Diagnostic performance and cost-effectiveness of portable digital pH meters and traditional dipsticks for urine pH monitoring in patients at risk of recurrent urolithiasis

Introduction: Urolithiasis affects up to 10% of the population and recurs in more than 50% of cases within ten years. Urinary pH plays a pivotal role in stone prevention, but dipstick testing, the most commonly used method, lacks accuracy, precision and reliability. Only portable digital pH meters classified as medical devices offer superior accuracy, sensitivity, specificity, and resolution, enabling more reliable urinary pH monitoring than dipstick testing. Nevertheless, their comparative cost-effectiveness remains unclear. 
Methods: we conducted a systematic review and cost-effectiveness analysis comparing a portable digital pH meter with dipsticks for urinary pH monitoring in recurrent stone formers. Following PrIsMA 2020 guidelines, studies reporting on accuracy, precision, or costs were included. Data were pooled using random-effects models. Cost estimates were derived from the European market sources and adjusted for inflation. Outcomes included analytical validity, cost per effective unit, number needed to treat (NNT), and cost per quality-adjusted life-year (QALy) gained.
Results: Thirteen studies involving 2,801 participants were included in the quantitative synthesis. The portable digital pH meter consistently outperformed dipsticks across all evaluated parameters, demonstrating higher explained variance (r² 0.97 vs 0.54), finer resolution (0.1 vs 0.5 pH units), and lower systematic bias (0.06 vs 0.36). The cost per effective unit was lowest for the portable digital pH meter (€ 179) compared with once-daily (€ 354) and twice-daily dipstick testing (€ 708). In compliance-adjusted models, the cost per lithiasis episode prevented was € 590 for the portable digital pH meter vs €1,169 and € 2.337 for dipsticks. In a simulated 1.,000-patient cohort, the portable digital pH meter yielded the lowest total costs (€ 601.376) and the greatest QALy gain (17.84), demonstrating a dominant result, being both more effective and less costly than all alternatives.
Conclusions: The portable digital pH meter demonstrated superior analytical performance and cost-effectiveness compared with dipsticks for urinary pH monitoring. Its broader implementation may enhance preventive strategies, reduce stone recurrence, and decrease the overall healthcare burden associated with recurrent urolithiasis. Considering these findings, the portable digital pH meters may warrant consideration for inclusion in major clinical guidelines on urolithiasis and for reimbursement by healthcare systems, potentially supporting their broader adoption in clinical practice.

1. Sorokin I, Mamoulakis C, Miyazawa K, et al. Epidemiology of stone disease across the world. World J Urol 2017; 35:1301-20. DOI: https://doi.org/10.1007/s00345-017-2008-6

2. Rule AD, Lieske JC, Li X, et al. The ROKS nomogram for predicting a second symptomatic stone episode. J Am Soc Nephrol 2014;25:2878-86. DOI: https://doi.org/10.1681/ASN.2013091011

3. Akram M, Jahrreiss V, Skolarikos A, et al. Urological Guidelines for Kidney Stones: Overview and Comprehensive Update. J Clin Med 2024; 13:1114. DOI: https://doi.org/10.3390/jcm13041114

4. Grases F, Costa-Bauzá A, Gomila I, et al. Urinary pH and renal lithiasis. Urol Res 2012; 40:41-6. DOI: https://doi.org/10.1007/s00240-011-0389-3

5. Galan-Llopis JA, Torrecilla-Ortiz C, Luque-Gálvez MP, et al. Urinary pH as a target in the management of lithiasic patients in real-world practice: monitoring and nutraceutical intervention for a nonlithogenic pH range. Clin Med Insights Urol 2019; 12. DOI: https://doi.org/10.1177/1179561119853556

6. Jiang P, Xie L, Arada R, et al. Qualitative review of clinical guidelines for medical and surgical management of urolithiasis: consensus and controversy 2020. J Urol 2021; 205:999-1008. DOI: https://doi.org/10.1097/JU.0000000000001478

