Cohort studies of aetiology and prognosis: they're different

Preoperative measures of pain at rest and movement-evoked pain in knee arthroplasty: Associations with pain and function outcome trajectories from a prospective multicentre longitudinal cohort study

BACKGROUND

The study of pain at rest (PAR) and movement-evoked pain (MEP) in persons with musculoskeletal pain has received substantial attention. Despite strong interest, relatively little attention has been directed to the psychometric development of these constructs. Our purpose was to explore the relationship between PAR and MEP and to examine the prognostic utility of these measures in persons with knee arthroplasty.

METHODS

We used prospectively collected data from persons scheduled for knee arthroplasty who had moderate to high levels of pain catastrophizing. Preoperative latent variables for PAR and MEP were developed and used to determine if they were associated with a binary latent variable of good versus poor pain and function outcome trajectories. Factor correlations were used to determine the extent to which the variance for PAR and MEP was overlapping.

RESULTS

PAR and MEP are significant predictors of good versus poor pain and function classes. Odds ratios ranged from 1.21 to 1.64 (p < 0.001) indicating a significant increase in the likelihood of poor outcome. Correlation between PAR and MEP latent variables was high (r = 0.89; 95% CI: 0.86-0.92) indicating substantially overlapping variance.

CONCLUSIONS

PAR and MEP, as defined in our study, can be used to make prognostic judgements regarding risk of poor postoperative outcome trajectory following knee arthroplasty. However, PAR and MEP showed substantially overlapping variance indicating that measurements of both are not necessary when making prognostic assessments.

SIGNIFICANCE STATEMENT

Preoperative PAR and MEP latent variables, as defined in our study, had prognostic significance for 1 year pain and function outcome trajectories. PAR and MEP latent variables had substantially overlapping variance which suggested that only one is needed to make prognostic judgements. The prognostic significance of PAR and MEP as well as their substantially overlapping variance is new to the field prognostic research in knee arthroplasty.

Detection and Characterization of Endplate Structural Defects on CT: A Diagnostic Accuracy Study

STUDY DESIGN

Diagnostic test study.

OBJECTIVE

To determine the reliability and validity or diagnostic accuracy of two previously described endplate structural defect (EPSD) assessment methods.

SUMMARY OF BACKGROUND DATA

Studies of EPSD may further the understanding of pathoanatomic mechanisms underlying back pain. However, clinical imaging methods used to document EPSD have not been validated, leaving uncertainty about what the observations represent.

MATERIALS AND METHODS

Using an evaluation manual, 418 endplates on CT sagittal slices obtained from 19 embalmed cadavers (9 men and 10 women, aged 62-91 yr) were independently assessed by two experienced radiologists and a novice for EPSD using the two methods. The corresponding micro-CT (µCT) from the harvested T7-S1 spines were assessed by another independent rater with excellent intra-rater reliability (k=0.96).

RESULTS

Inter-rater reliability was good for the presence (k=0.60-0.69) and fair for specific phenotypes (k=0.43-0.58) of EPSD. Erosion, for which the Brayda-Bruno classification lacked a category, was mainly (82.8%) classified as wavy/irregular, while many notched defects (n=15, 46.9%) and Schmorl's nodes (n=45, 79%) were recorded as focal defects using Feng's classification. When compared to µCT, endplate fractures (n=53) and corner defects (n=28) were routinely missed on CT. Endplates classified as wavy/irregular on CT corresponded to erosion (n=29, 21.2%), jagged defects (n=21, 15.3%), calcification (n=19, 13.9%), and other phenotypes on µCT. Some focal defects on CT represented endplate fractures (n=21, 27.6%) on µCT. Overall, with respect to the presence of an EPSD, there was a sensitivity of 70.9% and a specificity of 79.1% using Feng's method, and 79.5% and 57.5% using Brayda-Bruno's method. Poor to fair inter-rater reliability (k=0.26-0.47) was observed for defect dimensions.

CONCLUSION

There was good inter-rater reliability and evidence of criterion validity supporting assessments of EPSD presence using both methods. However, neither method contained all needed EPSD phenotypes for optimal sensitivity, and specific phenotypes were often misclassified.

Changes in spinal motor behaviour are associated with reduction in disability in chronic low back pain: A longitudinal cohort study with 1-year follow-up

BACKGROUND

The need to improve spinal motor behaviour in chronic low back pain (CLBP) rehabilitation remains unclear. The objective of this study was to test if changes in spinal motor behaviour were associated with changes in disability after an interdisciplinary rehabilitation program (IRP) in patients with CLBP.

METHODS

Seventy-one patients with CLBP participating in an IRP were included. Spinal motor behaviour was assessed with biomechanical (lumbar angular amplitude and velocity, erector spinae muscle activity and duration of the task), cognitive-emotional (task-specific fear [PRF]) and pain-related (movement-evoked pain [MEP]) measures during a lifting task before and after the IRP. Disability was measured before and after the IRP, and at 3-month and 1-year follow-ups.

RESULTS

After adjusting for confounders, changes in disability were significantly associated with MEP changes (β adj. = 0.49, p < 0.001) and PRF changes (β adj. = 0.36, p = 0.008), but not with changes in any of the biomechanical measures. MEP at the end of IRP was also associated with disability at 3 months (β adj. = 0.37, p = 0.001) and 1 year (β adj. = 0.42, p = 0.01). Biomechanical measures at the end of the IRP were not associated with disability, except for the duration of the task that was significantly associated with reduction of disability at 3 months (β non-adj = 0.5, p < 0.001).

CONCLUSIONS

Pain-related and cognitive-emotional measures of spinal motor behaviour were associated with reduction in disability following an IRP. Future research is needed to further investigate causal relationships between spinal motor behaviour and disability.

SIGNIFICANCE STATEMENT

This study supports a multidimensional understanding and analysis of spinal motor behaviour, integrating the cognitive-emotional, pain-related and biomechanical domains. It also supports the consideration of spinal motor behaviour as a potentially important treatment target in chronic low back pain management. Moreover, it suggests that reducing movement-evoked pain and task-specific fear may have more influence on disability than changing lumbar amplitude, lumbar angular velocity or erector muscle activity, which may have important implications for rehabilitation.

