Clean intermittent self-catheterization (CISC) is a standard approach for managing chronic urinary retention and neurogenic lower urinary tract dysfunction (NLUTD). It is known to reduce intravesical pressure and help preserve renal function, particularly in the short term. However, the long-term impact of CISC on renal function remains insufficiently understood, underscoring the need for further investigation. In this study, we retrospectively evaluated renal function in patients who had been undergoing CISC for more than two years, with the aim of clarifying long-term renal outcomes and identifying potential factors contributing to changes in renal function. We retrospectively evaluated long-term renal function in male patients using CISC to assess potential changes over time.

This retrospective study analyzed clinical data from male patients who had initiated CISC at our institution, continued it for more than two years, and underwent regular blood testing during the follow-up period. Patients aged 20 years or younger and those requiring CISC due to spinal cord injury were excluded from the study. The primary outcome was changes in renal function, assessed using estimated glomerular filtration rate (eGFR) at the initiation of CISC, at one year, two years, and at the final follow-up.

A total of 24 patients were included in the analysis (mean age: 66.8 ± 12.0 years). The median follow-up period was 71.5 months (IQR: 44–112.5 months).
eGFR at the initiation of CISC, and at 1 year, 2 years, and final follow-up was 66.9, 65.8, 66.6, and 67.4 mL/min/1.73m², respectively. The corresponding p-values for changes from baseline were 0.681, 0.893, and 0.921, indicating no significant differences over time.
We also analyzed whether comorbidities such as diabetes, hypertension, and hyperlipidemia; underlying disease being NLUTD; impaired renal function at the initiation of CISC (eGFR <60 mL/min/1.73m²); or the occurrence of febrile urinary tract infections during CISC follow-up had any impact on renal function. However, none of these factors showed a statistically significant association.

In this study, we observed that renal function, as assessed by eGFR, remained stable over a long-term follow-up in male patients undergoing CISC.
The absence of a significant association between febrile urinary tract infections and changes in renal function may be attributable to regular urological surveillance, which facilitated timely identification and appropriate management of infections, thereby preventing severe progression and limiting potential damage to the upper urinary tract.
These results support the use of long-term CISC as a viable management strategy for lower urinary tract dysfunction in male patients, without compromising renal function.
However, as this was a retrospective study conducted at a single institution with a limited sample size, further prospective studies with larger cohorts are warranted to validate these findings.

Long-term CISC appears to be a safe and effective strategy for managing lower urinary tract dysfunction in men, without compromising renal function.