The Impact of Metabolic Syndrome on the Outcomes of Transurethral Resection of the Prostate

Abstract

Purpose:

To investigate the effect of metabolic syndrome (MS) and its components on the outcomes of transurethral resection of the prostate (TURP).

Patients and Methods:

Fifty patients with MS and 50 without MS were enrolled for the study. Patients without MS were assigned to Group 1 and patients with MS were in Group 2. Patients were evaluated by the International Prostate Symptom Score (IPSS), Quality of Life index (QoL), maximum urine flow rate (Qmax), prostate-specific antigen level, and urinary ultrasonography. Six months after surgery, patients were again evaluated by IPSS and uroflowmetry; then comparison was made between the groups with respect to IPSS, QoL, and Qmax.

Results:

Postoperative IPSS was determined as 11.2±0.87 in Group 1 and 12.9±0.88 in Group 2 (P<0.05). Postoperative Qmax values were determined as 18.2±0.81 and 13.9±1.12 for the two groups, respectively (P<0.05). After multivariate analyses, elevated fasting glucose (EFG) and dyslipidemia were determined to have a significant correlation with IPSS improvement. EFG and hypertension had a significant negative impact on Qmax, and hypertension and abdominal obesity had a significant correlation with QoL improvement.

Conclusions:

MS as a comorbidity seems to diminish the effects of TURP. Further well-designed prospective, randomized studies with larger cohorts are needed to confirm the findings of this study.

Introduction

Lower urinary tract symptoms (LUTS), an important health issue usually concerning older men, can result in a dramatic deterioration in quality of health. Even though there are many causes, such as neurogenic bladder, bladder cancer, etc., LUTS are usually thought to be from benign prostatic obstruction (BPO).¹ The most established operative treatment method for patients with BPO is transurethral resection of the prostate (TURP).¹

Metabolic syndrome (MS), which is frequently encountered, is described as a clustering of hyperglycemia/insulin resistance, obesity, and dyslipidemia. There are many definitions of MS, but one of the most widely used was outlined in the National Cholesterol Education Program Adult Treatment Panel III, which was updated in 2005.² Reports have demonstrated the initiation and aggravation of many urologic diseases by MS. The links between MS and kidney stones, erectile dysfunction, and BPO have been reported.^3
–5 Recent studies have focused on the link between BPO and/or LUTS and MS, with emphasis on the aggravation of LUTS caused by MS.⁶

Many patients complain of LUTS even after TURP. MS is one of the most frequently encountered factors that may cause the continuation of symptoms after TURP.⁵ In this study, we aimed to investigate the effect of MS and its components on the outcomes of TURP.

Patients and Methods

All patients who had undergone TURP had symptoms that were refractory to alpha-receptor blocker and/or combination treatment. The refractory status of the patients to alpha-blocker treatment was assessed by the International Prostate Symptom Score (IPSS) (>20) and maximum urine flow rate (Qmax) values (<15 mL/s) in uroflowmetry. The exclusion criteria were the use of medication affecting LUTS (e.g., diuretics) a history of transurethral surgery, prostate surgery, neurogenic bladder, urethral stricture, and postoperative pathology other than benign prostatic hyperplasia (BPH). Patients were individualized to their components of MS.

MS was established as the presence of three or more of the following criteria: Waist circumference more 90 cm, blood pressure >130 mm Hg (systolic) and 85 mm Hg (diastolic), high density lipoprotein (HDL) level <40 mg/dL, fasting blood glucose levels >110 mg/dL (elevated fasting glucose: EFG), and triglyceride levels >150 mg/dL.²

After the local ethical committee approval, the study comprised 50 consecutive TURP patients without MS as Group 1 and 50 consecutive TURP patients with a diagnosis of MS as Group 2 between September 2012 and March 2013. The International Prostate Symptom Score (IPSS), Quality of Life (QoL) index (IPSS, question 8), Qmax measured with uroflowmetry, prostate-specific antigen (PSA) level, and prostate volume and postvoiding residual volume measured by transabdominal ultrasonography (USG) were recorded for both groups. Postoperative evaluation with IPSS and uroflowmetry was performed at 6 months after TURP in all patients. Comparisons were made between the groups of the preoperative and postoperative parameters.

The primary outcome measures were IPSS, Qmax, and QoL after 6 months. Improvement was defined as an IPSS score <9, Qmax >15 mL/s, and QoL >3. Multivariate analysis was performed on the improvement of primary outcome measures in MS components.

Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) 20 software (SPSS Inc., Chicago, IL). All the data were presented as mean±standard deviation.

The distribution of the data was evaluated by the Kolmogorov-Smirnov test. The comparisons of the groups were performed using the Student t test. For multivariate analyses, the multinomial logistic regression analysis test was used. A value of P<0.05 was considered statistically significant.

Results

The preoperative parameters of age, prostate volume, IPSS, QoL, and Qmax were similar in both groups. The demographic data and comparisons are summarized in Table 1.

Table 1.

Preoperative Patient Demographics

Preoperative parameters	Group 1 n=50	Group 2 n=50	p
Patient age	64.56±5.45	62.18±6.11	0.198
IPSS	27.09±0.52	27.25±0.33	0.963
Qmax	8.4±0.9	8.9±0.8	0.744
Quality of Life index	3.2±1.12	3±0.82	0.648
Prostate volume (cc)	49.8±2.52	50.6±3.11	0.827
Postvoiding residual volume (mL)	48±7.1	49±3.1	0.721
PSA	1.9±0.31	2.0±0.54	0.654

IPSS=International Prostate Symptom Score; Qmax=maximum urine flow rate; PSA=prostate-specific antigen.

All patients underwent monopolar TURP. Two patients in Group 1 and three patients in Group 2 had urinary tract infections that were treated with oral antibiotics. Three patients in Group 2 had hematuria postoperatively. The overall complication rate was higher in Group 2 than in Group 1 (P<0.05).

The comparison of preoperative and postoperative outcomes revealed a significant improvement in both groups. When the groups were compared, the improvement in Group 1 was significantly better than in Group 2. At 6 months postoperatively, IPSS was found to be 11.2±0.87 in Group 1 and 12.9±0 .88 in Group 2. Postoperative Qmax was 18.2±0.81 and 13.9±1.12 for Groups 1 and 2, respectively. The group comparison revealed a significantly better improvement in Group 1 with respect to IPSS, Qmax, and QoL. The outcomes are summarized in Table 2. In terms of QoL, there was a statistically significant improvement in both groups after treatment, but when the groups were compared at 6 months postoperatively, the patients in Group 1 had improved significantly more than those in Group 2 (P=0.034).

Table 2.

Patient Demographics After Transurethral Resection of the Prostate After 6 Months

	Group 1 n=50	P^*	Group 2 n=50	P^**	P^***
IPSS	11.2±0.87	0.022	12.9±0.88	0.03	0.049
Qmax	18.2±0.81	0.011	13.9±1.12	0.021	0.033
Quality of Life Index	4.7±1.1	0.001	2.8±1.0	0.046	0.034

P ^*: Comparison of parameters of Group 1 between preoperative and postoperative 6 months.

P ^**: Comparison of parameters of Group 2 between preoperative and postoperative 6 months.

P ^***: Comparison of postoperative parameters between groups.

IPSS=International Prostate Symptom Score; Qmax=maximum urine flow rate.

MS components were further evaluated in Group 2. There were 35 (70%) patients with fasting glucose more than 100 mg/dL, 31 (62%) patients had abdominal obesity, 40 (80%) patients had hypertension, 21 (42%) patients had dyslipidemia, and 12 (24%) patients had high triglyceride levels.

After multivariate analyses, EFG and dyslipidemia were determined to have a significant correlation with the difference of IPSS between the groups. EFG and hypertension had a significant negative impact on Qmax and hypertension, and abdominal obesity had a significant correlation with QoL. The effects of the MS parameters on primary outcome measures are summarized in Table 3.

Table 3.

Metabolic Syndrome Components and Their Affect on Primary Outcomes ^*

	Elevated fasting glucose	Hypertension	Dyslipidemia	Abdominal obesity	High triglyceride levels
IPSS^*
OR (95% CI)	6.762 (0.361–8.607)	4.747 (0.816–27.626)	4.873 (0.929–25.564)	1.512 (0.265–8.618)	0.891 (0.215–3.698)
p	0.028	0.083	0.041	0.642	0.873
Qmax^*
OR (95% CI)	7.907 (0.550–21.347)	8.691 (1.241–60.884)	4.646 (0.811–26.623)	1.11 (0.183–6.756)	0.525 (0.118–2.331)
p	0.041	0.029	0.085	0.909	0.397
QoL^*
OR (95% CI)	0.427 (0.074–2.465)	10.75 (3.254–34.298)	5.253 (0.700–39.415)	7.286 (0.727–73.059)	3.485 (0.563–21.585)
p	0.466	<0.001	0.107	0.043	0.180

Primary outcomes consist of IPSS, QoL, and Qmax at 6 months after surgery.