Indeed, Correlation Does Not Indicate Causation!

Author response to the JOSPT Letter to the Editor-in-Chief "Lower-Limb Kinematics and Clinical Outcomes: Correlation Does not Imply Causality" J Orthop Sports Phys Ther 2023;53(11):723-725. doi:10.2519/jospt.2023.0203-R.

Reduction in pain-related fear is not associated with improvement in spinal biomechanics but with decrease in movement-evoked pain in patients with chronic low back pain

BACKGROUND AND AIMS

While a causal relationship between pain-related fear and spinal movement avoidance in patients with chronic low back pain (CLBP) has frequently been postulated, evidence supporting this relationship is limited. This study aimed to test if decreases in pain-related fear or catastrophizing were associated with improvements in spinal biomechanics, accounting for possible changes in movement-evoked pain.

METHODS

Sixty-two patients with CLBP were assessed before and after an interdisciplinary rehabilitation program (IRP). Pain-related fear was assessed with general and task-specific measures. Lower and upper lumbar angular amplitude and velocity as well as paraspinal muscle activity were recorded during five daily-life tasks to evaluate spinal biomechanics. Relationships were tested with multivariable linear regression analyses.

RESULTS

The large decreases in pain-related fear and catastrophizing following the IRP were scarcely and inconsistently associated with changes in spinal biomechanics (< 3% of the models reported a statistically significant association). Results remained comparable for activities inducing more or less fear, for specific or general measures of pain-related fear, and for analyses performed on the entire population or limited to subgroups of patients with higher levels of task-specific fear. In contrast, reductions in task-specific pain-related fear were significantly associated with decreases in movement-evoked pain in all tasks (r = 0.26-0.62, p ≤ 0.02).

CONCLUSION

This study does not support an association between pain-related fear and spinal movement avoidance. However, it provides evidence supporting a direct relationship between decreased pain-related fear and decreased movement-evoked pain, possibly explaining some mechanisms of the rehabilitation programs.

Predicting readiness for return to sport and performance after anterior cruciate ligament reconstruction rehabilitation

BACKGROUND

Determining readiness to return to sport after anterior cruciate ligament (ACL) reconstruction is challenging.

OBJECTIVES

To develop models to predict initial (directly after rehabilitation) and sustainable (one year after rehabilitation) return to sport and performance in individuals after ACL reconstruction.

METHODS

We conducted a multicentre, prospective cohort study and included 208 participants. Potential predictors - demographics, pain, effusion, knee extension, muscle strength tests, jump tasks and three sport-specific questionnaires - were measured at the end of rehabilitation and 12 months post discharge from rehabilitation. Four prediction models were developed using backward logistic regression. All models were internally validated by bootstrapping.

RESULTS

All 4 models shared 3 predictors: the participant's goal to return to their pre-injury level of sport, the participant's psychological readiness and ACL injury on the non-dominant leg. Another predictor for initial return to sport was no knee valgus, and, for sustainable return to sport, the single-leg side hop. Bootstrapping shrinkage factor was between 0.91 and 0.95, therefore the models' properties were similar before and after internal validation. The areas under the curve of the models ranged from 0.74 to 0.86. Nagelkerke's R2 varied from 0.23 to 0.43 and the Hosmer-Lemeshow test results varied from 2.7 (p = 0.95) to 8.2 (p = 0.41).

CONCLUSION

Initial and sustainable return to sport and performance after anterior cruciate ligament reconstruction rehabilitation can be easily predicted by the sport goal formulated by the individual, the individual's psychological readiness, and whether the affected leg is the dominant or non-dominant leg.

Effects of psychological distress on the general health to self-reported pain and function outcome relationship in knee arthroplasty: A causal mediation study

Objectives

We examined two potential causal pathways that could be intervention targets to enhance knee arthroplasty outcomes. Data from a no-effect trial of persons with moderate to high pain catastrophizing were used to determined whether pain catastrophizing, depressive symptoms causally mediate the effect of preoperative general health on postoperative knee pain and functional difficulty.

Methods

We used natural-effects models to conduct causal mediation analyses using the preoperative dichotomized EQ-5D-5L general health measure as the exposure, 2-month postoperative pain catastrophizing, depressive symptoms, and localized knee pain as potential mediators, and 12-month dichotomized Western Ontario and McMaster's University Osteoarthritis Index (WOMAC) Pain and Function scores reflecting good versus poor outcome as the outcomes.

Results

Estimates of the indirect (mediating) effect suggested that pain catastrophizing mediated the effect of preoperative general health on 12-month WOMAC pain score by increasing odds of a good outcome by 8% (natural indirect effect odds ratio ​= ​1.08, 95% CI: 0.88, 1.29). The direction of mediating effects and their magnitude were similar for depressive symptoms; Sensitivity analyses suggested similar magnitudes and mediating effects to those reported for the main analyses.

Conclusions

Our findings suggested that pain catastrophizing and depressive symptoms have a mediating role on the effect of baseline general health on self-reported pain and function outcomes. These findings support the continued treatment of pain catastrophizing and depressive symptoms as viable targets for interventions to potentially enhance pain and function outcomes for patients with moderate to high levels of psychological distress prior to surgery.

Prognostic value of balance performance for improvements of community ambulation among stroke patients: a cohort study

BACKGROUND

Despite the positive impact of improving the level of community ambulation among stroke patients, little prognostic research has focused on this indicator.

AIM

To investigate the prognostic value of the side-by-side, semi-tandem, and tandem standing balance positions and the five-sit-stand (5STS) test for discriminating patients undergoing physical rehabilitation who improve level of functional ambulation and predicting transition time.

DESIGN

A cohort study with assessments repeated monthly until discharge for classifying patients in a community ambulation class.

SETTING

A neurological rehabilitation unit of a hospital in Spain.

