Impact of body mass index on clinical outcomes associated with percutaneous nephrolithotomy

Effect of Body Mass Index on Outcomes of Percutaneous Nephrolithotomy: A Systematic Review and Meta-Analysis

Objective

The current study aimed to assess the efficacy and safety of percutaneous nephrolithotomy (PCNL) in obese and overweight individuals based on body mass index (BMI).

Methods

We electronically explored the databases of PubMed, CENTRAL, ScienceDirect, Embase, and Google Scholar databases for all types of comparative studies investigating the role of BMI on PCNL outcomes. Only studies defining obesity as >30 kg/m² were included. Efficacy outcomes were stone-free rates and operating time while safety outcomes were complications and length of hospital stay (LOS).

Results

Eighteen studies with 101,363 patients were included. We noted no difference in the stone-free rates after PCNL for morbid obese vs normal BMI patients (OR: 0.78 95% CI, 0.57, 1.08 I²= 7% p = 0.13), overweight vs normal (OR: 1.01 95% CI, 0.89, 1.15 I²= 1% p = 0.83) and obese vs normal patients (OR: 1.00 95% CI, 0.87, 1.16 I²= 0% p = 0.95). PCNL operative time was significantly increased in morbid obese (MD: 9.36 95% CI, 2.85, 15.88 I²= 76% p = 0.005) and obese patients as compared with normal patients (MD: 2.15 95% CI, 1.20, 3.10 I²= 0% p < 0.00001), but not for overweight patients. There was no difference in the odds of complications between morbid obese vs normal (OR: 1.26 95% CI, 0.93, 1.72 I²= 0% p = 0.13), overweight vs normal (OR: 1.11 95% CI, 0.96, 1.28 I²= 0% p = 0.15), and obese vs normal patients (OR: 1.07 95% CI, 0.91, 1.27 I²= 0% p = 0.40). LOS was significantly reduced in obese patients (MD: −0.12 95% CI, −0.20, −0.04 I²= 0% p = 0.004) as compared to normal patients, but not for morbid obese or overweight patients.

Conclusion

PCNL has similar efficacy and safety in morbidly obese, obese, and overweight patients as compared to normal BMI patients with no difference in the stone-free and complication rates. Evidence suggests that operating time is increased in morbidly obese and obese patients and the latter may have shorter LOS.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifier: CRD42022313599.

Outcomes of Flank-Free Modified Supine Percutaneous Nephrolithotomy Based on BMI

OBJECTIVE

To evaluate the impact of body mass index (BMI) on the outcomes of percutaneous nephrolithotomy (PCNL) in the flank-free modified supine position.

PATIENTS AND METHODS

A prospective study was carried out in the urology department during the period from May 2015 to October 2019 on 464 patients admitted for PCNL. The patients were divided into 4 matched groups according to their BMI: group A, normal weight with 18.5 ≤ BMI <25 kg/m2; group B, overweight with 25 ≤ BMI <30 kg/m2; group C, obese with 30 ≤ BMI <40 kg/m2; and group D, morbid obesity with BMI ≥40 kg/m2. All operative data as well as postoperative outcomes are recorded and compared to each other.

RESULTS

The 4 studied groups were matched regarding age. The comorbidities were slightly higher in groups C and D. The operative time and fluoroscopy time were slightly high in obese and morbid obese groups but with no significant difference. The rate of complications either major or minor was comparable in all groups. No significant difference was seen among all groups regarding hemoglobin loss, stone-free rate, hospital stay, and need for auxiliary procedures.

CONCLUSIONS

The outcome of PCNL in flank-free modified supine position is not affected by changes in BMI. The procedure can be performed in obese and morbid obese patients safely with results similar to and comparable to nonobese patients.

Nephrolithiasis in the Obese Patient

PURPOSE OF REVIEW

The link between metabolic syndrome (MetS)/obesity and kidney stone disease (KSD) has gained importance over recent years due to the increasing prevalence and healthcare burden worldwide. This review analyses the literature exploring the link between MetS/obesity and KSD and the impact that obesity has on KSD management.

