Esther T. Kok
Utrecht University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Esther T. Kok.
The Journal of Urology | 2009
S.P. Rynja; Gerlof Wouters; Maaike Van Schaijk; Esther T. Kok; Tom P.V.M. de Jong; Laetitia M.O. de Kort
PURPOSE We assessed long-term results after hypospadias surgery with respect to urinary and sexual function, cosmetic appearance and intimate relationships. MATERIALS AND METHODS We contacted 116 patients who are now adults and who underwent surgery between 1987 and 1992. Participation included mailed questionnaires containing the International Prostate Symptom Score, International Index of Erectile Function and the Dutch Survey of Intimate Relations (Nederlandse Relatie Vragenlijst) as well as uroflowmetry and cosmesis assessment using the Pediatric Penile Perception Score. A control group of 151 male students completed the International Prostate Symptom Score and International Index of Erectile Function, and underwent uroflowmetry. RESULTS A total of 91 patients (78%) were traceable, 57% returned the questionnaires and 27% visited the clinic. Hypospadias was distal, mid shaft and proximal in 47, 8 and 11 patients, respectively. International Prostate Symptom Score was greater than 7 in 9 of 64 patients (14%) compared to 10 of 151 controls (7%). Patients with distal hypospadias complained more about micturition. Patients with proximal hypospadias had lower maximum urine flow than other patients and controls. For sexuality the total International Index of Erectile Function did not differ between patients and controls. Patients with proximal hypospadias reported less satisfaction with penile length and objectively penile length was less than the average of all patients (10.8 vs 12.1 cm). Cosmetic outcome was considered satisfactory. Outcomes in the 33 patients who returned the Dutch Survey of Intimate Relations correctly were above average, especially for sexuality and independence. CONCLUSIONS Patients with distal hypospadias have a higher International Prostate Symptom Score and patients with proximal hypospadias have lower maximum urine flow than controls. Sexual function and cosmesis are rated good. The quality of intimate relationships is above average.
The Journal of Urology | 2009
Esther T. Kok; Boris W. Schouten; Arthur M. Bohnen; Frans P.M.W. Groeneveld; Siep Thomas; J.L.H. Ruud Bosch
PURPOSE We explored risk factors for lower urinary tract symptoms suggestive of benign prostatic hyperplasia in the open population. MATERIALS AND METHODS A longitudinal, population based study with a followup of 6.5 years was done in 1,688 men who were 50 to 78 years old. Data were collected on transrectal ultrasound of prostate volume, urinary flow rate, ultrasound estimated post-void residual urine volume, generic and disease specific quality of life, and symptom severity based on the International Prostate Symptom Score. Lower urinary tract symptoms suggestive of benign prostatic hyperplasia were defined as an International Prostate Symptom Score of greater than 7 after a report of a score of less than 7 in the previous round. A multivariate Cox proportional hazard model was constructed to determine risk factors for clinical benign prostatic hyperplasia after correcting for patient age. RESULTS Total followup was 4,353 person-years. During followup 180 events of attaining an International Prostate Symptoms Score of greater than 7 occurred. Multivariate analysis showed that functional bladder capacity, post-void residual urine volume, treatment for cardiac diseases, education level, antidepressant use, calcium antagonist use, erectile function or dysfunction, prostate specific antigen and a family history of prostate cancer were determinants with a significant HR. CONCLUSIONS In addition to age, we established 9 significant determinants for lower urinary tract symptoms suggestive of benign prostatic hyperplasia. However, not all risk factors for lower urinary tract symptoms suggestive of benign prostatic hyperplasia are accounted for since we can conclude that 1 of 3 men without these risk factors will still be diagnosed with lower urinary tract symptoms suggestive of benign prostatic hyperplasia between ages 50 and 80 years.
