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Personality traits and styles may affect the reporting of chronic pruritus: a cross-sectional study

Kini, Seema MD, MSa,*; Chen, Kuang-Ho PhDa; Chen, Suephy C. MD, MSa,b

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doi: 10.1097/itx.0000000000000020
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Abstract

Introduction

Chronic pruritus (CP), defined as itch persisting for 6 weeks or longer by the International Forum for the Study of Itch (IFSI) is common, yet may be a major diagnostic and therapeutic challenge for dermatologists1. The effect of CP on quality of life (QoL), has been well-documented and has been described to significantly impact some of the most essential spheres of life including mood, concentration, eating habits, sexual function, and sleep2–4.

Those of us who treat patients with CP recognize that itch is a subjective experience and disease severity alone cannot fully account for QoL impact of CP or why therapeutic agents that should provide adequate relief do not. Verhoeven and colleagues postulated a framework for CP as a biopsychosocial model whereby internal factors (eg, personality) and external factors (eg, social stressors) interface with a variety of mediating factors (eg, coping, perceived social support) can trigger a disease or itch (Fig. 1)5. We hypothesize that these factors also distinctly impact itch related QoL, a broader definition that takes into account how itch affects both physical and mental health over time.

Figure 1
Figure 1:
Biopsychosocial model of chronic pruritus. Biopsychosocial factors can best be shown in a diathesis-stress model, which is based on the hypothesis that internal vulnerability factors (diathesis), such as personality, interact with external environmental factors (such as major life events and other stressors) to trigger a disease or itch5.

Indeed, several cross-sectional have studies have demonstrated an association between negative affective disorders (eg, depression and anxiety) and CP6. An emerging area of interest is how personality traits might affect reporting of CP. This is particularly relevant in CP as itch is a subjective experience and symptom severity depends largely on how the sensation is perceived. Psouni and colleagues7 sought to assess the potential explanatory value of personality traits for the reporting of pruritus compared with mood disorders such as depression and anxiety and found the personality trait of “neuroticism” to be the strongest predictor of experimentally induced itch in healthy individuals8.

The psychology of personality is a broad discipline, yet one of the most widely accepted conceptual frameworks for identifying individual differences in personality is the Five-Factor Model (FFM). The FFM is rooted in the idea that the major determinants of personality are based on 5 broad traits, namely: extraversion, neuroticism, agreeableness, conscientiousness, and openness to experience9. These personality traits are considered to be heritable, stable over time and generalizable across cultures.

A more nuanced understanding of personality involves examining personality styles, the interaction between 2 individual personality traits (eg, neuroticism and conscientiousness). Psychological theory holds that a single personality trait can be intensified, weakened, or cancelled by the its’ standing on another personality trait. Thus personality styles allow one to examine the interactive effects between the factors of the FFM to explore whether combination of traits have unique effects. For example, Terracino and Costa10 investigated the association between smoking status and personality and found that neuroticism was related to smoking among individuals with low conscientiousness, indicating a lack of impulse control.

We believe that personality traits influence patient reporting of the QoL impact of CP. To explore this further, we conducted a survey of patients with CP from the National Eczema Association Conference and Veterans from the VA Pruritus Patient Database.

Methods

Study subjects and survey content

This study was approved by the Emory University Institution Review Board (IRB00035578) and the VHA Office of Research and Development. In this cross-sectional study, survey instruments were administered to further characterize patient demographics, medical history, quality of life impact of pruritus, and personality data. The 3 survey instruments utilized in this study include:

  • Pruritus QoL: the ItchyQoL is a validated, 22-item pruritus-specific instrument that measures the degree to which pruritus impacts QoL. This impact is quantified into 3 constructs: symptom subscale (6 items, eg, “my itchy skin hurts, burns or stings”), function subscale (7 items, eg, “my itchy skin condition makes it hard to work or do what I enjoy,” “my itchy skin condition affects how well I sleep”) and emotion subscale (9 items, eg, “I am frustrated by my itchy skin,” “I am embarrassed by my itchy skin”). The total ItchyQoL score for a patient is the sum of the symptom, function, and emotion subscale scores where a higher score corresponds to greater burden of disease, that is greater QoL impact11.
  • Demographics: demographics and pruritus characteristics questionnaire. A survey assessing basic demographic information and characteristics of pruritus, namely, duration, frequency, and severity [measured on a visual analog scale, anchored at 1 (least) and 10 (most)].
  • Personality: NEO-Five Factor Inventory (NEO-FFI). Developed by psychologists at the National Institutes of Health, this 60-item short-form survey is predicated on the FFM of personality, that stable individual differences in emotions, cognition, and behavior can be explained by 5 independent traits: neuroticism, conscientiousness, extraversion, agreeableness, openness to experience. Each item is rated on a 5-point Likert scale ranging from “strongly agree” to “strongly disagree.” One step further, a personality style is a more precise interpretation of personality where a specific style is composed of the interaction of 2 different personality traits. For example, the Style of Impulse control is an intersection of the neuroticism and conscientiousness personality traits whereby “Style of Well-Being” (N+E), Style of Defense (N+O), Style of Anger Control (N+A), Style of Impulse Control (N+C), Style of Interests (E+O), Style of Interactions (E+A), Style of Activity (E+C), Style of Attitudes (O+A), Style of Learning (O+C), Style of Character9.

Participants

Participants were derived from 2 main groups: the National Eczema Association and the VHA National Patient Care Database. All eligible participants were required to be English speaking, adults (18 y or older) and report symptoms of pruritus for 6 weeks or longer.

National Eczema Association (NEA)

Subjects were recruited through the NEA by 2 primary mechanisms. First, eligible subjects were recruited, in person, though the NEA patient conference held in Atlanta, GA June 28, 2012. As an adjunct measure to recruit participants through the NEA who were not able to attend the patient conference, an electronic posting was made on the “Clinical Trials” section of the NEA website inviting potential subjects to participate. A link on the website directed patients to a secure Survey Monkey site, which displayed a brief lay summary of the study introducing the purpose and significance of the research followed by the option to agree to participate in this study by giving informed consent. Thereafter, patients were able to complete all survey instruments with responses recorded electronically. Of note, only deidentified information was collected. Of the total 120 subjects, 32 had >10% missing data and were excluded leaving 78 for inclusion in our study.

VHA National Patient Care Database

Subjects were also drawn from the VHA National Patient Care Database—from which a stratified random sample of 6000 Veterans was collected using the US Census Bureau’s 6 geographic areas to ensure diverse geographic representation. For additional details regarding the methods in creating this sample, please refer to the study by Carr et al12. As our focus is the impact of CP on QoL, our analysis utilizes the reply from the 405 veterans with CP.

Statistical analyses

All analyses were performed with SAS software Version 9.3 (SAS Institute Cary, NC). The primary outcome variable was total mean ItchyQol score whereas each of ItchyQoL subscale (symptom, emotion, function) scores represented secondary outcome variables. Any subject with survey data with >10% missing responses were excluded from the analyses.

ItchyQoL scoring

ItchyQol subscale scores (eg, scores for each symptom, emotion, and function construct) are summations of the numerical responses for each item. The total ItchyQoL score is the sum of the symptom, function, and emotion subscores.

NEO-FFI

As specified in the Revised NEO Personality Inventory (NEO-PI-R) and NEO-FFI professional manual, we scored missing items as neutral and created raw scores. We then used the adult combined gender norms in the NEO Manual to convert raw scores into T scores which have a mean of 50 and SD of 10. For the purpose of the analyses, T scores were centered on a mean of 509.

Uncentered T scores for each of the trait were used to determine whether participants could be classified in terms of a personality style; that is, a combination of 2 personality traits. Participants were characterized on NEO style graphs13 by converting their raw T scores into z scores and then plotting all 10 possible combinations of 2 dimensions against one another14. Each plot yielded 4 quadrants reflecting whether a participant was high or low on the first dimension and high or low on the second dimension (Fig. 2). For each possible pairing of traits, participants whose z scores were at least one-half SD above or below average for both traits were classified as being high-high (++), high-low (+−), low-high (−+), or low-low (−−); participants who fell into one of these 4 classifications were coded as 1 for that classification and 0 for the other 3 classifications. In this study, 5 subjects had z scores that fell within the average range on both traits and were classified as not having a style; these participants were coded as 0. Thus, the styles represent individuals who did not score in the average range on both dimensions.

