Psychosocial and Sensory Factors Contribute to Self-Reported Pain and Quality of Life in Young Adults with Irritable Bowel Syndrome

Abstract

Purpose:

Psychosocial and sensory factors including anxiety, depression, and pressure pain threshold have been used to cluster chronic symptoms in irritable bowel syndrome (IBS). However, little is known about the contribution of psychosocial sensory factors on pain interference and quality of life (QOL) in this population.

Design:

We performed a cross-sectional analysis of baseline data from a randomized controlled trial.

Sample:

Eighty young adults with IBS aged 21 ± 2.57 years (76.25% female).

Methods:

Demographic and psychosocial factors including anxiety, depression, fatigue, cognition/general concerns, sleep disturbance, self-efficacy, coping, and food intake were measured as independent variables. Quantitative sensory testing (QST) was conducted to measure mechanical, thermal, and pressure pain thresholds. Self-reported pain measured by the brief pain inventory (BPI) and IBS-QOL were assessed as the outcome variables. Regression analysis and mediation analysis were conducted to determine the associated factors of IBS pain and QOL.

Results:

Age, sex, and psychosocial factors including coping, self-efficacy, alcohol intake, mechanical pain sensitivity, and cold pain threshold were significantly associated with pain interference (all p < 0.05). Coping, and self-efficacy were significantly associated with IBS-QOL (all p < 0.05). In the mediation analysis, coping catastrophizing and self-efficacy were indirectly associated with IBS-QOL mediated by fatigue.

Conclusions:

Psychosocial factors including coping and self-efficacy, and QST factors significantly correlate with self-reported pain and QOL among young adults with IBS. This preliminary research calls for further interventional studies that target personalized psychosocial and quantitative sensory factors to improve pain management and quality of life in IBS patients.

Introduction

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder considered a medical challenge in the 21^st century (Ford et al., 2020; Ikechi et al., 2017). IBS with a prevalence of 10–15% is responsible for 3.1 million annual ambulatory office visits in the USA which results in a direct cost of $20 billion (Ikechi et al., 2017; van Tilburg et al., 2013). Intense, recurrent abdominal (visceral) pain is the predominant symptom of IBS and the leading cause of patient visits to a gastrointestinal specialist (Lacy et al., 2015). Individuals with IBS report that pain is the most distressing symptom and has the greatest impact on the quality of life (QOL) (Lacy et al., 2015). Despite the enormous burden to the healthcare system and distress to patients, IBS-related visceral pain and QOL remain unsatisfactorily managed, especially by conventional pharmacological approaches.

It has been documented in the literature that sex and age are the two major sociodemographic factors that play significant roles in the onset or severity of IBS pain and related outcomes. Although some studies (Chang & Heitkemper, 2002; Heitkemper et al., 2003) showed no sex effects on IBS pain severity, in a systematic review and meta-analysis on 22 studies concerning sex differences in IBS symptoms, women reported more severe abdominal pain with a higher incidence than men in age-matched groups (Y. S. Kim & Kim, 2018). Across different age groups, both younger women and men report more severe IBS-related pain compared to older adults (Tang et al., 2012a). In general, a higher rate of abdominal pain has been observed among younger people compared to older individuals (Kosako et al., 2018).

Abdominal pain has a profound negative impact on QOL in IBS patients. A negative correlation between abdominal pain and IBS-QOL had been found both in men and women (Choghakhori et al., 2017). In addition, IBS pain and QOL correlate with several psychosocial factors including anxiety, depression, and sleep disturbance. There is significant comorbidity of depression and sleep disturbance among IBS patients (Farup & Hestad, 2015; Ford & Cooper-Patrick, 2001). Sleep disturbance was found to be significantly correlated with worse IBS pain, higher mood disorder, and lower QOL, and the connection between sleep disturbance and IBS pain symptoms was partly mediated by mood disorder (Cho et al., 2011; Patel et al., 2016). Anxiety and depression, psychological disorders that are more common among females, and negatively affect QOL in female IBS patients (Tang et al., 2012a; Tang et al., 2012b).

The perception and processing of IBS-related pain are highly individualized. Heightened perception of visceral pain in IBS patients is likely caused by sensitization of the nervous system, including central and peripheral sensation as well as mechanisms engaged within the bowel (Camilleri et al., 2012; Wong et al., 2016). While it is unclear how abnormal pain signaling along the pain processing pathway contributes to IBS pain burden, approximately half of all patients with IBS have visceral hypersensitivity and report distress and pain during normal bowel functions (Frissora & Koch, 2005; Kanazawa et al., 2011; Whitehead et al., 2002). These alterations in pain processing escalate pain perception and can increase vulnerability to other comorbid pain disorders which individuals with IBS frequently suffer, e.g., fibromyalgia, migraine, and interstitial cystitis (Frissora & Koch, 2005; Whitehead et al., 2002).

