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Predictors of Nerve Stimulation Success in Patients with Overactive Bladder
Bennett Sluis, BA¹, Kristian Stensland, MD², Jay Vance, MS¹, Jared Schober, MD², Lara MacLachlan, MD², Arthur Mourtzinos, MD MBA².
¹Tufts University School of Medicine/Lahey Hospital and Medical Center, Boston, MA, USA, ²Lahey Hospital and Medical Center, Burlington, MA, USA.

Background: Patients suffering from overactive bladder (OAB) without response to behavioral and pharmaceutical intervention may opt for third-line therapy with sacral nerve stimulation (SNS). SNS is performed in two stages, with a ‘trial period’ interceding initial lead placement and final device implantation. Patients with a successful trial as defined by a significant reduction in OAB symptoms have permanent implantation while unsuccessful trial leads to explant of the leads. Data predicting which patients will have a successful trial are limited. The present study examines patients undergoing SNS implantation to identify factors associated with successful SNS trial.
Methods: Patients undergoing treatment for OAB at Lahey Hospital and Medical Center between 2004 and 2016 were identified. Demographic, clinical and treatment data were extracted from patient charts. Univariate analyses were conducted to identify factors associated with SNS treatment success using chi-squared and t-test statistics as appropriate. A multivariate logistic regression model using the significant and a priori clinical factors to predict SNS treatment success was also created. Significance was defined at the α= 0.05 level.
Results: Of 268 patients in the OAB database, 123 patients met inclusion criteria. Of these, 95 (77.2%) had treatment success. On univariate analysis, sex, prior diagnosis of prostate cancer, diagnosis of BPH, and lower volume at first urge during urodynamic study (UDS) were associated with an unsuccessful SNS trial (Table 1). On multivariate analysis using age, sex, prostate cancer, BPH, and volume at first urge as covariates, male gender (OR 0.145, 95% CI 0.0360-0.531) and lower volume at first urge on UDS (OR 0.982, 95% CI 0.967-0.995) were associated with unsuccessful SNS trial.
Conclusions: SNS is frequently successful at relieving OAB symptoms. Male patients and those with a lower volume at first urge on UDS are more likely to have an unsuccessful SNS trial. Patients in these groups should be counseled on the lower likelihood of SNS success. Further examination of factors associated with SNS from more diverse patient populations may aid in identification of other factors predictive of unsuccessful SNS trial.
TABLE 1: Univariate Associations with Unsuccessful SNS Trial:

Factor	% successful	% unsuccessful	P value
Gender (female)	73.7	28.6	<0.001
Diabetes	22.1	25.0	0.9
Hypertension	54.7	42.9	0.4
Hyperlipidemia	55.8	46.4	0.5
MS	2.11	0	1
CP	1.05	0	1
Spinal Cord Injury	5.26	0	0.5
Peripheral Neuropathy	5.26	3.57	1
Epilepsy	4.21	7.14	0.9
History of UTI	6.32	7.14	1
History of TURP	3.16	7.14	0.7
Prostate Cancer	0	10.7	0.01
Atrophic Vaginitis	10.53	3.57	0.4
History of Hysterectomy	20.0	10.7	0.4
BPH	10.5	28.6	0.04
Erectile Dysfunction	10.5	10.7	1
Depression	40.0	21.4	0.1
Anxiety	14.7	14.3	1
Hypothyroidism	9.47	14.3	0.7
Fibromyalgia	3.16	0	0.8
Stroke/CVA	6.32	10.7	0.7
Fecal Incontinence	8.42	0	0.2
Constipation	13.7	7.14	0.5
IBS	11.6	0	0.1
Interstitial Cystitis	2.11	3.57	1
Antimuscarinic Use	24.2	35.7	0.3
Beta Agonist Use	8.42	7.14	1
Self-Catheterization	3.16	3.57	1

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