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Non-invasive experimental bladder pain assessment in painful
bladder syndrome
Frank F. Tu, MD, MPH1,2,3, Julia N. Kane, MA1,2, and Kevin M. Hellman, PhD1,2,3
1Department of Obstetrics and Gynecology, University of Chicago Medical Center, Chicago, IL,
USA
2Department of Obstetrics and Gynecology, NorthShore University HealthSystem, Evanston, IL,
USA
3University of Chicago, Pritzker School of Medicine, Chicago, IL, USA
Abstract
Objective—To compare bladder sensitivity between pelvic pain and pain-free patients
undergoing noninvasive, controlled bladder distension via diuresis. We also sought to measure
potential mechanisms underlying bladder sensitivity.
Design—prospective observational study
Setting—community teaching hospital
Population—Reproductive-age women with non-bladder chronic pelvic pain (CPP, n=23),
painful bladder syndrome (PBS, n=23) and pelvic pain-free controls (n=42)
Methods—Participants were compared on cystometric capacity, pelvic floor pressure-pain
thresholds (PPTs), pelvic muscle function, O’Leary-Sant bladder questionnaire, and psychosocial
instruments using Wilcoxon rank-sum tests. Multivariate regression was used to identify factors
underlying bladder pain phenotypes.
Main outcome measures—self-reported bladder distension pain, pelvic floor pain thresholds
Results—Participants with PBS exhibited higher bladder distension pain than those with CPP,
with both groups reporting pain higher than controls (p’s <0.05). No significant associations were
found between bladder distension pain and pelvic muscle structure or pain sensitivity measures.
However, bladder distension pain positively correlates with both vaginal PPTs adjacent to the
bladder (r=0.46), and pain with transvaginal bladder palpation (r=0.56). Pain at maximal
Editorial Correspondence (and address for all authors): Frank F. Tu, M.D., M.P.H., Division of Gynecological Pain and Minimally
Invasive Surgery, 2650 Ridge Avenue, Suite 1530, Evanston, IL 60201, ftu@northshore.org, 847-570-2520 (office), 847-570-1846
(fax).
Presented in poster format at 15th annual meeting of the International Association for the Study of Pain in Buenos Aires, Argentina
October 6–11, 2014
Disclosure of interests: none to report. The ICMJE disclosure forms are available as online supporting information.
Contribution to authorship: FT conceived/designed experiment, performed experiments, analyzed data, wrote the paper; KH
conceived/designed experiment, performed experiments, analyzed data, wrote the paper; JK performed experiments, analyzed data,
wrote the paper
Details of ethics approval: NorthShore University HealthSystem IRB approval (EH 08-073) 8/1/08
HHS Public Access
Author manuscript
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Published in final edited form as:
BJOG
. 2017 January ; 124(2): 283–291. doi:10.1111/1471-0528.14433.
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distension was less influenced by somatic sensitivity than bladder symptoms (r=0.35 vs. r=0.59,
p<0.05). Multivariate regression identified three independent components of bladder symptoms in
PBS: bladder distension pain, bladder sensation, and somatic symptoms.
Conclusions—Diuresis-induced bladder pain differentiates CPP from PBS. Experimental
bladder pain is not predicted by pelvic floor sensitivity. Compared to patient-reported outcomes it
appears less influenced by psychological factors. Further study is needed to determine screening
for experimental bladder pain sensitivity could predict future risk of PBS.
Tweetable abstract
Controlled, water ingestion-provoked bladder pain can objectively identify visceral pain sensitivity
Keywords
Pelvic Pain; Painful Bladder Syndrome; Pressure Pain Threshold; Quantitative Sensory Testing
Introduction
Painful bladder syndrome/interstitial cystitis (PBS) is a poorly understood chronic pain state
arising in part from an amalgam of disrupted peripheral and central pain regulatory circuits.
Since few treatments are consistently effective, preventative strategies are urgently needed.
A well-recognized finding in PBS is increased bladder pain with bladder filling.1 Although
self-report of distress in PBS appears to reflect both urgency/frequency (International
Continence Society [ICS] terms this
increased bladder sensation)
and pain, the physiological
basis for these dual contributions is not precisely known.2 In a preliminary study, during a
standardized cystometry task, PBS patients report prolonged and more intense discomfort
compared to healthy controls.3
The induction of pain at low filling volumes in patients with PBS parallels findings showing
that many irritable bowel syndrome patients also report pain at lower distension pressures
during anal manometry.4 In functional bowel disorders, standard assays of visceral
hyperalgesia are well-recognized research tools and have been used to characterize the
relevant nerve pathways and molecular underpinnings of these symptoms.5,6 Targeting the
bladder for visceral pain testing is limited by discomfort from urethral catheterization and
infectious risk. Validating more comfortable, non-invasive tests could enhance research
participation.