Journal of Endourology | 2009
Ronald O.P. Draga; Esther T. Kok; Marique R. Sorel; Ruud Bosch; Tycho M.T.W. Lock
OBJECTIVE Fever after the first postoperative day (POD1) after percutaneous nephrolithotomy (PCNL) is most likely caused by an infection that increases hospital stay and healthcare costs. The aim of this study was to find factors associated with fever after POD1 and systemic inflammatory response syndrome (SIRS). PATIENTS AND METHODS Ninety patients underwent 117 PCNLs. Patient characteristics, stone burden, and pre- and postoperative treatments were analyzed for association with fever (temperature >or=38 degrees C) and SIRS using univariate analysis. RESULTS In 35% of the patients with fever (temperature >or=38 degrees C), fever was present after POD1. Twelve patients developed signs of SIRS (11.2%). In univariate analysis, significant association was observed between fever after POD1 and previous ipsilateral PCNL (p = 0.022, odds ratio OR = 3.1), and between SIRS and paraplegia (p = 0.005, OR = 10.7) and caliceal stones (p = 0.03, OR = 4.8). CONCLUSIONS Previous ipsilateral PCNL increases the risk of fever after POD1. Paraplegic patients are at risk for developing SIRS after PCNL.
European Urology | 2011
Menno A. van Leeuwen; Jacob J. Brandenburg; Esther T. Kok; Peter L.M. Vijverberg; J.L.H. Ruud Bosch
BACKGROUND Adult anterior urethral stricture disease is most often treated with dilatation or direct vision internal urethrotomy (DVIU). Although evidence suggests that anastomotic urethroplasty for short bulbar strictures is more efficient and cost effective in the long term, no consensus exists. It is unclear by whom and how often urethroplasties are performed in The Netherlands and how results are being evaluated. OBJECTIVE To determine national practice patterns on management of anterior urethral strictures among Dutch urologists. This information will help to define the nationwide need for training in urethral surgery. DESIGN, SETTING, AND PARTICIPANTS We conducted a 16-question survey among all 323 Dutch urologists. RESULTS AND LIMITATIONS The response rate was 74%. DVIU was practised by 97% of urologists. Urethroplasty was performed at least once yearly by 23%, with 6% performing more than five urethroplasties annually. In the group of urologists younger than 50 yr of age, 13% performed urethroplasty, with 3% of those performing more than five annually. In the case of a 3.5-cm-long bulbar stricture, DVIU was preferred by 49% of responders. Even after two recurrences, 20% continued to manage a 1-cm-long bulbar stricture endoscopically. Of responders, 79% believed that urethroplasty should be proposed only after a failed endoscopic attempt. Diagnostic workup and evaluation of success varied greatly. CONCLUSIONS Most Dutch urologists believe that urethroplasty is an option only after failed DVIU. Endoscopic procedures are widely used, even when the risk of recurrence is virtually 100%. The definition of success is hampered by nonstandardised methods of follow-up. Only a small group of mainly older urologists frequently performs urethroplasties. Training programmes seem necessary to guarantee a high standard of care for stricture disease in The Netherlands. A pan-European practice survey might be interesting to clarify the need for centralised fellowship programmes.
European Urology | 2010
Ronald O.P. Draga; Matthijs C. M. Grimbergen; Esther T. Kok; Trudy N. Jonges; Christiaan F. P. van Swol; J.L.H. Ruud Bosch
BACKGROUND Photodynamic diagnosis (PDD) is a technique that enhances the detection of occult bladder tumors during cystoscopy using a fluorescent dye. OBJECTIVE To study the differential effects of bacillus Calmette-Guérin (BCG) and mitomycin C (MMC) intravesical therapy on the false-positive rate of PDD of bladder cancer. DESIGN, SETTING, AND PARTICIPANTS This study included 552 procedures and 1874 biopsies. INTERVENTION Tumors were resected and biopsies were taken from suspicious areas, under guidance of white-light endoscopy and 5-ALA (5-aminolevulinic acid)-induced fluorescence cystoscopy. MEASUREMENTS The influence of intravesical BCG immunotherapy and intravesical MMC chemotherapy on pyuria, inflammation, and PDD specificity was examined in univariate analyses. RESULTS AND LIMITATIONS BCG significantly results in inflammation (odds ratio [OR]: 1.53, p=0.002), leukocyturia (OR: 1.84, p=0.034), and false positives in PDD (OR: 1.49, p=0.001). However, a single BCG instillation within 3 mo before PDD is most likely not associated with increased false-positive rates (OR: 0.35, p=0.26). Leukocyturia normalizes within 6 wk after the last BCG instillation, but PDD specificity is reduced up to 3 mo. CONCLUSIONS BCG is an important predictor for false positives in PDD (5-ALA). More than one BCG instillation within 3 mo before fluorescence cystoscopy decreases the specificity of PDD.
