Hypothesis / aims of study
Sacral neuromodulation (SNM) is recommended for the treatment of refractory overactive bladder (OAB) syndrome and non-obstructive urinary retention (1). Prior to 2019, only one device (Medtronic® InterStim™ II) with head-MRI compatibility was available. However since then, three full-body, MRI-compatible SNM devices (Medtronic® InterStim™II recharge-free, Medtronic® InterStim™ Micro rechargeable and Axonics® r-SNM™ rechargeable) with different characteristics have become available thus offering more choice for patients and allowing more patients to have this therapy. The two rechargeable devices provide stimulation thanks to a very small implantable stimulator, and they are tested to deliver the therapy for at least 15 years.
Due to the recent introduction of these devices, no study has been carried out to determine which criterion seems to best guide the patient in the choice of treatment.
We conducted a quality improvement project to capture the patient preferences regarding choice of SNM device to help develop a patient decision aid.
Study design, materials and methods
All patients undergoing a test phase percutaneous nerve evaluation (PNE) lead placement were prospectively enrolled between 10/2020 – 12/2020.
Patients were shown the different devices with detailed discussion about their characteristics. Then, they were asked to fill a structured questionnaire before and after the test phase, if responders.
Patients were asked to assess different items: size of the battery, size of the remote control, items about the rechargeability, about the number of programs, the number of revision surgery,… and they were asked to rate each item between 0 and 5 regarding the importance of the item in patient’s choice.
Finally, they were asked to determine which device they would prefer to have. Graph Pad Software has been used to conduct statistical analyses.
Results
40 adult patients were included (34 Female, 6 Male) in the study.
Among the responders, 25 patients filled the questionnaire after the test phase.
The median scores obtained by items are detailed in Fig 1.
For each item, regarding the median score, no difference was observed between before and after the test phase. When comparing each item with each other: no difference was observed between scores in the overall population, either before or after the test phase.
In the overall population, the highest scores obtained were for items 4, 5 and 6 which were related to rechargeability of the device, and item 7 related to number of programs.
Before the test phase, the number of revision surgeries needed in the future (item 8) was also important in patient’s choice.
Regarding the scores obtained by item, according to the patient’s choice of the device (Fig 2), a statistically significant difference was observed between Medtronic® InterStim™ II recharge-free and Medtronic® InterStim™ Micro for item 1, size of the battery, and item 8, number of revision surgery.
No other difference was observed.
The 3 most important criteria in patient’s choice were as follows: first the size of the battery, then the ease of recharging, then the frequency of recharging.
8 patients changed their mind during the test period:
-2 for a non-rechargeable device (from Medtronic® InterStim™ Micro to Medtronic® InterStim™ II recharge-free),
-3 changed for a rechargeable device (from Medtronic® InterStim™ II recharge-free to Medtronic® InterStim™ Micro)
-And 3 patients changed between 2 rechargeable devices (Axonics® r-SNM™ rechargeable and Medtronic® InterStim™ Micro), the final choice being Medtronic® InterStim™ Micro for the 3 patients.
Among the 25 patients who filled the questionnaire after the test phase, the final choice of the devices was as follows: Medtronic® InterStim™ II recharge-free for 13 patients (52%) and Medtronic® InterStim™ Micro rechargeable for 12 patients (48%).
Interpretation of results
Since 2019, new devices are available for Sacral Neuromodulation, with new characteristics, in particular MRI-compatibility, rechargeability, smaller size, and longer life expectancy.
The choice of the device is made by considering the surgeon's preferences, in terms of cost, number of revisions, number of clinic visits, and is also made by considering the patient's preference, related to lifestyle, ability and willingness to deal with a rechargeable device, considering the constraints that this weekly recharge may represent.
To help patient to make the decision, the different devices must be shown, and a leaflet with devices characteristics may be given to the patient, with further details.
In our study, items related to rechargeability, size of the battery, and life expectancy of the device (the number of surgeries needed in the future) were the main criteria to guide patients’ choice of device.
The final choice was a rechargeable device for half the patients and a non-rechargeable device for the other half.
These results highlight the fact that the recharge burden can be experienced as an important constraint in the daily life of patients, even if the stimulator has a smaller size and a longer life expectancy.
In our experience, the PNE test phase gave patients an opportunity to consider their options.
Concluding message
Rechargeability of the device, size of the battery, and the number of surgeries needed in the future were the main criteria to guide patients’ choice of device.
Patients should be counselled and accompanied in their choice, and all the devices should be shown, with the various characteristics explained.
Patients must be aware of the burden related to rechargeable device, even if the implant size is smaller with a higher life expectancy.
The PNE test phase gave patients an opportunity to consider their options.