POPULATION

A consecutive sample of 109 stroke patients (68.5±12.0 years) was screened and included within four months post stroke. Of them no one refused, 3 died, and 5 were lost earlier to transition or discharge.

METHODS

Balance tests, the 5STS and gait speed were measured at the center at baseline and monthly until discharge. Transition from household or limited community ambulation to a higher ambulatory capacity or class. Area under the curve (AUC) were used to compare discriminative abilities of the tests and Cox regression analysis to evaluate the association between the tests and time of transition.

RESULTS

For household non-ambulators, the semi-tandem was the best discriminative test (AUC=0.850) and the three balance tests showed an association with time to transition. Among the limited community ambulators, the 5STS test also revealed discriminative ability (AUC: 0.822 [0.63-1.00]), with a good prognostic cut-off (14.8 seconds) and association with time to transition (Hazard Ratio: 1.22; 95%CI: 1.05-1.43).

CONCLUSIONS

Semi-tandem and the 5STS tests can discriminate patients who improve level of functional ambulation and predict transition times within three months in non-ambulators and limited community ambulation patients, respectively.

CLINICAL REHABILITATION IMPACT

The semi-tandem and the 5STS tests can be performed easily in clinical settings to predict improvement of functional ambulation level in patients following stroke.

Development and external validation of a prediction model for patient-relevant outcomes in patients with chronic widespread pain and fibromyalgia

BACKGROUND

The objective of this study was to develop prediction models and explore the external validity of the models in a large sample of patients with chronic widespread pain (CWP) and fibromyalgia (FM).

METHODS

Patients with CWP and FM referred to rehabilitation services in Norway (n=986) self-reported data on potential predictors prior to entering rehabilitation, and self-reported outcomes at one-year follow-up. Logistic regression models of improvement, worsening and work status, and a linear regression model of health-related quality of life (HRQoL), were developed using lasso regression. Externally validated estimates of model performance were obtained from the validation set.

RESULTS

The number of participants in the development and the validation sets was 771 and 215 respectively; only participants with outcome data (n = 519-532 and 185, respectively) were included in the analyses. On average, HRQoL and work status changed little over one year. The prediction models included 10-11 predictors. Discrimination (AUC statistic) for prediction of outcome at follow-up was 0.71 for improvement, 0.67 for worsening, and 0.87 for working. The median absolute error of predictions of HRQoL was 0.36 (0.22-0.51). Reasonably good predictions of working at follow-up and HRQoL could be obtained using only the baseline scores as predictors.

CONCLUSIONS

Moderately complex predictions models (10-11 predictors) generated poor to excellent predictions of patient-relevant outcomes. Simple prediction models of working and HRQoL at follow-up may be nearly as accurate and more practical.

Fear of Reinjury Following Surgical and Nonsurgical Management of Anterior Cruciate Ligament Injury: An Exploratory Analysis of the NACOX Multicenter Longitudinal Cohort Study

OBJECTIVES

The purpose of this study was to compare fear and certainty of reinjury between follow-up time points and treatment groups (no anterior cruciate ligament [ACL] reconstruction [no ACLR], pre-ACLR, post-ACLR) and to identify prognostic factors for fear of reinjury at 3 and 12 months following injury or ACLR.

METHODS

An exploratory analysis of the Natural Corollaries and Recovery After ACL-injury multicenter longitudinal cohort study was conducted. Patients (n = 275) with primary ACL injury and 15 to 40 years of age received usual care (initial physical therapist-supervised rehabilitation, before considering ACLR). Fear of reinjury (as measured with the Anterior Cruciate Ligament Quality of Life instrument [ACL-QOL] item 31 and the Anterior Cruciate Ligament Return to Sport After Injury instrument [ACL-RSI] item 9) and certainty of reinjury (as measured with the Knee Self-Efficacy Scale item D2) were evaluated at baseline and at 3, 6, and 12 months following ACL injury or ACLR. Comparisons were performed with linear mixed models. Linear regression assessed potential prognostic factors (age, sex, preinjury activity, baseline knee function, baseline general self-efficacy, and expected recovery time) for fear of reinjury (ACL-QOL item 31) at the 3- and 12-month follow-up assessments.

RESULTS

Fear of reinjury was common regardless of ACL treatment. Fear of reinjury decreased between 3 and 6 months and 3 and 12 months (mean difference: ACL-QOL = 9 [95% CI = 2 to 15]; ACL-RSI = 21 [95% CI = 13 to 28]) after injury. This improvement was not observed in patients who later underwent ACLR, who reported worse fear of reinjury at 3 months (ACL-QOL = 10 [95% CI = 3 to 18]) and at 12 months (ACL-RSI = 22 [95% CI = 2 to 42]) postinjury compared with those who did not proceed to ACLR. Following ACLR, fear of reinjury decreased between the 3- and 12-month follow-up assessments (ACL-QOL = 10 [95% CI = 4 to 16]; ACL-RSI = 12 [95% CI = 5 to 19]). Greater baseline general self-efficacy was associated with reduced fear of reinjury at 12 months after injury (adjusted coefficient = 1.7 [95% CI = 0.0 to 3.5]). Female sex was related to more fear of reinjury 3 months after ACLR (-14.5 [95% CI = -25.9 to -3.1]), and better baseline knee function was related to reduced fear of reinjury 12 months after ACLR (0.3 [95% CI = 0.0 to 0.7]).

CONCLUSION

People who had ACLR reported worse fear of reinjury before surgery than those who did not proceed to ACLR. Different prognostic factors for fear of reinjury were identified in people treated with ACLR and those treated with rehabilitation alone.

IMPACT

Fear of reinjury is a concern following ACL injury. Clinicians should evaluate and address reinjury fears. These results may assist in identifying individuals at risk of fear of reinjury following surgical and nonsurgical management of ACL injury.

