Obstructive sleep apnea syndrome (OSAS), a prevalent disorder in middle-aged men, is associated with urological conditions like erectile dysfunction, nocturia, overactive bladder, urgency, and urge incontinence. However, the impact of OSAS on postoperative urinary outcomes following RARP remains unknown. This study aimed to investigate the association between pre-existing OSAS and urinary continence outcomes in men who underwent RARP.
We analyzed our institutional RARP database from January 2015 to December 2018. We identified a total of 82 patients with OSAS and selected 131 controls who were matched for age and BMI. These patients had follow-up data available for patient-reported continence. To ensure unbiased results, we performed a propensity score-matched analysis.
In the study, a total of 213 patients were included initially, with 82 having Obstructive Sleep Apnea Syndrome (OSAS) and 131 serving as the control group. After conducting propensity score-matched analyses, there were no significant differences in baseline demographics and tumour characteristics between the two groups. The median time to achieve total continence was 6.6 months for the control group and 13.0 months for the OSAS group. The continence rates at 6, 12, and 24 months were lower in the OSAS group compared to the control group. Univariate and multivariate analyses both showed that non-OSAS was associated with a higher continence rate.
Table 1: Cox Regression Model Assessing Factors Predicting Continence Recovery in Patients After Robot-Assisted Radical Prostatectomy
|
Univariate |
Multivariable |
|||||
|
Variable |
HR |
95% CI |
p-value |
HR |
95% CI |
p-value |
|
OSAS |
||||||
|
OSAS group |
— |
— |
— |
— |
||
|
Control group |
2.1 |
1.45, 3.04 |
<0.001 |
2.44 |
1.61, 3.72 |
<0.001 |
|
Age |
1 |
0.98, 1.03 |
0.933 |
0.99 |
0.95, 1.02 |
0.5 |
|
PSA (ng/mL) |
||||||
|
<10 |
— |
— |
— |
— |
||
|
>20 |
0.7 |
0.22, 2.22 |
0.541 |
0.57 |
0.16, 2.07 |
0.4 |
|
10-20 |
2.66 |
1.45, 4.88 |
0.002 |
1.98 |
0.92, 4.29 |
0.082 |
|
BMI |
||||||
|
Normal |
— |
— |
— |
— |
||
|
Overweight |
1.06 |
0.61, 1.83 |
0.833 |
1.19 |
0.62, 2.25 |
0.6 |
|
Obese |
1.06 |
0.63, 1.81 |
0.823 |
1.12 |
0.61, 2.07 |
0.7 |
|
Morbid obese |
1.13 |
0.26, 4.88 |
0.874 |
2.59 |
0.52, 12.8 |
0.2 |
|
Prostate Volume |
1 |
0.99, 1.01 |
0.732 |
0.99 |
0.98, 1.00 |
0.14 |
|
Pathological Tumor Staging |
||||||
|
T2 |
— |
— |
— |
— |
||
|
T3a |
0.98 |
0.65, 1.48 |
0.933 |
0.92 |
0.58, 1.46 |
0.7 |
|
T3b |
2.4 |
1.38, 4.19 |
0.002 |
1.82 |
0.75, 4.41 |
0.2 |
|
SHIM score |
1.01 |
0.98, 1.03 |
0.627 |
1.01 |
0.98, 1.04 |
0.7 |
|
IPSS |
1 |
0.97, 1.04 |
0.806 |
1.05 |
0.98, 1.13 |
0.2 |
|
IPSS classification |
||||||
|
Mild |
— |
— |
— |
— |
||
|
Moderate |
0.95 |
0.67, 1.36 |
0.782 |
0.75 |
0.37, 1.51 |
0.4 |
|
Severe |
0.29 |
0.04, 2.13 |
0.226 |
0.22 |
0.02, 2.46 |
0.2 |
|
ISUP grade group |
||||||
|
1 |
— |
— |
— |
— |
||
|
2 |
1.11 |
0.65, 1.87 |
0.703 |
1.22 |
0.64, 2.31 |
0.6 |
|
3 |
1.04 |
0.58, 1.89 |
0.886 |
1.11 |
0.53, 2.33 |
0.8 |
|
4 |
2.53 |
1.17, 5.45 |
0.018 |
1.87 |
0.58, 6.06 |
0.3 |
|
5 |
1.21 |
0.52, 2.80 |
0.661 |
0.96 |
0.33, 2.77 |
>0.9 |
|
Surgical Margins |
||||||
|
Negative |
— |
— |
— |
— |
||
|
Positive |
0.91 |
0.63, 1.32 |
0.62 |
0.64 |
0.40, 1.02 |
0.062 |
|
HR = Hazard Ratio, CI = Confidence Interval, OSAS = Obstructive Sleep Apnea Syndrome, PSA = Prostate-Specific Antigen, BMI = Body Mass Index, SHIM = Sexual Health Inventory For Men, IPSS = International Prostate Symptom Score, ISUP = International Society Of Urological Pathology |
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While age is a strong predictor of incontinence, with older patients taking longer to regain continence, the aggressiveness of the tumour correlates with poorer continence rates due to tumour-related angiogenesis affecting surrounding structures. The results from our study showed that patients with OSAS had a longer time to achieve continence and higher odds of experiencing incontinence compared to the matched control group.
The severity of Obstructive Sleep Apnea Syndrome (OSAS) is directly associated with the negative impact on quality of life (QoL) caused by lower urinary tract symptoms (LUTS), including urge incontinence. The urological symptoms associated with OSAS can be multifactorial, involving abnormal inflammatory processes and oxidative stress. Additionally, a relationship has been observed between urgency and hypoxia, with patients experiencing urinary urgency spending more time with low oxygen saturation levels. The underlying mechanisms behind these changes are not yet fully understood but could involve altered muscle fibre-type composition and inflammatory cytokines induced by hypoxia. Altered microRNA profiles in upper airway skeletal muscles due to chronic oxidative changes caused by OSAS may also contribute to these findings. In terms of postoperative continence, patients with OSAS had higher incontinence rates compared to controls, and OSAS showed a trend towards worse continence on multivariate analysis. The elevated mean BMI of the patients in both the OSAS and non-OSAS groups may explain the low continence rates observed. Obesity and metabolic syndrome, often associated with elevated BMI, have been shown to impact urinary continence recovery post-RARP through mechanisms involving inflammation, insulin resistance, autonomic hyperreflexia, and changes in pelvic floor vasculature.
In our matched analysis, we observed that patients without Obstructive Sleep Apnea Syndrome (non-OSAS) exhibited a trend towards improved urinary continence compared to patients with OSAS. However, the underlying mechanisms responsible for these findings still need to be fully understood and require further investigation to validate and gain a deeper understanding of our initial results.
Written by:
- Mohammed Shahait, MB, BS, Division of Urology, Department of Surgery, University of Pennsylvania, Philadelphia, PA
- Ryan W Dobbs, MD, Division of Urology, Department of Surgery, University of Pennsylvania, Philadelphia, PA
- David I Lee, MD, Department of Urology, University of California Irvine, Orange, CA