Table 1.
Characteristics of studies comparing biological agents with placebo
| Study | Participants | Intervention | Control treatment | Length of follow-up | Outcomes |
|---|---|---|---|---|---|
| Korhonen et al. [27, 28] Finland, non-RCT | 72 patients with nerve root pain confirmed by imaging. Data for TNF group only (no data for control group); mean duration 7.2 weeks; mean age 39 years; 80 % men | Intra-venous infusion of infliximab 3 mg/kg | Periradicular saline injection | 12 months | Number of painless patients (>75 % decrease from baseline leg pain score); back and leg pain intensity (VAS); Oswestry Disability Index; number of sick leave days; clinical status, adverse effects |
| Korhonen et al. [23, 24] Finland, RCT | 41 patients with first or recurrent episode of nerve root pain confirmed by imaging; median duration 61 days; mean age 41 years; 60 % men | Intravenous infliximab 5 mg/kg | Intravenous saline injection | 12 months | Number of painless patients (>75 % decrease from baseline leg pain score); back and leg pain intensity (VAS)a,b; Oswestry Disability Indexa,b; RAND-36 health questionnaire; number sick leave days; number discectomies; clinical status, adverse effects |
| Karppinen et al. [22] Finland, RCT | 15 patients with nerve root pain confirmed by imaging; disc herniation at L3/4 or L4/5; mean duration 58 days; mean age 53 years; 67 % men | Intravenous infliximab 5 mg/kg | Intravenous saline injection | 6 months | Back and leg pain intensity (VAS)a,b; Oswestry Disability Indexa,b; RAND-36 health questionnaire; number sick leave days; number discectomies; clinical status, adverse effects |
| Cohen et al. [20] USA, RCT | 24 patients with nerve root pain confirmed by imaging; median duration 3–7 months; median age 41–46 years; 71 % men | Transforaminal epidural injection etanercept: 2 mg (Group 1) 4 mg (Group 2) 6 mg (Group 3) |
Transforaminal epidural injection normal saline | 6 months | Number with a positive outcome [>50 % reduction in leg pain + global perceived effect (combination of pain, daily activities improved & satisfaction)]; back and leg pain intensity (numerical rating scale)c; Oswestry Disability Indexc; drug consumption; (Results from groups 1–3 combined for the meta-analysis) |
| Okoro et al. [25] UK, RCT | 15 patients with nerve root pain confirmed by imaging for at least 24 weeks; mean age not stated; 40 % men | Subcutaneous injection of etanercept 25 mg | Subcutaneous injection of saline | 3 months | Leg pain intensity (VAS)d; Oswestry Disability Indexd; modified somatic perception; modified Zung depression index; subjective walking distance; adverse effects |
| Genevay et al. [21] Switzerland, RCT | 61 patients with first or recurrent episode of nerve root pain confirmed by imaging; mean duration 3.6 weeks; mean age 49 years; 57 % men | Subcutaneous injection of adalimumab 40 mg ×2 | Subcutaneous injection of saline ×2 | 6 months | Number of responders (>30 % improvement from baseline leg or back pain score or Oswestry Disability Index); back and leg pain intensity (VAS); Oswestry Disability Index, SF-12v2; drug consumption; number of discectomies; work status; adverse effects |
| Cohen et al. [26] USA, Germany, RCT | 84 patients with nerve root pain confirmed by imaging; mean duration 2.7 months; mean age 42 years; 70 % men | Transforaminal epidural injection etanercept 4 mg + local anaesthetic 0.5 ml × 2 | Transforaminal epidural injection normal saline + local anaesthetic 0.5 ml × 2 | 6 months (large proportion left study after 1 month)e | Positive categorical outcome (>50 % decrease in leg pain + positive global perceived effect obviating the need for further treatment); back and leg pain intensity (NRS); Oswestry Disability Index; reduction in analgesic consumption |
NRS numeric rating scale, RCT randomised controlled trial, SD standard deviation, SF-12 short form 12, TNF tumour necrosis factor, VAS visual analogue scale
aSD not reported, imputed from other studies in meta-analyses
bMedians reported
cResult from only a single patient in control group at 6 month follow-up
dMean leg pain intensity and SDs obtained from authors
eAfter 1 month participants who received no benefit exited the study to pursue other treatments