RECENT FINDINGS

Metabolic syndrome has been shown to increase an individual's risk of developing kidney stone disease, with insulin resistance forming a core component of the pathophysiology. The body habitus of an individual also influences the type of intervention that is most appropriate, with flexible ureteroscopy increasingly being the preferred option in obese patients. It is important for urologists to consider the features of metabolic syndrome to effectively manage episodes of KSD in obese patients. In addition, better quality evidence is required to effectively compare different treatment options in this group of patients.

Costs variations for percutaneous nephrolithotomy in the U.S. from 2003-2015: A contemporary analysis of an all-payer discharge database

INTRODUCTION

We sought to evaluate population-based costs variations and predictors of outlier costs for percutaneous nephrolithotomy (PCNL) in the U.S.

METHODS

Using the Premier Healthcare Database, we identified all patients diagnosed with kidney/ureter calculus who underwent PCNL from 2003-2015. We evaluated 90-day direct hospital costs, defining high- and low-cost surgery as those >90th and <10th percentile, respectively. We constructed a multilevel, hierarchical regression model and calculated the pseudo-R² of each variable, which translates to the percentage variability contributed by that variable on 90-day direct hospital costs.

RESULTS

A total of 114 581 patients underwent PCNL during the 12-year study period. Mean cost in the low-cost group was $5787 (95% confidence interval [CI] 5716-5856) vs. $38 590(95% CI 37 357-39 923) in the high-cost group. Cost variations were substantially impacted by patient (63.7%) and surgical (18.5%) characteristics and less so by hospital characteristics (3.9%). Significant predictors of high costs included more comorbidities (≥2 vs. 0: odds ratio [OR] 1.81; p=0.01) and hospital region (Northeast vs. Midwest: OR 2.04; p=0.03). Predictors of low cost were hospital bed size of 300-499 beds (OR 1.35; p<0.01) and urban hospitals (OR 2.77; p=0.01). Factors less likely to be associated with low-cost PCNL were more comorbidities (Charlson Comorbidity Index [CCI] ≥2: OR 0.69; p<0.0001), larger hospitals (OR 0.61; p=0.01), and teaching hospitals (OR 0.33; p<0.0001).

CONCLUSIONS

Our contemporary analysis demonstrates that patient and surgical characteristics had a significant effect on costs associated with PCNL. Poor comorbidity status contributed to high costs, highlighting the importance of patient selection.

Effects of body mass index on the outcomes of percutaneous nephrolithotomy

OBJECTIVE

To examine the the effect of body mass index (BMI) on PNL results and complications with a large number of patients.

MATERIALS AND METHODS

A total of 958 patients were included in the study, who underwent percutaneous nephrolithotomy in our clinic between 2008 and 2015. Patients were divided into 2 groups according to their body mass index. Patients with a BMI < 30 kg/m2 were classified as group 1 (n:676) and patients with a BMI ≥ 30 kg/m2 were classified as group 2 (n:282). Achieving stone-free status or having residual stones of ≤ 4 mm were considered as operational success.

RESULTS

The mean age was 47.9 years for group 1 and 48.9 years for group 2 patients. At postoperative first month CT analysis, residual stone was not observed in 466 patients (69%) of group 1 and 20 (72%) patients of group 2. There was no significant difference between the groups in terms of stone-free status (p=0.348). There was no significant difference between two groups complications. Also, there was no difference between the groups for requiring additional intervention (p=0.924). No other complications were observed in the patients.

CONCLUSIONS

BMI does not affect the outcomes of percutaneous nephrolithotomy as well as complication rate.

Totally tubeless percutaneous nephrolithotomy is feasible in morbidly obese patients

OBJECTIVE

Regarding technical difficulties that obese body habitus might impose to percutaneous nephrolithotomy (PNL) success and higher risk of peri-operative complications in this group of patients, we decided to retrospectively gather data from our patients during past 8 years to determine the stone free and complication rates.

MATERIAL AND METHODS

Between January 2007-December 2015, seventy-eight obese patients with body mass index over 35 who had indication for PNL including stones larger than 2 cm in pelvi-calyceal system or smaller extracorporeal shock wave lithotripsy (ESWL) resistant stones or who were not a fit candidate for ESWL due to increased skin to target distance, with no contraindication of PNL (including bleeding diathesis, inability to be positioned in prone) were enrolled. They were randomly assigned to group 1 (standard PNL with nephrostomy and ureteral stent) or group 2 (totally tubeless PNL with no ureteral stent and no nephrostomy). The outcomes were compared.

