RESULTS
Patient profiles
Table 1 shows patient profiles before and after propensity score matching. A total of 175 patients with 33 patients in ADM group were enrolled in this study. Before propensity score-matching, the ADM group contained lower age, size of tumor, and volume of specimen, than those in the Control group. Moreover, the type of parotidectomy in the Control group were significantly difference than the type in the ADM group (P = 0.008). As a result, the rate of male and hypertension in both groups was similar (P = 0.447, P =0.902). After propensity score-matching, both groups were well matched in all parameters. 30 patients each were allocated to the ADM group and the Control group. Pleomorphic adenomas and Warthin’s tumors were the most frequent histological type in two groups. 25 patients (83%) or 23 patients (77%) underwent partial superficial parotidectomy, followed by superficial parotidectomy (4 patients in ADM group and 6 patients in Control group).
Complications
Overall complication rates are shown in Table 2. ADM group were associated with a total of 5 complications (17%), whereas Control group were associated with a total of 13 complications (43%) (P =0.024).
Postoperative facial function was graded on the House-Brackmann scale in all patients. 3 patients (10%) in the ADM group and 4 patients (13%) in the Control group had facial palsy, with initially founded on the first day after operation. The postoperative facial palsy did not get statistical significance between two groups. All patients except the two Nerve Schwannoma patients fully regained normal facial function within 6 months. The two Nerve Schwannoma patients in either group developed permanent facial palsy with grade IV.
1 patient (3%) in the ADM group and 6 patients (20%) in the Control group developed a sialocele or salivary fistula. No significant difference was achieved between the two groups (P =0.108).
1(3%) patient in the ADM group and 9(30%) patients in the Control group experienced sweating over the preauricular regions 6 months after the operation. There was statistically significant difference between the two groups in subjective Frey syndrome (FS) (P =0.015).
The most common complication was sensory deficit in both groups. Numbness in the infra-auricular region occurred in 4 patients (13%) in the ADM group and in 7 patients (23%) in the Control group (P =0.317). 9 of the 11 patients with sensory deficit recovered sensation within 6 months after the operation.
None of the patients in the ADM group experienced complications at the donor site. No patient in either group had tumor recurrence and seromas during the follow-up period.
Postoperative drainage
The postoperative drainage in the ADM group was 59.7+ 26.0 mL, whereas the postoperative drainage in the Control group was 110.0+ 78.7mL. Postoperative drainage was significantly decreased in the ADM group compared with the Control group (Fig. 2A) (P =0.002). The postoperative drainage time in the ADM group was 3.6+ 0.8 days, whereas the postoperative drainage time in the Control group was 4.7+ 1.7days. Postoperative drainage time was significantly lower in the ADM group compared with the Control group (Fig. 2B) (P =0.001).
Expect the sialocele or salivary fistula patients, the postoperative drainage in the ADM group (29 patients) was 58.3+ 25.3 mL, whereas the postoperative drainage in the Control group (24 patients) was 95.3+ 72.6mL. Postoperative drainage was also significantly decreased in the ADM group compared with the Control group (P =0.013). The postoperative drainage time in the ADM group was 3.6+ 0.8 days, whereas the postoperative drainage time in the Control group was 4.5+ 1.6days. Postoperative drainage time was also significantly lower in the ADM group compared with the Control group (P =0.010).
Subjective aesthetic score
Patients in the ADM group had a subjective aesthetic score of 6.1+ 1.7 compared with 5.2+ 1.7 in the Control group (Fig. 3). The subjective aesthetic score for patients in the ADM group was higher than those in the Control group (P =0.040).