Ethnicity, catastrophizing, and qualities of the pain experience

Abstract

Objective

It is generally well established that catastrophizing exerts a potent influence on individuals' experience of pain and accompanying emotional distress. Further, preliminary evidence has shown that meaningful differences among various pain relevant outcomes (e.g., pain ratings, endogenous pain inhibitory processes) can be attributed to individuals' ethnic background. The mechanisms that might explain ethnic differences in pain outcomes are unclear, and it remains to be fully established whether the relation between ethnicity and pain response may be indirectly affected by pain catastrophizing.

Design

In the current study, we examined differences in pain responses by ethnicity among healthy, young adults (N = 62), and attempted to determine whether such an ethnicity-pain relation was mediated by catastrophizing using the standard Pain Catastrophizing Scale (PCS) and a modified version of the PCS reflecting situational catastrophizing during a cold pressor task.

Results

Results showed that pain responses varied by ethnicity, as did reported catastrophizing. Catastrophizing mediated the relation between ethnicity and affective and sensory pain responses.

Conclusions

To better explicate our findings, we described the context in which these findings occurred following a ‘who, what, where, when, and why’ approach. This approach provides an efficient description of how our findings align with previous research, while identifying future research that should clarify the theoretical underpinnings of catastrophizing and pain and also inform clinical intervention.

Introduction

Recent research investigating relations between ethnicity and pain has produced few firm generalizations, in part because ethnicity and pain are multidimensional constructs that vary by individual and are shaped by culture. Despite the complexities inherent in the study of ethnicity and pain, several reviews of this literature have been undertaken and published. A review by Edwards and colleagues (1), addressed laboratory and clinical studies of ethnic differences in pain whereby two key, yet general, themes emerged; 1) findings from laboratory-based studies suggest greater sensitivity to experimental pain stimuli among African-Americans compared to Caucasians, and 2) higher levels of pain and disability have been reported among African-Americans relative to Caucasian patients that were treated for a variety of acute and persistent pain conditions. Ethnic differences in pain are becoming well-documented; however explaining these differences is more challenging.

How one copes with pain consistently predicts important clinical outcomes, including pain severity and disability (2). One of the most robust predictors of pain outcomes is catastrophizing (3), which is defined as a negative emotional and cognitive response to pain that involves elements of magnification, helplessness, and pessimism. Traditional conceptualizations have suggested that catastrophizing is a relatively enduring mode of responding either directly to a painful experience or in anticipation of such an experience (3). Contrary to trait conceptualization, more recent views have regarded catastrophizing as also a potentially modifiable, situation-specific cognitive style (4). Several studies have examined what has come to be termed “standard” (i.e., trait conceptualization) versus “situational” (i.e., situation-specific conceptualization) catastrophizing processes in relation to experimental pain outcomes (5, 6). Although a review of the methodology for assessing standard versus situational catastrophizing is beyond the scope of the current study, results from previous investigation preliminarily suggest that assessment of situational catastrophizing (i.e., the assessment of current catastrophic thinking during an experimental pain task) better predicts individuals' propensity to report pain and distress during experimental acute pain induction than standard catastrophizing (7, 8). Whether standard and situational catastrophizing represent the same construct, differing aspects of the same construct or separate constructs altogether remains unclear and is currently a topic of debate.

To our knowledge, the inter-relations among ethnicity, standard and situational catastrophizing, and pain reports have not been previously examined in an experimental context. Further, the literature is inconsistent with some studies showing no ethnic differences in pain reports (9) and mixed results in the use of pain coping strategies including catastrophizing (10). Inconsistencies within the ethnicity and pain literature may be at least partially attributable to unexplored and/or inconsistent assessment of the various qualities of pain-related study outcomes (e.g., affective-motivational versus sensory-discriminative dimensions of pain reporting) Pain-related outcomes such as tolerance and ratings of pain unpleasantness may primarily reflect the affective-motivational dimension of pain, while pain threshold and ratings of pain intensity may be more strongly associated with sensory-discriminative aspects of the experience (11). It has been theorized that ethnic differences in pain response may be most prominent for the affective-motivational dimension of pain (12, 13); however, ethnic differences in the sensory-discriminative aspects of pain perception have been reported (14). Therefore, additional examination of ethnic differences in relation to affective and sensory dimensions of pain response is warranted.

