ were found to be reproducible, valid, and responsive for the assessment of pain in patients with musculoskeletal conditions.