Quantitative assessment of nonpelvic pressure pain sensitivity in urologic chronic pelvic pain syndrome: a MAPP Research Network study

Abstract

Experimental pain sensitivity was assessed in individuals with urologic chronic pelvic pain syndrome (UCPPS) as part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. A series of computer-controlled pressure stimuli were delivered to the thumbnail bed, an asymptomatic site distant from the area of UCPPS pain that is considered to be indicative of overall body pain threshold. Stimuli were rated according to a standardized magnitude estimation protocol. Pain sensitivity in participants with UCPPS was compared with healthy controls and a mixed pain group composed of individuals with other chronic overlapping pain conditions, including fibromyalgia, chronic fatigue, and irritable bowel syndromes. Data from 6 participating MAPP testing sites were pooled for analysis. Participants with UCPPS (n = 153) exhibited an intermediate pain sensitivity phenotype: they were less sensitive relative to the mixed pain group (n = 35) but significantly more sensitive than healthy controls (n = 100). Increased pain sensitivity in patients with UCPPS was associated with both higher levels of clinical pain severity and more painful body areas outside the pelvic region. Exploratory analyses in participants with UCPPS revealed that pain sensitivity increased during periods of urologic symptom flare and that less pressure pain sensitivity at baseline was associated with a greater likelihood of subsequent genitourinary pain improvement 1 year later. The finding that individuals with UCPPS demonstrate nonpelvic pain hypersensitivity that is related to clinical symptoms suggests that central nervous system mechanisms of pain amplification contribute to UCPPS.

Trial registration: ClinicalTrials.gov NCT01098279.

Conflict of interest statement

Conflicts of Interest

Dr. Harte reports grants from National Institutes of Health (NIH) during the conduct of the study; and grants from NIH, Veterans Affairs, Cerephex, Eli Lilly, American Cancer Society, grants and personal fees from Aptinyx, personal fees from SUFU, Longitudinal Capital Management, University of North Carolina - Chapel Hill, and Arbor Medical Innovations (AMI) outside the submitted work. In addition, Dr. Harte has a patent (US 9307906) for the MAST System with royalties paid to Arbor Medical Innovations. Dr. Schrepf reports grants from NIH during the conduct of the study. Dr. Gallop has nothing to disclose. Dr. Kruger reports grants from NIH during the conduct of the study; grants and personal fees from AMI outside the submitted work. In addition, Dr. Kruger has a patent (US9307906) with royalties paid to AMI. Dr. Lai reports grants from NIH during the conduct of the study; other support from Medtronic, Allergan, Teva, and Aquinox outside the submitted work. Dr. Sutcliffe has nothing to disclose. Mrs. Halvorson has nothing to disclose. Mr. Ichesco has nothing to disclose. Dr. Naliboff has nothing to disclose. Dr. Afari reports grants from NIH during the conduct of the study. Dr. Harris reports grants and other support from Pfizer and Aptinyx outside the submitted work. Dr. Farrar reports personal fees from Pfizer, Daiichi Sankyo, Cara Therapeutics, Biogen, Aptinyx, Campbell Alliance, NIH-NIAMS, Analgesic Solutions, Novartis, DepoMed, Jansen, Evadera, and Wolhers Kluwer Health all outside the submitted work. Dr. Tu reports personal fees from AbbVie outside the submitted work. Dr. Landis has nothing to disclose. Dr. Clauw reports grants and personal fees from Aptinyx and Pfizer, and personal fees from Daiichi Sankyo, Intec Pharma, Eli Lilly and Company, Samumed, Theravance, Tonix, Williams & Connolly LLP, and Zynerba outside the submitted work.

Figures

Fig. 1

Density plots depicting the distribution of unadjusted pressure pain sensitivity values for each group. Density (y-axis) refers to the proportion of values at each pressure level (x-axis). The peaks of each plot indicate where values are most concentrated, with median values shown as dashed lines.

Fig. 2

Box plots and unadjusted Pain50 values for 22 participants with discordant flare data. Middle lines are median values, lower edge shows 25th percentile, upper edge shows 75th percentile. Blue box is no flare; red box is flare.