Ethnic groups with minority status may be more prone to engaging in negative coping strategies such as catastrophizing, which could affect their pain perception and subsequent reports of painful experiences. The current study examined the association between ethnicity, standard and situational catastrophizing, and affective and sensory dimensions of pain perception in a multi-ethnic sample of self-identified Caucasians, African Americans, and Asian/Pacific Islanders. Specifically, the following questions were examined: 1) Are there significant ethnic differences in the report of pain across various dimensions of pain quality (e.g., affective and sensory), 2) Are there significant ethnic differences in the report of standard and situational pain catastrophizing, and 3) does standard and/or situational catastrophizing mediate the relation between ethnicity and the report of pain in response to experimental noxious stimulation. Lastly, results of this study were addressed in a discussion offering an approach for the advancement of catastrophizing and pain theory.

Methods

Participants

A total of 64 participants qualified for participation in the study. Two participant sessions were discontinued prior to the completion of pain testing due to apparent hypertension and acute illness, respectively. These participants' data were omitted leaving a final sample of 62 participants. Participants were healthy college students (61% women) ranging in age from 18 to 25 years with an average Body Mass Index (M = 22.1, SD = 3.01). The sample was racially diverse; 18% African American, 24% Asian/Pacific Islander, 42% Caucasian, 3% Hispanic, 2% Native American, and 11% Other (racial classifications adhered to prior guidelines and not the current census guidelines implemented in Census 2000). Potential participants completed screening questionnaires to determine their eligibility for the study. Participants were required to be physically and psychologically healthy, without a history of persistent pain and without current pain. Criteria for exclusion included: (a) age less than 18 or over 45 years; (b) ongoing chronic pain problems; (c) diagnosed with hypertension or taking medication for blood pressure; (d) circulatory disorders; (e) history of cardiac events; (f) history of metabolic disease or neuropathy; (g) pregnant; (h) currently using prescription analgesics, tranquilizers, antidepressants, or other centrally acting agents; (i) use of nicotine; (j) use of prescription medication; and (k) psychiatric disorders (e.g., depression).

Ethics

The study was approved by the University's institutional review board. Participants completed written informed consent prior to initiation of study procedures and were compensated for their participation.

Study Design

Participants were paired with experimenters of the same sex to minimize the effects of experimenter sex on participants' report of pain (15). Prior to pain testing, participants completed the PCS using standard instructions and a measure of depressive symptoms. Next, pain testing involved repeated immersions of the dominant hand into a cold water bath for a maximum total duration of 420 seconds. Similar to Dixon and colleagues (7), participants were encouraged to keep their hand immersed for at least 2 minutes during the final cold water immersion, but were told they could remove their hand at any time. Pain testing was immediately followed by completion of pain ratings and the situational PCS, with modified instructions that directed participants to report on catastrophizing with respect to the cold pressor pain just experienced.

Assessment

Pain Testing

The Cold Pressor Task (CPT), a cold water acute pain stimulus, was administered using a circulating cold water bath (ThermoNeslab RTE17, Portsmouth, NH) maintained at a temperature of 4°C. Participants completed five cold water immersions. The first four immersions were for a maximum duration of 60 seconds, with 60-120 seconds between immersions, and the final immersion was for a maximum duration of 180 seconds.

Standard and Situational Pain Catastrophizing

The standard Pain Catastrophizing Scale (PCS) (16) is a 13-item scale that assesses catastrophic thinking in response to pain. The standard PCS assesses catastrophic pain-related cognitive-emotional processes by asking participants to recall their experiences during past occurrences of pain. In the current study, as is typically done in experimental pain studies, the standard PCS was administered prior to the initiation of the laboratory pain task and was considered an assessment of individuals' tendency to engage in pain-related catastrophizing. The PCS total score, calculated by summing the 13-item responses, provides a good index of the catastrophizing construct through the inclusion of the highly correlated subscales of helplessness, rumination, and magnification. Higher scores on the PCS are indicative of greater pain-related catastrophizing (17). Subsequently, the situational PCS used the same 13-items as the standard PCS, with modified instructions and item wording (see Figure 1). The situational PCS was administered immediately following the completion of the final cold water immersion and the instructions asked participants to refer to the pain experienced during the cold water immersions when answering the questions pertaining to pain-related catastrophizing. In the current study, the internal consistency of the total standard PCS score prior to pain testing was good (Cronbach's α = .82), and the internal consistency of the situational score immediately after pain testing was excellent (Cronbach's α = .92).

Figure 1.

Standard Pain Catastrophizing Scale (PCS) Compared with the Situational PCS.

Depressive Symptoms

The Beck Depression Inventory (BDI) (18) is a self-report measure that consists of 21-items rated on a four-point Likert-type scale (0-3), with higher scores reflecting more severe symptoms. The BDI was administered to participants prior to pain testing to assess the frequency and severity of a variety of cognitive, affective, physiological, and motivational symptoms of depression (18). The BDI has well-established psychometric properties (18). In the current study, the internal consistency of the BDI was adequate (Cronbach's α = .73).

