Table 2. Characteristics and results of included studies.
| Reference | Participants recruited (completed) | Design and duration | Intervention (n = patient episodes) | Maximum dose studied | Primary Outcome | Data (ITT) | Superior to placebo? |
| Youle M et al 2007 [36] | 90(76) | Parallel: 2 wks | Acetyl-L-carnitine 500 mg bd i.m. (n = 43); placebo (n = 47) | 1000mg/day | VAS (0–10cm) change: baseline to wk 2. | ITT: Acetyl-L-carnitine: −1.32 (SD 1.84); placebo −0.61 (SD 1.55)(p = 0.07) | No |
| Shlay JC et al 1998 [38] | 136 (105) | Parallel: 14 wks | Amitriptyline (n = 71); placebo (n = 65) | 75mg/day | GP score: change baseline to wk 14. | ITT with LOCF: Amitriptyline: −0.26; placebo: −0.30;difference 0.00 95%CI(−0.18 to 0.19)(p = 0.99) | No |
| Paice JA et al 2000 [29] | 26(14) | Parallel:4 wks. | Capsaicin 0.075% cream q.d.s. (n = 15); placebo (n = 11) | 0.075% q.d.s. | NRS (0–10): change from baseline to wk 4. | No numeric data given. Stated no statistically significant difference between capsaicin 0.075% and placebo (p>0.05) | No |
| Simpson DM et al 2008 [28] | 307(274) | Parallel: 12 wks follow-up. | Capsaicin 8% patch for 30min (n = 72); 60min (n = 78); 90min (n = 75); placebo (capsaicin 0.04%) (n = 82) | 8% for 90min. | NPRS: % change baseline to wk 12. | ITT with LOCF: Capsaicin: −22.8 (SD 30.6); placebo −10.7 (SD 30.8); (p = 0.0026) | Yes |
| Abrams DI et al 2007 [40] | 55(50) | Parallel: 5 days | Smoked cannabis (n = 27); placebo (n = 28) | 3.56% Δ-9- tetrahydrocannabinol t.d.s. | VAS: % change from baseline to day 5. | ITT: Cannabis: −34% (IQR −71 to −16); placebo −17% (IQR – 29 to 8) (p = 0.03) | Yes |
| Ellis RJ et al 2009 [41] | 34(27) | Crossover: 5 days, 2 wks washout, 5 days treatment. | Smoked cannabis (n = 28); placebo (n = 28) | Max tolerable: 1 to 8% Δ-9- tetrahydrocannabinol q.d.s. | DDS (0–20): median change from baseline to day 5. | Difference in DDS reduction cannabis vs placebo for PP: −3.3 p = 0.016, no data for ITT: said to be ‘similar’ with p = 0.020 | Yes |
| Hahn K et al 2004 [30] | 26(24) | Parallel: 4 wks treatment. | Gabapentin (n = 15); placebo (n = 11) | 2400mg/day | VAS: median change: baseline to wk 4. | Gabapentin: −44.1; placebo: −29.8. Stated as being not statistically significant. | No |
| Simpson DM et al 2010 [50] | 302(241) | Parallel: 14 wks treatment. | Pregabalin (n = 151); placebo (n = 151) | 1200mg/day | NPRS: mean change: baseline to wk 14. | ITT: Pregabalin: −2.88; placebo −2.63 (p = 0.39) | No |
| Simpson DM et al 2000 [51] | 42(29) | Parallel: 14 wks treatment | Lamotrigine (n = 20); placebo (n = 22) | 300mg/day | GP score: mean change: baseline to wk 14. | ITT with LOCF: Lamotrigine: −0.242 (SE 0.092); placebo: −0.183 (SE 0.087) (p = 0.65) | No |
| Simpson et al 2003 [31] | 227(172) | Parallel:12 wks treatment. | Lamotrigine (n = 150); placebo (n = 77) | 600mg/day | GP score: change: baseline to wk 12. | PP: Lamotrigine vs placebo. No data given, stated no statistically significant difference seen in all or ARV stratum. | No |
| Keiburtz K et al 1998 [39] | 145(104) | Parallel: 8 wks | Mexilitine (n = 48); amitriptyline (n = 47); placebo (n = 50) | Mexilitine: 300mg/day Amitriptyline: 100mg/day | GP score: mean change: baseline to wk 8. | ITT: Amitriptyline: −0.31 (SD 0.31); mexilitine: −0.23 (SD 0.41); placebo −0.20 (SD 0.30) No p value given, stated no statistical significance | No |
| McArthur JC et al 2000 [53] | 270(235) | Parallel:18 wks | Recombinant human NGF (n = 180); placebo (n = 90) | 0.3µg/kg s.c. twice weekly | GP score: median change: baseline to wk 18. | ITT with LOCF: NGF 0.1µg/kg: −0.18 (−0.10 to −0.25)(p = 0.05); NGF 0.3µg/kg: −0.21 (−0.14 to −0.29)(p = 0.04); placebo: 0.06 (+0.01 to −0.14) | Yes |
| Simpson DM et al 1996 [54] | 104(81) | Parallel: 12 wks | Peptide-T (n = 40); placebo (n = 41)* PP data | 6mg/day intranasal | Modified GP score: mean change: baseline to wk 12. | PP: Peptide-T: −0.24 (±0.45); placebo −0.39 (±0.19) (p = 0.32). ITT results not presented but stated showed the ‘same pattern’. | No |
GP - Gracely Pain Score, VAS – Visual Analogue Scale, ITT – Intention To Treat population, PP -Per Protocol population, NRS – Numerical Rating Scale, NPRS- Numerical Pain Rating Scale, DDS – Descriptor Differential Scale, LOCF - Last Observation Carried Forward.