RESULTS

The transfusion rate, operation time, and the hemoglobin drop were same across the groups (p>0.05). Total analgesic use was equivalent of 33.8 vs. 14.7 mgs of morphine sulfate (18-77 mg) and was significantly lower in total tubeless group (p=0.001). Return to normal activity was described as total number of in-patient and outpatient days from time of admission to the point which the patients returns to normal life activity such as going to job or school and was 19.4 vs. 9.3 days (6-30 days, p=0.001).

CONCLUSION

Totally tubeless PNL in obese subjects would have lower analgesic use and return to normal activity versus standard PNL. Totally tubeless PNL is recommended for obese patients.

Has the pelvic renal stone position inside the upper loop of JJ stent any influence on the extracorporeal shock wave lithotripsy results?

Background

JJ stents are often encountered in patients with pelvic renal stones referred for shock wave lithotripsy, most of them being placed either for obstructive renal pelvic stones or for ureteric stones mobilized retrograde during the JJ stent insertion. The aim of the study was to determine whether the relative stone position in the upper loop of the JJ stent during extracorporeal shock wave lithotripsy (SWL) influences the efficiency of the procedure. The study was designed as a prospective cohort study on 162 patients addressing the same urological department, with single renal pelvic stone (primary or mobilized to the renal pelvis during the insertion of JJ stent), smaller than 15 mm, with JJ stent, treated by SWL using a second generation spark gap lithotripter, 18 kV, 3000 waves/session. Patients were divided in three groups according to the relative position of the stone to the upper loop of the JJ stent as appears on plain X-ray: stone-inside-loop, loop-crossing-stone and stone-outside the loop. The SWL success rate was the primary outcome of the study. p Value, Chi square and Kruskal–Wallis tests were used for statistical analysis.

Results

For stone-inside-loop cases, SWL efficiency was 22.7 versus 42 % for all the other cases (p = 0.002). Other factors for decreased SWL success rate were: higher stone radio-opacity, larger JJ of stent and obese patients. Study limitation is represented by the relative small study group and by the evaluation of stone density using plain X-ray instead of computer tomography.

Conclusions

For pelvic renal stones having the same density characteristics studied by plain X-ray, the SWL efficiency is lower in stone-inside-loop cases comparing with the other positions. The overall stone free rate for renal pelvic stones could be explained by the second generation lithotripter used for all procedures.

Ultrasound Guidance to Assist Percutaneous Nephrolithotomy Reduces Radiation Exposure in Obese Patients

OBJECTIVE

To evaluate the impact of body mass index (BMI) on perioperative outcomes and radiation exposure for ultrasound (US)-guided percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

Data were prospectively collected for consecutive patients who underwent PCNL at the University of California, San Francisco, from July 2013 to November 2015. Patients were divided into 3 groups according to their BMI: <25 (normal weight), 25-29.9 (overweight), and >30 (obese) kg/m². Perioperative outcomes were compared between patients who underwent US-guided vs fluoroscopy-guided PCNL.

RESULTS

One hundred thirty-five patients were enrolled; 93 cases were performed under US and 42 under fluoroscopic guidance. US successfully guided renal access in 76.9% of normal weight, 79.0% of overweight, and 45.7% of obese patients (P < .05). Mean fluoroscopic screening time and radiation exposure dose were reduced for US compared to fluoroscopy cases across all BMI categories (P < .05). As BMI increased, radiation exposure dose rose disproportionately faster compared to screening time (P < .001). No significant differences among the BMI groups were found with regard to complication rate, hospital stay, and stone-free status.

CONCLUSION

US-guided PCNL may be more difficult in obese patients, but with its use, the overweight and obese experience the largest absolute reduction in radiation exposure. Because these patients are inherently at greater risk for radiation exposure compared to normal weight patients, they may benefit the most from adoption of US for PCNL.

Risk factors for fever and sepsis after percutaneous nephrolithotomy

Objective

Percutaneous nephrolithotomy (PCNL) is commonly used in the management of large renal stones. Postoperative infections are one of the most common complications of this procedure. The present study is to determine and assess the factors that may increase the risk to develop fever and urinary sepsis after PCNL.