7. Kwong T, Robinson C, Spencer D, et al. Accuracy of urine pH testing in a regional metabolic renal clinic: is the dipstick accurate enough? Urolithiasis 2013; 41:129-32. DOI: https://doi.org/10.1007/s00240-013-0546-y

8. Sanz-Gómez I, Angerri O, Baboudjian M, et al. Role, cost, and availably of urinary pH monitoring for kidney stone disease-A systematic review of the literature. Curr Urol Rep 2023; 24:381-88. DOI: https://doi.org/10.1007/s11934-023-01166-5

9. Fink HA, Wilt TJ, Eidman KE, et al. Medical management to prevent recurrent nephrolithiasis in adults: a systematic review for an American College of Physicians Clinical Guideline. Ann Intern Med 2013; 158:535-43. DOI: https://doi.org/10.7326/0003-4819-158-7-201304020-00005

10. Ferraro PM, Curhan GC, D’Addessi A, et al. Risk of recurrence of idiopathic calcium kidney stones: analysis of data from the literature. J Nephrol 2017; 30:227-33. DOI: https://doi.org/10.1007/s40620-016-0283-8

11. Grases F, Rodriguez A, Berga F, et al. A new device for simple and accurate urinary pH testing by the stone-former patient. Springerplus 2014; 3:209. DOI: https://doi.org/10.1186/2193-1801-3-209

12. López JM, Mainez JA, Mora CJ, et al. Usefulness and acceptability of a Smart pH meter and mobile medical App as a monitoring tool in patients with urolithiasis: short-term prospective study. Arch Esp Urol 2022; 75:60-8. DOI: https://doi.org/10.37554/en-j.arch.esp.urol-20211108-3552-36

13. Mainez JA, Galán JA, López JM, et al. User profile and engagement with a digital health application for urolithiasis management: A descriptive study of the first 699 users. Actas Urol Esp 2025;49:501819. DOI: https://doi.org/10.1016/j.acuroe.2025.501819

14. Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021; 372:n71. DOI: https://doi.org/10.1136/bmj.n71

15. Wells GA, Shea B, O’connell D, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality if nonrandomized studies in meta-analyses. ScienceOpen; 2015.

16. Canvasser NE, Alken P, Lipkin M, et al. The economics of stone disease. World J Urol 2017; 35:1321-29. DOI: https://doi.org/10.1007/s00345-017-2003-y

17. Lotan Y, Buendia Jiménez I, Lenoir-Wijnkoop I, et al. Increased water intake as a prevention strategy for recurrent urolithiasis: major impact of compliance on cost-effectiveness. J Urol 2013;189:935-39. DOI: https://doi.org/10.1016/j.juro.2012.08.254

18. Instituto Nacional de Estadística. INEbase/Standard of living and living conditions/Consumer Price Index (CPI). https://www.ine.es/dyngs/INEbase/en/operacion.htm

19. Polotti C, Tan B, Borglum N, et al. Relationship between the Wisconsin stone quality of life (WISQOL) and preference-based/health utility measures of health-related quality of life (HRQoL) in kidney stone patients. Urology 2020; 141:33-8. DOI: https://doi.org/10.1016/j.urology.2020.03.049

20. Vallejo-Torres L. Estimating the incremental cost per QALY produced by the Spanish NHS: a fixed-effect econometric approach. Pharmacoeconomics 2025; 43:109-22. DOI: https://doi.org/10.1007/s40273-024-01441-4

21. De Coninck V, Keller EX, Rodríguez-Monsalve M, et al. Evaluation of a Portable urinary pH meter and reagent strips. J Endourol 2018; 32:647-52. DOI: https://doi.org/10.1089/end.2018.0202

22. Angerri O, Pascual D, Haro J, et al. Comparative study between a medical device and reagent dipsticks in measuring pH. Arch Esp Urol 2020; 73:546-53.

