Carvalho M et al, 2016: Effect of potassium citrate supplement on stone recurrence before or after lithotripsy: systematic review and meta-analysis.
Carvalho M, Erbano BO, Kuwaki EY, Pontes HP, Liu JW, Boros LH, Asinelli MO, Baena CP.
Escola de Medicina, PUCPR-Pontifícia Universidade Católica do Paraná, Rua Imaculada Conceição, 1155-Prado Velho, Curitiba, Paraná, Brazil.
Hospital de Clínicas, UFPR-Universidade Federal do Paraná, Rua General Carneiro, 181-Alto da Glória, Curitiba, Paraná, Brazil.
Hospital Marcelino Champagnat, Av. Pres. Affonso Camargo, 1399-Cristo Rei, Curitiba, Paraná, Brazil.
This meta-analysis summarizes the available evidence on the effectiveness of citrate supplement for preventing the recurrence of nephrolithiasis in patients undergoing extracorporeal shock wave lithotripsy (SWL). Electronic searches were conducted using Medline-PubMed, Web of Science, Embase, BVS (Scielo, Lilacs), and Google Scholar literature databases. The authors worked in pairs to select studies that met the following criteria: randomized controlled trials that were conducted in adults and assessed the effect of potassium citrate supplement before or after SWL therapy for urolithiasis. Our primary aim was to asses the stone-free rate among the groups included in the studies. Fixed effect was used in the meta-analysis with 95% confidence interval (95% CI). Heterogeneity was analyzed by the I 2 value. A total of 2505 references were initially selected. Of those, four were subjected to meta-analysis contributing five samples. These four studies included 374 participants who were followed for a period of 12 months after SWL. Mean potassium citrate dosage was approximately 55 mEq/day (18 mmol). The results showed that citrate supplement significantly protected against the recurrence of nephrolithiasis during 1 year after SWL [RR; 95% CI 0.21 (0.13, 0.31)]. The heterogeneity was not significant across the analyzed studies (p = 0.224). The quality of the analyzed studies was generally low. The available evidence shows that citrate supplement effectively reduces the recurrence of nephrolithiasis in patients undergoing SWL. However, statistical analysis of a larger trial conducted with methodological rigor is warranted.
Urolithiasis. 2016 Dec 3. [Epub ahead of print]
It is highly interesting if medical treatment further can improve the final outcome of SWL. The present report is a meta-analysis on the effects of potassium citrate as a method to counteract stone recurrences and to achieve a stone-free state. Only four randomized studies were extracted form a large number of publications. With a short follow-up it is likely that the measured effect is related to problems associated only with growth or passage of residual fragments. Direct effects on new stone formation will require much longer follow-up periods.
One point that deserves attention is the fact that potassium citrate generally was administered in three daily doses. Although such a dosage possibly can be used during a limited period of time, I cannot see how such a regimen can be continued during longer periods.
The overall conclusion is that supplements of potassium citrate favourably can be used after SWL to counteract recurrent problems in a short-term perspective and to get stone-free urinary tracts. But for optimal compliance it is absolutely necessary to find a dosage regimen different from the need to take this medication three times a day.