European Urology | 2013
Boris van Doorn; Marco H. Blanker; Esther T. Kok; Paul Westers; J.L.H. Ruud Bosch
BACKGROUND Nocturnal polyuria (NP) is common in older men and can lead to nocturia. However, no longitudinal data are available on the natural history of NP. OBJECTIVE To determine prevalence, incidence, and resolution rates of NP. DESIGN, SETTING, AND PARTICIPANTS A longitudinal, community-based study was conducted among 1688 men aged 50-78 yr in Krimpen aan den IJssel, The Netherlands (reference date: 1995), with planned follow-up rounds at 2, 4, and 6 yr. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS NP was determined with frequency-volume charts. Two definitions of NP were used: (1) a nocturnal urine production (NUP) of >90 ml/h (NUP90) and (2) the nocturnal voided volume plus first morning void being >33% of the 24-h voided volume (NUV33). Nocturia was defined as two or more voids per night. We determined the prevalence of NP at each study round. At first follow-up, we determined the incidence in men without baseline NP and the resolution in men with baseline NP. Prevalence of NP in men with or without nocturia was also determined. RESULTS AND LIMITATIONS At baseline, the prevalence of NUP90 was 15.0% and increased to 21.7% after 6.5 yr, whereas the prevalence of NUV33 was 77.8% at baseline and 80.5% after 6.5 yr. At 2.1 yr of follow-up, the incidences of NUP90 and NUV33 were 13.6% and 60.3%, respectively, and the resolution rates were 57.0% and 17.8%, respectively. Because of this fluctuation in NP, no reliable long-term incidences could be calculated. At baseline, NUP90 was prevalent in 27.7% of men with nocturia and in 8.0% of those without nocturia. At baseline, NUV33 was prevalent in 91.9% of men with nocturia and in 70.1% of men without nocturia. CONCLUSIONS Due to the fluctuation of NP, it is advisable to first determine its chronicity and cause before starting treatment. Because of the high prevalence of NP in men without nocturia, NUV33 should be reconsidered as a discriminative definition of NP.
The Journal of Urology | 2011
Boris van Doorn; Marco H. Blanker; Esther T. Kok; Paul Westers; J.L.H. Ruud Bosch
PURPOSE Nocturia is a highly prevalent and bothersome symptom that might (spontaneously) resolve. However, longitudinal data are not available on the incidence and resolution of nocturia assessed with frequency-volume charts. In this study we determined the prevalence, incidence and resolution rates of nocturia assessed by frequency-volume charts, and compared nocturnal voiding frequency over time as assessed by frequency-volume charts and questionnaires. MATERIALS AND METHODS A longitudinal, population based study was conducted among 1,688 men 50 to 78 years old with followup rounds at 2.1, 4.2 and 6.5 years. Nocturnal voiding frequency was determined with frequency-volume charts and, for comparison purposes, with a question from the International Prostate Symptom Score. Nocturia was defined as nocturnal voiding frequency 2 or greater. Prevalence, incidence and resolution rates were also determined. RESULTS At the 2.1-year followup the incidence rate was 23.9% and the resolution rate was 36.7%. The incidence rate was highest in the oldest group (70 to 78 years) and lowest in the youngest (50 to 54 years), whereas the resolution rate was highest in the group 55 to 59 years old and lowest in the oldest group. Because of the high resolution rate, no reliable incidence rates can be calculated. Despite fluctuation, the prevalence of nocturia increased with age and over time (from 34.4% to 44.7% for the total group, p <0.05). Men who had a frequency-volume chart-nocturnal voiding frequency less than International Prostate Symptom Score-nocturnal voiding frequency (6% of the population) more often had this later on. CONCLUSIONS In this population frequency-volume chart assessed nocturia shows considerable fluctuation. Nevertheless, prevalence increases over time and with increasing age. Men who once had frequency-volume chart-nocturnal voiding frequency less than International Prostate Symptom Score-nocturnal voiding frequency are more likely to have this again. Therefore, frequency-volume charts as well as the International Prostate Symptom Score should be used when evaluating nocturia.