A previous study also reported that patients with somatic disorders and chronic pain had distinguished quantitative sensory testing (QST) profiles including mechanical hyperalgesia and thermal hypothiesm compared with healthy control (Achenbach et al., 2020). Another study reported that anxiety, depression, pressure pain threshold, and somatization could be used as phenotype algorithm indicators to cluster chronic pain patients including individuals afflicted by IBS (Gaynor et al., 2021). However, a comprehensive QST profile for IBS, including thermal and mechanical pain threshold was not reported.

Although several neuro-psychosocial underlying factors have been suggested to contribute to the development and intensity of IBS pain and related symptoms, further studies are required to quantitatively determine the underlying mechanisms associated with IBS symptoms and guide precise management. To that end, this study systematically investigated the contribution of psychosocial and sensory factors on pain and QOL among young adults with IBS.

Methods

Study Design

A descriptive correlational study design was used to analyze the baseline data from a randomized controlled trial (RCT; NCT03332537). The parent RCT was designed to examine the effects of a precision IBS-pain Self-Management intervention plus nurse-led support on IBS self-management behaviors and related health outcomes (Cong et al., 2018).

Study Setting

The study participants were recruited and enrolled from two gastrointestinal (GI) clinics, general communities, as well as two large campuses of a public university in the Northeastern United States. The data collection was conducted in the biobehavioral labs on two university campuses.

Participants

In order to participate in the study, volunteers must have received a diagnosis of IBS from a healthcare provider and daily access to a computer with an internet connection. Inclusion criteria: a) Men and women 18 – 29 years of age; b) Diagnosis of IBS from a healthcare provider with a current report of pain (volunteers asked to bring provider-verification of IBS diagnosis based on Rome-III criteria to initial study appointment); c) Able to read and speak English; and d) Daily access to a computer connected to the internet. Exclusion criteria: a) Other chronic painful conditions including but not limited to fibromyalgia, chronic pelvic pain, or chronic interstitial cystitis; b) Infectious diseases (hepatitis, HIV, MRSA); c) Celiac disease or inflammatory bowel disease; d) Diabetes mellitus; e) Serious mental health conditions (e.g., bipolar disorder, schizophrenia, and mania); f) Women during pregnancy or within 3 months postpartum period; g) Regular use of opioids, iron supplements, prebiotics/probiotics or antibiotics; or substance abuse; and h) Injury to non-dominant hand or presence of open skin lesions, disturbed sensation, carpal tunnel syndrome or rash. The rationale for these exclusion criteria was to control for factors that could be correlated to pain sensitivity and genetic and genomic attributes and IBS-related health outcomes. Eighty male and female young adults were recruited in the original study.

Study Measures

All study measurements were collected and managed using the university Research Electronic Data Capture (REDCap) system. The REDCap application was used to capture data, validate data entry, track data manipulation, and export procedures.

Demographics characteristics:

These include age, sex, race, ethnicity, education level, and other factors. A demographics form recommended by the National Institute of Nursing Research (NINR) common data elements (CDEs) was used to measure these variables.

Psychosocial factors:

These factors were measured by questionnaires from the NINR CDEs (https://cde.nlm.nih.gov/cde/search?selectedOrg=NINR), Coping Strategies Questionnaire-Revised (CSQ-R), and Food Frequency Questionnaire (FFQ).

The NINR CDEs including Patient-Reported Outcomes Measurement Information System (PROMIS®) and self-management questionnaires were used in this study. The PROMIS® measuring for Anxiety, Depression, Fatigue, Sleep disturbance, and Cognition-general concerns were used in the study. The T-scores of PROMIS measures were calculated following the NIH instruction, with a range of 0 to 100. A T-score greater than 50 indicates that the participant perceived a higher level of the symptom than the reference population (usually the U.S. general population) for each of the aforementioned 5 symptoms, therefore a higher T-score indicates a worse symptom experienced by the participant (Cong et al., 2018). Self-management questionnaires include the 6-item Self-Efficacy for Managing Chronic Disease (SEMCD) (Lorig et al., 2001) and the 9-item Index of Self-Regulation (ISR) (Yeom et al., 2011). Items of SEMCD were rated on a numerical scale from 1 (not confident at all) to 10 (totally confident). The total score of the SEMCD was calculated as the mean score of the 6 items ranging from 1 to 10, with a higher score indicating better self-efficacy. The total ISR score also used the mean of each items, ranging from 1 to 6, with a higher score indicating greater self-regulation (Yeom et al., 2011).