Prognostic value of the five-repetition sit-to-stand test for mortality in people with chronic obstructive pulmonary disease

BACKGROUND

Prognostic studies suggest that some musculoskeletal and functional capacity tests are independently associated with mortality in chronic obstructive pulmonary disease (COPD), but comparing their prognostic value is difficult because of differences in the selected covariates for regression modelling in those studies.

OBJECTIVES

To assess the prognostic value of five musculoskeletal and functional capacity tests in predicting mortality risk in patients with COPD after adjusting for existing and confounding prognostic factors and to compare their ability to correctly discriminate the mortality of individual participants using the 6-min walk test (6MWT). We hypothesized that the examined tests have different prognostic value.

METHODS

Prospective and longitudinal study. A total of 137 patients with stable COPD (mean [SD] age 67 [8.33] years; 87% male) were recruited from a hospital in Spain during 2014 and followed for 5 years (2014-2019). No one refused and only one was lost to follow-up. The outcome measure was 5 year all-cause mortality.

RESULTS

A total of 37 patients died within 5 years. All musculoskeletal tests were associated with 5 year all-cause mortality in Cox proportional-hazards regression models. However, only the five-repetition sit-to-stand test (5-STS) score was an independent prognostic factor (hazard ratio 1.04 per sec, 95% confidence interval 1.01-1.08) after adjusting for history of heart disease, number of previous severe exacerbations, and dyspnoea. This model explained 50.7% of the variance in mortality. This test exhibited similar discriminative ability as the 6MWT for 5 year mortality (area under the receiver operating characteristic curve: 0.741vs 0.722; p = 0.92), and a highly prognostic cut-off for discriminating (15.98 s). This cut-off had higher likelihood ratios (LRs) than the 6MWT cut-off (∼350 m), especially for negative LRs (1/LR-: 7.69vs 2.00).

CONCLUSIONS

The 5-STS is an objective measure for predicting mortality in patients with COPD and has good discriminative ability, with a cut-off for discriminating survival slight better than the 6MWT. The prognostic value of the other tests remains to be confirmed.

Number of musculoskeletal pain sites leads to increased long-term healthcare contacts and healthcare related costs - a Danish population-based cohort study

BACKGROUND

People with musculoskeletal pain seek more healthcare than the general population, however little is known about the long-term effect on healthcare use. The aim of this study was to examine the consequences of number of musculoskeletal pain sites on long-term care-seeking and healthcare-related costs and explore how health anxiety influences this relationship.

METHODS

We conducted a Danish population-based longitudinal cohort study of 4883 participants combining self-reported survey data from 2008 with ten-year follow-up data from national health registers. Using a causal inference framework, we examined associations between number of pain sites (range 0-7)/level of health anxiety (high/low level) and face-to-face healthcare contacts/healthcare-related costs. Data were analyzed using negative binomial regression with generalized estimating equations. Regression models were adjusted for sex, age, duration of pain, level of education, comorbidity, personality traits, risk of depression, marital status, physical job exposure, and previous healthcare utilization.

RESULTS

For each additional pain site general healthcare contacts (Incidence Rate Ratio (IRR): 1.04 (95% CI: 1.03-1.05)), healthcare-related costs (IRR: 1.06 (95% CI: 1.03-1.08) and musculoskeletal healthcare contacts (IRR: 1.11 (95% CI:1.09-1.14) increased. Those with high levels of health anxiety at baseline had a slightly higher number of general healthcare contacts (IRR 1.06 (1.01-1.11), independent of number of pain sites. However, level of anxiety did not influence the effect of number of pain sites on any healthcare use or cost outcomes.

CONCLUSIONS

We found evidence for a causal association between increasing number of pain sites and greater healthcare use and cost, and high levels of health anxiety did not increase the strength of this association. This suggests that number of pain sites could be a potential target for biopsychosocial interventions in order to reduce the need for future care-seeking.

Characteristics Associated With People With Chronic Low Back Pain Meeting Physical Activity Guidelines and Recommendations for Sedentary Behavior: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to identify factors associated with meeting physical activity guidelines and sedentary recommendations in people with chronic low back pain (LBP).

METHODS

This was a cross-sectional study including 171 people with chronic LBP. Trained assessors collected information regarding demographic, anthropometric, and clinical data. Physical activity levels and sedentary time were objectively measured using a tri-axial accelerometer. Participants were classified as being physically active (ie, performing at least 150 minutes of moderate or 75 minutes of vigorous physical activity per week) and sedentary (ie, more than 8 hours of time spent in sedentary activities per day). Multivariable logistic regression analyses were used to determine the association of being physically active or sedentary with the range of demographic, anthropometric and clinical variables.

RESULTS

Our results showed that although lower body mass index (odds ratio [OR] = 0.91; 95% CI: 0.85-0.98) and higher self-reported levels of leisure time physical activity (OR = 3.46; 95% CI: 1.94-6.15) were associated with being physically active, lower self-reported levels of physical activity at work (OR = 0.56; 95% CI: 0.39-0.81) was associated with being sedentary.

CONCLUSION

Our findings showed that, in people with LBP, lower body mass index and higher levels of leisure time physical activity may be important factors for identifying those physically active. In contrast, lower levels of physical activity at work may be considered when identifying sedentary people with LBP. Future studies should consider these factors when designing interventions aiming to promote physical activity and decrease sedentary behavior in this population.

Paretic and Nonparetic Step Tests Are Noninterchangeable in Stroke: A Prospective Cohort Study

OBJECTIVE

The step test (ST) is a common clinical assessment of dynamic balance among survivors of stroke. The ST assesses a person's ability to place their paretic (paretic ST) or nonparetic (nonparetic ST) foot rapidly and repeatedly on and off a standardized block while standing. No study has formally explored if the 2 tests are interchangeable. Our study aimed to: (1) differentiate the correlates of paretic and nonparetic ST, and (2) compare their associations with physical function and falls.

