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Gender, coping and the perception of pain
Pain 97 (2002) 195–201 www.elsevier.com/locate/pain
Gender, coping and the perception of pain Edmund Keogh*, Malin Herdenfeldt Department of Psychology, Goldsmiths College, University of London, New Cross, London SE14 6NW, UK Received 18 May 2001; received in revised form 13 August 2001; accepted 17 September 2001
Abstract Research consistently indicates that gender differences exist in pain perception, with females typically reporting more negative responses to pain than males. It also seems as if males and females use and benefit from different coping strategies when under stress; females seem to prefer emotion-focused coping, whereas males prefer sensory-focused coping. Unfortunately, experimental research that examines such differences in the context of pain has not yet been adequately investigated. The aim of the current study was, therefore, to determine whether gender differences would be found in the effect that sensory-focused and emotion-focused coping instructions have on cold pressor pain experiences. Participants consisted of 24 male and 26 female healthy adults, all of whom reported no current pain. A consistent pattern of effects was found, over both behavioural and self-report measures of pain. Compared to females, males exhibited less negative pain responses when focusing on the sensory component of pain (i.e. increased threshold, tolerance and lower sensory pain). Furthermore, compared to sensory focusing, emotional focusing was found to increase the affective pain experience of females. Together these results confirm that important differences exist between men and women in the effects pain coping instructions have on the experience of pain. The implications of such findings for research and practice are discussed. q 2002 International Association for the study of Pain. Published by Elsevier Science B.V. All rights reserved. Keywords: Pain; Attention; Gender; Cold pressor; Coping
1. Introduction It is now generally accepted that males and females exhibit important differences in their pain experiences (Fillingim and Maixner, 1995; Berkley and Holdcroft, 1999; Fillingim and Ness, 2000). For example, epidemiological studies indicate that females report more pain experiences and more negative responses to pain compared to males (Unruh, 1996). Furthermore, clinically based research suggests that there are important gender differences in susceptibility to pain-related diseases, analgesic effectiveness, as well as recovery from anaesthesia (Berkley, 1997; Ciccone and Holdcroft, 1999; Myles et al., 2001). Finally, experimental pain induction studies reveal that females consistently exhibit lower thresholds and tolerance to a wide range of noxious stimuli (Riley et al., 1998; Rollman et al., 2000). Numerous explanations have been proposed to account for such gender differences (Fillingim, 2000). While most explanations concentrate on biological mechanisms (e.g. genetic, hormonal, cardiovascular), it is becoming increasingly clear that social and psychological factors are also
* Corresponding author. Tel.: 144-20-7919-7893; fax: 144-20-79197873. E-mail address: [email protected] (E. Keogh).
important (e.g. developmental, emotional and cognitive). One psychological mechanism that is thought to play an important role in effective pain management is cognitive coping strategy. Although there are many different types of coping (Jensen et al., 1991; Boothby et al., 1999), most can be classified as either focused or avoidant strategies. In terms of the effect such strategies have on pain, Suls and Fletcher (1985) report that avoidance provides some benefit in the short term, whereas in the long term the effectiveness of such a strategy is questionable. Interestingly, experimental paradigms that have compared focused and avoidance instructions also find negative pain effects for cognitive avoidance in otherwise healthy individuals (e.g. Cioffi and Holloway, 1993). Such research led Boothby et al. (1999) to argue that the strategies that seem associated with better outcome are those that involve the patient actively focusing on the pain rather than passively avoiding it. Given that individuals develop their own strategies for coping with painful sensations, and since men and women experience pain differentially, it is likely that males and females will develop different coping styles (Jensen et al., 1994; Weir et al., 1996; Robinson et al., 2000). Unfortunately, little research has investigated whether gender moderates (or mediates) the effectiveness of pain coping strategies (Sullivan et al., 2000; Keefe et al., 2000). This
0304-3959/02/$20.00 q 2002 International Association for the study of Pain. Published by Elsevier Science B.V. All rights reserved. PII: S 0304-395 9(01)00427-4
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is surprising given that the research that has been conducted suggests that important gender differences exist. Unruh et al. (1999), for example, presented results from a communitybased telephone survey of people who reported pain in the 2 weeks before the interview. They found that compared to men, women reported significantly more intense pain, as well as using a greater range of coping strategies, i.e. greater social support seeking, problem-solving, positive self-statements and palliative behaviours. In a second study, Grossi et al. (2000) investigated gender differences in coping strategies used by patients with musculoskeletal pain. They found that for women a poorer ability to cope with pain was related to a higher level of emotional distress, greater disability, and a history of treatments for pain. No such effects were found for men. Together the results of Unruh et al. (1999) and Grossi et al. (2000) indicate that there are important gender differences in the use of coping strategies. What is unclear from these studies, however, is whether such differences cause the variability in pain experience. Fortunately, experimental designs that manipulate coping instructions allow a more rigorous investigation of such gender effects. Keogh et al. (2000), for example, investigated differences between men and women in the efficacy of focused and avoidance coping instructions on cold pressor pain responses. As expected, males were found to be more tolerant to cold pressor pain than females. However, males also reported less sensory pain when they attended toward the pain than when they avoided it. This beneficial effect of sensory focusing was not found in women suggesting that such a strategy may only be useful for males (see also Keogh and Mansoor, 2001). Why should females fail to benefit from sensory focusing? One possible explanation could be that the instructions given to women did not match their preferred coping style, and so were ineffective. Indeed, previous research indicates that women report higher pain tolerance levels when coping strategies are matched with preferred coping style (Rokke and al’Absi, 1995). Therefore, if women prefer to focus on the emotional component of pain, they might not necessarily benefit from instructions to focus on the sensory component. Evidence supporting this view comes from Robinson et al. (2000) who discuss how men and women generally respond to stress. They argue that stress responses tend to be consistent with dominant cultural gender role stereotypes; women focus more on the interpersonal and emotional aspects of a situation, while men seem to concentrate more on problemsolving (e.g. Vingerhoets and Van Heck, 1990). Unfortunately, no study has yet investigated whether males and females differentially respond to the effect sensory- and emotion-focused instructions have on experimental pain. The aim of the current study was, therefore, to investigate gender differences and coping instructions on the experience of cold pressor pain. It was predicted that the current study would: 1. replicate the findings of Keogh et al. (2000), in that men
would benefit from focusing on the sensory component of pain, and 2. find that women benefit from focusing on the emotional component rather than the sensory component of pain.