The Coping Strategies Questionnaire-Revised (CSQ-R) is a 27-item self-report questionnaire designed to assess 6 cognitive coping responses to pain (Robinson et al., 1997). Subjects rate the frequency of using each coping strategy and perceived control over their pain on a 7-point Likert-type scale, from “never do that” to “always do that”, scoring from 1 to 7, respectively (Robinson et al., 1997). The subscales of CSQ-R have shown adequate internal consistency with Cronbach’s alpha ranging from 0.72 to 0.91 (Hastie et al., 2004), and stable factor structure in patients with chronic pain and healthy populations (Hastie et al., 2004; Riley & Robinson, 1997). A higher score in each of the CSQ-R subscales indicates that the relevant coping strategies were applied more frequently by the participants.

The self-reported Food Frequency Questionnaire (FFQ) was used to measure the type and quantity of food intake (Kristal et al., 1997). The reliability of the FFQ was established by the National Health and Nutrition Examination Survey (NHANES II) (Hu et al., 1999). In the Women’s Health Initiative study, the test-retest reliability of the nutrient intake estimates from the FFQ was reported as high with intra-class correlation coefficients ranging from 0.67 to 0.92 (Patterson et al., 1999). A higher number in each of the measures means a higher intake of the nutrition elements.

Quantitative Sensory Measurement:

Quantitative sensory testing (QST) was implemented to measure pain sensitivity by applying standardized nociceptive and nonnociceptive stimuli on the medial side of the subject’s non-dominant arm, which allowed quantitative assessment of the peripheral and central sensory neural pathways (Rolke et al., 2006; Verdugo & Ochoa, 1992). A standardized QST testing protocol reported by our team (Starkweather et al., 2016) was followed, including examination room conditions and instructions provided for the patient. Designed to quantify thirteen functional sensory pathways, our QST protocol consists of seven tests to cover three categories of pain in the following order: cutaneous mechanical pain, thermal pain, and deep pressure pain. Details of the protocol were reported by us previously (Starkweather et al., 2016). Briefly, mechanical pain sensitivity was assessed by determining the mechanical detection threshold (MDT), mechanical pain threshold (MPT), mechanical pain sensitivity (MPS), and wind-up ratio (WUR) to mechanical probing of the subject’s medial forearm skin with a standard set of von Frey-like monofilaments (Optihair₂-Set, Marstock Nervtest, Germany). The round-tipped monofilaments of 0.5mm in diameter exert standardized forces of 0.25 to 512 millinewton (mN) against the participant’s skin. Dynamic mechanical allodynia (ALL) was tested by applying three-light tactile stimuli to the subject’s medial forearm skin using a standardized brush (cleaned with antiseptic toilette between testing) that generates ascending levels of tactile stimuli. Vibration detection threshold (VDT) was tested by placing a Rydel-Seiffer tuning fork (64 Hz, 8/8 scale) on the skin surface while asking the participants if they perceive the vibration and then counting the number of seconds until vibration was no longer detected. Thermal testing was performed using the Medoc Pathway System^™ (Medoc Ltd., Ramat Yishai, Israel). Thermal pain sensitivity was assessed using the following end-points: cold detection threshold (CDT), warm detection threshold (WDT), cold pain threshold (CPT), and heat pain threshold (HPT). The mean threshold temperature of three consecutive measurements was calculated and used for analysis. Pressure pain threshold was assessed using a Medoc algometer (Medoc Ltd., Ramat Yishai, Israel) with manually applied ascending pressure from 50 up to 600 kPa, with the mean calculated from three consecutive measurements.

Brief Pain Inventory (BPI):

The BPI was used in the study to measure two domains of pain, pain severity and pain interference (Keller et al., 2004). The measure of pain severity includes self-reported worst and least pain in the last 24 hours, the average pain, and pain at the time of completing the BPI. Pain interference indicates the impact of pain on physiological functions and was calculated as the mean of the 7 items. Cronbach’s alpha reliability of the BPI ranges from 0.77 to 0.91.