METHODS

Eighty-one survivors of stroke were consecutively recruited from inpatient rehabilitation units (n = 4) and were assessed within 1 week prior to discharge. In addition to the ST, a handheld dynamometer and computerized posturography were used to measure lower limb muscle strength and standing balance, respectively. Self-selected gait speed and Timed Up and Go test were also assessed as measures of physical function. Falls data were monitored for 12 months post discharge using monthly calendars. Multivariable regression analyses were used to differentiate (1) the correlates of paretic and nonparetic STs, and (2) their associations with physical function and falls.

RESULTS

The median score for the paretic and nonparetic STs were 8 and 9 steps, respectively. Paretic ankle plantar-flexor and dorsiflexor strength were the strongest correlates of nonparetic ST, whereas both paretic ankle and knee extensor strength were the strongest correlates of paretic ST. In multivariable analyses adjusting for each other, both STs were independently associated with gait speed and Timed Up and Go scores. Paretic ST (odds ratio = 0.37; 95% CI = 0.22 to 0.62) was a stronger predictor than nonparetic ST (odds ratio = 0.51; 95% CI = 0.34 to 0.78) in predicting future falls.

CONCLUSION

This study confirmed that the paretic and nonparetic STs are noninterchangeable. ST scores should be assessed separately to achieve a more complete interpretation.

IMPACT

To our knowledge, this study is the first to objectively evaluate the similarities and differences between paretic and nonparetic STs. This information may refine the use and interpretation of the 2 STs for survivors of stroke.

Incidence and predictive factors for developing vesicoureteric reflux in individuals with suprasarcral spinal cord injury: a historical cohort study

STUDY DESIGN

A historical cohort study OBJECTIVES: The aim of the study was to examine the incidence of and predictive factors for VUR in individuals with suprasacral spinal cord injury (SCI).

SETTING

Srinagarind Hospital, Khon Kaen University, Thailand METHODS: Medical records were reviewed for all individuals with SCI and neurogenic bladder admitted for urological check-up between 1996 and 2016. The primary outcome was the cumulative incidence of VUR. The statistical tests used included the Nelson-Aalen Estimator and Cox Proportional Hazard Ratio. Harrell's C concordance statistic was used to evaluate the discrimination ability of the predictive model.

RESULTS

293 participants with SCI (102 tetraplegic and 191 paraplegic) were included. Most participants were male (67%), and the median age was 52 years. The overall incidence of VUR was 7.5 cases per 100 person-years (95% CI, 6.15-9.4). In the multivariate analysis, the predictive factors for VUR were: (1) maximum detrusor pressure at first visit ≥ 75 cm of water (HR_adj: 2.4 [95% CI: 1.4-4.1]); (2) indwelling urethral catheterization (IUC) (HR_adj: 11.1 [95% CI: 3.9-31.7]) and clean intermittent catheterization (CIC) (HR_adj: 6.5 [95% CI: 2.2-18.7]); (3) age ≥ 60 years at onset of SCI (HR_adj: 1.7 [95% CI: 1.1-2.8]); and, (4) absence of antimuscarinic medication (HR_adj: 3.8 [95% CI: 2.4-6.1]). The predictive model had an overall C-index of 0.78.

CONCLUSIONS

The incidence of VUR was high up to 12 years after SCI. High maximum detrusor pressure, IUC, age ≥ 60 years and absence of antimuscarinic medication were predictive factors for VUR.

Predictors of low back disability in chiropractic and physical therapy settings

Background

Predicting ongoing disability for chronic non-specific low back pain (LBP) is important to avoid prolonged disability.

Objective

Determine predictors of disability at 6 month follow-up in patients with LBP at medium risk of ongoing disability.

Methods

Baseline data was collected from 108 patients with medium-risk chronic non-specific LBP (mean age 50.4 years, SD 13.6) from six private chiropractic and physiotherapy clinics in Australia who took part in a randomised control trial. All patients received a pragmatic course of multimodal physical treatments [e.g., manual therapy (spinal manipulation or mobilization and/or soft tissue massage)] combined with advice, education and exercise. Baseline prognostic variables included sociodemographic, physical and psychological characteristics. Primary outcome was disability (Roland Morris Disability) at 6 month follow-up. Multivariable linear regression analysis was conducted.

Results

Variables remaining in the final multivariable model: lower work ability (β = − 1.05, 95% CI − 1.40 to − 0.70; p < 0.0001) and consultation with a medical specialist for back pain in the preceding 3 months (β = 3.35, 95% CI 1.14 to 5.55; p < 0.003), which significantly predicted higher disability at 6 months (unadjusted R ² = 0.31). Those with a lower work ability (scale 1 to 10) and who had seen a medical specialist for their back pain were more likely to report greater LBP-related disability at 6 months.

Conclusion

Patients with chronic LBP presenting to primary care with lower work ability and recent consultation with a medical specialist for LBP are more likely to have a worse prognosis; these are indicators to clinicians that standard conservative care may not adequately manage the patients’ needs.

A conceptual framework for prognostic research

BACKGROUND

Prognostic research has many important purposes, including (i) describing the natural history and clinical course of health conditions, (ii) investigating variables associated with health outcomes of interest, (iii) estimating an individual's probability of developing different outcomes, (iv) investigating the clinical application of prediction models, and (v) investigating determinants of recovery that can inform the development of interventions to improve patient outcomes. But much prognostic research has been poorly conducted and interpreted, indicating that a number of conceptual areas are often misunderstood. Recent initiatives to improve this include the Prognosis Research Strategy (PROGRESS) and the Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis (TRIPOD) Statement. In this paper, we aim to show how different categories of prognostic research relate to each other, to differentiate exploratory and confirmatory studies, discuss moderators and mediators, and to show how important it is to understand study designs and the differences between prediction and causation.