2. Method 2.1. Design A mixed-groups design was employed. The betweengroups factor was gender (male vs. female) and the within-groups factor was coping instruction (sensoryfocused vs. emotion-focused). The dependent variables consisted of pain experience measures, including pain tolerance, pain threshold and self-report measures of pain. 2.2. Participants Fifty students were recruited from Goldsmiths College, University of London. There were 26 females and 24 males between 18 and 39 years of age (mean 24.11 years, SD 5.79). Age was not recorded for five participants. 2.3. Pain induction technique Following our previous coping study (Keogh et al., 2000) the cold pressor task was selected as the experimental pain induction technique. In order to provide a baseline starting temperature (Wolff, 1984), participants placed their nondominant arm in a warm water bath (378C) for 2 min before transferring the hand into an ice-water bath maintained at a temperature of 1–28C. Unknown to participants, an upper time limit of 2 min was used at which point they were asked to remove their hand from the cold tank (Wolff, 1984). The cold pressor task allows the measurement of pain threshold, which is the point of just noticeable pain, and pain tolerance, which is the point at which individuals can no longer tolerate pain and as a result withdraw from the noxious stimulus. This task has previously been found to possess excellent reliability and validity (Reading, 1984; Wolff, 1984; Chapman et al., 1985; Edens and Gil, 1995). 2.4. Attention manipulation instructions Participants were initially allocated randomly to one of two attentional strategy conditions. When in the sensoryfocused condition, participants were instructed to concentrate on the physical sensations they experienced from the cold water. They were required to concentrate on the cold water and the sensory feelings and experiences it produced. When in the emotion-focused condition, participants were instructed to concentrate on the emotional feelings and responses that the cold water evoked. A ‘control’ condition was not included in the current study, since pilot work revealed that it is difficult for participants to be ‘neutral’ in such situations. Indeed, previous
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research by Cioffi and Holloway (1993) also indicates that a control no-instruction condition results in participants choosing an avoidant or focused strategy anyway. They ended up dropping their control group because the results from this group were difficult to interpret. Finally, a simple ‘yes/no’ manipulation check was administered following each cold pressor task. Participants were simply asked whether they were able to carry out the attention-focused instructions. All participants reported success in carrying out such instructions. 2.5. Procedure Participants were initially screened to ensure that they did not currently suffer from pain, had no history of cardiovascular disease or diabetes, and were not currently on any medication. No participant reported any of the above. All participants were then required to sign a consent form indicating that they were aware of the pain manipulation to be used and that they agreed to participate. The experimental procedure was approved by Goldsmiths College Human Ethical Committee, and conformed to the ethical guidelines for pain research in humans as recommended by the International Association for the Study of Pain, Committee on Ethical Issues (1995). All participants completed both the sensory- and emotion-focused attention conditions in the same testing session, with a 15 min gap between each task. Participants were randomly allocated to complete either the sensoryfocused or emotion-focused instruction condition first, followed by the second version of the task. The order of coping instructions was entered as a between-groups factor in all analyses but was not found to have a significant effect. These results indicate that carry-over effects were not a problem in this study and so are not reported any further. During the first cold pressor task, the hand was immersed in the ice water, to which participants indicated at what point they first began to feel pain (i.e. pain threshold) and at what point they could no longer tolerate it (i.e. pain tolerance). Participants then completed the McGill Pain Questionnaire – Short Form (MPQ-SF; Melzack, 1987), the short form version of the Depression Anxiety Stress Scale (DASS; Lovibond and Lovibond, 1995) and the Balanced Inventory of Desirable Responding (BIDR; Paulhus, 1991). Participants then completed a second cold pressor pain task with an alternative focused coping instruction, depending on which condition they had previously been in, followed by a second MPQ-SF. All trials were conducted by the same experimenter (M.H.). Although the experimenter was not blind to the attention manipulation, great care was taken to ensure the standardization of instructions throughout. The duration of the experiment was approximately half an hour, by which time the effect of the pain manipulation had dissipated. Participants were fully debriefed on conclusion of the task. The MPQ-SF was employed as a self-report measure of
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pain. The pain descriptor scale contains 11 sensory pain descriptors (e.g. throbbing, shooting) and four affective pain descriptors (e.g. sickening, fearful). Each descriptor is given a score between 0 (none) and 3 (severe). Validation data from a variety of therapeutic interventions before and after treatment (post-surgical, obstetric, physiotherapy and dental) reveal a high degree of consistency found between the full and short versions of the MPQ (Melzack, 1987), as well as demonstrating sensitivity to the effects of analgesic drugs, epidural blocks and transcutaneous electrical nerve stimulation. This scale has also been used with similar groups in previous research by the current authors (e.g. Keogh and Birkby, 1999; Keogh et al., 2000; Keogh and Mansoor, 2001). The DASS and BIDR were included to ensure that males and females did not differ significantly with respect to either current mood or social desirability. The DASS is a 21-item self-report scale that measures depression (DASS-D), anxiety (DASS-A) and stress (DASS-S) experienced over the past week. Recent research indicates that it has excellent reliability and validity and it is particularly good at discriminating between anxiety and depression (for discussion see Keogh and Reidy, 2000). The BIDR is a 40-item measure of social response bias and consists of two scales: self-deceptive enhancement (SDE; the tendency to give self-reports that are honest but positively biased) and impression management (IM; deliberate self-presentation to an audience). The BIDR is also reported to have good reliability and validity (Paulhus, 1991). Independent t-tests were performed between males and females on age and scores from the DASS and BIDR (for means see Table 1). The only significant differences found were on the DASS-S (tð48Þ ¼ 2:30, P , 0:05) and BIDRIM scales (tð48Þ ¼ 2:25, P , 0:05). Females scored higher on the stress and IM scales when compared to males (see below). 3. Results 3.1. Data screening Pain experience scores taken following the sensory- and emotion-focused instruction conditions are shown separately for makes and females in Table 2. Data screening Table 1 Differences between males and females in self-reported mood and social desirability a
DASS-S* DASS-A DASS-D SDE IM* a
Males
Females
8.00 (7.96) 4.08 (5.82) 5.83 (6.62) 4.58 (3.54) 2.54 (2.32)
14.15 (10.66) 4.77 (5.40) 6.23 (7.12) 3.88 (2.58) 4.04 (2.37)
Standard deviations are in parentheses. *P , 0:05.