Pain Measures

The short-form McGill Pain Questionnaire (SF-MPQ) (19) is a self-report measure that consists of 15-items rated on a four-point Likert-type scale, with higher scores indicating greater pain. The SF-MPQ allows quantitative, multidimensional pain ratings to be obtained in a brief period of time (19). The SF-MPQ was given immediately after pain testing and included instructions that asked the participant to report on the pain experienced during the cold water pain procedures. The sensory and affective pain scale scores were used. The SF-MPQ is reliable and valid, and is commonly used in clinical and research applications (19, 20). In the current study, the internal consistency of the SF-MPQ sensory pain score (Cronbach's α = .76) and affective pain score (Cronbach's α = .84) were adequate to good. Additionally, participants completed a pain intensity rating using a numerical rating scale (NRS). Participants rated pain intensity on a scale of 0 (no pain) to 100 (most intense pain imaginable) immediately prior to removal of their hand from the cold water bath during the final CPT immersion. Pain intensity is suggested to approximate a sensory rating of pain (21). Total pain exposure, a more objective indicator of pain, was assessed as the total time in seconds of hand immersion in the cold water bath (420 seconds maximum duration over five immersions). Among the four pain measures, the inter-correlations were moderate and ranged from .45 to .62; however, total pain exposure was only associated with the pain intensity rating (r(61) = −.26, p = .045.

Statistics

MANCOVA, ANCOVAs and regression analyses were used to examine the three research questions. A MANCOVA with pain responses as outcomes was used to examine the main effects of ethnicity, controlling for sex and depressive symptoms, with pain responses. ANCOVAs, for standard and situational catastrophizing were used to examine the main effects of ethnicity, controlling for sex and negative affect, with catastrophizing. Finally, Baron and Kenny's (22) guidelines were followed for the mediation analyses to clarify ethnicity differences in pain responses. Specifically, catastrophizing was proposed to mediate the effect of ethnicity in predicting pain responses. The racial categories examined were African Americans (n = 11), Asian/Pacific Islanders (n = 15), and Caucasians (n = 26); to examine differences in ethnicity post hoc t-test comparisons were used. Participants from other ethnicities (i.e., Hispanic, n = 2; Native American, n = 1; and Other, n = 7) were dropped given sample size constraints.

The first two analyses hold general data assumptions, with attention to normality and compound symmetry or sphericity particularly relevant to guard against inflated Type 1 error. Though the data were roughly normal (i.e., skewness/SE of skewness < 3), total pain exposure was significantly skewed. A base 10 log transformation was used, but this approach did not normalize the data, therefore given its limited association with the other three pain measures it was dropped from further analysis, though the means and standard deviations for the sample are reported in Table 1.

Table 1.

Pain Relevant Responses by Sex and Ethnicity.

Variable	Total (N = 62)		Female (n = 38)		Male (n = 24)		African American (n = 11)		Asian/Pacific Islanders (n = 15)		Caucasian (n = 26)
	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
SF-MPQ Affective	2.95	3.23	3.86	3.49	1.67	2.28	5.55	3.23	3.53	3.72	2.04	2.76
SF-MPQ Sensory	16.16	8.18	19.81	7.07	11.12	6.52	21.45	5.85	18.59	8.30	13.53	6.99
Pain Intensity NRS	80.21	26.77	90.08	20.47	65.00	28.55	93.09*	11.79	93.20*	9.10	65.00*	33.33
Tolerance	165.72	34.33	159.59	40.36	175.17	18.75	149.73	51.67	165.82	28.46	174.46	16.47

Note: SF-MPQ = Short-Form McGill Pain Questionnaire; NRS = Numerical Rating Scale.

^*p < .05.

Covariates

Sex differences in pain catastrophizing and pain responses have been well researched, with females often reporting more clinical and experimental pain (23, 24, 25) and catastrophic cognitions (26, 27) than males when exposed to experimental acute pain. Furthermore, in some cases, greater catastrophizing has been shown to account for observed sex differences in clinical pain reports (24). Depressive symptoms are also related to pain and catastrophizing (28, 29). Therefore, sex and depressive symptoms were included as covariates in analyses.

