Choosing the right outcome measurement instruments for patients with low back pain

Prediction of Oswestry Disability Index (ODI) using PROMIS-29 in a national sample of lumbar spine surgery patients

PURPOSE

The primary purpose was to examine the measurement properties of the PROMIS-29 to better understand its use in patients undergoing spine surgery. A secondary objective was to calculate a predictive equation between PROMIS-29 and ODI, to allow clinicians and researchers to determine a predicted ODI score based on PROMIS short form scores.

METHODS

719 patients with PROMIS v2.0 and ODI responses were queried from the quality outcomes database. Validity was assessed using coefficient omega, ceiling/floor effects, and confirmatory factor analysis. Multivariable regression predicting ODI scores from PROMIS-29 domains was used to create a predictive equation. Predicted ODI scores were plotted against ODI scores to determine how well PROMIS-29 domains predicted ODI.

RESULTS

Results showed good reliability and validity of PROMIS-29 in patients undergoing lumbar spine surgery: convergent and discriminant validity, low floor/ceiling effects, and unidimensional domains. The conversion equation used 6 PROMIS-29 domains (ODI_% =  37.847- 1.475*[PF_raw] + 1.842*[PAIN_raw] + 0.557*[SD_raw] - 0.642*[SR_raw] + 0.478*[PI_raw] + 0.295*[DEP_raw]). Correlation between the predicted and actual ODI scores was R = 0.88, R² = 0.78, suggesting that the equation predicted ODI scores that are strongly correlated with actual ODI scores.

CONCLUSIONS

Good measurement properties support the use of PROMIS-29 in spine surgery patients. Findings suggest accurate ODI scores can be derived from PROMIS-29 domains. Clinicians who want to move from ODI to PROMIS-29 can use this equation to obtain estimated ODI scores when only collecting PROMIS-29. These results support the idea that PROMIS-29 domains have the potential to replace disease-specific traditional PROMs.

Do prognostic variables predict a set of outcomes for patients with chronic low back pain: a long-term follow-up secondary analysis of a randomized control trial

Objective: The objective was to explore for universal prognostic variables, or predictors, across three different outcome measures in patients with chronic low back pain (LBP). We hypothesized that selected prognostic variables would be 'universal' prognostic variables, regardless of the outcome measures used. Methods: This study was a secondary analysis of data from a previous randomized controlled trial comparing the McKenzie treatment approach with placebo in patients with chronic LBP. Ten baseline prognostic variables were explored in predictive models for three outcomes: pain intensity, disability, and global perceived effect, at 6 and 12 months. Predictive models were created using backward stepwise logistic and linear multivariate regression analyses. Results: Several predictors were present including age, expectancy of improvement, global perceived effect; however, we only identified baseline disability as a universal predictor of outcomes at 6 months. The second most represented universal predictor was baseline pain intensity for outcomes at 12 months. Discussion: Only two predictors demonstrated an association with more than one outcome measure. High baseline disability predicts multidimensional outcome measures at 6 months in patients with chronic LBP while baseline pain intensity can best predict the outcome at 12 months. Nevertheless, other predictors seem to be unique to the outcome used. Level of evidence: 2c.

Sexual disability in patients with chronic non-specific low back pain-a multicenter retrospective analysis

[Purpose] Oswestry Disability Index includes an item (Oswestry Disability Index-8) aiming to assess sexual disability associated to low back pain. The aim of this study is to investigate the percentage of participants who answered the Oswestry Disability Index-8, and the relevance and characteristics of sexual disability due to low back pain in Italian patients. [Participants and Methods] Design: multicenter retrospective analysis. Population: six hundred and ninety-seven outpatients with non-specific low back pain. Variables: pain characteristics (amount, localization, and duration of perceived pain), disability, and psychological variables (anxiety, depression, catastrophizing, kinesiophobia, pain acceptance, and pain vigilance and awareness). [Results] Seventy-seven participants (11.05%) did not answer the Oswestry Disability Index-8. The odds of being not responding to the Oswestry Disability Index-8 item appeared related to age (odds=7.50 for over 60), gender (odds=2.65 for females), and marital status (odds=2.33 for not married). Concerning the psychological variables, Activity Avoidance (coefficient=0.071), Depression (coefficient=0.068), and Rumination (coefficient=0.031) showed a positive impact on sexual disability. [Conclusion] In Italian patients, the percentage of not-responding to Oswestry Disability Index-8 was relatively low. In addition, sexual disability was related to depression, activity avoidance, and rumination.