MAIN TEXT

We propose that there are four main objectives of prognostic studies - description, association, prediction and causation. By causation, we mean the effect of prediction and decision rules on outcomes as determined by intervention studies and the investigation of whether a prognostic factor is a determinant of outcome (on the causal pathway). These either fall under the umbrella of exploratory (description, association, and prediction model development) or confirmatory (prediction model external validation and investigation of causation). Including considerations of causation within a prognostic framework provides a more comprehensive roadmap of how different types of studies conceptually relate to each other, and better clarity about appropriate model performance measures and the inferences that can be drawn from different types of prognostic studies. We also propose definitions of 'candidate prognostic factors', 'prognostic factors', 'prognostic determinants (causal)' and 'prognostic markers (non-causal)'. Furthermore, we address common conceptual misunderstandings related to study design, analysis, and interpretation of multivariable models from the perspectives of association, prediction and causation.

CONCLUSION

This paper uses a framework to clarify some concepts in prognostic research that remain poorly understood and implemented, to stimulate discussion about how prognostic studies can be strengthened and appropriately interpreted.

Modifiable Factors Associated With Poststroke Physical Activity at Discharge From Rehabilitation: Prospective Cohort Study

BACKGROUND

People with stroke are not meeting recommended levels of physical activity. The modifiable factors associated with poststroke physical activity levels need to be identified to develop targeted interventions.

OBJECTIVE

The objective of this study was to investigate the factors at discharge from inpatient rehabilitation that are associated with physical activity levels at 3 months following discharge.

DESIGN

This was a prospective cohort study.

METHODS

Sixty-four people with stroke completed baseline assessments at discharge from inpatient rehabilitation and 55 completed the follow-up 3 months later. The candidate factors (ie, gait speed, balance, strength, cognition, mood, and motivation) were measured at discharge. The primary outcome measure at follow-up was walking-related activity (measured by wrist-worn accelerometer). Secondary outcome measures were physical activity participation (Activity Card Sort) and intensity of physical activity (International Physical Activity Questionnaire-Short 7 days). Adjusted separate multivariable linear regression models or proportional odds regression models were used to evaluate the associations between candidate factors and physical activity.

RESULTS

Gait speed and balance were associated with all aspects of physical activity. Higher level of intrinsic motivation was also associated with higher physical activity participation. Anxiety demonstrated a significant nonlinear relationship with physical activity participation.

LIMITATIONS

Inclusion of fatigue and individual muscle strength could have provided further insights into associations with steps per day.

CONCLUSION

The results demonstrated that better physical function at discharge from inpatient rehabilitation was associated with future increased levels of physical activity. Additionally, higher levels of motivation impacted on increased physical activity participation. The influence of anxiety on physical activity participation requires further exploration. Mixed-method study designs can be utilized to further understand the factors associated with poststroke physical activity.

Is there a causal relationship between acute stage sensorimotor cortex activity and the development of chronic low back pain? a protocol and statistical analysis plan

INTRODUCTION

Why some people develop chronic pain following an acute episode of low back pain is unknown. Recent cross-sectional studies have suggested a relationship between aberrant sensorimotor cortex activity and pain persistence. The UPWaRD (Understanding persistent Pain Where it ResiDes) cohort study is the first prospective, longitudinal investigation of sensorimotor cortex activity in low back pain. This paper describes the development of a causal model and statistical analysis plan for investigating the causal effect of sensorimotor cortex activity on the development of chronic low back pain.

METHODS AND ANALYSIS

Sensorimotor cortex activity was assessed within 6 weeks of low back pain onset using somatosensory evoked potentials and transcranial magnetic stimulation mapping techniques. Chronic low back pain is defined as ongoing pain (Numerical Rating score ≥1) or disability (Roland Morris Disability Questionnaire score ≥3) at 6 months follow-up. Variables that could confound the relationship between sensorimotor cortex activity and chronic low back pain were identified using a directed acyclic graph and content expertise was used to specify known causal paths. The statistical model was developed 'a priori' to control for confounding variables identified in the directed acyclic graph, allowing an unbiased estimate of the causal effect of sensorimotor activity in acute low back pain on the development of chronic pain. The statistical analysis plan was finalised prior to follow-up of all participants and initiation of analysis.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from Western Sydney University Human Research Ethics Committee (H10465) and from Neuroscience Research Australia (SSA: 16/002). Dissemination will occur through presentations at national and international conferences and publications in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12619000002189 (retrospectively registered).

Prediction of 2-year work participation in sickness absentees with neck or shoulder pain: the contribution of demographic, patient-reported, clinical and imaging information

Background

In cases of neck and shoulder pain, the responsibility for assessing work prognosis is held by clinicians with access to different domains of information. One of these domains is magnetic resonance imaging (MRI), and although MRI is increasingly used, it is unknown which domains of information contribute the most to the prediction of work prognosis. This retrospective cohort study explored the contribution of demographic, patient-reported, clinical, and MRI information to the prediction of work participation in sickness absentees with neck or shoulder pain.

Methods

From a secondary care setting, 168 sickness absentees with neck or shoulder pain were included. Based on registry data, a successful work outcome was defined as ≥50% work participation score (WPS) from Weeks 1 to 104 after enrolment. Prognostic variables were categorized into four domains (demographic, patient-reported, clinical, and MRI) resembling the order of information obtained in a clinical setting. Crude logistic regression analyses were used to identify prognostic variables for each domain (p < 0.2). This was followed by multivariable analyses including the identified variables in a domain-wise order. For each added domain, the probability of successful WPS was dichotomized leaving two possible classifications: ≥ 50% chance of successful WPS or not. In cross-tabulations of chance and the actual WPS outcome, positive and negative predictive values (PPV and NPV), sensitivity, specificity and area under the curve (AUC) were calculated.

Results

The combination of demographic and patient-reported variables yielded an NPV of 0.72 and a PPV of 0.67, while specificity was 0.82, sensitivity 0.54 and AUC 0.77. None of these values improved notably by adding clinical and MRI variables as predictors of successful WPS.

Conclusions

These results suggest that - among sickness absentees with neck or shoulder pain – clinical and MRI variables provide no additional information for the prediction of work participation compared with only demographic and patient-reported information.