Figure 2
Figure 2:
Personality style graph. Example personality style graph of the combination of Neuroticism and Conscientiousness (Style of Impulse Control). Individuals who fall within the area of the blue circle are considered not to have a type; that is, those who score within one-half SD (T score between 45 and 55) from the mean on Neuroticism or Conscientiousness14.

Univariate analyses

The Fisher least significant difference T test was used to compare pairwise comparisons of mean ItchyQoL score among each of the 4 subgroups of the 10 personality styles to identify those styles that were significantly associated with impacting the main outcome variable, mean ItchyQoL score at the 0.05 level of confidence.

Multivariate analyses

A multivariate linear regression was performed to identify the potential influence of demographic data, itch characteristics, and personality factors in the way they impacted the primary outcome variable, mean ItchyQoL score. In this model the 15 covariates included: (1) age, (2) race, (3) marital status, (4) itch duration, (5) itch frequency, and (6–15) each of the 10 personality styles. For each of the personality styles, a dummy variable was created with 4 degrees of freedom. Although we did not conduct a sample size calculation, using a rule of thumb of 10 subjects for each independent variable, we would require at least 150 subjects. A level of 0.05% significance was used.

Results

Sample size and demographics

Demographic characteristics are summarized in Table 1. In this sample, the mean age of participants was 54 (SD=15) with an average duration of symptoms for 149.8 weeks (SD=161.2) and moderate severity of symptoms 5.53 (SD=2.3). 76 (15%) of the participants reported itching “all the time.” Most participants were white 344 (71%) and male (369, 76%). Nearly half of participants (222, 45%) were married.

Table 1
Table 1:
Demographic data and itch characteristics.

Personality styles: association with total ItchyQoL and subscale scores

The results of the multivariate analysis with ItchyQoL score as the outcome variable are summarized in Table 2. The lethargic personality style (low extraversion, low conscientiousness) was associated with a greater mean total ItchyQoL score (β=11.65, P=0.04). Similarly, for the ItchyQoL symptom subscale, both the Overcontrolled (high neuroticism, high conscientiousness) and Undercontrolled (high neuroticism, low conscientiousness) personality styles were significantly associated with greater ItchyQoL symptom score (β=2.76, P=0.01 and β=2.34, P=0.03), respectively. For the ItchyQoL function subscale no personality styles were significant at the 0.05 level, though it is worth noting that the Lethargic (low extraversion, low conscientiousness) trended to significance (β=3.71, 0.07). The Undistinguished (low agreeableness, low conscientiousness) personality styles trended to significance (β=−3.66, P=0.08) for lower ItchyQoL function subscale scores. No personality styles were significantly associated with greater ItchyQoL emotion subscale scores.

Table 2
Table 2:
Results of the multivariate linear regression model.

Demographic and itch characteristics covariates: association with total ItchyQoL and subscale scores

Overall, a younger age was significantly associated with lower total ItchyQoL scores overall and for each of the ItchyQoL symptom, emotion, and function subscales though the covariates were so small that this is unlikely to represent a clinically relevant finding. African American race was significantly associated with greater mean ItchyQoL score (β=8.14, P<0.01), ItchyQoL emotion subscale score (β=2.98, P=0.02) and trended to significance for ItchyQoL symptom score (β=1.23, P=0.06). Curiously, white race (β=1.2, P=0.04) and sex (β=2.54, P=0.05) were associated with greater ItchyQoL function subscale scores only. It is worth noting that “single” marital status trended to significance for higher mean ItchyQoL score (β=3.79, P=0.06).

Discussion

There are numerous studies to support substantial QoL impact of CP2,4,15 yet the factors that contribute to burden of disease are not well understood. This study adds to the body of literature, specifically with respect to exploring how race, social support structures, personality and patient reported QoL in pruritus are related and how the interaction of these factors may affect one’s ability to cope with chronic disease.

Personality and CP: conscientiousness

Conscientiousness as measured by the NEO-FFI reflects an individual’s degree of self-discipline, achievement, and organization. In the literature relating personality to health outcomes with respect to mortality, high conscientiousness has demonstrated higher health-related QoL in patients with other chronic diseases such as HIV/AIDS16. Low levels of conscientiousness predicted high levels of disease burden in patients with multiple sclerosis17.

