Kang DH et al, 2016: Comparison of High, Intermediate, and Low Frequency Shock Wave Lithotripsy for Urinary Tract Stone Disease: Systematic Review and Network Meta-Analysis.
Kang DH, Cho KS, Ham WS, Lee H, Kwon JK, Choi YD, Lee JY.
Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea.
Department of Urology, Gangnam Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea.
Division of Epidemic Intelligence Service, Korea Centers for Disease Control and Prevention, Osong, Korea.
Department of Urology, Severance Check-Up, Yonsei University Health System, Seoul, Korea.
OBJECTIVES: To perform a systematic review and network meta-analysis of randomized controlled trials (RCTs) to determine the optimal shock wave lithotripsy (SWL) frequency range for treating urinary stones, i.e., high-frequency (100-120 waves/minute), intermediate-frequency (80-90 waves/minute), and low-frequency (60-70 waves/minute) lithotripsy.
MATERIALS AND METHODS: Relevant RCTs were identified from electronic databases for meta-analysis of SWL success and complication rates. Using pairwise and network meta-analyses, comparisons were made by qualitative and quantitative syntheses. Outcome variables are provided as odds ratios (ORs) with 95% confidence intervals (CIs).
RESULTS: Thirteen articles were included in the qualitative and quantitative synthesis using pairwise and network meta-analyses. On pairwise meta-analyses, comparable inter-study heterogeneity was observed for the success rate. On network meta-analyses, the success rates of low- (OR 2.2; 95% CI 1.5-2.6) and intermediate-frequency SWL (OR 2.5; 95% CI 1.3-4.6) were higher than high-frequency SWL. Forest plots from the network meta-analysis showed no significant differences in the success rate between low-frequency SWL versus intermediate-frequency SWL (OR 0.87; 95% CI 0.51-1.7). There were no differences in complication rate across different SWL frequency ranges. By rank-probability testing, intermediate-frequency SWL was ranked highest for success rate, followed by low-frequency and high-frequency SWL. Low-frequency SWL was also ranked highest for low complication rate, with high- and intermediate-frequency SWL ranked lower.
CONCLUSIONS: Intermediate- and low-frequency SWL have better treatment outcomes than high-frequency SWL when considering both efficacy and complication.
PLoS One. 2016 Jul 7;11(7):e0158661. doi: 10.1371/journal.pone.0158661. eCollection 2016. FREE ARTICLE
For those readers who are fans of math statistics the original paper is a must-read. The methods of calculation are described extensively and in detail. 953 low, 486 intermediate and 599 high frequency ESWLs were evaluated in 13 RCTs.
In this metaanalysis only 8 of the 13 papers analysed reported on complication. Complications were reported in different depth. All complications were graded by the present authors according to the Clavien system but a look at the original publications shows that only 2 actually did a Clavian grading. There is no uniformly agreed grading of ESWL complications. This is a weakness of the present publication.
Another problem is mentioned by the authors: ”One limitation of our meta-analysis is that we did not assess the impact of the total number of SWs delivered as a function of SW frequency, which may have introduced critical bias.”
Unfortunately two conclusions of this metaanalysis reveal that the results of such statistics depend on the quality of primary data.
“Because it remains difficult to conclusively determine the treatment outcome of the intermediate versus low SW rate with the existing data, large-sample RCTs should be performed.”
“Thus, an additional study on complications of SWL depending on applied SW frequency is needed.”
One aspect is stone disintegration and it is difficult to understand that its principles have not been fully evaluated by in-vitro studies. I do not think that studies on patients will give a reliable answer but it might be necessary to go back to the lab in the future to improve ESWL.
The other aspect is tissue trauma. It seems that neither the clinical experience nor animal models so far are capable to predict type and grade of trauma after ESWL. Again there is room for improvement.