Fankhauser CD et al, 2018: Prevalence of hypertension and diabetes after exposure to extracorporeal shock-wave lithotripsy in patients with renal calculi: a retrospective non-randomized data analysis.
Fankhauser CD, Mohebbi N, Grogg J, Holenstein A, Zhong Q, Hermanns T, Sulser T, Steurer J, Cedric P.
Division of Nephrology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Department of Pathology of Molecular Pathology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Cancer Data Science Group, Children's Medical Research Institute, University of Sydney, Sydney, NSW, Australia.
Horten Centre for Patient Oriented Research and Knowledge Transfer, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
PURPOSE: To evaluate the association of shock-wave lithotripsy (SWL) for kidney stones and hypertension or diabetes.
METHODS: Patients with urolithiasis treated by SWL were retrospectively identified. To assess whether shock-wave application to the kidney is associated with long-term adverse effects, patients after SWL for kidney stones were selected as the main group of interest. Patients treated with shock waves for distal ureter stones only were chosen as a comparison group. A questionnaire was sent to all patients to assess the prevalence of hypertension and diabetes. The Swiss Health Survey (SHS) dataset was used as an additional comparison group.
RESULTS: After a median follow-up of 13.7 years, the odds ratio (OR) to report hypertension [OR 1.30 (95% CI 1.10-1.95)] or diabetes [OR 1.54 (95% CI 1.21-1.97)] was significantly higher in patients treated with SWL compared to the SHS dataset. In comparison with the kidney group, participants in the SHS had a significantly lower OR to report hypertension at follow-up [OR 0.79 (95% CI 0.65-0.95)], while the OR to report hypertension [1.16 (95% CI 0.79-1.70)] was not significantly different in the distal ureter group. For diabetes, a significantly lower [OR 0.60 (95% CI 0.46-0.78)] in the SHS group and a non-significantly lower [OR 0.68 (95% CI 0.38-1.22)] in the ureter group was noted compared to the kidney group.
CONCLUSION: Compared to the SHS data set SWL was in general associated with hypertension and diabetes. However, no clear difference between patients after SWL to the kidney compared to SWL to the distal ureter was seen and thus the data do not support a causal relationship.
Int Urol Nephrol. 2018 May 21. doi: 10.1007/s11255-018-1857-2. [Epub ahead of print]
Hypertension as a late complication of ESWL is an important and controversial issue. With the present paper the battel continues. This group has previously published a systematic literature review on the weak data published on the development of hypertension after ESWL: Fankhauser CD, Kranzbuhler B, Poyet C, Hermanns T, Sulser T, Steurer J (2015) Long-term adverse effects of extracorporeal shock-wave lithotripsy for nephrolithiasis and ureterolithiasis: a systematic review. Urology 85(5):991–1006. (Reviewed)
Similar to the present study Denburg et al. compared a group with ESWL on the kidney vs. a group with ESWL or URS to the lower ureter. They described an increased risk of late hypertension after ESWL, only after treatment of kidney stones but not of URS or ESWL for lower ureteric stones. (Denburg MR, Jemielita TO, Tasian GE, Haynes K, Mucksavage P,Shults J, Copelovitch L. Assessing the risk of incident hypertension and chronic kidney disease after exposure to shock wave lithotripsy and ureteroscopy. Kidney Int. 2016 Jan;89(1):185-92. ) (Reviewed).
This discrepancy is discussed by the authors of the present study: ”In both studies, it was not possible to account for number and size of kidney stones. Therefore, patients with more and/or larger stones due to worse metabolic disease are more likely to be in the kidney stone group, which represent a possible confounder.”
The important factors like stone analysis, recurrence rate and the duration of the stone disease are never included in similar studies. Even for single stones the duration of the disease can vary by decades (Kok DJ, Boellaard W, Ridwan Y, Levchenko VA. Timelines of the "free-particle" and "fixed-particle" models of stone-formation: theoretical and experimental investigations. Urolithiasis 2017; 45(1): 33–41).
Another puzzling result not properly explained by the authors is that the rate of hypertension or diabetes observed increased with increasing numbers of shock waves applied: “Compared to the SHS data set, the odds to report hypertension was significantly and incrementally higher after every 1000 shock waves applied to the kidneys … or in every 1000 shock waves applied to the distal ureter …. Similarly, the OR to report diabetes at follow-up was significantly higher in patients with more shock waves applied to the kidneys … but not to the distal ureter.”
From previous reviews on that subject, I have learned that the results of such studies may lead to completely contradictory statements depending on the way the control group is selected. The interested reader is referred to our reviews of the following paper:
Lu YM, Chien TM, Chou YH, Wu WJ, Huang CN. Is Extracorporeal Shock Wave Lithotripsy Really Safe in Long-Term Follow-Up? A Nationwide Retrospective 6-Year Age-Matched Non-Randomized Study. Urol Int. 2017;98(4):397-402.
The conclusion was:” The results of this study demonstrated that an association exists between nephrolithiasis patients who were treated with SWL and subsequent hypertension diagnosis.”
The same authors have concluded in the same year on the same patient material compared to a different control group:“There was no difference in the incidence of new hypertension between SWL and comparison groups.”
Chien TM, Lu YM, Chou YH, Wu WJ, Huang CN. Shock wave lithotripsy for renal stones is not associated with development of hypertension in Taiwan's Chinese population Urological Science 28 (2017) 219-222
My comment was: ”I do not believe any more in ESWL induced hypertension if described in studies which are based on reviews of statistics without seeing and examining the patients.”
In the present study the blood pressure of the patients was not measured and the control group was derived from the Swiss Health Survey (SHS) which evaluated the Swiss population by questionnaires for the prevalence of hypertension in 5 year intervals.
Data on the control group can be found at http://www.portal-stat.admin.ch/sgb2012/files/de/02d.xml (French, German and Italian language). Some English information in is available at https://www.bfs.admin.ch/bfs/en/home/statistiken/kataloge-datenbanken/publikationen.assetdetail.1543-1700.html
In the present study the prevalence of hypertension at follow-up for the kidney group, ureter group and the SHS data set were 47.5, 49.4 and 27.5%.
Oddly enough the authors of the present study refer to a publication on the liability of the SHS data (Volken T. Second-stage non-response in the Swiss health survey: determinants and bias in outcomes BMC Public Health 2013, 13:167) Here the author concludes:“Consequently, these MSHS outcomes should be used and interpreted with care.” To the interested reader I recommend to start reading the SHS report.