BJUI | 2010
Robert J. Hoekstra; Harm H.E. van Melick; Esther T. Kok; J.L.H. Ruud Bosch
Study Type – Therapy (RCT) Level of Evidence 1b
Transplant International | 2005
Jan B. Oostenbrink; Esther T. Kok; Renate M. Verheul
Organ transplantations are among the most expensive surgical treatments performed today, but estimates of the costs of organ transplantations vary widely between settings. The aim of this study is to estimate the costs of renal, liver and heart transplantation in a university hospital, adopting a similar costing methodology for all the three kinds of transplantation. Resource use data were collected from 803 patients transplanted between January 1995 and August 2001. Data about the time physicians and other hospital employees spent per transplantation were based on interviews. All costs from pretransplantation screening up to 3 years post‐transplantation were taken into account and divided into costs of patient care and programme‐related costs. Mean cost of renal transplantation varied from € 70 723 for cadaveric donor transplantations to € 76 577 for living donor transplantations. Mean costs of liver transplantation were € 141 510 and the mean costs of heart transplantation were € 171 828. Direct costs of patient care contributed to 79%, 87% and 92% of the costs of renal, liver and heart transplantation respectively. Inpatient hospital days were the largest contributor to the costs of patient care. The mean number of inpatient hospital days from pretransplantation screening to 3 years post‐transplantation varied from 46 days for renal transplantation from a living donor to 58 days for renal transplantation from cadaveric donors, 83 days for heart transplantation and 108 days for liver transplantation. In conclusion, costs of liver and heart transplantation were approximately 2.0 and 2.5 times higher than the cost of renal transplantation. Length of inpatient hospital stay for transplantation did not change substantially over time between 1995 and 2001.
European Urology | 2002
Esther T. Kok; Joseph McDonnell; Elly A. Stolk; Herman Stoevelaar; Jan J. V. Busschbach
OBJECTIVE Lower Urinary Tract Symptoms (LUTS) suggestive of Benign Prostatic Obstruction (BPO) cause a reduction in quality of life, but the magnitude of that reduction cannot be estimated empirically. This is because survey instruments currently available merely sum the symptoms found, but do not value their impact on quality of life. It is therefore difficult to determine whether the effects of treatments for LUTS suggestive of BPO justify the costs. This complicates economic evaluations. METHODS We valued the impact on quality of life of patients with LUTS suggestive of BPO, by valuing health states defined by the International Prostate Symptom Score (IPSS) using the time trade-off (TTO). TTO values ranged from 1.0 for perfect health to 0.0 for the value of death, and can be used to calculate Quality-Adjusted Life Years (QALYs), the preferred outcome measure in health economics. RESULTS We reduced the number of health states defined by the IPSS using factor analysis. The resulting nine health states were valued by a representative sample of the general public (N=170) using TTO. The worst IPSS health state was valued at 0.87. CONCLUSION The values for health states defined by the IPSS revealed that LUTS suggestive of BPO has a mild impact on quality of life. The valuation of the IPSS facilitates economic evaluations of treatments for LUTS suggestive of BPO, because QALYs (the preferred outcome measure in health economics) can be determined empirically.