IBS-Quality of Life (IBS-QOL) Questionnaire:

The IBS-QOL instrument consists of 34 self-report items and was specifically designed to assess QOL in IBS populations (Hahn et al., 1997). A five-point Likert scale (0 to 4) is used to measure the perception of respondents regarding the impact of IBS on daily function. The total scores are calculated as the sum of all item scores and higher scores indicate better QOL. The IBS-QOL instrument is reliable (Cronbach’s alpha, 0.94) and valid and has high reproducibility (ICC = 0.93, p < 0.001).

Data Collection Procedures

The study protocol was approved by the University of Connecticut Institutional Review Board (IRB) and affiliated study settings. Recruitment took place through advertisements in local newspapers and transportation vehicles, general flyers in clinics and hospitals, communities, public places, major local university campuses, and email invitations at major campuses, which instructed potential participants to call a research-designated phone line. Those who responded and were eligible for the study were scheduled for an initial baseline appointment. Data collection took place in one of the private research bio-behavioral laboratories on the university campus.

Data Analysis

Statistical data analysis was performed by customized programming in R 3.5.1. Categorical variables in the questionnaires and demographics were calculated as proportions, while continuous variables including age and year of IBS diagnosis were calculated for average, standard deviation, and range. Demographic factors, psychosocial factors (PROMIS measurements, SEMCD, ISR, CSQ-R, and FFQ), and QST measurements were defined as independent variables to determine their relationships with IBS pain and QOL. Since the data included a large number of independent variables, we first conducted variable selection controlling for demographic variables based on the least absolute shrinkage and selection operator (LASSO) method using the ‘glmnet’ package in R (Tibshirani, 1996). After that, Linear regression models were implemented with the selected independent variables. We considered IBS pain and QOL as response variables. Moreover, we implemented the mediation analysis with the selected independent variables. We considered SEMCD, CRQ-R, and QST as mediators transmitting the effect of PROMIS variables on QOL. To test the statistical significance of the direct and indirect effects, we constructed 95% confidence intervals (CI) using the bootstrap algorithm with 1,000 iterations using the ‘lavaan’ package in R (Rosseel, 2012).

Results

Demographic Characteristics of the IBS subjects

A total of 80 young adults diagnosed with IBS were analyzed in the study (Table 1). The majority of participants were non-Hispanic (85.00%), White (77.50%) female (76.25%) college students, with an average age of 21 ± 2.57 years old. Participants had a diagnose of IBS for an average of 3.6 ± 3.02 years (range 0 to 13 years) and 31.3% of the participants had a family history of IBS.

Table 1.

Demographic information of the participants (N=80)

Demographic	n	Percent (%)
Gender
Female	61	76.250 (%)
Male	19	23.750 (%)
Race
White	62	77.500 (%)
Asian	10	12.500 (%)
Black or African-American	8	10.000 (%)
Ethnicity
Not Hispanic or Latino	68	85.000 (%)
Hispanic or Latino	7	8.750 (%)
Not reported	5	6.250 (%)
Education
High school or lower	7	8.750 (%)
Some college or associate degree	46	57.500 (%)
Bachelor degree	13	16.250 (%)
Graduate or Doctorate degree	14	17.500 (%)
Caregiver Primary Type
Parent or legal guardian	39	48.750(%)
Self	40	50.000(%)
Spouse or Partner	1	1.250(%)
Employment Status
Student	57	71.250(%)
Working now	20	25.000(%)
Looking for work, Unemployed	3	3.750(%)
Marital Status
Never married	77	96.250(%)
Married	3	3.750(%)
Family member with IBS
No	55	68.750(%)
Yes	25	31.250(%)
	Mean (SD)	Range
Age	21.387 (2.573)	18 – 28
Year of IBS diagnosis	3.112 (3.019)	0 – 13

Psychosocial Characteristics of the IBS subjects

Table 2 shows psychosocial characteristics of the IBS subjects including PROMIS T-scores, scores of self-efficacy for managing chronic disease and index of self-regulation measurements, scores of CSQ-R, and food intake categories. IBS participants reported significantly higher anxiety T-scores (60.0 ± 8.8) and lower cognition/general concerns T-scores (36.0 ± 7.2) compared to the normative reference scores (T-score Maps are available at http://www.healthmeasures.net/score-and-interpret/interpret-scores/promis/t-score-maps). The overall Indices of self-regulation (ISR) and self-efficacy for managing chronic disease were within the fair category, with an average score of 4.5 (±1.2) of 6 and 7.2 (±1.9) of 10 respectively. Results from the CSQ-R questionnaire show that the Positive Coping Self-statement (4.9 ± 1.2) was the most commonly used coping strategy among this IBS group. Other strategies used include ignoring sensation, distraction, praying, catastrophizing, and distancing from pain. Food intake measurements including energy, protein, fat, cholesterol, and carbohydrate are also summarized in Table 2.

