A comparison of survival lifetime of the Provox and the Provox2 voice prosthesis.

The Provox (Atos Medical AB, Hörby, Sweden) voice prosthesis was developed between 1988 and 1990 and has been used at our centre with regular success since 1993. Since 1996, a second generation of Provox (Provox2) has been used, which can be inserted by an anterograde technique. The aim of this study is to compare the survival lifetime of both voice prostheses. The survival time of the two voice prostheses were compared retrospectively in 152 devices placed in 38 patients. A Kaplan-Meier analysis was performed to determine the survival lifetimes and a log rank test was performed to compare the two curves. Clinical factors affecting the lifetime were also analysed with a Kaplan-Meier plot. The median survival lifetime of the Provox and Provox2 were 303 and 144 days respectively. The Kaplan-Meier estimation shows that this difference is statistically significant (p=0.02). It is considered an early failure if it occurs within the first three months. There was a larger number of early failures with the Provox2 than with the Provox (p=0.04). Neither the gender nor the age affected the lifetime of the devices. Radiotherapy seemed to lengthen the lifetime of the first valve. The survival lifetime of the second generation Provox2 valve is shorter than the lifetime of the first generation Provox. This could be due to the difference in elasticity of these valves that could lead to a different level of colonization and invasion of the valves by micro-organisms.