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Table 2 Means and standard deviations (in parentheses) for pain measures by gender (males vs. females) and attention instructions (sensory- vs. emotion-focused) Male (n ¼ 24)
Threshold Tolerance MPQ-SF: sensory MPQ-SF: affective a
Female (n ¼ 26)
Sensory-focused
Emotion-focused
Sensory-focused
Emotion-focused
18.66 (10.96) a 60.48 (45.02) 10.25 (4.25) 1.71 (1.76)
15.53 (6.91) a 48.84 (34.99) 12.13 (3.66) 1.46 (1.56)
11.56 (6.42) 28.65 (17.60) 14.54 (5.43) 1.81 (1.86)
12.90 (8.47) 34.65 (22.63) 13.19 (5.11) 2.35 (2.33)
n ¼ 23.
of the raw data revealed that the pain threshold score for one male was an extreme outlier. Following the recommendations of Tabachnick and Fidell (2000) this data point was removed from the pain threshold analysis. 3.2. Correlational analysis Since differences between males and females were found in stress and IM, it is possible that pain scores may be confounded with such measures. Correlational analyses were conducted between the averaged pain scores and the DASS and BIDR scales separately for men and women. Neither of the social desirability scales were significantly correlated with any of the pain measures, indicating that while gender differences may exist in IM, such differences are not related to pain scores. However, some correlations involving the DASS scales were found. Amongst females, the DASS-A scale was positively related to sensory pain scores (r ¼ 0:45, P , 0:05), and all three DASS scales were significantly correlated with the affective pain scale score (DASS-S, r ¼ 0:60, P , 0:001; DASS-A, r ¼ 0:66, P , 0:001; DASS-D, r ¼ 0:68, P , 0:001). Interestingly, similar significant relationships were not found amongst men. In order to control for the potential confounding overlap between the pain measures and the various DASS scales, DASS-A was included as a covariate in the sensory pain index analysis, whereas a composite DASS score was included as a covariate for the affective pain index. A composite total DASS score was used rather than the three subscales since Tabachnick and Fidell (2000) warn against using multiple covariates due to reductions in power.
effects analysis revealed that when in the sensory-focused condition, males had a higher pain threshold compared to women (Fð1; 47Þ ¼ 7:86, P , 0:01). Furthermore, for men, focusing on the sensory component resulted in a higher threshold than focusing on the emotional component (Fð1; 47Þ ¼ 7:48, P , 0:01). No other significant effects were found. 3.4. Pain tolerance For pain tolerance a similar pattern of results was found. A significant main effect was found for gender (Fð1; 48Þ ¼ 7:08, P , 0:05). Females exhibited lower pain tolerance levels (mean 31.65 s) when compared to males (mean 55.66 s). Additionally, a significant interaction was found between gender and attentional strategy (Fð1; 48Þ ¼ 9:17, P , 0:005; see Fig. 2). Simple effects analysis revealed that when in the sensory-focused condition, men had a higher pain tolerance compared to women (Fð1; 48Þ ¼ 11:17, P , 0:005). Furthermore, amongst men, focusing on the sensory component resulted in a higher tolerance than focusing on the emotional component (Fð1; 48Þ ¼ 13:61, P , 0:005). No other significant effects were found. 3.5. Sensory experience of pain In order to determine the role of gender and coping instructions on the subjective experience of pain, mixed-
3.3. Pain threshold A mixed-groups analysis of variance (ANOVA) was performed with gender (males vs. female) serving as the between-groups factor and coping instruction (sensory vs. emotion) as the within-groups factor. For pain threshold, a significant main effect of gender was found (females ¼ 12:23 s, males ¼ 17:09 s; Fð1; 47Þ ¼ 4:67, P , 0:05). However, this should be interpreted in light of a significant interaction between gender and attentional strategy (Fð1; 47Þ ¼ 8:10, P , 0:01; see Fig. 1). Simple
Fig. 1. Mean (^SEM) effect of focusing on sensory and emotional components of pain on the pain threshold of men and women. *Significant difference between conditions (P , 0:01).
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Fig. 2. The effect of focusing on sensory and emotional components of pain on the pain tolerance of men and women. *Significant difference between conditions (P , 0:05).
groups analysis of covariance (ANCOVA) was conducted on the sensory and affective dimensions of the MPQ-SF. For the sensory dimension, initial analysis revealed that when DASS-A was entered as a covariate, it was not found to be significant, and so was dropped from the analysis (there was no difference in the pattern of results with or without this covariate included). Analysis revealed a significant main effect for gender (Fð1; 48Þ ¼ 4:56, P , 0:05). Females exhibited higher sensory pain levels (mean 13.87 s) when compared to males (mean 11.19 s). In addition, a significant interaction was found between gender and attentional strategy (Fð1; 48Þ ¼ 13:44, P , 0:001; see Fig. 3). Simple effects analysis revealed that when in the sensory-focused condition, males reported lower sensory pain than women (Fð1; 48Þ ¼ 9:57, P , 0:005). Furthermore, amongst men, focusing on the sensory component resulted in a lower sensory pain score than focusing on the emotional component (Fð1; 48Þ ¼ 8:76, P , 0:01). Amongst females, however, sensory pain reports increased when focusing on sensory pain responses compared to when focusing on emotional responses (Fð1; 48Þ ¼ 4:89, P , 0:05). 3.6. Affective experience of pain The final analysis was conducted on the affective pain
Fig. 3. The effect of focusing on sensory and emotional components of pain on the reported sensory pain experiences of men and women (controlling for anxiety). *Significant difference between conditions (P , 0:05).