Table 2.

Psychosocial Characteristics of the participants (N = 80)

	Mean	SD	Range
PROMIS®
Emotional Distress - Anxiety	59.975	8.786	39.100 – 82.400
Emotional Distress - Depression	51.251	8.914	38.400 – 66.900
Fatigue	55.246	8.169	33.400 – 71.000
Sleep Disturbance	51.153	7.825	31.700 – 70.100
Cognition – General Concerns	35.959	7.155	24.800 – 49.200
SEMCD	6.619	1.889	2 – 8
ISR	4.517	1.137	1.889 – 6.000
CSQ-R
Coping Self Statement	4.922	1.233	1.000 – 7.000
Coping Ignoring Sensation	3.665	1.561	1.000 – 7.000
Coping Distraction	3.425	1.551	1.000 – 6.400
Coping Praying	2.908	2.105	1.000 – 7.000
Coping Catastrophizing	2.602	1.269	1.000 – 7.000
Coping Distancing	1.994	1.400	1.000 – 6.000
FFQ
Food energy (kcal)	1651.647	690.540	389.620 – 3659.700
Protein (g)	75.211	39.227	16.310 – 213.250
Total fat (g)	58.424	27.177	6.830 – 132.920
Saturated fat (g)	18.683	8.994	1.600 – 45.220
Monounsaturated fat (g)	22.802	10.919	1.850 – 51.180
Polyunsaturated fat (g)	12.057	6.294	2.360 – 29.770
Cholesterol (mg)	237.479	129.293	3.900 – 578.950
Carbohydrate (g)	208.087	85.323	31.050 – 434.100
Dietary fiber (g)	21.795	11.126	4.250 – 74.800
Alcohol (g)	5.331	5.002	0.000 – 18.010
Amount of food (grams)	1996.650	861.805	320.230 – 4766.150
Total number of grain servings	5.341	2.856	0.67 – 14.37
Total number of dairy servings	1.181	0.938	0.01 – 4.74
Total drinks of alcohol	0.387	0.366	0.00 – 1.32
Total Dietary Fiber (g)	22.129	11.240	4.61 – 75.54
Insoluble Dietary Fiber (g)	15.067	7.986	3.08 – 52.78
Soluble Dietary Fiber (g)	6.946	3.428	1.51 – 22.43
Total Trans fatty acids (g)	4.054	2.229	0.46 – 9.86
Glycemic load	98.816	41.787	13.77 – 205.79

Note: CSQ-R, Coping Strategies Questionnaire-Revised; FFQ, food frequency questionnaire; ISR, Index of Self-Regulation; PROMIS, Patient-Reported Outcomes Measurement Information System; SEMCD, Self-Efficacy for Managing Chronic Disease

Quantitative Sensory Test

The QST results are summarized in Table 3. The average MDT and MPT were 3.053 (± 0.222) mN and 6.199 (± 0.469) mN, respectively. The average VDT was 11.259 (± 4.186) seconds. The average CDT, WDT, CPT, and HPT were 29.131 (± 1.287), 34.853 (± 1.114), 18.277 (± 8.612), and 40.5 (± 2.896) °C. The average PPT was 234.433 (± 110.967) kPa.

Table 3.

Quantitative Sensory Testing (QST) Measurements of the participants (N = 80)

	Mean	SD	Range
Mechanical detection threshold (MDT), mN	3.053	0.222	2.830 – 3.637
Mechanical pain threshold (MPT), mN	6.199	0.469	5.220 – 6.650
Mechanical pain sensitivity (MPS) (NRS, 0–10)	1.948	1.593	0.000 – 6.333
Wind-up ratio (WUR)	1.353	1.008	0.341 – 6.667
Dynamic mechanical allodynia (ALL)	0.683	1.192	0.000 – 7.667
Vibration detection threshold (VDT), s	11.259	4.186	4.717 – 34.450
Cold detection threshold (CDT), °C	29.131	1.287	25.800 – 31.300
Warm detection threshold (WDT), °C	34.863	1.114	33.167 – 38.200
Cold pain threshold (CPT), °C	18.277	8.612	0.000 – 29.833
Heat pain threshold (HPT), °C	40.500	2.896	35.000 – 46.667
Pressure pain threshold (PPT), kPa	234.433	110.967	75.800 – 601.000

Note: mN, millinewton.