Results

Pain Relevant Responses: Ethnicity Differences

Average pain responses were assessed for the total sample and across ethnicity and sex (see Table 1). Using a MANCOVA, main effects of ethnicity, controlling for sex and depressive symptoms, on the SF-MPQ affective subscale, SF-MPQ sensory subscale, and pain intensity NRS during acute pain were examined. African Americans and Asian/Pacific Islanders, who did not significantly differ from each other, reported significantly greater pain intensity than Caucasians [pain intensity during acute pain: (F (3, 79) = 3.60, p = 0.035), η_p²= .133].

Catastrophizing in Response to Acute Pain: Ethnicity Differences

Two ANCOVAs, for standard and situational catastrophizing, were used to examine whether each catastrophizing report varied by ethnicity, controlling for sex and depressive symptoms. Standard catastrophizing did not significantly vary by ethnicity (p = .90). Situational catastrophizing did significantly vary by ethnicity, such that African Americans reported greater situational catastrophizing than Asian/Pacific Islanders and Caucasians, who did not differ [F (3, 79) = 4.35, p = .019, η_p²= .156].

Catastrophizing as a Mediator of the Relation of Ethnicity with Pain

Multiple regression analyses were completed to determine whether pain catastrophizing mediated differences in pain responses across ethnicity, controlling for sex and depressive symptoms. Mediation analyses for the standard PCS were not performed given the findings in hypothesis two that standard catastrophizing did not differ by ethnicity. Using Sobel's test (22), the situational PCS total score was a significant mediator of the relation of ethnicity with SF-MPQ Affective subscale (t(56) = 2.15, p = .03) and the rating of pain intensity (t(56) = 2.01, p = .045), but not the SF-MPQ Sensory subscale (t(56) = 1.79, p = .073) (see Table 3).

Table 3.

Models of Situational Pain Catastrophizing Mediating the Association of Ethnicity with Pain Responses, Controlling for Depressive Symptoms and Sex.

Variable		SF-MPQ Affective	SF-MPQ Sensory	Pain Intensity NRS
		β	β	β
Step 1a	Sex	.34 *	.50 **	.28 *
	African Americans b	ns	ns	.32 *
	Asian/Pacific Islanders b	.34 *	.26 *	.30 *
	Full Model:	R2 = 0.23*, f2= .30	R2 = 0.39**, f2= .64	R2 = 0.34*, f2= .52
Step 2 b	Sex	.33 *	.33 *	.33 *
	African Americans b	ns	ns	ns
	Asian/Pacific Islanders b	.38 **	.38 **	.38 **
	Full Model:	R2 = 0.29*, f2= .41	R2 = 0.29*, f2= .41	R2 = 0.29*, f2= .41
Step 3 b	PCS	.61***	.43**	.55**
	Sex	ns	.36 **	ns
	African Americans b	ns	ns	.31 *
	Asian/Pacific Islanders b	ns	ns	ns
	Full Model:	R2 = 0.53***, f2=1 .13	R2 = 0.52***, f2=1 .08	R2 = 0.55***, f2=1 .22

Note: PCS=Pain Catastrophizing Scale; BDI=Beck Depression Inventory; SF-MPQ=Short-Form

McGill Pain Questionnaire; NRS=Numerical Rating Scale.

^aBDI was not significant at any step in the models.

^bethnicity was dummy coded as two variables, the first compared African Americans with Caucasians and the second compared Asian/Pacific Islanders with Caucasians.

^*p < .05.

^**p < .001.

^***p < .0001.

Discussion

The objective of the present study was to examine ethnic differences in various reports of pain quality (i.e., affective and sensory) and standard (i.e., recall thoughts and feelings during past experiences of pain) and situational (i.e., recall thoughts and feelings of an experimental pain task just experienced) pain catastrophizing. Additionally, we examined catastrophizing as a potential mediator of the relation between ethnicity and pain responses to clarify one potential mechanism for explaining ethnicity differences in pain reporting.

First, pain responses were examined. African Americans and Asian/Pacific Islanders, who did not differ from each other, reported greater pain intensity than Caucasians. The findings provide evidence that reports of various qualities of pain differentially vary across ethnicity, which necessitates identification of potential mechanisms such as catastrophizing to explain the relation. Therefore, we examined catastrophizing, and we found that only situational catastrophizing varied by ethnicity, with African Americans reporting greater catastrophizing than Asian/Pacific Islanders and Caucasians, who did not differ. To our knowledge, no research has examined how pain quality and standard and situational catastrophizing reports vary by ethnicity. Research suggests that racial differences in pain responses may be associated with ethnicity-related differences in catastrophizing. Chibnall and colleagues (30) examined differences in pain catastrophizing in African Americans and Caucasians with low-back injuries. Even after controlling for socio-economic status, African Americans showed greater catastrophizing. The present study showed similar findings in a healthy sample of African Americans, in that African Americans reported greater situational catastrophizing and pain than other ethnicities. It is possible that ethnicity, as a social construct, is merely a marker for the myriad other factors that influence differences in pain responses (e.g., access to healthcare or perceived racism). Thus, caution must be used when interpreting the findings as strictly a function of ethnicity (9).