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Fig. 4. The effect of focusing on sensory and emotional components of pain on the reported affective pain experiences of men and women (controlling for negative mood). *Significant difference between conditions (P , 0:05).
scores, with the composite DASS index included as a covariate. Even though the DASS composite was found to be a significant covariate (Fð1; 47Þ ¼ 13:23, P , 0:001), an interaction between gender and attentional strategy was still found to be significant (Fð1; 48Þ ¼ 4:30, P , 0:05; see Fig. 4). Simple effects analysis revealed that amongst females, an increase in affective pain responses was found when focusing on the emotional component of pain compared to when focusing on the sensory component (Fð1; 48Þ ¼ 5:40, P , 0:05). No other significant effects were found.
4. Discussion The results of the current study clearly confirm that gender differences exist in the perception of pain. Females had lower cold pressor pain thresholds and pain tolerance levels, as well as reporting greater sensory pain than males. These results are not only consistent with experimental research into gender differences in pain perception (e.g. Keogh and Birkby, 1999; Keogh et al., 2000), but are also consistent with the growing body of clinical and epidemiological evidence that females report more negative pain experiences than males (Unruh, 1996; Berkley, 1997). The primary aim of the current study was, however, to determine whether men and women would differentially respond to sensory- and emotion-focused coping instructions. When focusing on the sensory component of pain, males had a higher threshold and tolerance to pain, as well as reporting lower sensory pain when compared to females. The fact that sensory focusing seems to benefit men but not women is consistent with the results of Keogh et al. (2000) who also found that males benefited from sensory focusing when compared to females. However, the Keogh et al. (2000) study found that sensory focusing was only beneficial for self-reported sensory pain, whereas the current study found sensory focusing to increase threshold and
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tolerance as well. Even so, regardless of the slight differences between these two studies, the basic pattern of effects has been replicated; sensory focusing is beneficial for men but not necessarily for women. In addition to investigating gender differences in sensory focusing, the current study also examined emotion-focused instructions. It was predicted that since females benefit from emotion focusing when under stress (see Robinson et al., 2000), a similar pattern would be found for pain. Somewhat surprising, therefore, was the finding that compared to focusing on sensory responses, when focusing on emotional responses to pain, females reported higher affective pain scores. This suggests that rather than benefiting women, concentrating on the emotional responses may actually have a detrimental effect in terms of women’s subjective experience of affective pain. If so, then not all types of focusing are beneficial. One possible reason why, compared to men, women did not benefit from either sensory- or emotion-based focusing could be that the emotions being experienced were negative. Indeed, negative cognitions and emotions, especially those relating to catastrophizing, are known to affect women more than men (Osman et al., 1997; Sullivan et al., 2000; Keefe et al., 2000). An alternative explanation could be that females prefer and benefit from a greater choice of strategies. Previous research certainly indicates that women report using a wider range of coping strategies (Unruh et al., 1999). Given that the current study only allowed use of a single strategy at a time, women may have benefited from a greater choice of strategies. Alternatively, it is possible that a greater range of strategy use could reflect the failure of coping strategies to substantially reduce pain, and so alternative techniques are sought. If many coping strategies are generally ineffective for women, this may explain why they are more likely than men to make use of alternative approaches to pain management, such as herbal remedies (Berkley and Holdcroft, 1999). The implications of the current study are potentially important for pain management since they suggest that men and women differ in their response to cognitive coping instructions. We are already aware of differences between men and women in analgesic responsiveness (Ciccone and Holdcroft, 1999), and the current results suggest that psychological differences also exist. These results certainly indicate that we need to know more about the beneficial, and possibly detrimental, effects of coping instructions. Unfortunately, one of the main problems is that the literature on the effectiveness of pain coping strategies is quite mixed, and very few studies directly investigate the role of gender on the efficacy of coping strategies (Jensen et al., 1991; Robinson et al., 2000). Regarding potential limitations with the current study, it should be noted that no attempt was made to determine the menstrual cycle phase or the use of oral contraceptives. If the menstrual phase affects attentional processes, then it is possible that one reason why sensory focusing fails to have
a beneficial effect for females, compared to males, could be due to the variable hormonal status of women. An additional limitation is that the (female) experimenter was not blind to the attention manipulation. Given that the sex of the experimenter has been found to influence participants’ pain experiences (Levine and De Simone, 1991), experimenter effects and expectations cannot be ruled out. However, the inclusions of the BIDR scale should have, to some extent, controlled for such socially desirable responses. Finally, since it is not possible to devise a neutral ‘control’ strategy condition (see also Cioffi and Holloway, 1993), it is unclear how the sensory- and emotion-focused instructions affect pain relative to baseline. Such limitations should be taken into consideration when interpreting the current results. In terms of future directions it would be interesting to compare sensory avoidance and emotional avoidance instructions. It is possible that women may benefit from emotional avoidance, especially given that the current study found that women seem to respond negatively to emotional focusing. It is also important to determine whether sensory-focused strategies are useful in clinical settings for acute and chronic pain patients. It is likely that while pain coping strategies are important, they are probably going to be most effective as part of a multidisciplinary pain management intervention rather than being administered in isolation. Future research may also wish to extend the current study by taking hormonal and cardiovascular measures, both of which are linked to differences in pain perception amongst men and women, and determine whether they are also affected by coping manipulations. Finally, and perhaps most importantly, it has yet to be ascertained which coping strategies may most benefit women. Most research tends to show that women are at a disadvantage, and so further research is required to determine more generally which strategies actually reduce the negative impact of pain for women. In conclusion, the current study clearly indicates that pain coping instructions have a differential effect on the pain experiences of men and women. This study replicates the findings of Keogh et al. (2000) by finding that males benefit from focusing on the sensory component of pain when compared to females. This study also extends previous research by demonstrating that males do not necessarily benefit from focusing on the emotional component of pain. Furthermore, for females, emotional focusing instructions (compared to sensory focusing) actually resulted in an increase in affective pain experiences. Further research is clearly required to determine which coping strategies are best suited to men and women and in doing so lead to a more effective management of pain.