A Pulsed Electromagnetic Field Therapy Device for Non-Specific Low Back Pain: A Pilot Randomized Controlled Trial

Introduction

Low back pain (LBP) poses a significant burden of disease worldwide, and identifying safe and effective non-pharmacologic treatment options for LBP is a research priority. The aim of this study was to pilot a clinical trial of a portable pulsed electromagnetic field (PEMF) therapy device for subjects with mixed duration non-specific LBP.

Methods

This work was a randomized, double-blind, sham-controlled, parallel-group study conducted at a chiropractic school outpatient clinic. The primary end point was functional capacity measured by the Oswestry Disability Index (ODI) at baseline, 6 weeks, and 12 weeks. Analysis was conducted on the intent-to-treat population and as a trend of change in pain scores over time using the Freidman test of repeated measures.

Results

Forty-two participants were randomized to receive usual care plus PEMF therapy or usual care plus sham, and 25 completed the study. Significant improvements in ODI scores from baseline to week 6 were reported in the experimental group (χ² = 14.68, p < 0.001, compared with patients in the sham group, χ² = 4.00, p = 0.135, n.s.). This difference persisted at week-12 follow-up. Adverse events were rare and mild.

Conclusion

It is feasible to conduct a clinical trial of a PEMF therapy device for non-specific LBP. This work shows that the device was safe and provides preliminary evidence of effectiveness in improving function in patients with non-specific LBP.

Trial Registration

ClinicalTrials.gov identifier, NCT03053375.

Funding

Aerotel Ltd.

Commentary: Statistical significance and clinical significance - A call to consider patient reported outcome measures, effect size, confidence interval and minimal clinically important difference (MCID)

In healthcare research an intervention may be statistically significant based on quantitative analysis; however, simultaneously it may be relatively insignificant to the health or quality of life of patients affected by a particular condition or disease being treated by the intervention - thus may be interpreted as having low clinical significance. An understanding of statistics is fundamental for evidence informed healthcare. Patient-reported outcome measures (PROMs) direct patients to evaluate aspects of their own health, including quality of life, disability and function. Data obtained from PROMs can be used to demonstrate the impact of healthcare interventions on these elements of a person's quality of life. To interpret outcome measure data for clinical decision making, a clinician must understand the concepts of statistical significance and clinical significance. This commentary explores the concepts of patient reported outcome measures (PROMs), their statistical and clinical significance, and explores their relationship with a practical example for the clinician. Limitations of research that only reports p-values and the need to consider effect size, confidence intervals, and minimal clinically important difference are also discussed. Together, these concepts can assist the clinician to evaluate whether an intervention may be suitable for their clinical practice.

Physical Therapy Approaches in the Treatment of Low Back Pain

Globally, in 2016, low back pain (LBP) contributed 57.6 million of total years lived with disability. Low Back Pain Guidelines regularly recommend the use of physical exercise for non-specific LBP. Early non-pharmacological treatment is endorsed. This includes education and self-management, and the recommencement of normal activities and exercise, with the addition of psychological programs in those whose symptoms persist. The aim of physical treatments is to improve function and prevent disability from getting worse. There is no evidence available to show that one type of exercise is superior to another, and participation can be in a group or in an individual exercise program. Active strategies such as exercise are related to decreased disability. Passive methods (rest, medications) are associated with worsening disability, and are not recommended. The Danish, United States of America, and the United Kingdom Guidelines recommend the use of exercise on its own, or in combination with other non-pharmacological therapies. These include tai chi, yoga, massage, and spinal manipulation. Public health programs should educate the public on the prevention of low back pain. In chronic low back pain, the physical therapy exercise approach remains a first-line treatment, and should routinely be used.

Development, validity and reliability of the Italian version of the Copenhagen neck functional disability scale

BACKGROUND

Valid and reliable patient-reported outcome measures support health professionals in evaluating the results of clinical research and practice. The Copenhagen Neck Functional Disability Scale (CNFDS) has shown promising measurement properties to measure disability in patients with neck pain, but an Italian version of this questionnaire is not available. The objective of this study was to cross-culturally adapt the CNFDS into Italian (CNFDS-I), and to assess its validity and reliability in patients with neck pain.

