What are kidney stones?
Stones can form in the kidneys, bladder, ureters (the tubes that carry urine from the kidney to the bladder), or urethra (the tube through which urine leaves the body) when there is not enough fluid in the urine to dilute the minerals or other substances it contains. If the stones form in the kidneys, we call them kidney stones. People who drink too little water, have a poor diet, are overweight, have certain medical conditions, or use certain medicines are more likely to get kidney stones. Kidney stones can cause pain, kidney infection, and kidney failure (when a kidney cannot work on its own).
How are kidney stones treated?
Treatment of kidney stones includes extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), and retrograde intrarenal surgery (RIRS). ESWL uses shock waves from outside the body to break a stone inside the kidney into tiny pieces without cutting the skin. The broken stone fragments are small enough to pass out in the urine. PCNL is a surgical method of removing kidney stones that involves inserting a small tube through the skin to the kidney, breaking up the stones using different instruments (such as laser and ultrasound), and removing the fragments through the tube. RIRS is another surgical method, which involves placing a small viewing tube through the urethra and ureter into the kidney, then crushing or evaporating the stone or grabbing and removing it with small pincers.
What did we want to find out?
We wanted to find out how ESWL compares to PCNL and RIRS in terms of treatment success, quality of life, complications, length of hospital stay, and other outcomes that are important to people with kidney stones.
What did we do?
We only included randomized controlled trials (studies that randomly assign the people taking part to an experimental group or a comparator group) that compared ESWL to PCNL or RIRS. We compared and summarized their results and rated our confidence in the evidence.
What did we find?
We found 31 studies that included 3361 people (1360 people were treated by ESWL, 786 by PCNL, and 925 by RIRS). The biggest study included 649 people and the smallest study included 30 people. The studies were conducted in countries around the world; most were set in Europe (12 studies). Medical device companies funded two of the studies. The average stone size was 13.4 mm.
Main results
Compared with PCNL, ESWL may have lower treatment success; for every 1000 people treated, only 619 treated with ESWL might have no stones after three months, compared to 923 people treated with PCNL. ESWL and PCNL may have similar effects on quality of life: on a scale of 0 to 100, where a meaningful difference is 10 points, people treated with ESWL might score 1.5 points lower than those treated with PCNL. ESLW probably leads to fewer complications than PCNL: for every 1000 people treated, 134 treated with ESWL probably have complications, compared to 216 people treated with PCNL.
Compared with RIRS, ESWL may have lower treatment success: for every 1000 people treated, 721 treated with ESWL might have no stones after three months, compared to 848 people treated with RIRS. We are very uncertain about the effect of ESWL compared to RIRS on quality of life and unwanted effects.
What are the limitations of the evidence?
Depending on the outcome, our confidence in the evidence was moderate to very low. This was mainly because some studies had flawed methods, because there were important differences in results across studies that we could not explain, and because some studies included few people. Therefore, our results are likely to change if further evidence becomes available.
How up to date is this evidence?
This review updates our previous review published in 2014. We included evidence published up to 6 December 2022.
ESWL compared with PCNL may have lower three-month success rates, may have a similar effect on QoL, and probably leads to fewer complications. ESWL compared with RIRS may have lower three-month success rates, but the evidence on QoL outcomes and complication rates is very uncertain. These findings should provide valuable information to aid shared decision-making between clinicians and people with kidney stones who are undecided about these three options.
Nephrolithiasis is a common urological disease worldwide. Extracorporeal shock wave lithotripsy (ESWL) has been used for the treatment of renal stones since the 1980s, while retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PCNL) are newer, more invasive treatment modalities that may have higher stone-free rates. The complications of RIRS and PCNL have decreased owing to improvement in surgical techniques and instruments. We re-evaluated the best evidence on this topic in an update of a Cochrane Review first published in 2014.
To assess the effects of extracorporeal shock wave lithotripsy compared with percutaneous nephrolithotomy or retrograde intrarenal surgery for treating kidney stones.
We performed a comprehensive search in CENTRAL, MEDLINE, Embase, and ClinicalTrials.gov with no restrictions on language or publication status. The latest search date was 6 December 2022.
We included randomized controlled trials (RCTs) and quasi-RCTs that compared ESWL with PCNL or RIRS for kidney stone treatment.
Two review authors independently classified studies, extracted data, and assessed risk of bias. Our primary outcomes were treatment success rate at three months (defined as residual fragments smaller than 4 mm, or as defined by the study authors), quality of life (QoL), and complications. Our secondary outcomes were retreatment rate, auxiliary procedures rate, and duration of hospital stay. We performed statistical analyses using a random-effects model and independently rated the certainty of evidence using the GRADE approach.
We included 31 trials involving 3361 participants (3060 participants completed follow-up). Four trials were only available as an abstract. Overall mean age was 46.6 years and overall mean stone size was 13.4 mm. Most participants (93.8%) had kidney stones measuring 20 mm or less, and 68.9% had lower pole stones.
ESWL versus PCNL
ESWL may have a lower three-month treatment success rate than PCNL (risk ratio [RR] 0.67, 95% confidence interval [CI] 0.57 to 0.79; I2 = 87%; 12 studies, 1303 participants; low-certainty evidence). This corresponds to 304 fewer participants per 1000 (397 fewer to 194 fewer) reporting treatment success with ESWL. ESWL may have little or no effect on QoL after treatment compared with PCNL (1 study, 78 participants; low-certainty evidence). ESWL probably leads to fewer complications than PCNL (RR 0.62, 95% CI 0.47 to 0.82; I2 = 18%; 13 studies, 1385 participants; moderate-certainty evidence). This corresponds to 82 fewer participants per 1000 (115 fewer to 39 fewer) having complications after ESWL.
ESWL versus RIRS
ESWL may have a lower three-month treatment success rate than RIRS (RR 0.85, 95% CI 0.78 to 0.93; I2 = 63%; 13 studies, 1349 participants; low-certainty evidence). This corresponds to 127 fewer participants per 1000 (186 fewer to 59 fewer) reporting treatment success with ESWL. We are very uncertain about QoL after treatment; the evidence is based on three studies (214 participants) that we were unable to pool. We are very uncertain about the difference in complication rates between ESWL and RIRS (RR 0.93, 95% CI 0.63 to 1.36; I2 = 32%; 13 studies, 1305 participants; very low-certainty evidence). This corresponds to nine fewer participants per 1000 (49 fewer to 48 more) having complications after ESWL.