Therefore it is conceivable that those individuals with a Lethargic personality style (E–C–) characterized as “unenthusiastic and have few plans or goals to motivate them, tend to be passive and respond only to the most pressing demands”14 would be significantly associated with a greater mean total ItchyQoL score, indicating greater overall burden of disease. The Lethargic personality style has been associated with greater risk of major depression18 and possibly by reducing the threshold for the sensation of pruritus6.

Personality and CP: neuroticism

Our group previously reported that neuroticism, one of the 5 main personality traits, to be associated with greater ItchyQoL score in a study of 405 Veterans with CP >6 weeks. Our expanded data continues to support this finding. In this study both of the personality styles characterized by high levels of neuroticism (overcontrolled, N+C+ and undercontrolled, N+C–) were significantly associated with greater symptomatic impact from pruritus even after controlling for disease (eg, severity, duration) and other demographic characteristics. The symptom subscale consists of 6 items including bleeding, hurts, burns/stings, scar, scratch, and temperature aggravation. Those with higher scores of neuroticism tend to be particularly “sensitive, emotional, and are prone to experience feelings that are upsetting”19.

Our results suggest that those with higher levels of neuroticism may perceive their symptoms as more distressing due to one’s ability to manage impulses and feelings. This hypothesis is consistent with prior studies that have documented high levels of neuroticism associated with lower health-related QoL in other chronic diseases such as chronic kidney disease20 and irritable bowel syndrome21.

Also interesting is the lack of any significant association between emotional impact and any of the personality styles. Rather than concluding that the emotional impact of CP does not affect any personality style, one may also speculate that all personality styles are affected by emotional impact to the extent that there is no difference between them.

Marital status, race, and impact of pruritus

Our results from this and previous studies22 suggest that support structures (our surrogate being marital status) may alleviate the impact of CP. Such support structures may take the form of patient advocacy group meetings (eg, the National Eczema Association) or could form the basis of a therapeutic intervention. The apparent racial disparity in the impact of pruritus is also notable. Research results have been heterogeneous in correlating QoL and race in chronic diseases12. A study by our group Carr et al12 found self-identified nonwhite race to be an important risk factor for both CP and self-reported severity of pruritus. The root causes for racial disparities in health are myriad in the United States and include limitations in health care access, perceived racism, which has been associated with psychological distress have all been found to contribute. In addition to psychosocial determinants of health, studies evaluating genetic factors in pain processing have found that African Americans report lower pain thresholds and increased sensitivity to pain compared with non-Hispanic whites. This may be explained by enhanced central sensitization in ethnic minorities as has been studied in chronic pain models and may apply to CP as well.

The greatest limitation of this study is the cross-sectional study design which limits the inferences we can make from our findings relating to personality traits and QoL impact of CP. Moreover, while having a spouse has been used in other studies as a proxy for social support, we recognize that there are many other avenues by which patients garner social support (eg, steady partner, friends, relatives) which we did not directly assess for in our study. In addition, as this was a convenience sample, there is a potential for response bias as more symptomatic patients may have been more inclined to participate.

Despite these limitations the aim of this study was to explore the interaction of personality as it relates to QoL imapct of CP. Our findings suggest that those patients who have a lethargic personality style will have the worst QoL burden from CP, whereas those with personality styles with high levels of neuroticism will report the greatest symptoms.

Our findings in this study augment the Verhoeven biopsychosocial model of CP where underlying personality factors, support structures (with marital status being a surrogate), and race all interact to determine how patients experience, report, and cope with their disease. One of the challenges for clinicians who treat CP is how to achieve adequate relief for those patients who have had an insufficient response to adequate trials of a variety of therapeutics including topical steroids, antihistamines, and even immunosuppressive medications. In this subset of patients, it may be helpful to consider where nonpharmacologic approaches such as biofeedback and cognitive and mindfulness-based therapies may have an adjunct role.

Sources of funding

The Veterans Health Administration (VHA) provided financial support and access to the Veterans Hospital Patient Database.

Conflicts of interest

The authors declare that they have no financial conflict of interest with regard to the content of this report.

Acknowledgments

The authors are indebted to the National Eczema Association, the Center of Social and Urban Research at the University of Pittsburgh and the Veterans Health Administration.

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Keywords:

pruritus; personality traits; quality of life

Copyright © 2018 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The International Forum for the Study of Itch.