Methods

A total of 60 patients (38 males and 22 females) with a mean age of 40.25 years enrolled in this study in Sulaimania Teaching Hospital. Patients had renal stone disease need operation with different socioeconomic status, body mass index and different type and size of stones were included in this study. Patients with preoperative positive urine culture and sensitivity were excluded. Preoperative investigations done for all patients. All Patients received prophylactic antibiotic gentamicin intravenously at the induction of anaesthesia. Renal pelvis urine sample were taken from all patients after puncturing the pelvicalyceal system and send for culture and sensitivity. Patients were monitored closely in the postoperative period for the development of fever and sepsis.

Results

Mean duration of the operations was 77.08 min ranged 40–120 min. All patients had postoperative nephrostomy tube. Seventeen (28.33%) patients developed post PCNL fever and the statistically significant factors for post PCNL fever were diabetes mellitus (DM) (p = 0.001), stone burden (p = 0.001), number of the stones (p < 0.001), degree of hydronephrosis (p = 0.001), duration of the operation (p < 0.001), residual stones (p = 0.001) and number of tracts (p = 0.038). Three (5.00%) patients developed post PCNL sepsis, and the statistically significant risk factors for post PCNL sepsis were duration of the operation (p = 0.013) and intraoperative blood loss, postoperative drop in haemoglobin (HB) level (p = 0.046).

Conclusion

DM, staghorn stones, degree of hydronephrosis, duration of the operation and number of tracts are risk factors for post PCNL fever, while number of stones, intraoperative blood loss, duration of the operation and residual stones are risk factors for post PCNL sepsis.

Effect of body mass index on operative time, hospital stay, stone clearance, postoperative complications, and postoperative analgesic requirement in patients undergoing percutaneous nephrolithotomy

OBJECTIVE

To compare the effect of body mass index (BMI) on operative time, hospital stay, stone clearance, postoperative complications, and postoperative analgesic requirement in patients undergoing percutaneous nephrolithotomy (PCNL) by comparing three BMI groups.

MATERIAL AND METHODS

This is a retrospective analysis of 129 patients who underwent PCNL from January 2010 to August 2013. All the patients underwent PCNL by a standard technique. The patients were divided into three groups: patients having a BMI ≤24 kg/m(2) were included in the normal group, those having a BMI of 24.1-30.0 kg/m(2) were included in the overweight group, and those having a BMI >30 kg/m(2) were included in the obese group. Three groups were compared for operative time, hospital stay, stone clearance, postoperative complications, and postoperative analgesic requirement.

RESULTS

A total of 129 patients including 44 females and 85 males were included with a mean age of 45.00±1.44 years. The mean age in the normal group was 43.29±1.69 years, 47.08±1.29 years in the overweight group, and 43.61±1.25 years in the obese group. The mean stone size in the normal group was 25.46±8.92 mm, 28.01±8.40 mm in the overweight group, and 26.84±7.41 mm in the obese group. Our results showed no statistically significant difference with respect to mean operative time, mean hospital stay, and stone clearance in the normal, obese, and overweight patients undergoing PCNL. Postoperative complications and analgesia requirement were also similar in all the three groups.

CONCLUSION

There was no effect of BMI on operative time, hospital stay, stone clearance, postoperative complications, and postoperative analgesic requirement in patients undergoing PCNL. PCNL is a safe and effective procedure for the removal of renal stones in obese patients.

Outcomes of Systematic Review of Ureteroscopy for Stone Disease in the Obese and Morbidly Obese Population

PURPOSE

With a rising incidence of obesity and urolithiasis, we wanted to look at the outcomes of ureteroscopy (URS) for stone management in this group of patients.

METHODS

We did a systematic review of literature in accordance with Cochrane review and preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines on all English language articles between 1990 and June 2015 for URS and stone treatment in obese patients. Data were retrieved for patient and stone demographics, outcomes of URS, complications, and follow-up.

RESULTS

Fifteen studies (835 patients) were identified with a mean age of 49 years and a mean body mass index (BMI) of 40.5 kg/m(2). The overall stone size was 14.2 mm (range: 3-72 mm) with almost a third of the stones in the lower pole. The initial and final stone-free rate (SFR) was 76.9% and 82.5%, respectively, with an overall complication rate of 9.3% (n = 78). Except one patient with myocardial infarction, all other complications were Clavien grade I-III. The complication rate for morbidly obese patients (17.6%) was twice that of the obese patients (8.4%), although they were all graded as Clavien I or II.