The present study extends our prior studies of non-invasive bladder distension in studying
menstrual pain and cross-organ visceral sensitivity in otherwise healthy controls, with the
objective of determining if bladder distension pain differs between CPP and PBS patients
(vs. healthy controls).7 Since patients with PBS have widespread reduced pain tolerance and
report more somatic symptoms, we also explored secondarily if non-specific factors and
psychological distress might affect experimental bladder pain testing.1,8 In particular, we
specifically assessed whether pelvic floor sensitivity predicts bladder distension pain, as
pelvic physical therapy reduces bladder pain symptoms, but the underlying mechanism for
this efficacy is unknown.9
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Methods
Overview
This study was a planned analysis for one aim of an overall study of pelvic floor function
and bladder pain sensitivity. We prospectively recruited chronic pelvic pain (CPP) and PBS
patients, as well as pain-free controls prospectively for a cross-sectional study at Evanston
Hospital (Evanston, Illinois) between July 2010 and September 2013 from nearby clinics
and community advertisements.
Participants
CPP was defined as pain lasting three months or longer in the area between the umbilicus
and inguinal ligament. Symptoms could not solely be perceived on the skin, only involve the
hip or back, or only occur with menses. PBS patients were defined by International
Continence Society (ICS) criteria: complaint of pelvic pain related to bladder function,
accompanied by other symptoms such as increased daytime and nighttime frequency, in the
absence of proven urinary infection or other obvious pathology reported urgency or
frequency symptoms,2 Controls were pelvic pain-free, PBS cohort age-matched patients (±5
years) and recruited from the same population. Cases were limited to ages 18–55 years old.
Exclusion criteria included: pregnancy, active urogenital infection, prior urogenital
malignancy, unexplained hematuria, active nephro/ureterolithiasis, vaginal prolapse
exceeding second degree, and unwillingness to avoid short-acting opioids prior to
examination. All participants received modest stipends. The NorthShore University Health
System Institutional Review Board approved the study, and all participants gave informed
consent.
Study procedure
All examinations and tests were performed in a research examination room. Participants
were asked to complete a screen visit and two assessment visits.
Screen Visit
All participants signed consent before any study procedures were executed. A complete
abdominopelvic examination was performed by the primary author. The exam included
asking participants to rate pain from palpation at multiple sites using a 0–10 rating scale (0,
no pain, to 10, worst imaginable pain). Vaginal tissue compliance, voluntary pelvic floor
contractility, and pelvic floor gross muscle strength were quantified on exam using Likert
scales (for more details see Appendix S1). Participants also completed the O’Leary-Sant
Interstitial Cystitis Symptom (ICSI) and Problem Indices (ICPI) and University of
Wisconsin (UW) Interstitial Cystitis questionnaires of bladder function.10,11 They also
completed Patient Reported Outcomes Measurement Information System (PROMIS)
computer adaptive tests for anxiety and depression.12 A somatic symptom score was derived
as the total score of non-bladder symptoms (dizziness, chest pain, nausea, feelings of
suffocation, and tingling in fingers and toes) each rated on a 0–6 Likert scale from selected
UW reference scale questions, similar to those on the Brief Symptom Inventory assessing
somatization.11
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Assessment Visit 1
On the first assessment visit, external and internal pressure-pain thresholds (PPT) and
bladder testing were performed using our prior published standardized protocols.13 The
order of PPT and bladder testing was randomized, except for the PBS participants, who all
underwent bladder filling first. For pressure-pain threshold assessment, we first tested the
four external sites (shoulder, forehead, hip and knee), applying pressure at a rate between 0.5
and 1.0 kg/cm2/s using a pain pressure algometer with a 1 cm2 circular cap. The same
approach was next applied to test four transvaginal pelvic floor sites (right and left
iliococcygeus, anterior bladder, and posterior anorectal raphe) using a specially designed,
fingertip-mounted algometer. Averaged thresholds from two trials were used for the final
analysis. Extended details are presented in Appendix S1.
