Design of a Randomized Controlled Trial of Percutaneous Posterior Tibial Nerve Stimulation for the Treatment of Refractory Fecal Incontinence in Women: The NeurOmodulaTion for Accidental Bowel Leakage Study.

OBJECTIVES: High-level evidence for second-line noninvasive treatments for fecal incontinence in women is limited. We present the rationale for and design of the NeuromOdulaTion for Accidental Bowel Leakage trial, a randomized controlled trial of percutaneous tibial nerve stimulation (PTNS) and validated sham stimulation in women with refractory accidental bowel leakage. METHODS: The rationale and goals for a 2-part study with a run-in phase, use of a generic pulse generator for PTNS and sham stimulation, masking, participant inclusion, primary and secondary outcome measures, and adverse event collection are described. A superiority design will be used to compare change from baseline in St. Mark's score after 12 weekly stimulation sessions between PTNS and sham. Responders to initial treatment (PTNS or sham) will be assigned to scheduled or "as needed" intervention for up to 1 year. Secondary outcome measures include incontinence episodes and other bowel events recorded in a 14-day electronic bowel diary, general and condition-specific quality of life instruments, adaptive behavior, global impression of improvement, symptom control, and sexual function. RESULTS: Sample size calculations determined that 165 participants (110 PTNS and 55 sham) would provide 90% power to detect greater than or equal to 4-point difference between PTNS and sham in change from baseline in St. Mark's score at 12 weeks. CONCLUSIONS: The methods for the NeuromOdulaTion for Accidental Bowel Leakage trial will provide high-level evidence of the effectiveness and optimal maintenance therapy schedule of a low-cost PTNS protocol in community-dwelling women seeking second-line intervention for refractory accidental bowel leakage.

Methods for the defining mechanisms of anterior vaginal wall descent (DEMAND) study.

INTRODUCTION AND HYPOTHESIS: The protocol and analysis methods for the Defining Mechanisms of Anterior Vaginal Wall Descent (DEMAND) study are presented. DEMAND was designed to identify mechanisms and contributors of prolapse recurrence after two transvaginal apical suspension procedures for uterovaginal prolapse. METHODS: DEMAND is a supplementary cohort study of a clinical trial in which women with uterovaginal prolapse randomized to (1) vaginal hysterectomy with uterosacral ligament suspension or (2) vaginal mesh hysteropexy underwent pelvic magnetic resonance imaging (MRI) at 30-42 months post-surgery. Standardized protocols have been developed to systematize MRI examinations across multiple sites and to improve reliability of MRI measurements. Anatomical failure, based on MRI, is defined as prolapse beyond the hymen. Anatomic measures from co-registered rest, maximal strain, and post-strain rest (recovery) sequences are obtained from the "true mid-sagittal" plane defined by a 3D pelvic coordinate system. The primary outcome is the mechanism of failure (apical descent versus anterior vaginal wall elongation). Secondary outcomes include displacement of the vaginal apex and perineal body and elongation of the anterior wall, posterior wall, perimeter, and introitus of the vagina between (1) rest and strain and (2) rest and recovery. RESULTS: Recruitment and MRI trials of 94 participants were completed by May 2018. CONCLUSIONS: Methods papers which detail studies designed to evaluate anatomic outcomes of prolapse surgeries are few. We describe a systematic, standardized approach to define and quantitatively assess mechanisms of anatomic failure following prolapse repair. This study will provide a better understanding of how apical prolapse repairs fail anatomically.

Quantifying sequence proportions in a DNA-based diet study using Ion Torrent amplicon sequencing: which counts count?

A goal of many environmental DNA barcoding studies is to infer quantitative information about relative abundances of different taxa based on sequence read proportions generated by high-throughput sequencing. However, potential biases associated with this approach are only beginning to be examined. We sequenced DNA amplified from faeces (scats) of captive harbour seals (Phoca vitulina) to investigate whether sequence counts could be used to quantify the seals' diet. Seals were fed fish in fixed proportions, a chordate-specific mitochondrial 16S marker was amplified from scat DNA and amplicons sequenced using an Ion Torrent PGM™. For a given set of bioinformatic parameters, there was generally low variability between scat samples in proportions of prey species sequences recovered. However, proportions varied substantially depending on sequencing direction, level of quality filtering (due to differences in sequence quality between species) and minimum read length considered. Short primer tags used to identify individual samples also influenced species proportions. In addition, there were complex interactions between factors; for example, the effect of quality filtering was influenced by the primer tag and sequencing direction. Resequencing of a subset of samples revealed some, but not all, biases were consistent between runs. Less stringent data filtering (based on quality scores or read length) generally produced more consistent proportional data, but overall proportions of sequences were very different than dietary mass proportions, indicating additional technical or biological biases are present. Our findings highlight that quantitative interpretations of sequence proportions generated via high-throughput sequencing will require careful experimental design and thoughtful data analysis.