The wind-up ratio (WUR) is the average ratings of 3 higher stimuli (N2) normalized by the average rating of 3-initial stimulus (N1). In case that all N1 are zero, we added 0.1 to N1 to avoid dividing N2 by zero.

Self-reported pain and QOL

Participants’ self-reported pain severity, pain interference, and IBS-QOL are summarized in Table 4. On a scale of 0 to 10, mean worst pain and average pain were 3.232 (± 2.123) and 2.429 (± 1.65), respectively, whereas mean pain interference was 1.258 (± 1.556). The mean score of pain interference sub-scales ranged from 1.400 (relationship with other people) to 3.513 (sleep). The mean score of IBS-QOL was 25.315 (± 21.156), the mean scores in subscales ranged from 16.220 (relationship) to 53.125 (food avoidance).

Table 4.

Brief Pain Inventory (BPI) Measurement and IBS Quality of Life (IBS-QOL) Measurements (N = 80)

	Mean	SD	Range
BPI pain severity
Worst Pain	3.232	2.123	0 – 9
Average Pain	2.429	1.650	0 – 8
Right Now Pain	1.411	1.693	0 – 7
Least Pain	0.625	1.259	0 −7
BPI Pain Interference	1.258	1.556	0.000 – 8.286
Mood	3.513	2.531	0 – 10
Sleep	2.600	2.858	0 – 10
Enjoyment of life	2.413	2.618	0 – 10
General activity	2.113	2.228	0 – 8
Normal work	1.700	2.236	0 – 9
Walking ability	1.500	2.158	0 – 8
Relationship with other people	1.400	2.374	0 – 10
IBS-QOL: total score	65.938	20.981	4.412 – 97.059
IBS-QOL Subscales
Dysphoria	70.977	25.242	6.250 – 100
Interference with activity	65.580	25.287	3.571 – 100
Body image	62.422	25.305	0 – 100
Health worry	62.188	22.500	0 – 100
Food avoidance	40.938	31.550	0 – 100
Social reaction	66.250	25.071	0 – 100
Sexual	79.531	28.285	0 – 100
Relationship	77.292	21.461	8.333 – 100

Factors contributing to IBS Pain and QOL

In the regression analysis, multiple factors including age, sex, coping-catastrophizing, self-efficacy, alcohol intake, QST-MPS, and QST-CPT were significantly associated with pain interference (all p < 0.05, Table 5). Factors of coping-catastrophizing and self-efficacy were significantly associated with IBS-QOL (all p < 0.05), but not fatigue (p = 0.173, Table 6). The indirect effects of Fatigue on IBS-QOL passing through coping-catastrophizing (95% CI: −0.644, −0.063) and self-efficacy (95% CI: −0.641, −0.017) were statistically significant in the mediation analysis. Fatigue is positively associated with coping-catastrophizing, while coping-catastrophizing is negatively associated with IBS-QOL. We also observe that Fatigue is negatively correlated with self-efficacy, whereas self-efficacy is positively correlated with IBS-QOL. The total effect of Fatigue on IBS-QOL (95% CI: −1.465, −0.552) was statistically significant indicating a higher T-score of fatigue to be associated with lower QOL (Figure 1 and Supplementary Table 1).

Table 5.

Psychosocial and Quantitative Sensory Factors Contributing to Pain Interference (N=80)

Dependent variable	Independent variable	Estimate	Standard Error	t value	p value
Pain Interference (R-squared: 0.696)
	Age	−0.238	0.087	−2.742	0.008 **
	Female	−0.558	0.372	2.198	0.032 *
	Race: White	0.366	0.340	−1.645	0.105
	Ethnicity Not Hispanic or Latino	0.402	0.387	0.946	0.348
	Education: Bachelor or higher	−0.036	0.423	0.951	0.345
	Caregiver: Self	−0.067	0.331	−0.110	0.913
	Employment: Student	−0.558	0.337	−0.199	0.843
	Year of IBS diagnosis	−0.074	0.048	−1.528	0.132
	Coping distancing	0.174	0.116	1.501	0.138
	Coping catastrophizing	0.552	0.160	3.439	0.001**
	SEMCD	−0.282	0.098	−2.865	0.006**
	Alcohol	0.082	0.028	2.910	0.005**
	Number of grain serving	−0.084	0.047	−1.776	0.081
	QST MPS	0.279	0.093	3.006	0.004**
	QST CDT	−0.204	0.118	−1.727	0.089
	QST CPT	−0.035	0.018	−2.020	0.048*

Note: SEMCD, Self-Efficacy for Managing Chronic Disease; QST, Quantitative Sensory Testing; MPS, Mechanical pain sensitivity; CDT, Cold detection threshold; CPT, Cold pain threshold

^*p value < 0.05;

^**p value < 0.01.