Participants were asked to hydrate with 12 ounces of water one hour before the visit and
abstain from caffeine the day of testing. After an initial void, participants had baseline
volume measurement of the bladder while supine. Bladder volume was measured using a
Voluson 730 three-dimensional transabdominal 5.0 MHz ultrasound transducer (GE
Healthcare, Wauwatosa, WI). Measurement of bladder volumes was performed using the
scanner’s onboard Virtual Organ Computer-aided Analysis (VOCAL™) software with the
transducer oriented sagittally above the symphysis pubis. Volume was calculated from the
perimeter measurements of six serial plane sections separated by 30°. Validation and
reliability of this method by our research team has been previously published.7
Following the initial scan, participants were asked to drink 20 ounces of water within 5
minutes to further encourage diuresis. While participating they were offered light reading
and were asked not to do other distracting tasks such as making phone calls or engaging in
regular conversation. Participants were asked to report awareness upon reaching three levels
of bladder urgency: first sensation, first desire to void, and maximal capacity. At each of
these three thresholds, we measured bladder volume and then asked the participant to rate
their level of bladder pain and urgency (10 cm visual analogue scale [VAS]). The urgency
scale was anchored at opposite ends with the descriptors “no urgency” and “worst urgency
imaginable.” Similarly, the pain scale was anchored at opposite ends with the descriptors
“no pain” and “worst pain imaginable.” Additionally, every 15 minutes from the time that
participants finished drinking the priming dose of water, they were instructed to evaluate
their current level of pain and urgency using the same VAS measures. If a participant did not
reach maximum capacity by 45 and 60 minutes, she was asked to drink an additional ten
ounces of water (maximum of twenty additional ounces) to encourage diuresis. The bladder
testing was capped at two hours. Bladder filling rates were estimated by calculating the
change in volumes estimated at each cystometric threshold, divided by the elapsed time.
Assessment Visit 2
This visit was conducted approximately one month after assessment visit 1. All participants
underwent internal and external pressure testing and completed a similar battery of
questionnaires assessing pain levels and mental health as was collected during the screen
visit.
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Study Size
The study aim when the study was initially funded targeted a primary hypothesis that
bladder sensation and pelvic floor sensitivity are positively associated. Prior published data
suggested a Cohen’s d effect size of 1.1 for this association.1,3,14 A power analysis estimated
that to achieve that effect size with 80% power, we would need 38 CPP and/or PBS patients
(28 enhanced bladder sensation, and 10 with normal bladder sensation) to significantly
resolve a group difference (p<0.05). An additional aim was to assess if there were
differences in self-reported bladder sensation between pain groups and pain-free controls.
Statistical Analysis
For this paper we addressed three primary pre-defined contrasts: between diagnostic groups
we compared bladder pain at maximum capacity and a time series variable capturing overall
change in bladder pain during the experimental bladder task. We also compared average
pelvic floor pressure pain thresholds between pain patients exhibiting lower vs. higher first
sensation thresholds (≥100 mL cutoff).14 We had complete case data for all bladder testing
and accompanying ratings. Based on Shapiro-Wilk determinations of normality of variables,
group differences were evaluated with Wilcoxon rank-sum tests (followed by post-hoc
Dunn’s tests with Holm-Sidak corrections for multiple comparisons), repeated measures
ANOVA on the ranks, or chi-squared tests with STATA 13.0 (College Station, TX).
Relationships between bladder distension pain, somatic pain sensitivity, the ICSI and other
candidate contributing factors (pelvic floor tone, strength, flexibility and voluntary control;
anxiety; depression; and somatic symptoms) were analyzed with Spearman rank-order
correlation. Significant differences between correlation coefficients were verified with
Fisher-to-z transforms. To verify whether bladder distension pain or other factors were
independently related to bladder pain phenotypes, we performed multivariate linear
regression and determined receiver operating characteristic curves.
Results
Demographic Profile
As expected, the PBS group reported higher bladder distress on both the UW and ICSI
bladder-specific measures compared to pain-free controls (p’s<0.01, Table 1). Women with
CPP had intermediate UW and ICSI scores that were significantly higher than healthy
controls, but lower than participants with PBS (p<0.05). Diary data supported that both CPP
and PBS patients had more voids per day compared to healthy controls (p<0.05). Consistent
with prior published findings, both pain groups had significant duration of ongoing
symptoms, significant rates of comorbid diagnoses (IBS, endometriosis, fibromyalgia, abuse
history), and heightened levels of depression and anxiety.