23. Desai RA, Assimos DG. Accuracy of urinary dipstick testing for pH manipulation therapy. J Endourol 2008; 22:1367-70. DOI: https://doi.org/10.1089/end.2008.0053

24. Johnson KY, Lulich JP, Osborne CA. Evaluation of the reproducibility and accuracy of pH-determining devices used to measure urine pH in dogs. J Am Vet Med Assoc 2007; 230:364-69. DOI: https://doi.org/10.2460/javma.230.3.364

25. Hekmatynia F, Eskandarzadeh N, Imani M, et al. The diagnostic performance of human urinary dipsticks to estimate urine pH, specific gravity (SpG), and protein in horses: are they reliable? BMC Vet Res 2019; 15:242. DOI: https://doi.org/10.1186/s12917-019-1998-2

26. Ilyas R, Chow K, Young JG. What is the best method to evaluate urine pH? A trial of three urinary pH measurement methods in a stone clinic. J Endourol 2015; 29:70-4. DOI: https://doi.org/10.1089/end.2014.0317

27. Omar M, Sarkissian C, Jianbo L, et al. Dipstick spot urine pH does not accurately represent 24 hour urine PH measured by an electrode. Int Braz J Urol 2016; 42:546-49. DOI: https://doi.org/10.1590/S1677-5538.IBJU.2015.0071

28. Abbott JE, Miller DL, Shi W, et al. Optimization of urinary dipstick pH: Are multiple dipstick pH readings reliably comparable to commercial 24-hour urinary pH? Investig Clin Urol 2017; 58:378-82. DOI: https://doi.org/10.4111/icu.2017.58.5.378

29. Strohmaier WL, Hoelz KJ, Bichler KH. Spot urine samples for the metabolic evaluation of urolithiasis patients. Eur Urol 1997; 32:294-300. DOI: https://doi.org/10.1159/000480828

30. Wockenfus AM, Koch CD, Conlon PM, et al. Discordance between urine pH measured by dipstick and pH meter: implications for methotrexate administration protocols. Clin Biochem 2013; 46:152-4. DOI: https://doi.org/10.1016/j.clinbiochem.2012.10.018

31. Devicare Technical Department. Validation report of pH measurements. Report number: 13 IF026.00. 2016.

32. Shastri S, Patel J, Sambandam KK, et al. Kidney stone pathophysiology, evaluation and management: core curriculum 2023. Am J Kidney Dis 2023; 82:617-34. DOI: https://doi.org/10.1053/j.ajkd.2023.03.017

33. Vallejo-Torres L, García-Lorenzo B, Castilla I, et al. On the estimation of the cost-effectiveness threshold: why, what, how? Value Health 2016; 19:558-66. DOI: https://doi.org/10.1016/j.jval.2016.02.020

34. Ziemba JB, Matlaga BR. Epidemiology and economics of nephrolithiasis. Investig Clin Urol 2017; 58:299-306. DOI: https://doi.org/10.4111/icu.2017.58.5.299

35. Pietropaolo A, Keller EX, Sener TE, et al. Economic burden of imaging and interventions in endourology: a worldwide cost analysis from European Association of Urology Young Academic Urology Endourology and Urolithiasis Working Party. J Endourol 2025; 39:389-98. DOI: https://doi.org/10.1089/end.2024.0673

36. Zhang D, Tian J, Lu G, et al. Global, regional, and nation burden of urolithiasis in young adults from 1990 to 2021: analysis of data from the global burden of disease study 2021. Urolithiasis 2025;53:38. DOI: https://doi.org/10.1007/s00240-025-01712-5

37. Shahmoradi L, Azizpour A, Bejani M, et al. A smartphone-based self-care application for patients with urinary tract stones: identification of information content and functional capabilities. BMC Urol 2022; 22:181. DOI: https://doi.org/10.1186/s12894-022-01127-z

38. Alowais SA, Alghamdi SS, Alsuhebany N, et al. Revolutionizing healthcare: the role of artificial intelligence in clinical practice. BMC Med Educ 2023; 23:689. DOI: https://doi.org/10.1186/s12909-023-04698-z