Advice
Clinical and technical evidence
Clinical and technical evidence
A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.
Published evidence
Four studies are summarised in this briefing with a total of 682 patients. All studies used a retrospective case series or observational design and 1 was an abstract. Primary post-procedure stone-free rates ranged from 78% to 97%. About 20% of patients treated with MIP‑M experienced non-serious complications (Clavien–Dindo grades I to II), while about 5 to 6% of patients had more serious complications (Clavien–Dindo grade III or more).
In comparison to current standard procedures (RIRS and ESWL), using MIP‑M led to higher stone-free rates particularly for patients with larger stones (10 mm or more). However MIP‑M patients needed more postoperative care and were found to have a longer stay in hospital.
Table 3 summarises the clinical evidence as well as its strengths and limitations.
Overall assessment of the evidence
The size of kidney stones in the studies were different (both smaller and larger) than the ideal size for which MIP‑M is indicated. The stones varied in complexity, which may affect post-procedure stone-free rates and volume of blood loss. Patient characteristics such as age and sex that are associated with the presence of kidney stones were not always reported and all of the studies used a retrospective design, which may lead to biased patient selection. Prospective comparative studies or randomised controlled trials would be valuable to show the effectiveness of MIP‑M compared with standard care.
None of the studies included were done in the UK, but the outcomes reported are relevant to the NHS. It would be beneficial to have evidence directly comparing MIP‑M with NHS treatment options and patient selection criteria.
Table 3 Summary of selected studies
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Study size, design and location |
73 patients with renal stones >20 mm; mean stone size was 36.7 mm). Retrospective case series. Germany. |
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Intervention and comparator(s) |
Intervention was MIP-M. No comparator. |
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Key outcomes |
51 (61.4%) stones were classed as complex stones and 32 (38.6%) were classed as simple stones. Stone size not reported. Mean surgical time was 99.2 (SD=48.3) minutes. This did not significantly differ between complex and simple stones. Post-procedure, primary stone-free rate was 78.3% with 16.9% of patients needing an auxiliary procedure to become stone free, resulting in an overall stone-free rate of 95.2%. There was a significant difference in primary stone-free rates between simple stones (96.9%) and complex stones (66.7%). There were complications in 26.5% of patients; 20.5% of complications were Clavien–Dindo grades I or II and 6.0% were grade IIIb. Grade I complications were significantly more likely to happen with simple stones (33.3%) than with complex stones (5.8%). The grade IIIb complications were more likely to occur with complex stones, but this was not significant. No complications were grade IV or V. Haemoglobin-level decrease was not significantly different between simple and complex stone groups. One patient (who had complex stones) needed a blood transfusion. |
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Strengths and limitations |
No comparator device. Retrospective study design. |
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Study size, design and location |
98 patients with renal stones <20 mm and 93 with renal stones >20 mm. Retrospective observational study. Germany. |
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Intervention and comparator(s) |
Intervention was MIP‑M. No comparator. |
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Key outcomes |
There were 74 complex renal stones (58 large, 16 small) and 117 were simple (35 large, 82 small). Mean overall surgical time was 82.9 (±44.4) minutes. This was significantly longer in large stones compared with small stones (97.4 versus 69.2 minutes). Mean overall decrease in haemoglobin was 1.5 g/dl. This was significantly different between groups (large, 1.7 and small, 1.3). One participant (with a large complex stone) needed a blood transfusion. Primary stone-free rate was 83.8%. Some 13.1% of patients needed an auxiliary procedure to become stone free, resulting in an overall stone-free rate of 96.9%. There was a significant difference in primary stone-free rates between large stones (76.7%) and small stones (90.8%). The overall complication rate was 23%, with 17.8% of these Clavien–Dindo grade I or II, 5.3% grade IIIb and none grade IV or V. There was no significant difference in the complication rate between large and small stones. Mean hospital stay was 3.9±1.4 days. This was significantly longer for those with large stones compared with small (4.3 versus 3.7 days respectively). |
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Strengths and limitations |
No comparator device. Assessed consecutive MIP‑M procedures from a single site. |
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Study size, design and location |
482 patients having their first renal stone removal: 202 ESWL; 108 RIRS; and 172 MIP‑M procedure. Retrospective comparative observational study. Germany. |
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Intervention and comparator(s) |
Intervention was MIP‑M. Comparators were shock wave lithrotripsy and retrograde intrarenal surgery. |
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Key outcomes |
The mean stone size was significantly larger in the MIP‑M group compared with the comparator groups. Primary stone-free rates were significantly higher in the MIP‑M group compared with the RIRS and ESWL groups (79.7%, 77.8% and 58.4% respectively). There was a higher stone-free rate for patients with stones >10 mm when using MIP‑M compared with ESWL. RIRS and MIP‑M patients needed significantly more postoperative care compared with ESWL. Length of hospital stay was significantly higher in the MIP‑M group compared with RIRS and ESWL (4.5, 2.3 and 2.2 days respectively). Complication rates (Clavien–Dindo grades I to III), were higher in the RIRS and MIP‑M groups. For lower pole stones, MIP‑M showed significantly prolonged stone-free survival compared with RIRS and ESWL. |
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Strengths and limitations |
Moderate sample sizes. Comparator devices. Retrospective design. |
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Study size, design and location |
29 patients with renal stones between 8 mm and 15 mm in diameter. Retrospective chart review. Germany. |
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Intervention and comparator(s) |
Intervention was MIP‑M. No comparator. |
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Key outcomes |
96.5% were post-operatively stone free; 1 patient had further ureteroscopy to become stone free. No Clavien–Dindo grade VI or V complications were reported. No patients needed a blood transfusion. |
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Strengths and limitations |
No comparator. Abstract only. Small sample size. |
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Abbreviations: MIP‑M, minimally invasive percutaneous nephrolitholapaxy medium; ESWL, extracorporeal shock wave lithrotripsy; RIRS, retrograde intrarenal surgery. |
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