Bladder Testing Flow Rate
An important consideration in replacing pain measurements obtained with retrograde
bladder filling with natural diuresis is that different flow rates could affect sensation or pain
report. To determine the impact of natural variation in flow rate on perception we analyzed
empirical differences of average flow on sensation and pain. There were no significant
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differences in flow rate between groups (Healthy: 6.6 [5.6–8.0] ml/min, CPP: 6.6 [5.4–9.0].
PBS: 6.0 [5.0 – 6.8] mL/min, p=0.45). However, there was a significant positive correlation
between flow rate and maximum tolerance bladder volume (r=0.73, p<0.001). This is
potentially due to the fact that women with low bladder capacity drink less to improve
tolerability.15 Also flow rates increased over time. Across all participants, there was a
significant increase in flow rate from first sensation (4.3 [2.5–6.6] mL/min) to first urge (6.9
[5.3–9.2], p<0.001) and again from first urge to maximum tolerance (8.7 [7.0–10.8],
p<0.001). To account for any potential confounding, we examined tolerances across the
groups with a general linear model accounting for flow rate. In the general linear model,
there was a significant effect of rate on maximum tolerance (p<0.001), but women with PBS
still had a 112 [44 – 181] ml lower volume at maximal capacity compared to control women
or women with CPP (p<0.001).
Controlled bladder filling elicits greater pain in PBS
Women with PBS reached all cystometric thresholds (first sensation, first desire to void, and
maximal capacity) at significantly lower volumes and time-to-threshold than healthy
controls (Fig 1A, Table S1;p’s<0.05). The mean bladder volume and time-to-threshold was
significantly lower in PBS compared to the CPP group at maximal capacity only. Volume
and time-to-threshold at each cystometric threshold did not differ between CPP and healthy
controls. However, women with CPP reported more pain than healthy controls at all sensory
thresholds (Fig 1B, Table S1;p’s<0.05). Furthermore, women with PBS had higher bladder
pain than those with CPP at first sensation and first desire to void (Fig 1B, Table
S1;p’s<0.05).
Longitudinal report of bladder urgency and pain ratings are shown in Fig 1C–D, with a
significant effect of both time and group observed (p’s<0.001). Nested group×time
interactions indicated that women with CPP have significant increasing pain over time
compared to healthy participants, and PBS participants have worsening pain over time
compared to CPP participants (p’s<0.001).
Potential factors influencing bladder volume tolerance and pain report
In our prior work, full data was not available to evaluate potential predictors of either evoked
bladder pain or bladder volume sensitivity. We found some positive associations between
pelvic floor mechanical sensitivity and evoked bladder pain report. Pressure pain threshold
under the bladder and pain at first sensation was inversely correlated (Table 2, r=−0.46;
p<0.01). Pain evoked by clinical bladder exam was also correlated to bladder distension pain
at all cystometric thresholds (r=0.51–0.56; p<0.01). All other PPTs (transvaginal or
external), as well as pelvic floor anatomy and functional assessments (Table S2) were not
associated with bladder distension pain. For predictors of volume sensitivity, we had one
planned comparison of average pelvic floor PPT for only women with pain, to determine if
mechanical sensitivity was higher in women with volume sensitivity. No difference in
pressure thresholds were observed (high volume sensitive < 100 mL first sensation (1.19
kg/cm2 [1.00–1.44];n=21 vs. low volume sensitivity (1.00 kg/cm2 [0.85–1.23], n=25, p =
0.13). Likewise, no significant associations were seen between any volume sensitivity
threshold with any PPTs. As with pain, pelvic floor tone, strength, flexibility and voluntary
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control did not predict volume sensitivity (Table S2). Interestingly, prolonged duration of
pain report (aftersensation) following mechanical pressure testing (Table 2) correlated with
both bladder distension pain (r=0.50–0.55) and first desire (0.39) and maximal capacity
volumes (0.40, all p < 0.05).
Psychological factors have more impact on bladder symptom reporting than bladder
distension pain
Finally, we examined the associations of psychological factors and bladder distension pain
or volume sensitivity (Table 2). At first sensation, moderate positive correlations were
observed between bladder distension pain, somatic symptom reporting, depression, and
anxiety (0.4–0.48 p<0.05), while depression correlated with bladder pain similarly at first
urge and maximal capacity. We did not observe significant associations between volume
sensitivity and psychological factors, just as we found with mechanical sensitivity and pelvic
anatomy factors (Table S2).
