Use of pregabalin for the treatment of essential tremor

Review question

The authors of this review tried to assess the effectiveness and safety of pregabalin in people with essential tremor.

Backgound

Essential tremor is the most common movement disorder. Although benign in terms of its effect on life expectancy, it is typically progressive and potentially disabling. Treatment consists primarily of pharmacological agents (propranolol and primidone as first-line therapy), which could be ineffective for 25% to 55% of patients. Some specialists have suggested that pregabalin could be a potentially useful drug for treating the condition.

Study characteristics

We found one study comparing pregabalin versus placebo, involving 22 randomised participants with essential tremor.

Key results

The impact of pregabalin on functional abilities and adverse effects is uncertain because the quality of the evidence is very low.

Quality of the evidence

The lack of studies and the significant limitations in the one included trial preclude firm conclusions about the risk-benefit profile of this treatment.

Authors' conclusions: 

The effects of pregabalin for treating essential tremor are uncertain because the quality of the evidence is very low. One small study did not highlight any effect of this treatment; however, the high risk of bias and the lack of other studies on this topic limit further conclusion.

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Background: 

Essential tremor is one of the most common movement disorders. Treatment primarily consists of pharmacological agents. While primidone and propranolol are well-established treatments in clinical practice, they may be ineffective in 25% to 55% of patients and can produce serious adverse events in a large percentage of them. For these reasons, it is worth evaluating the treatment alternatives for essential tremor. Some specialists have suggested that pregabalin could be a potentially useful agent, but there is uncertainty about its efficacy and safety.

Objectives: 

To assess the effects of pregabalin versus placebo or other treatment for essential tremor in adults.

Search strategy: 

We performed a systematic search without language restrictions to identify all relevant trials up to December 2015. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, NICE, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (ICTRP). We handsearched grey literature and examined the reference lists of identified studies and reviews.

Selection criteria: 

We included all randomised controlled trials (RCTs) of pregabalin versus placebo or any other treatments. We included studies in which the diagnosis of ET was made according to accepted and validated diagnostic criteria. We excluded studies conducted in patients presenting secondary forms of tremor or reporting only neurophysiological parameters to assess outcomes.

Data collection and analysis: 

Two reviewers independently collected and extracted data using a data collection form. We assessed the risk of bias of the body of evidence, and we used inverse variance methods to analyse continuous outcomes and measurement scales. We compared the mean difference between treatment groups, and we combined results for dichotomous outcomes using Mantel-Haenszel methods and risk differences We used Review Manager software for data management and analysis.

Main results: 

We only found one study eligible for this review (22 participants). We assessed the risk of bias for most domains as unclear. We graded the overall quality of evidence as very low. Compared to placebo, patients treated with pregabalin showed no significant improvement of motor tasks on the 36-point subscale of the Fahn-Tolosa-Marin Tremor Rating Scale (TRS) (MD −2.15 points; 95% CI −9.16 to 4.86) or on the 32-point functional abilities subscale of the TRS (MD −0.66 points; 95% CI −2.90 to 1.58).The limited evidence showed no difference in study withdrawal (Mantel-Haenszel RD −0.09; 95% CI −0.48 to 0.30) and presentation of adverse events between pregabalin and placebo (Mantel-Haenszel RD 0.18; 95% CI −0.13 to 0.50).

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