CONCLUSION

URS and stone fragmentation are safe and efficient treatment methods in obese patients with a good SFR and a relatively low complication rate, although the complications tend to be higher in the morbidly obese patients.

[Flexible ureterorenoscopy in obese patients: results from a large monocenter cohort]

OBJECTIVE

To analyze results and morbidity after flexible ureterorenoscopy (fURS) in patients with a body mass index (BMI)>30 kg/m² and to compare with results obtained in a large cohort of non-obese patients.

METHODS

We conducted a retrospective monocenter study including all fURS for urinary lithiasis performed in our institution between January 2004 and December 2010. During the study period, 497 procedures were performed. Twenty-three had to be excluded because of missing data on BMI. Thus, a total of 474 procedures were included in the final analysis, 93 for obese patients (OP) and 381 for non-obese patients (NOP). Characteristics of the patients, stones and procedures were analyzed. Success was defined as clear imaging (completely stone-free) on renal tomography and ultrasonography.

RESULTS

Mean BMI was 33.5 ± 0.3 in OP vs 23.9 ± 0.1 kg/m² in NOP (P<0.0001). Mean stone size, location, and composition were not significantly different between groups. Technical aspects (operative time, ureteral dilatation, access sheath, monobloc extraction) were also similar in OP and NOP. The immediate (63.5% for OP vs 66.1% in NOP, P=0.62) and follow-up (65.1% for OP vs 71% in NOP, P=0.26) stone-free rate were not significantly different between the groups. For stone size<1cm, SFR raised to 77% in OP vs 83% in NOP (P=0.28). The rate of minor complications Clavien II was similar in OP (7.5%) and NOP (12%). No major complication (Clavien III or IV) was observed.

CONCLUSION

fURS is a safe and efficient option for the management of urinary lithiasis in obese patients.

Lessons learned from the CROES percutaneous nephrolithotomy global study

PURPOSE

The purpose of the study was to give an overview of the data derived from the CROES PCNL Global Study published previously in 25 articles.

METHODS

A comprehensive overview of the outcome of the CROES PCNL Global Study was made, analysed and compared with the current literature and guidelines.

RESULTS

Percutaneous nephrolithotomy (PCNL) was predominately performed in prone position. Although the supine position claims to be favourable over the prone approach, the present study showed a longer operation time and lower stone-free rate (SFR). This might be explained by differences in definition in operation time and methods in the evaluation of residual stones. Ultrasound (US)-guided access proves beneficial in lowering puncture time and radiation exposure. Renal anomalies can safely be treated by PCNL and have similar outcomes to a normal situation. In patients with a solitary kidney, however, there is a lower SFR and more bleeding. Also, severe chronic kidney disease (CKD) patients have less favourable outcome. Morbidity and complications following PCNL are dominated by fever (10.5%) and bleeding (7.8%). A matched control analysis confirmed that antibiotic prophylaxis gives a threefold lower post-operative fever rate. In a multivariate analysis, it was elegantly demonstrated that bleeding was directly related to the size of the dilatation: the larger the bore, the higher the chance for bleeding. Elderly patients are at higher risk of complications and longer hospital stay. Overall, obese patients have similar outcome as the general population; however, super-obese (BMI > 40) patients have a higher chance of more severe complications. For the first time, this database illustrated a significant relationship between results and complications of PCNL, and caseload volume. The optimal case volume per centre appears to be 120 PCNL's/year. Finally, a nomogram has been developed that enables better patient counselling and decision-making.

CONCLUSION

The CROES PCNL Global Study is the largest real-life study providing new insights into general and special conditions. Because of the vast number of patients included, rare conditions including renal anomalies, solitary kidneys and patient characteristics like severe CKD, super obesity and old age could be analysed. Besides this information, a nomogram was developed. And for the first time, the influence of caseload volume was established.

Does body mass index effect the success of percutaneous nephrolithotomy?

OBJECTIVE

In obese patients, the management of renal calculi presents a number of challenges for urologists. In this study, we aimed to evaluate the efficacy and safety of percutaneous nephrolithotomy (PNL) procedure in obese and morbidly obese patients.