Associations between physiological constructs, psychological profiles and disease-
specific outcomes measures
We also characterized how the combination of functional bladder pain, capacity and
psychosomatic factors influences bladder specific symptom reporting in PBS. Maximal
distension pain (r=0.56), maximal capacity volume (r=−.44), palpation evoked bladder pain
(r=0.60) and somatic symptoms (r=.59) were associated with clinical bladder
symptomatology (ICSI, Table 2). Interestingly, this general somatic symptom report
association with bladder symptom report, tis stronger than its relationship with cystometric
measures of sensitivity (maximal distension pain r=0.35 and capacity r=−0.18, respectively,
p<0.05 Fisher to Z transform). We next explored the distribution of these variables for each
group, to better understand the weight of bladder factors vs. somatic symptoms. We plotted
the summed standardized values for these three variables for each individual participant
adjusting for the general prevalence of CPP and PBS (Fig 2). Although significant bladder
distension pain was rare in the general population, half of patients with CPP had bladder
distension pain, but not necessarily accompanied by filling sensitivity. In patients with PBS,
19/23 had summed standardized scores for bladder pain, bladder sensation, and somatic
symptoms that exceeded 2 standard deviations from median values of a general population.
However, there was seemingly little relationship between the amount of bladder pain or
enhanced bladder sensation and somatic symptoms among patients with PBS. Multivariate
linear regression further identifies that maximal capacity pain, bladder sensitivity, and
somatic symptom reporting are each independent factors contributing to ICSI scores (Table
S3;R2=0.54, p<0.001). A receiver operating characteristics curve showed that the three
factor model generated an area under the curve (AUC) of 0.90 for identifying participants
with an ICSI score ≥6, the threshold for PBS diagnosis suggested in the original ICSI
validation paper (Fig 2).10 The three factor model was superior to a bladder factors-only
(AUC=0.83, p<0.05) or a somatic complaint-only model (AUC=0.74, p<0.01).
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Discussion
Main Findings
We applied a standardized protocol for measuring bladder pain and sensation exploiting the
simplicity of provoked diuresis and confirm distension-induced bladder pain is present in
both classic PBS as well as in half of CPP patients not meeting PBS criteria. Our non-
invasive measure empirically differentiates between relative degrees of visceral sensitivity
(CPP vs. PBS) and is less sensitive to non-specific somatic/psychological factors. The
simplicity of this measure could make it attractive as a general measure of visceral
hypersensitivity, with research applications beyond the urological field.5,6
Another key finding was that pelvic floor pain sensitivity did not predict visceral sensitivity.
Our original hypothesized relationship was based on previous clinical observations that
targeted pelvic floor physical therapy can improve bladder pain symptoms and can reduce
general pelvic floor sensitivity.9,16 In contrast, we found localized mechanical hyperalgesia
during palpation or vaginal pressure pain thresholds predicted bladder distension pain and
sensation, but only at the bladder site. We can thus conclude that somatovisceral
convergence is not a major contributor to bladder filling pain, yet pelvic floor dysfunction
could still incrementally influence inputs into brainstem descending inhibition and increase
overall bladder pain symptomatology.17 Since as many as 43% of patients do not
significantly respond to manual therapy, and questionnaire based studies are vulnerable to
somatization, quantitative sensory evaluation of the bladder and pelvic floor may be
necessary to elucidate the mechanisms modifiable through physical therapy. One likely
possibility is that PBS represents heterogeneous groupings of patients, some with
predominantly pelvic floor dysfunction, others mainly expressing dysfunctions in central
pain processing, and still others exhibiting predominantly pure bladder mechanical
hyperalgesia.18 A factorial approach to unpackaging pain mechanisms has been used to
identify patients with diabetic neuropathy that respond to duloxetine, a drug also used off-
label to treat PBS.19
Strengths
Several strengths of our study support diuresis-provoked bladder testing as a valid visceral
sensitivity task. First, we controlled for sociodemographic features within a reproductive age
cohort on bladder distension pain and found no influence. Our extensive demographic
characterization, including medical comorbidities (endometriosis, dysmenorrhea,
fibromyalgia, abuse exposure) will allow future studies to contrast their findings using these
parameters, as our sample is typical of a referral population of significantly distressed
women. Second, we controlled for potential psychological confounders with standardized
patient reported outcomes instruments, as studies of rectal distension have implied that
heightened sensation is entirely mediated by anxiety or somatization.20,21 This allowed us to
show that bladder distension pain may be a less biased outcome measure, perhaps reflecting
the lack of perceived threat (no catheter or manometry balloon insertion) presented by a
noninvasive test. Since self-reported symptom indices are vulnerable to somatization and
psychological factors, complete phenotypic assessment of pain states ideally includes
symptom-based and unbiased experimental visceral pain assessment.8,22,23 Third, we used a
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positive control group without significant bladder symptoms to untangle potential pain and
urgency relationships on visceral pain sensitivity.
