Central randomisation

In central randomisation the randomisation process is controlled and managed from a centralised point of contact. Each investigator makes a telephone call through an Interactive Voice Response System (IVRS) to this centralised point when they have identified a patient to be entered into the study and is given the next allocation, taken from the appropriate randomisation list. Blind can be preserved by simply specifying the number of the (pre-numbered) pack to be used to treat the particular patient the computerised system keeps a record of which packs have been used already and which packs contain which treatment. Central randomisation has a number of practical advantages  

Earlier we discussed the use of stratified randomisation in multi-centre trials and where the centres are large this is appropriate. With small centres however, for example in GP trials, this does not make sense and a stratified randomisation with region defining the strata may be more appropriate. Central randomisation would be essential to manage such a scheme. 

Stratified randomisation with more than a small number of strata would be difficult to manage at the site level and the use of central randomisation is then almost mandatory. 

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In multicentre trials, it is usual to use a separate randomisation procedure within each centre to ensure that there is balance - or at least near balance within each centre. In such circumstances ICH E9 (Section 2.3.2) recommends that the randomisation be performed centrally, with several blocks allocated to each centre. This procedure is a simple form of stratified randomisation. 

Birch. Efficacy of two cannabis based medicinal extracts for relief of central neuropathic pain from brachial plexus avulsion results of a randomised controlled trial. Pain 2004 112(3) ... 

Svendsen KB, Jensen TS, Bach FW. Does the cannabinoid dronabinol reduce central pain in multiple sclerosis Randomised double blind placebo controlled crossover trial. BMJ 2004 329(7460) 253. 

Cannabinoids are no more effective than codeine in controlling pain and have depressant effects on the central nervous system that limit their use. Their widespread introduction into clinical practice for pain management is therefore undesirable. In acute postoperative pain they should not be used. Before cannabinoids can be considered for treating spasticity and neuropathic pain, further valid randomised controlled studies are needed. 

A small controlled study (Svendsen et al. 2003) suggests that dronabinol (synthetic THC) may also be useful in MS-related pain. THC (maximum dose of 10 mg/day) was compared with placebo in a randomised, double-blind, crossover trial with 3-week treatment periods in 24 patients with central neuropathic pain. Spontaneous pain intensity and pain relief were both significantly improved by THC. There was no comment on unwanted effects in this conference abstract. 

Young CA, Rog DJ (2003) Randomised controlled trial of cannabis based medicinal extracts (CBME) in central neuropathic pain due to multiple sclerosis. Congress of the European Federation of lASP Chapters (EFIC), 2-6 September 2003, Prague... 

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Berman, J., Lee, J., Cooper, M., Cannon, A., Sach, J., McKerral, S., Taggart, M., Symonds, C., Fishe, K., and Birch, R. (2003) Efficacy of two cannabis-based medicinal extracts for relief of central neuropathic pain from brachial plexus avulsion results of a randomised controlled trial. Anaesthesia, 58 938. 

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Bong JJ, Kite P, Wilco MH, et al. Prevention of catheter related bloodstream infection by silver iontophoretic central venous catheters a randomised controlled trial. J Clin Pathol October 2003 56(10) 731-5. 

Gittins N S, Hunter-Blair YL, Matthews JN, Coulthard MG Comparison of alteplase and heparin in maintaining the patency of paediatric central venous haemodialysis lines a randomised controlled trial. Arch Dis Child 2007 92 499-501. 

K. F. Schulz, D. G. Altman, and D. Moher. CONSORT 2010 statement Updated guidelines for reporting parallel group randomised trials, BioMed Central Medicine, 8, 18, 2010. 

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