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Journal Club
Alcohol, Other Drugs, and Health: Current Evidence
March–April 2014
Featured Article
Gabapentin Can Decrease Heavy Drinking and Increase Abstinence for Patients with Alcohol
Dependence
Mason BJ, et al. JAMA Intern Med. 2014;174(1):70–77.
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Study Objective
• To determine whether gabapentin can increase rates of sustained abstinence and decrease rates of heavy drinking.
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Study Design
• A 12-week, double-blind, placebo-controlled randomized dose-ranging trial comparing three groups (N = 150 adults with current alcohol dependence). All groups received counseling.
• The three groups received:
– Gabapentin 900 mg/day
– Gabapentin 1800 mg/day
– Gabapentin 0 mg/day (control)
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Assessing Validity of an Article about Therapy
• Are the results valid?
• What are the results?
• How can I apply the results to patient care?
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Are the Results Valid?
• Were patients randomized?
• Was randomization concealed?
• Were patients analyzed in the groups to which they were randomized?
• Were patients in the treatment and control groups similar with respect to known prognostic variables?
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Are the Results Valid? (cont‘d)
• Were patients aware of group allocation?
• Were clinicians aware of group allocation?
• Were outcome assessors aware of group allocation?
• Was follow-up complete?
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Were patients randomized?
• Yes.– Patients were randomized using a computer-
generated randomization code.– Patients were randomized in a 1:1:1 ratio.
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Was randomization concealed?
• Yes.– The randomization code was kept
by the study pharmacist who administered the medication.
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Were patients analyzed in the groups to which they were
randomized?
• Yes.
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Were the patients in the treatment
and control groups similar?
• Yes.
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Were patients aware of group allocation?
• No.– Patients were blinded to group
allocation.
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Were clinicians aware of group allocation?
• No.– Only the study pharmacist was aware of
group allocation. Other researchers or clinicians were not.
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Were outcome assessors aware of group allocation?
• No.
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Was follow-up complete?
• No.
– The trial was 12 weeks long and patients were administered medication weekly.
– Number of patients who provided 12-week data for analysis: • Gabapentin 900 mg group: 27 of 54
initially enrolled• Gabapentin 1800 mg group: 28 of 47
initially enrolled• Control group: 30 of 49 initially enrolled
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What Are the Results?
• How large was the treatment effect?
• How precise was the estimate of the treatment effect?
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How large was the treatment effect?
• Gabapentin had a significant linear dose effect in increasing rates of abstinence (P = 0.04).
• The rate of 12-week abstinence was:– Gabapentin 900 mg group: 11.1% (95% CI, 5.2%–
22.2%)– Gabapentin 1800 mg group: 17% (95% CI, 8.9%–
30.1%; NNT = 8; OR = 4.8)
– Control: 4.1% (95% CI, 1.1%–13.7%)
• The rate of no heavy drinking at 12 weeks was:– Gabapentin 900 mg group: 29.6% (95% CI, 19.1%–
42.8%)– Gabapentin 1800 mg group: 44.7% (95% CI, 31.4%–
58.8%; NNT = 5; OR = 2.8)– Control: 22.5% (95% CI, 13.6%–37.2%)
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How Can I Apply the Results to Patient Care?
• Were the study patients similar to the patients in my practice?
• Were all clinically important outcomes considered?
• Are the likely treatment benefits worth the potential harm and costs?
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Were the study patients similar to those in my practice?
• The patients were treatment-seeking adult volunteers.
• All were people with current DSM-IV alcohol dependence; the majority had moderate dependence.
• They were excluded if urine toxicology screens revealed the use of any other substances besides alcohol or nicotine.
• They could not have significant medical or psychiatric disorders.
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Were all clinically important outcomes considered?
• Yes.
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Are the likely treatment benefits worth the potential harm and
costs?• Possibly.
– There were no differences in the rate of termination due to adverse events by study arm. Costs were not considered.
– Due to the loss to follow-up, further studies into acceptability and efficacy of gabapentin for treating alcohol use disorders are needed.
– Results may not be generalizable since it was a single-site study.
– The overlapping confidence intervals across the study groups suggest that widespread use of the treatment for dependence should await a larger effectiveness trial.
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