• Melissa Pynnonen, Jennifer V Brinkmeier, Marc C Thorne, Lee Yee Chong, and Martin J Burton.
• Department of Otolaryngology - Head and Neck Surgery, Taubman Center, 1500 E Medical Center Drive, Ann Arbor, Michigan, USA.
• Cochrane Db Syst Rev. 2017 Aug 22; 8: CD004619.

BackgroundTonsillectomy is a very common operation and is performed using various surgical methods. Coblation is a popular method because it purportedly causes less pain than other surgical methods. However, the superiority of coblation is unproven.ObjectivesTo compare the effects of coblation tonsillectomy for chronic tonsillitis or tonsillar hypertrophy with other surgical techniques, both hot and cold, on intraoperative morbidity, postoperative morbidity and procedural cost.Search MethodsThe Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2017, Issue 3); PubMed; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 20 April 2017.Selection CriteriaRandomised controlled trials (RCTs) of children and adults undergoing tonsillectomy with coblation compared with any other surgical technique. This review is limited to trials of extracapsular (traditional) tonsillectomy and excludes trials of intracapsular tonsil removal (tonsillotomy).Data Collection And AnalysisWe used the standard Cochrane methods. Our primary outcomes were: patient-reported pain using a validated pain scale at postoperative days 1, 3 and 7; intraoperative blood loss; primary postoperative bleeding (within 24 hours) and secondary postoperative bleeding (more than 24 hours after surgery). Secondary outcomes were: time until resumption of normal diet, time until resumption of normal activity, duration of surgery and adverse effects including blood transfusion and the need for reoperation. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics.Main ResultsWe included 29 studies, with a total of 2561 participants. All studies had moderate or high risk of bias. Sixteen studies used an adequate randomisation technique, however the inability to mask the surgical teams and/or provide adequate methods to mitigate the risk of bias put nearly all studies at moderate or high risk of detection and measurement bias for intraoperative blood loss, and primary and secondary bleeding. In contrast most studies (20) were at low risk of bias for pain assessment. Most studies did not report data in a manner permitting meta-analysis.Most studies did not clearly report the participant characteristics, surgical indications or whether patients underwent tonsillectomy or adenotonsillectomy. Most studies reported that tonsillitis (infection) and/or tonsillar hypertrophy (obstruction) were the indication for surgery. Seven studies included only adults, 16 studies included only children and six studies included both. Pain At postoperative day 1 there is very low quality evidence that patients in the coblation group had less pain, with a standardised mean difference (SMD) of -0.79 (95% confidence interval (CI) -1.38 to -0.19; 538 participants; six studies). This effect is reduced a SMD of -0.44 (95% CI -0.97 to 0.09; 401 participants; five studies; very low-quality evidence) at day 3, and at day 7 there is low quality evidence of little or no difference in pain (SMD -0.01, 95% CI -0.22 to 0.19; 420 participants; five studies). Although this suggests that pain may be slightly less in the coblation group between days 1 and 3, the clinical significance is unclear. Intraoperative blood loss Methodological differences between studies in the measurement of intraoperative blood loss precluded meta-analysis. Primary and secondary bleeding The risk of primary bleeding was similar (risk ratio (RR) 0.99, 95% CI 0.48 to 2.05; 2055 participants; 25 studies; low-quality evidence). The risk of secondary bleeding was greater in the coblation group with a risk ratio of 1.36 (95% CI 0.95 to 1.95; 2118 participants; 25 studies; low-quality evidence). Using the median of the control group as the baseline risk, the absolute risk in the coblation group was 5% versus 3.6% in the control group. The difference of 1.3% has a 95% CI of 0.2% lower in the coblation group to 3.5% higher. Secondary outcomes Differences in study design and data reporting precluded the identification of differences in the time to resumption of normal diet or activity, or whether there was a difference in the duration of surgery.Although we could not feasibly compare the costs of equipment or operative facility, anaesthetic and surgical fees across different healthcare systems we used duration of surgery as a proxy for cost. Although this outcome was commonly reported in studies, it was not possible to pool the data to determine whether there was a difference.Adverse events other than bleeding were not well reported. It is unclear whether there is a difference in postoperative infections or the need for reoperation.Authors' ConclusionsThe coblation technique may cause less pain on postoperative day 1, but the difference is small and may be clinically meaningless. By postoperative day 3, the difference decreases further and by postoperative day 7 there appears to be little or no difference. We found similar rates of primary bleeding but we cannot rule out a small increased risk of secondary bleeding with coblation. The evidence supporting these findings is of low or very low quality, i.e. there is a very high degree of uncertainty about the results. Moreover, for most outcomes data were only available from a few of the 29 included studies.The current evidence is of very low quality, therefore it is uncertain whether or not the coblation technique has any advantages over traditional tonsillectomy techniques. Despite the large number of studies, failure to use standardised or validated outcome measures precludes the ability to pool data across studies. Therefore, well-conducted RCTs using consistent, validated outcome measures are needed to establish whether the coblation technique has a benefit over other methods. In the included studies we identified no clear difference in adverse events. However, given the rarity of these events, randomised trials lack the power to detect a difference. Data from large-scale registries will provide a better estimate of any difference in these rare outcomes.

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