This Month in Adult Urology

Article Outline

• Cholelithiasis and Risk of Nephrolithiasis
• Increased Risk of Diabetes in Patients With Urinary Calculi
• Stress Urinary Incontinence Following Holmium Laser Enucleation of the Prostate
• Radical Prostatectomy in Academic Versus Nonacademic Institutions
• Renal Autotransplantation and Modified Pyelovesicostomy for Intractable Metabolic Stone Disease
• Multiparametric 3T Prostate MR Imaging to Detect Cancer
• Once Nocturia, Always Nocturia
• Copyright

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Cholelithiasis and Risk of Nephrolithiasis 

The literature suggests that there may be an association with gallstones and kidney stones. However, many of these studies are flawed from a perspective of bias either from the population studied or from detection bias as both may be seen on an x-ray. Taylor et al (page 1882) from Boston, Massachusetts examined Nurses' Health Studies I and II as well as the Health Professionals Follow-up Study in men which together included a total of more than 240,000 participants followed for 14 to 24 years. They performed multivariate odds ratio analysis using logistic regression to control for baseline covariates of age, body mass index, use of thiazide diuretics and other factors. The relative risk of kidney stone disease in participants with gallstone disease was 1.26 in older women, 1.32 in younger women and 1.28 in men. Lag analyses with at least a 4-year delay between the diagnosis of kidney stones or gallstones yielded similar results. The authors found that gallstones and kidney stones were positively associated, and postulated several mechanisms that could explain this association.

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Increased Risk of Diabetes in Patients With Urinary Calculi 

A growing body of evidence suggests that there may be a relationship between stone disease and diabetes. Some experts believe that diabetes is a risk for stone disease based on diet and other factors. Chung et al (page 1888) from Taipai Taiwan, Province of China compared a population of 23,569 patients diagnosed with urinary calculi between 2001 and 2003 with more than 70,000 matched study enrollees. Patients were then tracked for 5 years for any subsequent diagnosis of diabetes. Diabetes developed in 12% of the urinary calculi group vs 8.7% in the comparison cohort. Stratified Cox proportional analysis revealed that, after adjusting for hypertension, hyperlipidemia and obesity, the risk of diabetes within 5 years was 1.32 times greater for patients with urinary calculi than for the comparison group. The authors propose possible mechanisms for the association between urolithiasis and diabetes mellitus.

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Stress Urinary Incontinence Following Holmium Laser Enucleation of the Prostate 

As holmium laser enucleation of the prostate (HoLEP) has become more popular, it has been recognized that there is an associated small but real risk of stress urinary incontinence (SUI). In a retrospective analysis of 949 consecutive patients treated with HoLEP during a 10-year period by 1 surgeon Elmansy et al (page 1977) from Montreal, Quebec, Canada explored the relationship between SUI and HoLEP. Overall, the incidence of SUI in this series was 1.04% at 1 year. The rate of persistent SUI during a 12-year period decreased to 0.5%, which compares well with studies of other techniques such as transurethral resection of the prostate. Diabetes mellitus, prostate volume greater than 81 gm, operative time greater than 96 minutes and a reduction in prostate specific antigen to less than 84% were statistically significant for the development of SUI. Although the HoLEP results are comparable with other surgical techniques for the treatment of benign prostatic hyperplasia, the authors suggest that diabetes and prostate size are risk factors and that patients should be encouraged to start Kegel exercises in the immediate postoperative period.

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Radical Prostatectomy in Academic Versus Nonacademic Institutions 

Outcomes following radical prostatectomy can be related to surgical volumes, hospital volumes and surgeon skill. In a multi-institutional study Trinh et al (page 1849) examined data from the Health Care Utilization Project Nationwide Inpatient Sample, focusing on radical prostatectomies performed during 2001 to 2007. Data on close to 90,000 radical prostatectomies were analyzed, yielding a weighted national estimate of 442,811 radical prostatectomies. Multivariate analysis showed that patients undergoing surgery at academic hospitals experienced lower intraoperative and postoperative complication rates, shorter length of stay beyond median and lower blood transfusion rates. Even after adjusting for hospital case load and acuity of care, it was apparent that overall complication rates were lower. The authors suggest that processes of care might be different at academic institutions. On average, more favorable complication profile, shorter length of stay and lower transfusion rates should be expected at academic institutions. However, the authors state that the choice of an academic institution by itself does not guarantee better outcomes. Individual and institutional case load was not analyzed, which could affect any comparison.

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Renal Autotransplantation and Modified Pyelovesicostomy for Intractable Metabolic Stone Disease 

Flechner et al (page 1910) from Cleveland, Ohio present results for an established, yet rarely used, surgical approach for patients with a high frequency of active renal stone disease whose pain management often becomes a challenge. Renal autotransplantation and pyelovesicostomy were performed with the hope of freer stone passage and possibly less stone induced pain. Of 12 patients who underwent renal autotransplantation 92% were able to be weaned off daily narcotics and only 4 required subsequent medical intervention for which pain medication was required. Mean glomerular filtration rate was 77.2 preoperatively, and 73.5, 71.9 and 79.2 at 12, 36 and 60 months postoperatively, respectively. The authors conclude that autotransplantation and pyelovesicostomy offer an effective method of managing cases of intractable metabolic stone disease.

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Multiparametric 3T Prostate MR Imaging to Detect Cancer 

In a prospective study by Turkbey et al (page 1818) from Bethesda, Maryland 45 patients underwent preoperative magnetic resonance imaging (MRI) using endorectal and surface coils on a 3T scanner which included tri-plane T2-weighted MRI, apparent diffusion coefficient maps of diffusion weighted MRI, dynamic contrast enhanced MRI and spectroscopy. The positive predictive value of preoperative MRI, based on subsequent analysis of radical prostatectomy specimens, was 98% to 100%. Sensitivity, specificity and positive predictive value were higher for tumors larger than 5 mm in diameter as well as for tumors with Gleason scores greater than 7. The authors conclude that prostate MRI at 3T using a multimodal approach permits better detection of prostate cancer, and accurate correlation between the multiplanar MRI and histopathology. Yet it is important to note, as in the accompanying editorial, that some cancers would have been missed. Large-scale studies are necessary to determine the clinical usefulness and cost-effectiveness of this diagnostic approach.

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Once Nocturia, Always Nocturia 

In yet another analysis of the Dutch Krimpen study van Doorn et al (page 1956) from the Netherlands evaluated the records of more than 1,600 men who were followed to establish the prevalence, incidence and resolution of nocturia, defined as awakening more than once per sleep cycle. At 2.1 years of followup the incidence of nocturia was 23.9% and rate of resolution was 37%. The authors noted that because many reports of nocturia rely on recall, the frequency volume charts are the most accurate measure. Nocturia recurrence was highly predicted when nocturnal voiding frequency subtracted from the frequency volume chart was less than nocturnal voiding frequency subtracted from the International Prostate Symptom Score. Thus, the authors suggest using the frequency volume chart and International Prostate Symptom Score when evaluating nocturia for an accurate assessment of this complaint.