METHODS

The CNFDS-I was developed according to well-established guidelines for cross-cultural adaptation of patient-reported outcome measures. A cross-sectional clinimetric study was conducted to evaluate its validity and reliability. Patients with chronic neck pain (pain > 3 months) participated in this study. The following measurement properties (defined by the COSMIN initiative) were assessed: structural validity (exploratory factor analysis), internal consistency (Cronbach's α), construct validity [by testing hypotheses on expected correlations with the Neck Disability Index (NDI), the Neck Bournemouth Questionnaire (NBQ), and pain Visual Analogue Scale (VAS)]. Test-retest reliability [Intraclass Correlation Coefficient for agreement (ICCagreement)], and measurement error [Smallest Detectable Change (SDC)] were also assessed in 50 clinically stable patients. Floor/ceiling effects and acceptability were calculated.

RESULTS

One-hundred and sixty-two patients (mean age = 47.9 ± 14.5 years, 70% female) were included. The CNFDS-I exhibited sufficient unidimensionality (one factor explained 83% of the variability) and internal consistency (α = 0.83). Construct validity was sufficient as all correlations with the other questionnaires were as expected (r = 0.846 with NDI, r = 0.708 with NBQ, r = 0.570 with VAS). Test-retest reliability was excellent (ICCagreement = 0.99, 95% CI from 0.995 to 0.999), while measurement error was equal to 8.31 scale points (27% scale range). No floor/ceiling effects were detected. The average time for filling the questionnaire was two minutes.

CONCLUSIONS

The CNFDS-I proved to be a valid and reliable outcome measure to assess disability in patients with chronic neck pain. Head-to-head comparison studies on the CNFDS-I measurement properties against other disability measures for neck pain (e.g. NDI and NBQ) are required to determine the relative merits of these different measures.

Core outcome measurement instruments for clinical trials in nonspecific low back pain

To standardize outcome reporting in clinical trials of patients with nonspecific low back pain, an international multidisciplinary panel recommended physical functioning, pain intensity, and health-related quality of life (HRQoL) as core outcome domains. Given the lack of a consensus on measurement instruments for these 3 domains in patients with low back pain, this study aimed to generate such consensus. The measurement properties of 17 patient-reported outcome measures for physical functioning, 3 for pain intensity, and 5 for HRQoL were appraised in 3 systematic reviews following the COSMIN methodology. Researchers, clinicians, and patients (n = 207) were invited in a 2-round Delphi survey to generate consensus (≥67% agreement among participants) on which instruments to endorse. Response rates were 44% and 41%, respectively. In round 1, consensus was achieved on the Oswestry Disability Index version 2.1a for physical functioning (78% agreement) and the Numeric Rating Scale (NRS) for pain intensity (75% agreement). No consensus was achieved on any HRQoL instrument, although the Short Form 12 (SF12) approached the consensus threshold (64% agreement). In round 2, a consensus was reached on an NRS version with a 1-week recall period (96% agreement). Various participants requested 1 free-to-use instrument per domain. Considering all issues together, recommendations on core instruments were formulated: Oswestry Disability Index version 2.1a or 24-item Roland-Morris Disability Questionnaire for physical functioning, NRS for pain intensity, and SF12 or 10-item PROMIS Global Health form for HRQoL. Further studies need to fill the evidence gaps on the measurement properties of these and other instruments.

A systematic review highlights the need to investigate the content validity of patient-reported outcome measures for physical functioning in patients with low back pain

OBJECTIVES

To summarize the evidence on content and structural validity of 17 patient-reported outcome measures (PROMs) to measure physical functioning in patients with low back pain (LBP).

STUDY DESIGN AND SETTING

MEDLINE, EMBASE, CINAHL, PsycINFO, SportDiscus, and Google Scholar were searched (February 2017). Records on development and studies assessing content validity or unidimensionality in patients with LBP were included. Two reviewers defined eligible studies and assessed their methodological quality with updated Consensus-based Standards for the Selection of Health Measurement Instruments standards. Evidence was synthesized for three separate aspects of content validity: relevance, comprehensiveness, and comprehensibility, and for unidimensionality, a modified GRADE approach was applied to evidence synthesis.

RESULTS

High-quality evidence showed that 24-item Roland Morris Disability Questionnaire (RMDQ-24) is a comprehensible but not comprehensive PROM. Low to very low quality evidence underpinned the content validity of the other PROMs. Unidimensionality was: sufficient for Brief Pain Inventory pain interference subscale (moderate quality evidence); inconsistent for RMDQ-23, Oswestry Disability Index 2.1a (ODI 2.1a), and Quebec Back Pain Disability Scale (moderate quality); insufficient for RMDQ-24, ODI 1.0, and RMDQ-18 (high quality) and Short Form 36 physical functioning subscale (SF36-PF, moderate quality).

CONCLUSION

The content validity of PROMs to measure physical functioning in patients with LBP is understudied. Structural validity of several widely used PROMs is problematic.