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

ABSTRACT

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.

KEYWORDS:

• Pain intensity
• disability
• global perceived effect
• chronic pain
• secondary analysis
• prognostic variables

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Alessandra Narciso Garcia

Alessandra N. Garcia is a physiotherapist and post PhD student supervised by Dr. Chad Cook. She has clinical and teaching experience in physical therapy and now works primarily as a researcher of low back pain management.

Leonardo O. P. Costa

Dr. Leonardo Costa is a physiotherapist, PhD, professor of physical therapy and program director of the Masters and Doctoral Programs in Physical Therapy (UNICD). His research preferences involve measurement properties, evidence based practice, and studies related to low back pain.

Luciola Da Cunha Menezes Costa

Dr. Luciola Menezes Costa is a physiotherapist, PhD and professor of Physical Therapy. Her research focuses on low back pain, prognostic studies, clinical trials, systematic reviews and measurement properties.

Mark Hancock

Dr. Mark Hancock is a physiotherapist and associate professor of physiotherapy. He has over 20 years of clinical experience and now works primarily as an academic/researcher. His research focuses on the diagnosis and management of back pain.

Chad Cook

Dr. Chad Cook is a clinical researcher, physical therapist, productive researcher and academic, program director of Duke Doctor of Physical Therapy Program and profession advocate with a history of clinical care excellence and service. His passions include refining and improving the patient examination process and validating tools used in day-to-day physical therapist practice.