Table 6.

Psychosocial and Quantitative Sensory Factors Contributing to IBS-QOL (N=80)

Dependent variable	Independent variable	Estimate	Standard Error	t value	p value
QOL (R-squared: 0.645)
	Age	0.307	0.969	0.316	0.753
	Female	−6.041	3.829	−1.578	0.119
	Race: White	−6.035	4.204	−1.436	0.156
	Ethnicity: Not Hispanic
	or Latino	−8.533	4.548	−1.876	0.065
	Education: Bachelor or
	higher	2.925	4.651	0.629	0.532
	Caregiver: Self	1.599	3.916	0.408	0.684
	Employment: Student	3.079	3.999	0.770	0.444
	Fatigue	−0.303	0.220	−1.378	0.173
	Coping praying	−1.590	1.029	−1.546	0.127
	Coping catastrophizing	−6.529	1.982	−3.294	0.002**
	SEMCD	2.811	1.161	2.421	0.018*
	QST VDT	0.567	0.394	1.439	0.155

Note: SEMCD, Self-Efficacy for Managing Chronic Disease; QST, Quantitative Sensory Testing; VDT, vibration detection threshold

^*p value < 0.05;

^**p value < 0.01.

Fig 1.

Direct and Indirect Effect of Psychosocial Factors on QOL in Young Adults with IBS by Mediation Analysis

SEMCD, Self-Efficacy for Managing Chronic Disease

Discussion

The current study aimed to explore the contributing factors of self-reported pain and QOL in IBS young adults. We observed that IBS pain and QOL were influenced by various factors including demographics (age and year of IBS diagnosis), psychological factors (sleep disturbance, fatigue, self-efficacy, and coping strategy), and pain sensitivity. In addition, pain appeared to be the dominant factor causing reduced QOL in IBS patients.

Associations of sex and age with IBS pain

In the current study, we found that female participants were more likely to report pain than their male counterparts, which is consistent with prior studies (Adeyemo et al., 2010; Chang & Heitkemper, 2002), except for one study that reported comparable levels of abdominal pain between women and men (Lee et al., 2001). The sex difference in pain perception is likely caused by the different levels of sex hormones that play substantial roles in activating the antinociceptive systems, the difference in illness behavior, and differential response bias toward potentially nociceptive stimuli between women and men (Canavan et al., 2014; Lee et al., 2001). Regarding the factor of age in IBS pain, our current study indicated a negative correlation between age and pain interference despite a narrow range of age in our young participant sample. Our results are consistent with a prior report, which showed that older IBS participants reported milder abdominal pain than the younger group (Canavan et al., 2014). This suggests variability in IBS pain over the lifespan that can attenuate with aging.

Associations of psychosocial factors with IBS pain

The current study indicated that poor self-efficacy and coping were associated with increased pain, which is consistent with previous studies (Dąbek-Drobny et al., 2020; Endo et al., 2011). Participants with reduced self-efficacy and coping reported greater pain severity which was partially explained by their tendency to engage in more catastrophic thinking specific to pain. Reduced psychological well-being was previously found to be associated with reduced self-efficacy and using the maladaptive coping strategy (Knowles et al., 2017; Torkzadeh et al., 2019), and the connection between IBS symptoms and depression were shown to be partly mediated by catastrophizing (Lackner et al., 2004). In addition, reduced self-efficacy and use of maladaptive coping strategies were reportedly associated with sleep disturbance (Endo et al., 2011; Ten Brink et al., 2021), which may also lead to greater pain interference. Cognitive behavioral therapies target these psychosocial factors may improve pain management in individuals with IBS.