Finally, we performed mediation analyses to determine if catastrophizing would mediate the relation of ethnicity with pain responses. Standard catastrophizing was not a mediator given lack of variability across ethnicities. Situational catastrophizing was a significant mediator for affect and rating of pain intensity but not sensory pain. The shifting presence and absence of mediation highlight the complexity, and potentially limited use, of catastrophizing as a mechanism for explaining ethnicity differences in the report of various qualities of pain. Others report that coping strategies such as prayer differ across ethnicities as does the use of such pain-reducing strategies to control pain in undergraduates not experiencing chronic pain (10), suggesting that certain coping strategies may be appropriate for certain pain qualities. Additionally, one study with African Americans, Hispanics, and Caucasians with chronic pain did not find ethnic differences in pain responses, with slight, though statistically non-significant, differences in standard catastrophizing (9). Such a finding suggests that ethnic differences in pain may change from acute to chronic pain experiences, and possibly, that standard and situational catastrophizing are assessing different constructs.

Overall, we examined healthy adults' pain and catastrophizing in a laboratory setting with standard and situational assessment to better understand differences in reports of pain by ethnicity. We found support that catastrophizing with a situational focus and varying qualities of pain were differentially related to ethnicity. We also found that ethnicity differences in varying types of pain reports were at least partially mediated by situational catastrophizing.

A key charge of current research is to develop the theory underlying catastrophizing and its relation to pain. A simple approach to systematically examine our findings in comparison to past research is the ‘who, what, where, when, and why’ approach. Who? Populations experiencing acute or chronic pain, even healthy populations, have shown associations between catastrophizing and pain responses. What? There has also been considerable validation of what information catastrophizing reports suggest about the pain experience (e.g., that it is a negative experience made up of thoughts marked by helplessness, rumination, and/or magnification). Where? Measurement of catastrophizing has been done in laboratory, hospital and home environments with findings all supporting its relation to pain, despite the varied influences these settings may have. When? These measurements were originally focused in a general way with emphasis on prior experiences with pain, but more recent research has emphasized situational measurement, as it may be more related to pain (16). Why? Suggested mechanisms for the effects of catastrophizing on pain have varied from emotional to physiological (31, 32, 33, 34). These past findings focus on developing an understanding of catastrophizing as it relates to pain more broadly, but show little focus on how catastrophizing relates to specific types of reported pain (e.g., affective or sensory).

There are, however, several notable limitations to the current study. First, the power to detect effects with relevant outcomes was minimal given the sample size. However, these findings are similar to previous research (30, 35) with the added benefit that potential confounds may be minimized given that the current sample was comprised of healthy young adults attending college. Second, the ability to generalize these findings to chronic pain populations or those experiencing different types of pain is limited given that the study examined healthy young adults in an acute pain setting only. Finally, previous research has shown that situational catastrophizing is only moderately associated with standard catastrophizing measurement, and is more relevant to current sensory and affective pain responses (7, 8). However, situational catastrophizing may more closely approximate general distress following the pain experience, so it is necessary to clarify the validity of the construct, given its apparent relevance to ethnicity differences across pain qualities.

Conclusion

Future researchers should place priority on further explaining the contextual elements involved in their assessments of catastrophizing and explicating the qualities of pain reports. Catastrophizing is a stable predictor of pain in a variety of settings that is readily modifiable (36, 37, 38, 39). Particular treatment models may be more appropriate for addressing certain aspects of pain. To identify how the contextual modifications affect catastrophizing and ultimately the varied qualities of pain, a more systematic presentation of the context must be examined, with particular attention to the type of pain response under study.

Table 2.

Standard and Situational PCS Catastrophizing in Response to Acute Pain, by Sex and Ethnicity

Variable	Total (N = 62)		Female (n = 38)		Male (n = 24)		African American (n = 11)		Asian/Pacific Islanders (n = 15)		Caucasian (n = 26)
	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
PCS	15.90	8.21	17.24	8.24	13.79	7.84	18.73	8.03	17.33 d	9.51	14.62d	8.35
PCS a	20.76	11.86	24.21	10.64	15.29	11.84	31.64*	10.47	22.07*	10.07	17.73*	11.53

Note. PCS = Pain Catastrophizing Scale.

^asituational measure.

^*p < .05.