Study design, materials and methods
Patients who underwent LDRBt as monotherapy in our institution between 2002 -2020 were included in our retrospective observational cohort study. We interrogated our prospectively maintained database, identifying those with normal erectile function, defined as IIEF5 > 22 at baseline. We analysed change in erectile function over time for up to 8 years. Our primary outcome was mean difference between IIEF-5 score at baseline and at regular time intervals. A secondary outcome was the proportion of patients in each IIEF5 category at each timepoint: severe ED (<12), moderate ED (12-16), mild ED (17-21) and no ED (22-25).
Results
The median age of our cohort was 64 (41-84). 1017 patients baseline IIEF-5 scores recorded. Of these, 431 patients had IIEF5 >22, with a mean score of 23.9. During follow up the mean IIEF-5 score was 15, 14.3, 15.7, 15.9, 15.2, 15.1 and 15.2, at 6 weeks, 6 months, 1 year, 2 years, 3 years, 5 years and 8 years respectively. A mean reduction of 8.9 was seen at 6 weeks, 9.6 at 6 months, and between 8 and 8.8 at each time point for up to 8 years. These results are illustrated in table 1. The proportion of men who maintained normal erectile function was 34.6% at 6 weeks, 25.6% at 6 months and between 29.2% and 34.5% for the remainder of the follow up period. The proportion of men with varying degrees of ED is illustrated in figure 1.
Interpretation of results
Patients who underwent LDR brachytherapy experienced an early decline in sexual function, which may be explained by the implantation procedure. There is a peak of dysfunction at 6 months, and a small degree of functional recovery at 1 year which does not change significantly for the remainder of the follow up period. At 8 years, approximately half of the men retained erectile function with only mild impairment or no impairment.