IPSS=International Prostate Symptom Score; OR=odds ratio; CI=confidence interval; Qmax=maximum urine flow rate; QoL=quality of life.

Discussion

MS is a syndrome characterized by hypertension, increased waist circumference, insulin resistance, and dyslipidemia that has become a major health issue in recent years.⁷ There have been several studies investigating the relationship between MS and urologic diseases, especially LUTS.^4,8
–10 Rohrmann and associates¹¹ reported that in patients more than 25 years old, 80% of newly induced LUTS occurs with an increase in waist circumference. If EFG was present, an increase of 1.67-fold was reported in IPSS, and if hypertension was present, an increase of 1.76-fold.¹¹

The current study demonstrated that even though a significant improvement of IPSS was achieved in both groups with TURP, the improvement was significantly lower in patients with MS. In this study, it was determined that if EFG was present, there was 6.762-fold higher probability of not having satisfactory IPSS after the operation. The risk was found to be 4.873-fold if dyslipidemia was present in MS. Hypertension, abdominal obesity, and high triglyceride did not have any significant correlation with IPSS after TURP. In the final question of IPSS related to QoL, there was not found to be much improvement in patients with hypertension (10.75-fold) and abdominal obesity (7.286-fold). EFG, dyslipidemia, and elevated triglyceride levels did not have a significant correlation with QoL.

MS has a decremental effect on Qmax. Investigations have been designed to evaluate the effect of MS on Qmax. Michel and colleagues¹² compared patients with BPH and diabetes mellitus (DM) with BPH only and reported a significantly lower urine flow rate in the patients with DM. Michel and coworkers¹³ compared patients with BPH with patients with BPH and hypertension. In that study, IPSS and Qmax were observed to worsen in the presence of hypertension. In the current study, there was a significant improvement in both groups with respect to Qmax. It was also noted that the improvement in Group 1 was better than that in Group 2. MS components are believed to play an important role in the worsening of Qmax. With EFG, there is a 7.907-fold risk of none-improved Qmax (<15 mL/s). Hypertension increases the risk by 8.691-fold. Dyslipidemia, abdominal obesity, and high triglyceride levels did not correlate with nonsatisfactory Qmax.

MS might have an effect on the urinary tract through various mechanisms. The most blamed mechanism is the Rho-kinase (ROK) pathway, which is related to basal tonus and contractility.¹⁴ The ROK pathway is associated with cellular calcium transport, and its effect on contractility is well known.¹⁵ After the demonstration of the link between MS components and autonomic hyperreactivity by Landsberg and colleagues,¹⁵ Rees and associates¹⁶ showed the inhibition of the ROK pathway in autonomic hyperreactivity and proposed that this inhibition might cause LUTS in a rat model. Prostate inflammation in the presence of MS has been studied in recent years by various researchers. Gacci and coworkers¹⁷ investigated the role of prostatic inflammation on LUTS and demonstrated that MS was associated with prostate volume, prostate diameter, and prostatic inflammation. Cantiello and associates¹⁸ demonstrated the role of prostatic inflammation on LUTS.

In a recent study by Zhang and colleagues,¹⁹ patients with BPO were divided into two groups according to whether or not they had MS. The authors reported similar IPSS, PSA values, and Qmax levels but revealed higher prostate volumes and longer history of LUTS in patients with MS. In the current study, it was found that EFG significantly deteriorated IPSS and Qmax, hypertension deteriorated Qmax and QoL, dyslipidemia deteriorated IPSS, abdominal obesity deteriorated QoL, and high triglyceride levels did not have any significant impact on any parameters.

This study has some limitations—mainly, that even as an observational prospective study, the cohort was small in number. Also, subgroup analyses, such as storage and voiding score, might have given more important information concerning the effects of MS on outcomes. Resected volumes could have been presented. This study may aid physicians who are not experts on MS when dealing with patients and estimating the outcomes of TURP. It may also be helpful in forming opinions on the possible effect of MS on LUTS, especially after treatment with TURP. To the best of our knowledge, this is the first article researching the effect of MS on TURP outcomes.

The results of this study revealed the negative influence of MS as a cluster and its components on the outcomes of TURP. Physicians must be aware of MS before proceeding with operations and should be aware of the possible nonoptimal improvements. Further well-designed prospective, randomized studies with larger cohorts are needed to confirm the findings of this study.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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