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Table 1 Objectives and hypotheses of the AIM study

From: Antibiotic treatment In patients with chronic low back pain and Modic changes (the AIM study): study protocol for a randomised controlled trial

Objectives Hypotheses
Main objective Main hypothesis
To evaluate the effect of amoxicillin versus placebo on disease-specific disability evaluated by the RMDQ at 1-year follow-up in patients with chronic LBP and MCs type I or II at the level of a previously herniated disc Patients with MCs type I or II at baseline in the antibiotic treatment group report a significantly lower RMDQ score at 1-year follow-up than patients in the placebo group (hypothesis A)
Secondary objective (SO 1) Secondary hypotheses
To evaluate the effect of amoxicillin versus placebo on RMDQ at 1-year follow-up separately in patients with type I and type II MCs, respectively Patients with MCs type I at baseline in the antibiotic treatment group report a significantly lower RMDQ score at 1-year follow-up than patients in the placebo group (hypothesis B)
Patients with MCs type II at baseline in the antibiotic treatment group report a significantly lower RMDQ score at 1-year follow-up than patients in the placebo group (hypothesis C)
Key supportive (KSOs) and exploratory objectives Further hypotheses
To evaluate the effect of amoxicillin versus placebo on ODI at 1-year follow-up in the whole cohort of included patients (KSO 2) Patients with MCs type I or II at baseline in the antibiotic treatment group report a significantly lower ODI score at 1-year follow-up than patients in the placebo group (hypothesis D)
To evaluate the effect of amoxicillin versus placebo on LBP intensity at 1-year follow-up in the whole cohort of included patients (KSO 3) Patients with MCs type I or II at baseline in the antibiotic treatment group report a significantly lower LBP intensity NRS score at 1-year follow-up than patients in the placebo group (hypothesis E)
To evaluate whether the short tau inversion recovery (STIR) signal (intensity and extent) of MCs on baseline MRI predicts RMDQ score at 1-year follow-up (KSO 4) In the antibiotic treatment group, high signal from MCs on STIR at baseline MRI predicts a lower RMDQ score at 1-year follow-up (hypothesis F)
To assess whether change in STIR signal (intensity and extent) of MCs from baseline to 1-year follow-up is related to RMDQ score at 1-year follow-up (KSO 5) Reduced signal from MCs on STIR from baseline to 1-year follow-up MRI is associated with a lower RMDQ score at 1-year follow-up (hypothesis G)
To evaluate the effect of amoxicillin versus placebo on health-related quality of life (the EQ-5D) at 1-year follow-up in the whole cohort of included patients (KSO 6) Patients with MCs type I or II at baseline in the antibiotic treatment group report significantly better quality of life (EQ-5D) at 1-year follow-up than patients in the placebo group (hypothesis H)
To evaluate cost-effectiveness of amoxicillin versus placebo at 1-year follow-up in the whole cohort of included patients  
To evaluate the difference in incidence of AEs and SAEs between the two intervention groups from inclusion to 1-year follow-up in the whole cohort of included patients  
To investigate the effect of amoxicillin on epigenetic patterns, longitudinal gene and protein expression, genetic variation, from baseline to post treatment (100 days after start of treatment) and from baseline to 1 year (12 months’) follow-up in patients with MCs type I or II, and to evaluate correlations with clinical data  
To investigate the effect of amoxicillin on bowel flora, resistant bacteria and resistance genes  
To evaluate whether positive pain provocation tests at baseline predicts RMDQ score at 1-year (12 months’) follow-up  
Secondary clinical outcomes not specified above will be used to explore hypotheses regarding clinical effects post treatment and 1 year after start of treatment in the whole cohort and separately in patients with type I and type II MCs  
  1. RMDQ Roland Morris Disability Questionnaire, MCs Modic changes, KSO key supportive objectives, ODI Oswestry Disability Index, LBP Low back pain, NRS Numerical Rating Scale, STIR short tau inversion recovery, MRI magnetic resonance imaging, AE adverse event, SAE serious adverse event