Quantitative sensory testing and predicting outcomes for musculoskeletal pain, disability, and negative affect: a systematic review and meta-analysis

Hypersensitivity due to central pain mechanisms can influence recovery and lead to worse clinical outcomes, but the ability of quantitative sensory testing (QST), an index of sensitisation, to predict outcomes in chronic musculoskeletal disorders remains unclear. We systematically reviewed the evidence for ability of QST to predict pain, disability, and negative affect using searches of CENTRAL, MEDLINE, EMBASE, AMED, CINAHL, and PubMed databases up to April 2018. Title screening, data extraction, and methodological quality assessments were performed independently by 2 reviewers. Associations were reported between baseline QST and outcomes using adjusted (β) and unadjusted (r) correlations. Of the 37 eligible studies (n = 3860 participants), 32 were prospective cohort studies and 5 randomised controlled trials. Pain was an outcome in 30 studies, disability in 11, and negative affect in 3. Meta-analysis revealed that baseline QST predicted musculoskeletal pain (mean r = 0.31, 95% confidence interval [CI]: 0.23-0.38, n = 1057 participants) and disability (mean r = 0.30, 95% CI: 0.19-0.40, n = 290 participants). Baseline modalities quantifying central mechanisms such as temporal summation and conditioned pain modulation were associated with follow-up pain (temporal summation: mean r = 0.37, 95% CI: 0.17-0.54; conditioned pain modulation: mean r = 0.36, 95% CI: 0.20-0.50), whereas baseline mechanical threshold modalities were predictive of follow-up disability (mean r = 0.25, 95% CI: 0.03-0.45). Quantitative sensory testing indices of pain hypersensitivity might help develop targeted interventions aiming to improve outcomes across a range of musculoskeletal conditions.

Biomarkers of autonomic regulation for predicting psychological distress and functional recovery following road traffic injuries: protocol for a prospective cohort study

INTRODUCTION

Psychological distress is a prevalent condition often overlooked following a motor vehicle crash (MVC), particularly when injuries are not severe. The aim of this study is to examine whether biomarkers of autonomic regulation alone or in combination with other factors assessed shortly after MVC could predict risk of elevated psychological distress and poor functional recovery in the long term, and clarify links between mental and physical health consequences of traffic injury.

METHODS AND ANALYSIS

This is a controlled longitudinal cohort study, with follow-up occurring at 3, 6 and 12 months. Participants include up to 120 mild to moderately injured MVC survivors who consecutively present to the emergency departments of two hospitals in Sydney and who agree to participate, and a group of up to 120 non-MVC controls, recruited with matched demographic characteristics, for comparison. WHO International Classification of Functioning is used as the framework for study assessment. The primary outcomes are the development of psychological distress (depressive mood and anxiety, post-traumatic stress symptoms, driving phobia, adjustment disorder) and biomarkers of autonomic regulation. Secondary outcomes include indicators of physical health (presence of pain/fatigue, physical functioning) and functional recovery (quality of life, return to function, participation) as well as measures of emotional and cognitive functioning. For each outcome, risk will be described by the frequency of occurrence over the 12 months, and pathways determined via latent class mixture growth modelling. Regression models will be used to identify best predictors/biomarkers and to study associations between mental and physical health.

ETHICS AND DISSEMINATION

Ethical approvals were obtained from the Sydney Local Health District and the research sites Ethics Committees. Study findings will be disseminated to health professionals, related policy makers and the community through peer-reviewed journals, conference presentations and health forums.

TRIAL REGISTRATION NUMBER

ACTRN12616001445460.

Periodic Health Examination and Injury Prediction in Professional Football (Soccer): Theoretically, the Prognosis is Good

In professional soccer and other elite sports, medical and performance screening of athletes (also termed periodic health examination or PHE) is common practice. The purposes of this are: (1) to assist in identifying prevalent conditions that may be a threat to safe participation, (2) to assist in setting benchmark targets for rehabilitation or performance purposes and (3) to assist clinicians in determining which athletes may be at risk of future injury and selecting appropriate injury prevention strategies to reduce the perceived risk. However, when using PHE as an injury prevention tool, are clinicians seeking to identify potential causes of injury or to predict future injury? This Current Opinion aims to examine the conceptual differences between aetiology and prediction of injury while relating these areas to the capabilities of PHE in practice. We also introduce the concept of prognosis—a broader approach that is closely related to prediction—and why this may have greater applicability to PHE of professional athletes.

Does Health Care Utilization Before Hip Arthroscopy Predict Health Care Utilization After Surgery in the US Military Health System? An Investigation Into Health-Seeking Behavior

BACKGROUND

The influence of prior patterns of health care utilization on future health care utilization has had minimal investigation in populations with musculoskeletal disorders.

OBJECTIVES

The purpose of this study was to explore the relationship between presurgical health care utilization and postsurgical health care utilization in a population of patients undergoing hip surgery in the US Military Health System.

METHODS

In this observational cohort study, person-level data were collected for patients undergoing hip arthroscopy in the Military Health System from 2003 to 2015, capturing all encounters 12 months before and 24 months after surgery for every individual. Cluster analysis was used to categorize individuals with high and low health care utilization, based on preoperative health care visits. Unadjusted and adjusted Poisson and generalized linear models were generated. Health care utilization outcomes were targeted, including costs, visits, and medication use.

RESULTS

There were 1850 individuals in the final cohort (mean age, 32.18 years; 55.4% male). The high health care utilization group averaged 57.69 ± 25.87 visits, compared to 20.43 ± 8.36 visits in the low utilization group. There were significant differences between groups for total health care visits (58.17; 95% confidence interval [CI]: 57.39, 58.58), total health care costs ($11 539.71; 95% CI: $10 557.26, $12 595.04), hip-related visits (12.77; 95% CI: 12.59, 12.96), hip-related costs ($3325.07; 95% CI: $2886.43, $3804.51), days' supply of pain medications (752.67; 95% CI: 751.24, 754.11), opioid prescriptions (48.83; 95% CI: 48.47, 49.21), and cost of pain medications ($1074.80; 95% CI: $1011.91, $1137.68).