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Gender, coping and the perception of pain Edmund Keogh*, Malin Herdenfeldt Department of Psychology, Goldsmiths College, University of London, New Cross, London SE14 6NW, UK Received 18 May 2001; received in revised form 13 August 2001; accepted 17 September 2001
Abstract Research consistently indicates that gender differences exist in pain perception, with females typically reporting more negative responses to pain than males. It also seems as if males and females use and benefit from different coping strategies when under stress; females seem to prefer emotion-focused coping, whereas males prefer sensory-focused coping. Unfortunately, experimental research that examines such differences in the context of pain has not yet been adequately investigated. The aim of the current study was, therefore, to determine whether gender differences would be found in the effect that sensory-focused and emotion-focused coping instructions have on cold pressor pain experiences. Participants consisted of 24 male and 26 female healthy adults, all of whom reported no current pain. A consistent pattern of effects was found, over both behavioural and self-report measures of pain. Compared to females, males exhibited less negative pain responses when focusing on the sensory component of pain (i.e. increased threshold, tolerance and lower sensory pain). Furthermore, compared to sensory focusing, emotional focusing was found to increase the affective pain experience of females. Together these results confirm that important differences exist between men and women in the effects pain coping instructions have on the experience of pain. The implications of such findings for research and practice are discussed. q 2002 International Association for the study of Pain. Published by Elsevier Science B.V. All rights reserved. Keywords: Pain; Attention; Gender; Cold pressor; Coping
1. Introduction It is now generally accepted that males and females exhibit important differences in their pain experiences (Fillingim and Maixner, 1995; Berkley and Holdcroft, 1999; Fillingim and Ness, 2000). For example, epidemiological studies indicate that females report more pain experiences and more negative responses to pain compared to males (Unruh, 1996). Furthermore, clinically based research suggests that there are important gender differences in susceptibility to pain-related diseases, analgesic effectiveness, as well as recovery from anaesthesia (Berkley, 1997; Ciccone and Holdcroft, 1999; Myles et al., 2001). Finally, experimental pain induction studies reveal that females consistently exhibit lower thresholds and tolerance to a wide range of noxious stimuli (Riley et al., 1998; Rollman et al., 2000). Numerous explanations have been proposed to account for such gender differences (Fillingim, 2000). While most explanations concentrate on biological mechanisms (e.g. genetic, hormonal, cardiovascular), it is becoming increasingly clear that social and psychological factors are also
* Corresponding author. Tel.: 144-20-7919-7893; fax: 144-20-79197873. E-mail address: [email protected] (E. Keogh).
important (e.g. developmental, emotional and cognitive). One psychological mechanism that is thought to play an important role in effective pain management is cognitive coping strategy. Although there are many different types of coping (Jensen et al., 1991; Boothby et al., 1999), most can be classified as either focused or avoidant strategies. In terms of the effect such strategies have on pain, Suls and Fletcher (1985) report that avoidance provides some benefit in the short term, whereas in the long term the effectiveness of such a strategy is questionable. Interestingly, experimental paradigms that have compared focused and avoidance instructions also find negative pain effects for cognitive avoidance in otherwise healthy individuals (e.g. Cioffi and Holloway, 1993). Such research led Boothby et al. (1999) to argue that the strategies that seem associated with better outcome are those that involve the patient actively focusing on the pain rather than passively avoiding it. Given that individuals develop their own strategies for coping with painful sensations, and since men and women experience pain differentially, it is likely that males and females will develop different coping styles (Jensen et al., 1994; Weir et al., 1996; Robinson et al., 2000). Unfortunately, little research has investigated whether gender moderates (or mediates) the effectiveness of pain coping strategies (Sullivan et al., 2000; Keefe et al., 2000). This
0304-3959/02/$20.00 q 2002 International Association for the study of Pain. Published by Elsevier Science B.V. All rights reserved. PII: S 0304-395 9(01)00427-4
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is surprising given that the research that has been conducted suggests that important gender differences exist. Unruh et al. (1999), for example, presented results from a communitybased telephone survey of people who reported pain in the 2 weeks before the interview. They found that compared to men, women reported significantly more intense pain, as well as using a greater range of coping strategies, i.e. greater social support seeking, problem-solving, positive self-statements and palliative behaviours. In a second study, Grossi et al. (2000) investigated gender differences in coping strategies used by patients with musculoskeletal pain. They found that for women a poorer ability to cope with pain was related to a higher level of emotional distress, greater disability, and a history of treatments for pain. No such effects were found for men. Together the results of Unruh et al. (1999) and Grossi et al. (2000) indicate that there are important gender differences in the use of coping strategies. What is unclear from these studies, however, is whether such differences cause the variability in pain experience. Fortunately, experimental designs that manipulate coping instructions allow a more rigorous investigation of such gender effects. Keogh et al. (2000), for example, investigated differences between men and women in the efficacy of focused and avoidance coping instructions on cold pressor pain responses. As expected, males were found to be more tolerant to cold pressor pain than females. However, males also reported less sensory pain when they attended toward the pain than when they avoided it. This beneficial effect of sensory focusing was not found in women suggesting that such a strategy may only be useful for males (see also Keogh and Mansoor, 2001). Why should females fail to benefit from sensory focusing? One possible explanation could be that the instructions given to women did not match their preferred coping style, and so were ineffective. Indeed, previous research indicates that women report higher pain tolerance levels when coping strategies are matched with preferred coping style (Rokke and al’Absi, 1995). Therefore, if women prefer to focus on the emotional component of pain, they might not necessarily benefit from instructions to focus on the sensory component. Evidence supporting this view comes from Robinson et al. (2000) who discuss how men and women generally respond to stress. They argue that stress responses tend to be consistent with dominant cultural gender role stereotypes; women focus more on the interpersonal and emotional aspects of a situation, while men seem to concentrate more on problemsolving (e.g. Vingerhoets and Van Heck, 1990). Unfortunately, no study has yet investigated whether males and females differentially respond to the effect sensory- and emotion-focused instructions have on experimental pain. The aim of the current study was, therefore, to investigate gender differences and coping instructions on the experience of cold pressor pain. It was predicted that the current study would: 1. replicate the findings of Keogh et al. (2000), in that men
would benefit from focusing on the sensory component of pain, and 2. find that women benefit from focusing on the emotional component rather than the sensory component of pain.
