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Fig. 3. Results of the network meta-analysis concerning objective Frey syndrome prevention. (A) network plot of included interventions. Circles are weighted according to the number of studies, including the intervention, and lines are weighted according to the number of studies com paring the two connected techniques. (B) absolute risk of objective Frey syndrome incidence for each intervention. [Color fi gure can be viewed in the online issue, which is available at www.laryngoscope.com.]

TABLE II. League Table Showing Comparative Effectiveness of Analyzed Interventions in Network Meta-analysis Concerning Objective Frey Syndrome Prevention. FFG 1.32 (0.07, 52.16) TPFF 1.99 (0.13, 69.29) 1.49 (0.19, 13.87) ADM 6.51 (0.52, 205.90) 4.91 (0.95, 32.42) 3.29 (0.72, 16.02) SMAS 7.15 (0.59, 228.40) 5.42 (1.04, 34.64) * 3.63 (0.81, 17.05) 1.09 (0.45, 2.78) SCM 18.16 (1.61, 563.60) * 13.69 (3.02, 83.40) * 9.31 (2.28, 39.74) * 2.79 (1.42, 5.85) * 2.53 (1.35, 5.16) * None Different treatments are reported in order of objective Frey syndrome prevention ranking. Comparisons should be read from left to right. The estimate is located at the intersection of the column-de fi ning treatment and the row-de fi ning treatment. Data are reported as OR with 95% CI. An OR value greater than 1 favors the column-de fi ning treatment. * P value statistically signi fi cant.

P = .78; FFG, Intercept = − 1.68, P = .35; SCM, Inter cept = − 1.65, P = .32; SMAS, Intercept = 2.32, P = .40; TPFF, Intercept = − 2.47, P = .49), suggesting no obvious publication bias. Data related to the between-study heterogeneity for each intervention are shown in Supporting Table 4. Baujat plots created for each intervention are shown in Supporting Figure 3. Network Meta-analysis Subjective FS. The results of the network meta analysis concerning the incidence of clinical (subjective) FS are shown in Figure 2. If compared to no treatment, the greatest reduction of clinical (subjective) FS incidence was measured for the TPFF (OR: 0.07, CI: 0.004 – 0.57), the ADM (OR: 0.09, CI: 0.02 – 0.35), and the FFG (OR: 0.11, CI: 0.03 – 0.42) techniques. However, a signi fi cant difference was measured also for the SCM fl ap (OR: 0.38, CI: 0.18 – 0.73) and for the SMAS fl ap (OR: 0.42, CI: 0.19 – 0.97). TPFF treatment seemed to perform better than other treat ments according to the results of the rank probabilities test (50% chance of ranking fi rst compared with ADM [29%]

and FFG [20%]) (Supporting Figure 4A). The density plot revealed partial overlapping between these three treat ments (Supporting Figure 4B). Pooled estimates of ORs for clinical (subjective) FS are summarized in Table I. Objective FS. Figure 3A shows the geometry of the network for the incidence of positive starch-iodine test result (objective FS). Absolute risk of objective FS is shown in Figure 3B for each intervention. All treatments showed a signi fi cant reduction of the objective FS incidence if com pared to no treatment (FFG, OR: 0.06, CI: 0.002 – 0.62; TPFF, OR: 0.07, CI: 0.01 – 0.33; ADM, OR: 0.11, CI: 0.03 – 0.44; SMAS, OR: 0.36, CI: 0.17 – 0.71; SCM, OR: 0.40, CI: 0.19 – 0.74). The FFG has a 51% chance of ranking fi rst compared to TPFF (34%) and ADM (15%) at the rank prob ability test (Supporting Figure 5A), as con fi rmed by the absolute risk density plot (Supporting Figure 5B). Pooled estimates of ORs for positive starch-iodine test result (objective FS) are summarized in Table II.

DISCUSSION Current literature data are inconclusive about the best way to prevent FS after parotidectomy. Lack of high

Laryngoscope 131: August 2021

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