Limitations
The primary limitation of a naturalistic study is the inability to precisely control the
experimental stimulus. However, when we controlled for estimated filling rates, we found no
difference between diagnostic groups, and likewise no relationship to distension provoked
pain. Although impairments in compliance accounting for limitations in maximal capacity
are not associated with PBS, future studies using ultrasonographic elastography could
confirm this non-invasively.24,25 We acknowledge this is a modest sized study, but we were
adequately powered for our primary contrasts. Future replication of our results in larger
cohorts is obviously needed.
Interpretation
How should we investigate the utility of distension-mediated pain as a risk marker for future
PBS? We are still quite far from understanding the trajectory that leads from asymptomatic
bladder sensitivity to overt bladder pain symptoms. Large scale studies, like the ongoing
National Institutes of Health-funded Multidisciplinary Approach to Pelvic Pain network and
its predecessors, have not longitudinally characterized the changes in visceral pain
sensitivity in healthy participants, perhaps since catheterization elicits more apprehension
and pain particularly in younger populations.26,27 Our tool could be used to follow the
transition to chronic bladder pain if employed following cases of acute cystitis, focusing
selectively on patients exhibiting generalized somatic symptoms. Given that a key role has
been identified for somatization in temporomandibular joint disorder risk in a large-scale
longitudinal study, assessing visceral sensitivity and somatization simultaneously could be
quite enlightening.28
Conclusion
We show preliminary validity for diuresis-induced bladder pain as a visceral pain measure
reflecting local mechanical sensitivity. As an assessment tool for mechanism-based study of
CPP states, it may be less influenced by psychological factors than patient-reported
outcomes. The benefit of our visceral distension measure remains to be fully appreciated, as
this task can be studied in ambulatory settings, may be a marker for the emergence of PBS,
and potentially could be comingled with other therapeutic trials as an objective marker of
disease change following treatment.
Supplementary Material
Refer to Web version on PubMed Central for supplementary material.
Acknowledgments
We thank Dr.’s Daniel Clauw, Adam Gafni-Kane, Joel Greenspan, and James W. Griffith for valuable comments on
our manuscript.
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Funding: F.F.T. was supported by NIH grant K23HD054645, K.M.H. was supported by a Research Career
Development Award from the NorthShore University HealthSystem Research Institute, Evanston, IL. The content is
solely the responsibility of the authors and does not necessarily represent the official views of the National
Institutes of Health
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Figure 1.
Time course of provoked diuresis and evoked bladder pain by pain diagnostic category.
Panel A: The median volume and time are shown for first sensation (S), first desire (D), and
maximal capacity (M) for each of the 3 groups with error bars indicating 25–75th
percentiles. Panel B shows the relationship between volume and pain. C and D show
evolution of reported bladder and urgency (VAS 0–10) obtained every 15 minutes regardless
of cystometric thresholds.
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Figure 2.
Stacked bar chart of standardized relative severity of bladder pain, bladder capacity and
somatic complaint, individual level data. Results scaled for estimated frequency of CPP and
PBS in the general population (e.g. 0 = mean, 1 = 1 standard deviation higher than the
general population). A–C: Scores of individual participants were z-scored to represent the
prevalence using weighted-average scaling assuming 11% CPP only and 4% CPP with
PBS.29,30 Each bar represents a single subject. The total height or depth of the bar represents
the number of standard deviations above or below the population average. D: ROC curve for
using these three parameters to predict an ICSI score ≥6.
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Table 1
Sociodemographic and medical history profiles between controls and women with chronic pelvic pain (CPP) or painful bladder syndrome (PBS).
