Nitinol versus non-Nitinol prostheses in otosclerosis surgery: a meta-analysis

The aim of this study is to perform a systematic review and meta-analysis of observational studies in which hearing outcomes after primary stapes surgery have been reported. After the surgical procedure, the effectiveness of stapes surgery using nickel titanium (Nitinol) or other prostheses were systematically compared and evaluated using a meta-analytic method. A systematic search for articles before January 2017 in Embase, Medline and Cochrane Library databases was conducted. Only articles in English were included. Inclusion criteria for qualitative synthesis consisted of a population of otosclerosis patients, intervention with primary stapes surgery using the Nitinol heat-crimping prosthesis compared with other type of stapes stapedotomy prostheses, and hearing outcome. Inclusion criteria for quantitative analysis consisted of application of audiometry guidelines of the American Academy of Otolaryngology Head and Neck Surgery Committee on Hearing and Equilibrium for evaluation of conductive hearing loss. A postoperative air-bone gap (ABG) ≤ 10 dB was considered effective. A bias assessment tool was developed according to Cochrane guidelines. To evaluate the mean age of the samples we used the chi-square test. Of the 4926 papers identified through the electronic database search (3695 in Pubmed/Cochrane and 1231 in Embase), 540 studies matched the selection criteria (436 in Pubmed/Cochrane and 104 in Embase) after application of filters and elimination of duplicate articles. After analysis of the title and abstract, 459 were excluded (396 in Pubmed/Cochrane and 63 in Embase). Of the remaining 81 papers, 74 were excluded according to the study selection criteria. A total of seven eligible studies with 1385 subjects, consisting of 637 in the Nitinol group and 748 in the non-Nitinol group, were included in our study. There were statistically significant differences in the effectiveness of stapes surgery between the Nitinol and non-Nitinol prostheses; the data showed a combined odds ratio (OR) of 2.56 (95% CI 1.38-4.76, p = 0.003). There were no statistically significant differences in the mean pre-operative age between Nitinol and non-Nitinol prostheses (p = 0.931). Our results suggest that the effectiveness of Nitinol was higher than non-Nitinol prostheses, with superiority of the number of patients with ABG ≤ 10 dB.