Phenotyping Chronic Pelvic Pain Based on Latent Class Modeling of Physical Examination

Introduction. Defining clinical phenotypes based on physical examination is required for clarifying heterogeneous disorders such as chronic pelvic pain (CPP). The objective of this study was to determine the number of classes within 4 examinable regions and then establish threshold and optimal exam criteria for the classes discovered. Methods. A total of 476 patients meeting the criteria for CPP were examined using pain pressure threshold (PPT) algometry and standardized numeric scale (NRS) pain ratings at 30 distinct sites over 4 pelvic regions. Exploratory factor analysis, latent profile analysis, and ROC curves were then used to identify classes, optimal examination points, and threshold scores. Results. Latent profile analysis produced two classes for each region: high and low pain groups. The optimal examination sites (and high pain minimum thresholds) were for the abdominal wall region: the pair at the midabdomen (PPT threshold depression of > 2); vulvar vestibule region: 10:00 position (NRS > 2); pelvic floor region: puborectalis (combined NRS > 6); vaginal apex region: uterosacral ligaments (combined NRS > 8). Conclusion. Physical examination scores of patients with CPP are best categorized into two classes: high pain and low pain. Standardization of the physical examination in CPP provides both researchers and general gynecologists with a validated technique. 1. Introduction Establishing phenotypes for clinical conditions is a fundamental step in the development of diagnostic criteria, which are required for coherent research and evidence based clinical care [1]. From the categorization of fetal heart rate patterns to the description of pelvic organ prolapse, a validated nomenclature allows an apples-to-apples comparison of research studies and also lets clinicians translate research findings into practice by clearly describing a clinical condition in terms of objective findings. Chronic pelvic pain is an area of gynecology sorely in need of evidence based phenotypes [2]. The current phenotyping approaches are primarily symptom based and limited to urologic pain [3]. The challenges in this field are many and varied [4]. Since pain is subjective, an easily replicated standardized examination becomes even more important. How to perform the exam, which points to examine, and where to set thresholds between incidental pain and significant pain are all problems faced by clinicians on a daily basis [5]. Patients also are frustrated by a lack of uniformity in describing their condition and are hindered by incomplete evaluations [6]. Phenotyping