Variable Controls
n=42 CPP
n=23 p for
CPP
vs
Control
PBS
n=23 p for
PBS
vs
Control
p for
PBS
vs
CPP
Age 32 (23–44) 35 (29–44) .279 31 (27–39) .694 .185
Weight (lb) 146 (127–192) 170 (140–199) .244 145 (128–183) .814 .390
Married/Committed 20/42 (48%) 15/23 (65%) .519 14/23 (61%) .31 .999
Caucasian 30/41 (73%) 15/23 (65%) .999 21/23 (91%) .219 .096
Parous 12/42 (29%) 10/23 (43%) .684 11/23 (48%) .369 .999
UW Bladder 0 (0–2) 11 (4.5–17) .001 22 (19–31)
*
.001 .025
UW Reference 2 (0–5) 6.5 (3–19) .001 21 (4–30.5) .001 .468
ICSI 2 (1–3) 7 (3–9) .001 13 (10–14)
*
.001 .007
ICPI 0 (0–0) 4 (2–10) .001 11 (9–13)
*
.001 .007
Voids per day 7 (5–8) 9 (6–12) .030 10 (7–14) .011 .702
History of abuse 6/42 (14%) 12/23 (52%) .003 15/23 (65%) .003 .999
Dysmenorrhea 15/35 (43%) 14/15 (93%) .003 18/19 (95%) .003 .999
Endometriosis 0/42 (0%) 5/23 (22%) .003 8/23 (35%) .003 .972
Fibromyalgia 0/42 (0%) 3/23 (13%) .033 2/23 (9%) .117 .999
Irritable bowel syndrome 1/42 (2%) 3/23 (13%) .285 9/23 (39%) .003 .112
Pelvic pain (VAS 10 cm) 0 (0–0) 4.1 (2.7–6.5) .001 6.2 (3.4–7.2) .001 .554
Days in bed (last 3 months) - 4 (0–30) - 5 (0–20) - .423
Pain duration (years) - 3 (2–18) - 3.6 (1.4–9.5) - .151
CES-D score 2 (0–4) 13 (3–21) .001 15 (8–23) .001 .191
STAI score 27 (24–32) 38 (29–48) .001 43 (36–50) .001 .118
SF12 Physical Component 56 (56–59) 42 (31– 51) .001 37 (27–47) .001 .339
SF12 Mental Component 55 (49–57) 46 (36–55) .001 42 (35–51) .001 .578
Data are specified as median (interquartile range), or as a proportion (percent) for each group. Significance of exploratory analysis differences pain groups vs. pain free groups using a Dunn test with a
Holm-Sidak correction or a chi square with a Bonferroni correction.
*
differences between pain groups p < 0.05. As an exploratory analysis for potential group differences, reported significance should not be construed as formal hypothesis tests.
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UW – University of Wisconsin Symptom Scale, ICSI/ICPI – Interstitial Cystitis Symptom Index/Problem Index, CESD - Center for Epidemiologic Studies Depression survey, STAI -State-Trait Anxiety
Inventory, VAS – Visual Analog Scale, SF12- Short Form 12 Health Survey.
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Table 2
Spearman correlations of factors affecting bladder sensitivity, volume, and the Interstitial Cystitis Symptom Index (ICSI).
Bladder Pain Bladder Volume ICSI
First
sensation First
desire Maximal
capacity First
sensation First
desire Maximal
capacity
ICSI 0.54
*
0.53
*
0.56
*
−0.28 −0.34 −0.44
*
Pressure Sensitivity
Right PPT −0.30 −0.18 −0.19 0.00 −0.02 0.03 −0.21
Left PPT −0.26 −0.15 −0.16 0.14 0.06 0.09 −0.17
Bowel PPT −0.23 −0.16 −0.21 0.02 −0.05 0.01 −0.27
Bladder PPT −0.46
*
−0.32 −0.37 0.07 0.03 0.06 −0.32
Body PPT −0.18 −0.18 −0.13 0.15 0.13 0.09 −0.10
Pain Report
Aftersensation 0.55
*
0.50
*
0.51
*
−0.32 −0.39
*
−0.40
*
0.49
*
Bladder Palpation 0.56
*
0.51
*
0.55
*
−0.01 −0.10 −0.17 0.60
*
Psychological
Somatic Symptoms 0.40
*
0.36 0.35 −0.13 −0.13 −0.18 0.59
*
Depression 0.48
*
0.43
*
0.42
*
−0.14 −0.14 −0.17 0.49
*
Anxiety 0.40
*
0.35 0.37 −0.13 −0.21 −0.19 0.50
*
*
designates p<0.05 after Holm-Sidak corrections for multiple comparisons.
PPT – pelvic floor pain thresholds
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