Schulz C. et al., 2021: Outcomes and costs of ureteroscopy, extracorporeal shockwave lithotripsy, and percutaneous nephrolithotomy for the treatment of urolithiasis: an analysis based on health insurance claims data in Germany.

Health care expenditure are a worldwide economic burden. That is why this publication is important. Expenditures for the same procedure seem to differ from country to country. However, the variances are frequently due to different ways calculations are made in the cost-charge-claim-reimbursement system. A good understanding is only possible when the financial structure of the health system is known; this is frequently impossible even for those acting in the forefront of the system like the urologists.
Furthermore, the terms costs, fees, claims and reimbursement are often erroneously used synonymously in the literature, although they are calculated completely differently (1). One procedure may seem to be more costly than another is; however, a higher reimbursement may lead to more frequent application or coding (2). In the present study costs are expressed in a payer perspective “by using the corresponding claims data”.
I see at least two problems with the publication: a minor one is that the list OPS-codes of complications (Table 1 Suppl.) includes embolization by angiography, ventilation, blood transfusion, surgical removal of urinary bladder tamponade but also insertion, change and removal of a ureteral stent. The latter are a frequent part of URS. However, if listed as complications it may explain the reported higher complication rate of URS compared to ESWL and PNL.
A more essential problem is the use of the ICD-codes (Table 1 Suppl.)
N20 Calculus of kidney and ureter,
N21 Calculus of lower urinary tract,
N22 Calculus of urinary tract in diseases classified elsewhere and
N23 Unspecified renal colic
as one basis for the case selection. The discussion states: ” Probably, in our study PCNL was conducted for cases with particularly large or complex stones as intended, and these cases needed re-intervention more often than URS cases due to the complex nature of urolithiasis”
If the number of small ureteral stones extracted by URS in a few minutes and the number of staghorn stones requiring 120 minutes PNL is not known, it seems to be impossible to compare the effects of the different procedures in the given data set.


See also:
1. Canvasser NE, Alken P, Lipkin M, Nakada SY, Sodha HS, Tepeler A, Lotan Y. The economics of stone disease. World J Urol. 2017 Sep;35(9):1321-1329. doi: 10.1007/s00345-017-2003-y. Epub 2017 Jan 20. PMID: 28108799.
2. Herout R, Baunacke M, Groeben C, Aksoy C, Volkmer B, Schmidt M, Eisenmenger N, Koch R, Oehlschläger S, Thomas C, Huber J. Contemporary treatment trends for upper urinary tract stones in a total population analysis in Germany from 2006 to 2019: will shock wave lithotripsy become extinct? World J Urol. 2021 Aug 28. doi: 10.1007/s00345-021-03818-y. Epub ahead of print. PMID: 34453580. (Reviewers choice)

Peter Alken

Urinary stones show an increasing prevalence and incidence in most western countries. The condition is associated with a significant financial impact due to health care costs and loss of working hours. According to reports from the US, the annual costs of stone treatments have doubled over the last two decades [1, 2]. For England, Geraghty et al. recently calculated costs of up to £324 [3]. The work loss in the US was calculated with 19h per episode per patient [4]. For Germany, Strohmaier calculated in 2000 a work loss of 96 days per episode and patient, illustrating differences in health care and culture between distinct countries [5]. Considering this profound economic burden, robust data on loss of productivity, costs of medical management and reimbursement are certainly needed. However, as stated by Alken, these terms describe different parameters and must be used correctly. Furthermore, they are not necessarily linked why improvements on one side, i. e. treatment costs, may not lead to an overall benefit for the social system. Since there is no nationwide database available in Germany, our analysis was based on health insurance claims data of the largest health insurance company (AOK), covering one third of the German population. We could analyze 160.000 data sets over 9 years, making this study to one of the largest series for Germany. It is important to understand, that such data is based on hospital codes (ICD-10 and OPS) for in- and outpatient treatments, not on hospital records. Information on stone size, stone location, OR time, patient characteristics or concurrent morbidities were missing. This creates uncertainty on the clinical course, especially when several treatments were needed. Aim of this study was therefore to create information on costs when comparing extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy. We are aware, that the analysis of complications and re-treatments can never be precise. Higher costs for a specific treatment may be a result of complex stone burden, not a genuine consequence of the chosen approach. However, we believe that our data can unveil the direct costs of urolithiasis for health insurances and underline the impact of urolithiasis for the society. It may create a better awareness, which seems to be needed for better funding of research on urinary stones.

[1] Clark JY, Thompson IM, Optenberg SA. Economic impact of urolithiasis in the United States. J Urol. 1995;154:2020-4.
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[3] Geraghty RM, Cook P, Walker V, Somani BK. Evaluation of the economic burden of kidney stone disease in the UK: a retrospective cohort study with a mean follow-up of 19 years. BJU Int. 2020;125:586-94.
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[5] Strohmaier WL. [Socioeconomic aspects of urinary calculi and metaphylaxis of urinary calculi]. Urologe A. 2000;39:166.