2. Method 2.1. Design A mixed-groups design was employed. The betweengroups factor was gender (male vs. female) and the within-groups factor was coping instruction (sensoryfocused vs. emotion-focused). The dependent variables consisted of pain experience measures, including pain tolerance, pain threshold and self-report measures of pain. 2.2. Participants Fifty students were recruited from Goldsmiths College, University of London. There were 26 females and 24 males between 18 and 39 years of age (mean 24.11 years, SD 5.79). Age was not recorded for five participants. 2.3. Pain induction technique Following our previous coping study (Keogh et al., 2000) the cold pressor task was selected as the experimental pain induction technique. In order to provide a baseline starting temperature (Wolff, 1984), participants placed their nondominant arm in a warm water bath (378C) for 2 min before transferring the hand into an ice-water bath maintained at a temperature of 1–28C. Unknown to participants, an upper time limit of 2 min was used at which point they were asked to remove their hand from the cold tank (Wolff, 1984). The cold pressor task allows the measurement of pain threshold, which is the point of just noticeable pain, and pain tolerance, which is the point at which individuals can no longer tolerate pain and as a result withdraw from the noxious stimulus. This task has previously been found to possess excellent reliability and validity (Reading, 1984; Wolff, 1984; Chapman et al., 1985; Edens and Gil, 1995). 2.4. Attention manipulation instructions Participants were initially allocated randomly to one of two attentional strategy conditions. When in the sensoryfocused condition, participants were instructed to concentrate on the physical sensations they experienced from the cold water. They were required to concentrate on the cold water and the sensory feelings and experiences it produced. When in the emotion-focused condition, participants were instructed to concentrate on the emotional feelings and responses that the cold water evoked. A ‘control’ condition was not included in the current study, since pilot work revealed that it is difficult for participants to be ‘neutral’ in such situations. Indeed, previous
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research by Cioffi and Holloway (1993) also indicates that a control no-instruction condition results in participants choosing an avoidant or focused strategy anyway. They ended up dropping their control group because the results from this group were difficult to interpret. Finally, a simple ‘yes/no’ manipulation check was administered following each cold pressor task. Participants were simply asked whether they were able to carry out the attention-focused instructions. All participants reported success in carrying out such instructions. 2.5. Procedure Participants were initially screened to ensure that they did not currently suffer from pain, had no history of cardiovascular disease or diabetes, and were not currently on any medication. No participant reported any of the above. All participants were then required to sign a consent form indicating that they were aware of the pain manipulation to be used and that they agreed to participate. The experimental procedure was approved by Goldsmiths College Human Ethical Committee, and conformed to the ethical guidelines for pain research in humans as recommended by the International Association for the Study of Pain, Committee on Ethical Issues (1995). All participants completed both the sensory- and emotion-focused attention conditions in the same testing session, with a 15 min gap between each task. Participants were randomly allocated to complete either the sensoryfocused or emotion-focused instruction condition first, followed by the second version of the task. The order of coping instructions was entered as a between-groups factor in all analyses but was not found to have a significant effect. These results indicate that carry-over effects were not a problem in this study and so are not reported any further. During the first cold pressor task, the hand was immersed in the ice water, to which participants indicated at what point they first began to feel pain (i.e. pain threshold) and at what point they could no longer tolerate it (i.e. pain tolerance). Participants then completed the McGill Pain Questionnaire – Short Form (MPQ-SF; Melzack, 1987), the short form version of the Depression Anxiety Stress Scale (DASS; Lovibond and Lovibond, 1995) and the Balanced Inventory of Desirable Responding (BIDR; Paulhus, 1991). Participants then completed a second cold pressor pain task with an alternative focused coping instruction, depending on which condition they had previously been in, followed by a second MPQ-SF. All trials were conducted by the same experimenter (M.H.). Although the experimenter was not blind to the attention manipulation, great care was taken to ensure the standardization of instructions throughout. The duration of the experiment was approximately half an hour, by which time the effect of the pain manipulation had dissipated. Participants were fully debriefed on conclusion of the task. The MPQ-SF was employed as a self-report measure of
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pain. The pain descriptor scale contains 11 sensory pain descriptors (e.g. throbbing, shooting) and four affective pain descriptors (e.g. sickening, fearful). Each descriptor is given a score between 0 (none) and 3 (severe). Validation data from a variety of therapeutic interventions before and after treatment (post-surgical, obstetric, physiotherapy and dental) reveal a high degree of consistency found between the full and short versions of the MPQ (Melzack, 1987), as well as demonstrating sensitivity to the effects of analgesic drugs, epidural blocks and transcutaneous electrical nerve stimulation. This scale has also been used with similar groups in previous research by the current authors (e.g. Keogh and Birkby, 1999; Keogh et al., 2000; Keogh and Mansoor, 2001). The DASS and BIDR were included to ensure that males and females did not differ significantly with respect to either current mood or social desirability. The DASS is a 21-item self-report scale that measures depression (DASS-D), anxiety (DASS-A) and stress (DASS-S) experienced over the past week. Recent research indicates that it has excellent reliability and validity and it is particularly good at discriminating between anxiety and depression (for discussion see Keogh and Reidy, 2000). The BIDR is a 40-item measure of social response bias and consists of two scales: self-deceptive enhancement (SDE; the tendency to give self-reports that are honest but positively biased) and impression management (IM; deliberate self-presentation to an audience). The BIDR is also reported to have good reliability and validity (Paulhus, 1991). Independent t-tests were performed between males and females on age and scores from the DASS and BIDR (for means see Table 1). The only significant differences found were on the DASS-S (tð48Þ ¼ 2:30, P , 0:05) and BIDRIM scales (tð48Þ ¼ 2:25, P , 0:05). Females scored higher on the stress and IM scales when compared to males (see below). 3. Results 3.1. Data screening Pain experience scores taken following the sensory- and emotion-focused instruction conditions are shown separately for makes and females in Table 2. Data screening Table 1 Differences between males and females in self-reported mood and social desirability a
DASS-S* DASS-A DASS-D SDE IM* a
Males
Females
8.00 (7.96) 4.08 (5.82) 5.83 (6.62) 4.58 (3.54) 2.54 (2.32)
14.15 (10.66) 4.77 (5.40) 6.23 (7.12) 3.88 (2.58) 4.04 (2.37)
Standard deviations are in parentheses. *P , 0:05.
