Epigenetic and Molecular Biomarkers in Chronic Low Back Pain and Modic Changes

Low Back Pain Clinical Trial

Official title: Epigenetic and Molecular Biomarkers in Chronic Low Back Pain and Modic Changes

Status Recruiting

Clinical Trial Summary

In the present study the investigators aim to examine the presence of bacteria in the disc and Modic Changes (MCs) (bone). A prospective study with 1-year follow-up of two patient populations undergoing elective spinal surgery (spinal fusion or disc herniation surgery) will be conducted. Patients previously operated on at index level will also be included, and evaluated as sub-groups.

The following tissues are collected: dermis, sub-fascial tissue, nucleus pulposus, annulus fibrosus, and endplates. Endplate biopsies are only performed in patients undergoing fusion surgery.

All tissue samples undergoing culturing should be processed within 4 hours of sampling. The time for sampling and culture processing are noted for each sample.In short, 1 mL enrichment broth (Brain Heart Infusion, BHI) is added to each tissue sample and further homogenized using sterile beads or a mortar. In addition, a control sample containing only enrichment broth is included. The control sample also undergoes the homogenization step. Each sample is plated onto three agar plates: blood and chocolate for aerobic culturing and anaerobic medium (HM0 or FAA) anaerobic culturing. The blood and chocolate agar plates and the enrichment broth are incubated in 35oC (5% CO2) and the anaerobic plates are incubated anaerobically for a total of 14 days. On day 3 and 7, the enrichment broth is plated onto a chocolate and an anaerobic agar for aerobic and anaerobic incubation respectively. Aerobic plates are read every 1-2 days and the anaerobic plates are read every 2-3 days. All growth is identified and recorded. Colonies considered relevant are frozen at -80oC.

The pre-specification of microbiological results; significant growth, no growth and probable contamination (< 5 single colonies on primary plate and no growth from enrichement broth or no growth on primary plate, but growth from enrichement broth). Main endpoint for bacteriology is significant growth or no growth. A prespecification of PCR results in the probable contamination group seems to be premature, due to high risk of contamination. We will perform sensitivity analysis as the samples are analyzed, and PCR and histology will be used in combination to determine if a probable contamination should be considered in the significant growth group or in the no growth group. In addition to a pre-specified evaluation of growth or not, microbiologists and the pathologist are blinded to the knowledge of case or control. The clinicians are blinded to the results of aerob/anaerobe cultivation, PCR and histological report. Hence, the decision of no bacterial growth, probable contamination or significant growth cannot be influenced by information of case or control.

Blood-samples are collected to characterize gene expression patterns and related markers to gain insight into molecular mechanisms that may be important for low back pain (LBP) and the development of MCs

Clinical Trial Description

All included patients will be analyzed in the primary analysis, but power analysis was based on secondary- and sub-group analysis.

Planned analysis

Primary analysis:

MC1 and MC2 vs. control (significant growth from disc, yes/no)

Secondary analysis:

MC1 vs. control (significant growth from disc, yes/no)

Exploratory subgroup analyses:

MC1 and MC2 in previously operated vs. control (significant growth from disc, yes/no)

Large MCs vs. control (significant growth from disc, yes/no). Large MCs are defined as MCs with volume ≥ 25% of vertebral body volume or height > 50% of vertebral body height.

MC1 and MC2 vs. control in fusion group (significant growth from vertebral body biopsy, yes/no). Vertebral body biopsies are not performed in the disc herniation group.

Statistics and power:

The main aim of this study is to investigate if the proportions of perioperative biopsies showing significant bacterial growth differ between patients with or without MCs. The null hypothesis is that there is no difference between cases and controls. The alternative hypothesis is that there is a difference.

We calculated the sample size using a two-sided Pearson's chi-squared test with a 5% significance level, and based the calculation on the following estimates:

For the primary analysis, bacterial growth in biopsies from MC1 and MC2 vs controls, we aim to achieve 90% power to detect a between-group difference, based on an estimated difference of bacterial growth in 25% of cases (any MC1 or MC2) vs. 5% of controls (alfa 0.05). Therefore, we plan to analyze at least 100 cases and 50 controls.

For the secondary analysis, bacterial growth of disc biopsies in MC1 vs. control, we aim to achieve 80% power to detect a between-group difference based on an estimated difference of bacterial growth in 25% cases (MC1) vs. 5% of controls (alfa 0.05). We therefore plan to analyze at least 50 cases with MC1.

For the exploratory subgroup analyses, we will not perform a sample size calculation, because smaller sub-groups are more likely to be underpowered. ;

Related Conditions & MeSH terms

• Back Pain
• Low Back Pain

• NCT number: NCT03406624
• Study type: Observational
• Source: Oslo University Hospital
• Contact: Kjersti Storheim, PhD
• Phone: 22117740
• Email: kjersti.storheim@medisin.uio.no
• Status: Recruiting
• Start date: January 29, 2018
• Completion date: May 2024