The current study found higher alcohol intake was significantly associated with worse pain interference. As a trigger of IBS and IBS pain, alcohol can irritate the gastrointestinal tract and upset the gut microbiome profile (Ames et al., 2020). In addition, food intake affects the secretogranin (Ohman et al., 2012; Voreades et al., 2014) and specific foods can influence IBS pain (Böhn et al., 2013). Another potential mechanism could be that IBS pain is mediated by the gut microbiome which has been shown to be significantly associated with food intake (Barandouzi et al., 2021; Mars et al., 2020; Pittayanon et al., 2019).

Associations of sensory factors with IBS pain

To the best of our knowledge, this is the first study that examined a comprehensive set of QST responses in IBS patients. As hypothesized, pain sensitivity was significantly correlated with self-reported pain. Among different measurements of QST, we found that pain interference was highly correlated with mechanical pain sensitivity (MPS), but neither mechanical pain threshold (MDT) nor mechanical detection threshold (MDT), indicative of mechanical hyperalgesia but not allodynia in IBS participants. Although not directly measured in the current study, visceral hypersensitivity in the IBS population is common as reflected by exacerbated responses to mechanical colorectal distension (Farzaei et al., 2016). In addition, the cold pain threshold (CPT) and cold detection threshold (CDT), but neither heat pain threshold (HPT) nor heat detection threshold (HDT), was also significantly correlated with pain interference, indicative of enhanced cold detection and cold pain perception in IBS patients. A previous study suggested that understanding the sensory array of altered nociceptive processing of sensory and pain perceptions could be used to identify specific mechanisms involved (Uddin & MacDermid, 2016). However, QST measurements were significantly associated with pain interference in the regression analyses, but did not have a direct or indirect effect on pain interference.

Alterations in thermal sensitivity among IBS patients have been reported inconsistently (Jarrett et al., 2014; Zhou et al., 2010). Our results were also varied from previous reports on heat pain threshold (HPT) and cold pain threshold (CPT), both were lower in our study. The main reason may be related to different QST protocols used in these studies, such as different QST testing sites, i.e., hand and foot tested in the previous study (Zhou et al., 2010), but non-dominant forearm used in the current study. Given that there is no QST reference in the healthy and diverse populations in the United States, but race and age significantly impact the measures of QST (Kim et al., 2019), the QST measurements in our study may serve as a new reference for young adults with chronic visceral pain.

The QST indices have been reported to be efficient in clustering chronic pain and managing pain in a precision approach (Gaynor et al., 2021). In the context that the underpinning mechanism of pain sensation in IBS is still largely unclear, our results open new avenues of research in using QST to assess pain sensitivity in relation to self-reported pain in IBS patients. Further studies are needed to identify pain profiles in IBS patients by employing a clustering algorithm and integrating psychosocial factors and quantitative sensory testing to depict phenotypic characteristics of chronic pain.

IBS pain and QOL

QOL refers to an individual’s well-being related to physical, emotional, and social aspects of life (Mönnikes, 2011). Consistent with other studies (Enck et al., 2016; Mönnikes, 2011), our results indicate a low perceived QOL level among individuals with IBS. Also, participants with higher fatigue experienced lower QOL. Piche et al found that fatigue was an imperative determinant of QOL related to the severity of IBS symptoms such as pain (Piche et al., 2010). Moreover, fatigue was common in IBS subjects, which not only negatively affects QOL but can also exacerbate pain and mood (Borren et al., 2019; Piche et al., 2010). The interplay between psychosocial factors, fatigue, coping, and self-efficacy contributes to pain severity and reduced QOL levels in individuals with IBS.

Limitations

There are several limitations in this study. Only young adults aged 18 to 28 years old were included in this study, which limits the generalization of findings to older populations. Though diverse recruitment strategies were employed, 76.2% and 77.5% of the subjects were female and Non-Hispanic white, respectively. The imbalanced distribution of sex and race in this study should be addressed even though females and Non-Hispanic White are more likely to develop IBS. A cross-sectional design in this study can only identify correlation instead of causation between psychosocial factors such as fatigue, sleep disturbance, coping and self-efficacy, and IBS pain and QOL.

Conclusion

The current investigation found that psychosocial factors including fatigue, coping and self-efficacy, alcohol intake, and distinct sensory measures (mechanical pain sensitivity and cold pain threshold) significantly contributed to self-reported pain and reduced QOL among young adults with IBS. We also found that the indirect effect of coping and self-efficacy on QOL was mediated by fatigue. A comprehensive assessment integrating psychosocial and sensory factors highlighted in this study are recommend in future studies to further explore chronic pain experiences. Interventional studies could also target personalized psychosocial and sensory factors to improve pain management and QOL in individuals with IBS.