*2.2.5 Cost-effectiveness*

*Neurostimulation and Neuromodulation in Contemporary Therapeutic Practice*

One of the hallmarks of diagnosis of urinary and voiding dysfunction disorders

In its best practice statement, the ICS did not find sufficient evidence to support that urodynamic studies can predict outcomes of treatment for SNM, while it supported based on higher level of evidence a stronger recommendation for performing SNM trial phases as the "single most valuable tool" to predict outcome

Attention has been given to difference in SNM effects between certain patient populations. Gender differences have been long hypothesized, with attention focusing on SNM effects on pelvic floor rehabilitation and its close relatedness to urinary and chronic pelvic disorders in females as a potential modality of effect. In a matched pair analysis, a group of researchers reported on 80 patients who received SNM implants for urge urinary incontinence and found that more women tended to receive implants than men. While urinary frequency and symptom scores improved in both groups, over 3 years, the number of urge incontinence episodes per day improved in men more than women, while the severity of the incontinence improved in women more than men [38]. This gender discrepancy may be explained in part by SNM effect, but perhaps is also due to anatomical difference of the distal

Another patient population suspected to be at a lesser advantage from SNM efficacy are older patients and those with certain comorbidities such as obesity. Interestingly, one study did not only find no difference in response among older patients but further identified that age correlated with a lower rate of surgical revisions of the implantation—3% lower odds per year. In the same study, BMI did not

It is undeniable that there are identifiable structural changes in the bladder muscle and wall that incur from long standing overactive bladder and non-obstructive urinary retention, and hypotheses suggest this may affect the therapeutic outcomes of SNM as the symptom duration increases. However, even symptoms extending for more than 10 years have not been shown to have any significant effect on the success

SNM has proven an efficacious modality of treatment of different genitourinary disorders, with durable success rates between 70 to 80% in certain conditions such as refractory OAB [11, 31, 41, 42]. In one survey of SNM patients, satisfaction rates were reported to be over 95% with SNM therapy and were not affected by patient age or any complications or program type, a testament to the efficacy of this treatment [43]. The multitude of data in the literature also attests to the

History of prior back surgery may be deemed a challenging patient condition for SNM implantation, but a review of 500 patients has shown that such a history did not negatively affect SNM outcomes [45]. Even in patients with prior anti-incontinence

is the utility of urodynamic testing (UDS). Of different types and modes, this diagnostic test aims at reproducing patient symptoms and correlating them to net intradetrusor pressure, among other parameters, in simulated bladder filling and voiding phases. Much has been disputed about the need for UDS testing to diagnose straightforward and clinically apparent conditions such as overactive bladder, and whether UDS findings could help predict outcomes of therapy including SNM prior to its implantation. However, evidence suggests that no single UDS parameter or

*2.2.3 Predictors of effect*

of SNM [4].

finding can predict SNM success [37].

urinary tract in men and women.

influence explantation rates [39].

*2.2.4 Results of SNM and its efficacy*

general safety of SNM [44].

of SNM [40].

**216**

The debate continues on what is the cost-effectiveness of SNM compared to other available treatments for refractory voiding conditions be it OAB or UUI or others. These include in general combination medication, intradetrusor botulinum injections (repeated as the effect of one injection wears out necessitating periodic repeat injections), and more definite bladder or anti-incontinence surgeries.

The long term outcomes of SNM compared to the need for maximal medical therapy or repeated botulinum injections poses a cost-effective benefit superior to the aforementioned counterparts, with some authors even arguing that from a patient's perspective it may well be considered an appropriate primary therapy rather than a second or third line alternative [47]. Compared to botulinum injections in particular, SNM was shown in one study to be cost-effective from the third year of application onwards, with a clear dominance should treatment be continued for 10 years [48]. However, results from the ROSETTA randomized trial which compared SNM and botulinum bladder injections for refractory UUI showed SNM as a less cost-effective alternative [49].

Perhaps the arguments for and against the cost-effectiveness of SNM versus other treatments lay not just in the treatments it is being compared to but in terms of what condition these treatments are being utilized for. In a focus article on safety and cost of SNM compared to botulinum injections for OAB, although SNM was costlier, it was safer than intradetrusor botulinum injections. The latter carries a substantial side effect profile including urinary tract infections, hematuria, urinary retention, and more frequent emergency room visits, all not common occurrences, but may tip the scale in favor of SNM [50].