MATERIAL AND METHODS

We retrospectively reviewed the medical files of 2360 patients treated with PNL between March 2002 and April 2013. The patients were stratified into four groups according to the World Health Organization (WHO) classification of body mass index (BMI): <25 kg/m(2) (average), 25-29.9 kg/m(2) (overweight), 30-39.9 kg/m(2) (obese), and >40 kg/m(2) (morbidly obese). Patients under 18 years of age and those with a body mass index under 18 kg/m(2) were excluded from the study. Intra-, and postoperative outcomes of PNL were compared between groups.

RESULTS

A total of 2102 patients with a mean age of 43±13.62 years were enrolled in the study. The mean stone size, mean number of stones, staghorn stone rate and history of previous shock wave lithotripsy were similar in all groups. The overall stone-free rate was 82 percent. The mean operation time was longer in the morbidly obese group but it was not significantly different from that in the other groups. No differences were observed in hospital stay, complication or stone-free rate among four study groups.

CONCLUSION

Percutaneous nephrolithotomy is a safe and effective treatment for renal stone disease. Body mass index does not affect the success or complication rate in PNL.

Outcomes of intracorporeal lithotripsy of upper tract stones is not affected by BMI and skin-to-stone distance (SSD) in obese and morbid patients

PURPOSE

The purpose of this study is to determine if body mass index (BMI) and stone skin distance (SSD) affect stone free rate (SFR) in obese and morbid obese patients who underwent flexible URS for proximal ureteral or renal stones < 20 mm.

MATERIALS AND METHODS

A retrospective chart review was performed of consecutive patients that underwent flexible URS. Inclusion criteria were: proximal ureteral stones and renal stones less than 20 mm in the preoperative computed tomography (CT). SFR were then compared according to SSD and BMI.

RESULTS

A total of 153 patients were eligible for this analysis, 49 (32.02%) with SSD < 10 cm and 104 (67.97%) with SSD ≥ 10 cm. The mean stone size was 10.5 ± 6.4 mm. The overall SFR in our study was 82.4%. The SFR for the SSD < 10 and ≥ 10 were 79.6% and 83.7% respectively (p = 0.698) and for BMI < 30, ≥ 30 and < 40 and ≥ 40 were 82.9%, 81.7% and 90.9% respectively. Regression analysis showed no affect between BMI or SSD regarding SFR.

CONCLUSION

Ureteroscopy should be considered as a first-line of treatment for renal/proximal stones in obese and morbid obese patients. URS may be preferable to SWL in obese patients independently of the SSD, BMI or the location of proximal stones.

Is an overnight stay after percutaneous nephrolithotomy safe?

OBJECTIVES

To establish a clinical care pathway that plans for hospital discharge the day after percutaneous nephrolithotomy (PCNL), to evaluate the safety, effectiveness and feasibility of this pathway, and to identify factors associated with a postoperative length of hospital stay (LOS) of >1 day. PCNL is the treatment of choice for patients with large kidney stones and those in whom extracorporeal shockwave lithotripsy has failed, and the mean LOS is typically 2-5 days.

PATIENTS AND METHODS

We retrospectively reviewed the charts of 109 patients (mean age 57.4 years; 58 men, 53%) who had PCNL between 2006 and 2009. All had nephrostomy tubes placed after surgery. The patients' demographics, LOS, incidence of complications, clinical outcomes, stone-free rates, number of early postoperative emergency-room visits, need for subsequent admission and/or other procedures, were noted and analysed. The modified Clavien classification was used to describe the postoperative complications. Bivariate analyses were used to test for associations between LOS and other variables.

RESULTS

The mean (range) stone size was 2.2 (0.9-5.9) cm, and the mean (SEM) LOS was 1.7 (0.13) days. Of the 109 patients, 20% had a LOS of >1 day for surgical, 3% for medical and 5% for social reasons. The stone-free rate was 89%. There was no difference in the number of subsequent hospital visits or ancillary procedures for patients discharged after one or more postoperative nights. No variables were associated with a longer LOS.

CONCLUSIONS

An overnight hospital stay after PCNL is safe and represents an effective strategy for improved bed use in selected patients. A longer LOS was not affected by patient age or body mass index, stone size or operative time. We continue to use our clinical care pathway, as supported by these data.