Objectives
To re-evaluate the role of diabetes mellitus (DM) as a risk
factor for penile implant infection by exploring the
association between glycated haemoglobin (HbA1c) levels and
penile implant infection rates and to define a threshold value
that predicts implant infection.
Patients and Methods
We conducted a multicentre prospective study including all
patients undergoing penile implant surgery between 2009 and
2015. Preoperative, perioperative and postoperative
management were identical for the entire cohort. Univariate
analysis was performed to define predictors of implant
infection. The HbA1c levels were analysed as continuous
variables and sequential analysis was conducted using 0.5%
increments to define a threshold level predicting implant
infection. Multivariable analysis was performed with the
following factors entered in the model: DM, HbA1C level,
patient age, implant type, number of vascular risk factors
(VRFs), presence of Peyronie’s disease (PD), body mass index
(BMI), and surgeon volume. A receiver operating
characteristic (ROC) curve was generated to define the
optimal HbA1C threshold for infection prediction.
Results
In all, 902 implant procedures were performed over the
study period. The mean patient age was 56.6 years. The
mean HbA1c level was 8.0%, with 81% of men having a
HbA1c level of >6%. In all, 685 (76%) implants were
malleable and 217 (24%) were inflatable devices; 302
(33.5%) patients also had a diagnosis of PD. The overall
infection rate was 8.9% (80/902). Patients who had implant
infection had significantly higher mean HbA1c levels, 9.5%
vs 7.8% (P < 0.001). Grouping the cases by HbA1c level, we
found infection rates were: 1.3% with HbA1c level of 9.5% (P < 0.001). Patient age, implant type, and
number of VRFs were not predictive. Predictors defined on
multivariable analysis were: PD, high BMI, and high HbA1c
level, whilst a high-volume surgeon had a protective effect
and was associated with a reduced infection risk. Using
ROC analysis, we determined that a HbA1c threshold level
of 8.5% predicted infection with a sensitivity of 80% and a
specificity of 65%.
Conclusion
Uncontrolled DM is associated with increased risk of
infection after penile implant surgery. The risk is directly
related to the HbA1c level. A threshold HbA1c level of 8.5%
is suggested for clinical use to identify patients at increased
infection risk. |
