The SUMMIT Trial: A field comparison of buprenorphine versus methadone maintenance treatment. Pinto H, Maskrey V, Swift L, Rumball D, Wagle A, Holland R. Journal of Substance Abuse Treatment, 2010 39;4:340-352
Dear Reader,
This naturalistic description and follow up study from a drug service in England shows comparative retention rates in opiate maintenance patients with exhaustive comparisons between the two groups. The current study followed a previous abortive attempt at randomisation of the groups which failed to attract any subjects, so determined were they all on their preferred medication.
These authors enrolled 361 eligible applicants for opioid maintenance of whom 227 (63%) chose methadone with the rest opting for (pure) buprenorphine (37%).
Despite the methadone patients having ‘more severe substance abuse and psychiatric and physical problems’ their retention rate was substantially higher than the buprenorphine patients (70% vs. 43% at 6 months).
Only seven of 134 patients swapped from buprenorphine to methadone early in the trial (apparently none swapped the other way around). Of the remaining buprenorphine drop-outs 10 were planned detox episodes; 40 failed to attend; 13 were detained by police; 10 were involuntary discharges. Relating to buprenorphine retention the authors report that the only significant difference on multivariate analysis in the many features/opinions solicited from the subjects was a ‘belief as to whether buprenorphine blocked the effect of heroin’. While this belief is not soundly based, it might be a helpful street myth, keeping some patients away from dangerous drugs. However, it could also give some users a false sense of security in a high risk overdose situation.
The trial patients were prescribed a mean maximum daily dose for buprenorphine of 12mg (r 4-20mg); and for methadone of 73mg (r 10-170mg). There were two deaths in the methadone group, one in the induction period and another while on a stable dose of methadone caused by overdose of multiple depressants.
As in most such longitudinal studies the proportion of subjects successfully reducing their dose to zero was low - around 7% for buprenorphine and under 1% for those choosing methadone during a six month period. This is consistent with other research showing about 4% of opioid dependent people become abstinent each year (and this is regardless of the type of treatment - see Thorley’s seminal work from the UK).
Crucial to the results of this trial was the finding that 10% of the total said that they would not have attended if methadone were the only drug available. The derived figure of buprenorphine patients who stated that they would not have attended for methadone in the absence of an alternative was 28%. This is a novel finding to my knowledge but fits with clinical experience in other areas that greater choice yields greater patient acceptance, better enrolments, compliance (adherence) and retention. Apparently English health authorities are required to justify the expense of each medication and so this provides strong evidence in that regard which was one of the aims of the authors (see their previous paper).
Since these authors used pure buprenorphine SL tablets readers should be cautious about extrapolating these findings to buprenorphine-naloxone (Suboxone) … it may or may not be the case that buprenorphine-naloxone would have achieved similar results to pure buprenorphine on which most of the fundamental research has been performed to date (RCT, safety, etc). Another reason to favour pure buprenorphine is that it is available in 0.4mg tablets (in Australia). In our own practice we have at least a quarter of our patients taking increments requiring 0.4mg tablets.
While there must be end-points to any research trial, it would be instructive to know how many of the drop-outs had re-registered in treatment (if any). While the group was not able to examine this issue, other research would indicate largely negative results including a high mortality. Dr Bell investigated this from official enrolment statistics in New South Wales some years ago [Bell J, Burrell T, Indig D, Gilmour S. Cycling in and out of treatment; participation in methadone treatment in NSW, 1990–2002. Drug and Alcohol Dependence 2006 81; 1: 55-61]. Such research, as well as clinical experience with buprenorphine shows that there is indeed a ‘revolving door’ or ‘frequent flyer’ syndrome with this treatment, at least in comparison to methadone.
Because there was no randomisation to the intervention, this study does not give us scientific information about the different drugs. However, it does inform us for the first time I believe that the most seriously dependent patients are more likely to choose methadone and that they have a better retention rate in so doing. Less seriously dependent patients are more likely to choose buprenorphine and are more likely to drop out of treatment (and some successfully withdraw from treatment). So unsurprisingly, outcomes are a function of both the patient group and the treatment chosen. While this information is not a major benefit in individual clinical decision making, this study at the very least provides an excellent “barometer” by which we might measure our own practices regarding the proportion taking each drug and the dose ranges used.
Comments by Andrew Byrne ..