CONCLUSION

Presurgical patterns of health care utilization were associated with postsurgical patterns of health care utilization, indicating that those patients who used more care before surgery also used more care after surgery. Clinicians should consider prior patterns of health care utilization, including utilization unrelated to the index condition, when determining care plans and prognosis. J Orthop Sports Phys Ther 2018;48(11):878-886. Epub22 Jul 2018. doi:10.2519/jospt.2018.8259.

Low Back Pain With Impact at 17 Years of Age Is Predicted by Early Adolescent Risk Factors From Multiple Domains: Analysis of the Western Australian Pregnancy Cohort (Raine) Study

Study Design Prospective cohort study of the Western Australian Pregnancy Cohort (Raine) Study. Background Low back pain (LBP) commonly develops in adolescence and is a significant risk factor for adult LBP. A broad range of factors have been associated with the development of adolescent LBP, but prior literature has limitations related to characterization of LBP and the scope of risk factors considered. Objective This study aimed to identify potential factors contributing to the development of LBP, with and without impact, at 17 years of age, utilizing a broad range of exposures at 14 years of age. Methods Data from 1088 participants (52.1% female) with "no LBP," "LBP with minimal impact," and "LBP with impact" at 17 years of age and a range of measures from multiple domains, including spinal pain, physical, psychological, social, and lifestyle, at 14 years of age were collected for the study. Multivariable multinomial logistic regression was used to estimate the association of potential mechanistic factors at 14 years of age with LBP at 17 years of age. Results Female sex and back pain at 14 years of age were strongly associated with LBP at 17 years of age. Potential mechanistic factors for LBP outcomes at 17 years of age included exposures from the pain (neck/shoulder pain) and physical domains (standing posture subgroup membership, back muscle endurance, throwing distance), psychological domain (somatic complaints, aggressive behavior), social domain (socioeconomic area), and lifestyle domain (exercise out of school). Conclusion The findings support the multidimensional nature of adolescent LBP and highlight the challenge this presents for epidemiological research, clinical practice, and prevention initiatives in the general population. Level of Evidence Prognosis, level 1b. J Orthop Sports Phys Ther 2017;47(10):752-762. doi:10.2519/jospt.2017.7464.

Does Familial Aggregation of Chronic Low Back Pain Affect Recovery?: A Population-Based Twin Study

STUDY DESIGN

Longitudinal twin-cohort study.

OBJECTIVE

To investigate the effect familial aggregation of chronic low back pain (LBP) has on the recovery from chronic LBP.

SUMMARY OF BACKGROUND DATA

LBP is a worldwide problem, with pain and disability often becoming chronic. Genetics and familial behaviors could significantly affect the recovery from chronic LBP but have not been extensively investigated.

METHODS

A total of 624 Spanish twins from the Murcia Twin Registry reported experiencing chronic LBP within the past 2 years during the 2009/11 data collection wave and were followed up in 2013. Familial aggregation of chronic LBP was determined by the co-twin experiencing chronic LBP within the past 2 years at baseline. Twins reporting LBP "within the past 4 weeks" at follow-up were considered to have not recovered.

RESULTS

There were 455 twins with available data on LBP at follow-up and available data on LBP from their co-twin at baseline. Twins with an affected co-twin at baseline were significantly more likely to have not recovered from chronic LBP at follow-up (odds ratio [OR] = 1.6, 95% confidence interval [CI]: 1.0-2.4, P = 0.046). This relationship was stronger for monozygotic twins (OR = 2.5, 95% CI: 1.3-4.8, P = 0.006) (n = 172) but disappeared when considering only dizygotic twins (OR = 1.1, 95% CI: 0.6-2.0, P = 0.668) (n = 283). Sibling-relative recurrence risk (λ s) was 1.2 for the total sample, 1.5 for monozygotic twins, and 1.1 for dizygotic twins.

CONCLUSION

Having a sibling with chronic LBP at baseline increased the likelihood of LBP at follow-up by 20%, with this likelihood increasing to 50% if the sibling was an identical twin. These results are novel and highlight the important influence genetics have on people's recovery from chronic LBP. Information regarding the presence of chronic LBP within a family is easy to obtain and has the potential to inform clinicians on which patients are less likely to recover when treatment implementation is not considered.

LEVEL OF EVIDENCE

3.

Incidence and prognostic factors for postoperative frozen shoulder after shoulder surgery: a prospective cohort study

PURPOSE

Frozen shoulder is a potential complication after shoulder surgery. It is a clinical condition that is often associated with marked disability and can have a profound effect on the patient's quality of life. The incidence, etiology, pathology and prognostic factors of postoperative frozen shoulder after shoulder surgery are not known. The purpose of this explorative study was to determine the incidence of postoperative frozen shoulder after various operative shoulder procedures. A second aim was to identify prognostic factors for postoperative frozen shoulder after shoulder surgery.

METHODS

505 consecutive patients undergoing elective shoulder surgery were included in this prospective cohort study. Follow-up was 6 months after surgery. A prediction model was developed to identify prognostic factors for postoperative frozen shoulder after shoulder surgery using the TRIPOD guidelines. We nominated five potential predictors: gender, diabetes mellitus, type of physiotherapy, arthroscopic surgery and DASH score.

RESULTS

Frozen shoulder was identified in 11% of the patients after shoulder surgery and was more common in females (15%) than in males (8%). Frozen shoulder was encountered after all types of operative procedures. A prediction model based on four variables (diabetes mellitus, specialized shoulder physiotherapy, arthroscopic surgery and DASH score) discriminated reasonably well with an AUC of 0.712.

CONCLUSIONS

Postoperative frozen shoulder is a serious complication after shoulder surgery, with an incidence of 11%. Four prognostic factors were identified for postoperative frozen shoulder: diabetes mellitus, arthroscopic surgery, specialized shoulder physiotherapy and DASH score. The combination of these four variables provided a prediction rule for postoperative frozen shoulder with reasonable fit.

LEVEL OF EVIDENCE

Level II, prospective cohort study.