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Table 2 Means and standard deviations (in parentheses) for pain measures by gender (males vs. females) and attention instructions (sensory- vs. emotion-focused) Male (n ¼ 24)
Threshold Tolerance MPQ-SF: sensory MPQ-SF: affective a
Female (n ¼ 26)
Sensory-focused
Emotion-focused
Sensory-focused
Emotion-focused
18.66 (10.96) a 60.48 (45.02) 10.25 (4.25) 1.71 (1.76)
15.53 (6.91) a 48.84 (34.99) 12.13 (3.66) 1.46 (1.56)
11.56 (6.42) 28.65 (17.60) 14.54 (5.43) 1.81 (1.86)
12.90 (8.47) 34.65 (22.63) 13.19 (5.11) 2.35 (2.33)
n ¼ 23.
of the raw data revealed that the pain threshold score for one male was an extreme outlier. Following the recommendations of Tabachnick and Fidell (2000) this data point was removed from the pain threshold analysis. 3.2. Correlational analysis Since differences between males and females were found in stress and IM, it is possible that pain scores may be confounded with such measures. Correlational analyses were conducted between the averaged pain scores and the DASS and BIDR scales separately for men and women. Neither of the social desirability scales were significantly correlated with any of the pain measures, indicating that while gender differences may exist in IM, such differences are not related to pain scores. However, some correlations involving the DASS scales were found. Amongst females, the DASS-A scale was positively related to sensory pain scores (r ¼ 0:45, P , 0:05), and all three DASS scales were significantly correlated with the affective pain scale score (DASS-S, r ¼ 0:60, P , 0:001; DASS-A, r ¼ 0:66, P , 0:001; DASS-D, r ¼ 0:68, P , 0:001). Interestingly, similar significant relationships were not found amongst men. In order to control for the potential confounding overlap between the pain measures and the various DASS scales, DASS-A was included as a covariate in the sensory pain index analysis, whereas a composite DASS score was included as a covariate for the affective pain index. A composite total DASS score was used rather than the three subscales since Tabachnick and Fidell (2000) warn against using multiple covariates due to reductions in power.
effects analysis revealed that when in the sensory-focused condition, males had a higher pain threshold compared to women (Fð1; 47Þ ¼ 7:86, P , 0:01). Furthermore, for men, focusing on the sensory component resulted in a higher threshold than focusing on the emotional component (Fð1; 47Þ ¼ 7:48, P , 0:01). No other significant effects were found. 3.4. Pain tolerance For pain tolerance a similar pattern of results was found. A significant main effect was found for gender (Fð1; 48Þ ¼ 7:08, P , 0:05). Females exhibited lower pain tolerance levels (mean 31.65 s) when compared to males (mean 55.66 s). Additionally, a significant interaction was found between gender and attentional strategy (Fð1; 48Þ ¼ 9:17, P , 0:005; see Fig. 2). Simple effects analysis revealed that when in the sensory-focused condition, men had a higher pain tolerance compared to women (Fð1; 48Þ ¼ 11:17, P , 0:005). Furthermore, amongst men, focusing on the sensory component resulted in a higher tolerance than focusing on the emotional component (Fð1; 48Þ ¼ 13:61, P , 0:005). No other significant effects were found. 3.5. Sensory experience of pain In order to determine the role of gender and coping instructions on the subjective experience of pain, mixed-
3.3. Pain threshold A mixed-groups analysis of variance (ANOVA) was performed with gender (males vs. female) serving as the between-groups factor and coping instruction (sensory vs. emotion) as the within-groups factor. For pain threshold, a significant main effect of gender was found (females ¼ 12:23 s, males ¼ 17:09 s; Fð1; 47Þ ¼ 4:67, P , 0:05). However, this should be interpreted in light of a significant interaction between gender and attentional strategy (Fð1; 47Þ ¼ 8:10, P , 0:01; see Fig. 1). Simple
Fig. 1. Mean (^SEM) effect of focusing on sensory and emotional components of pain on the pain threshold of men and women. *Significant difference between conditions (P , 0:01).
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Fig. 2. The effect of focusing on sensory and emotional components of pain on the pain tolerance of men and women. *Significant difference between conditions (P , 0:05).
groups analysis of covariance (ANCOVA) was conducted on the sensory and affective dimensions of the MPQ-SF. For the sensory dimension, initial analysis revealed that when DASS-A was entered as a covariate, it was not found to be significant, and so was dropped from the analysis (there was no difference in the pattern of results with or without this covariate included). Analysis revealed a significant main effect for gender (Fð1; 48Þ ¼ 4:56, P , 0:05). Females exhibited higher sensory pain levels (mean 13.87 s) when compared to males (mean 11.19 s). In addition, a significant interaction was found between gender and attentional strategy (Fð1; 48Þ ¼ 13:44, P , 0:001; see Fig. 3). Simple effects analysis revealed that when in the sensory-focused condition, males reported lower sensory pain than women (Fð1; 48Þ ¼ 9:57, P , 0:005). Furthermore, amongst men, focusing on the sensory component resulted in a lower sensory pain score than focusing on the emotional component (Fð1; 48Þ ¼ 8:76, P , 0:01). Amongst females, however, sensory pain reports increased when focusing on sensory pain responses compared to when focusing on emotional responses (Fð1; 48Þ ¼ 4:89, P , 0:05). 3.6. Affective experience of pain The final analysis was conducted on the affective pain
Fig. 3. The effect of focusing on sensory and emotional components of pain on the reported sensory pain experiences of men and women (controlling for anxiety). *Significant difference between conditions (P , 0:05).
