Study characteristics are summarized in Table 1. Sample sizes of the included studies ranged from 32 to 150 patients, and in all studies, Harmonic technology was compared to conventional techniques in breast surgery. Different Harmonic device technologies were used in these analyses. The UltraCision Harmonic scalpel5,8,26,28,29,32,33 or Harmonic scalpel7,30 were used in nine studies, while the Harmonic FOCUS® device was used in two studies.4,6 The Harmonic UltraCision shears were used in one study.31 Overall, seven studies6,8,26,30–33 compared Harmonic technology to electrosurgery. One study7 compared Harmonic technology to standard scalpel blade and electrosurgery with scissors and ligations, and one compared Harmonic technology4 to standard scalpel blade and electrosurgery with scissors. Harmonic technology was compared to standard scalpel use in one study.28 Two three-armed studies5,29 were included in this analysis comparing Harmonic technology to electrosurgery or cold steel scalpel use; however, only results from the electrosurgery arm were reported in the conventional group of the current analysis. The mean number of lymph nodes removed was comparable between patients in Harmonic technology and conventional techniques groups, as reported by two of the included studies.6,7 One study reported the median number of lymph nodes removed with Harmonic technology as 24 versus 22 lymph nodes, respectively.7 The second study reported the mean number of lymph nodes removed as 21 for both Harmonic technology and conventional technique groups.6,7

The risk of bias varied across the included studies. Overall results of the risk of bias assessments are reported in Figure 2, and the quality assessment of individual studies is summarized in Table 2. The method of randomization was known in four studies.4,7,26,30 One study described randomization through the use of a random number table,4 and one described randomization by a computer-generated sequence.30 Two studies described randomization through the use of envelopes.7,26 One study8 was deemed to have a high risk of bias as the randomization sequence was generated through a systematic, nonrandom approach. Three studies6,7,26 described concealment of the randomization sequence. Blinding of patients to the surgical technique was reported in two studies,7,30 and one study7 described blinding of outcome assessors. Outcomes were considered objective and unlikely to be affected by a lack of blinding; thus, risk of performance bias was deemed low in nonblinded studies. There was no missing outcome data in all the included studies. Selective reporting remained unclear in eleven studies,4–8,26,28,29,31–33 while one study30 was deemed to have a low risk of bias, as it reported no difference in published outcomes compared to the study protocol.

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Operating time

Mean operating time (Harmonic technology: 105.21 minutes, conventional technique: 110.29 minutes) was reduced by 5.07 minutes (95% confidence interval [95% CI]: −10.98 to 0.83; P=0.09; ten studies; I2=83%), although results were not statistically significant (Table 3). This translates to a 4.60% decrease with Harmonic technology compared to conventional methods in breast surgery. For all surgery subgroups, results were not significantly different, with the exception of the mastectomy only (no lymph node dissection) subgroup that reported a significant reduction in operating time with Harmonic technology.32

(To view a larger version of Table 3, click here.)