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Fig. 4. The effect of focusing on sensory and emotional components of pain on the reported affective pain experiences of men and women (controlling for negative mood). *Significant difference between conditions (P , 0:05).
scores, with the composite DASS index included as a covariate. Even though the DASS composite was found to be a significant covariate (Fð1; 47Þ ¼ 13:23, P , 0:001), an interaction between gender and attentional strategy was still found to be significant (Fð1; 48Þ ¼ 4:30, P , 0:05; see Fig. 4). Simple effects analysis revealed that amongst females, an increase in affective pain responses was found when focusing on the emotional component of pain compared to when focusing on the sensory component (Fð1; 48Þ ¼ 5:40, P , 0:05). No other significant effects were found.
4. Discussion The results of the current study clearly confirm that gender differences exist in the perception of pain. Females had lower cold pressor pain thresholds and pain tolerance levels, as well as reporting greater sensory pain than males. These results are not only consistent with experimental research into gender differences in pain perception (e.g. Keogh and Birkby, 1999; Keogh et al., 2000), but are also consistent with the growing body of clinical and epidemiological evidence that females report more negative pain experiences than males (Unruh, 1996; Berkley, 1997). The primary aim of the current study was, however, to determine whether men and women would differentially respond to sensory- and emotion-focused coping instructions. When focusing on the sensory component of pain, males had a higher threshold and tolerance to pain, as well as reporting lower sensory pain when compared to females. The fact that sensory focusing seems to benefit men but not women is consistent with the results of Keogh et al. (2000) who also found that males benefited from sensory focusing when compared to females. However, the Keogh et al. (2000) study found that sensory focusing was only beneficial for self-reported sensory pain, whereas the current study found sensory focusing to increase threshold and
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tolerance as well. Even so, regardless of the slight differences between these two studies, the basic pattern of effects has been replicated; sensory focusing is beneficial for men but not necessarily for women. In addition to investigating gender differences in sensory focusing, the current study also examined emotion-focused instructions. It was predicted that since females benefit from emotion focusing when under stress (see Robinson et al., 2000), a similar pattern would be found for pain. Somewhat surprising, therefore, was the finding that compared to focusing on sensory responses, when focusing on emotional responses to pain, females reported higher affective pain scores. This suggests that rather than benefiting women, concentrating on the emotional responses may actually have a detrimental effect in terms of women’s subjective experience of affective pain. If so, then not all types of focusing are beneficial. One possible reason why, compared to men, women did not benefit from either sensory- or emotion-based focusing could be that the emotions being experienced were negative. Indeed, negative cognitions and emotions, especially those relating to catastrophizing, are known to affect women more than men (Osman et al., 1997; Sullivan et al., 2000; Keefe et al., 2000). An alternative explanation could be that females prefer and benefit from a greater choice of strategies. Previous research certainly indicates that women report using a wider range of coping strategies (Unruh et al., 1999). Given that the current study only allowed use of a single strategy at a time, women may have benefited from a greater choice of strategies. Alternatively, it is possible that a greater range of strategy use could reflect the failure of coping strategies to substantially reduce pain, and so alternative techniques are sought. If many coping strategies are generally ineffective for women, this may explain why they are more likely than men to make use of alternative approaches to pain management, such as herbal remedies (Berkley and Holdcroft, 1999). The implications of the current study are potentially important for pain management since they suggest that men and women differ in their response to cognitive coping instructions. We are already aware of differences between men and women in analgesic responsiveness (Ciccone and Holdcroft, 1999), and the current results suggest that psychological differences also exist. These results certainly indicate that we need to know more about the beneficial, and possibly detrimental, effects of coping instructions. Unfortunately, one of the main problems is that the literature on the effectiveness of pain coping strategies is quite mixed, and very few studies directly investigate the role of gender on the efficacy of coping strategies (Jensen et al., 1991; Robinson et al., 2000). Regarding potential limitations with the current study, it should be noted that no attempt was made to determine the menstrual cycle phase or the use of oral contraceptives. If the menstrual phase affects attentional processes, then it is possible that one reason why sensory focusing fails to have
a beneficial effect for females, compared to males, could be due to the variable hormonal status of women. An additional limitation is that the (female) experimenter was not blind to the attention manipulation. Given that the sex of the experimenter has been found to influence participants’ pain experiences (Levine and De Simone, 1991), experimenter effects and expectations cannot be ruled out. However, the inclusions of the BIDR scale should have, to some extent, controlled for such socially desirable responses. Finally, since it is not possible to devise a neutral ‘control’ strategy condition (see also Cioffi and Holloway, 1993), it is unclear how the sensory- and emotion-focused instructions affect pain relative to baseline. Such limitations should be taken into consideration when interpreting the current results. In terms of future directions it would be interesting to compare sensory avoidance and emotional avoidance instructions. It is possible that women may benefit from emotional avoidance, especially given that the current study found that women seem to respond negatively to emotional focusing. It is also important to determine whether sensory-focused strategies are useful in clinical settings for acute and chronic pain patients. It is likely that while pain coping strategies are important, they are probably going to be most effective as part of a multidisciplinary pain management intervention rather than being administered in isolation. Future research may also wish to extend the current study by taking hormonal and cardiovascular measures, both of which are linked to differences in pain perception amongst men and women, and determine whether they are also affected by coping manipulations. Finally, and perhaps most importantly, it has yet to be ascertained which coping strategies may most benefit women. Most research tends to show that women are at a disadvantage, and so further research is required to determine more generally which strategies actually reduce the negative impact of pain for women. In conclusion, the current study clearly indicates that pain coping instructions have a differential effect on the pain experiences of men and women. This study replicates the findings of Keogh et al. (2000) by finding that males benefit from focusing on the sensory component of pain when compared to females. This study also extends previous research by demonstrating that males do not necessarily benefit from focusing on the emotional component of pain. Furthermore, for females, emotional focusing instructions (compared to sensory focusing) actually resulted in an increase in affective pain experiences. Further research is clearly required to determine which coping strategies are best suited to men and women and in doing so lead to a more effective management of pain.
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