Fear of Pain in Recurrent Headache Sufferers
Karl G. Hursey, Ph.D. and S. Daniel Jacks, M.S.
Reprint requests to: Dr. K. G. Hursey, Department of Psychology, Texas A&M University, College Station TX 77843. Accepted For Publication: March 29, 1992 SYNOPSIS
We investigated the role of fear of pain in headache sufferers using the Fear of Pain Questionnaire (FPQ). Seventy-six headache sufferers and 58 controls completed the FPQ and measures of depression, anxiety, and anger. Headache sufferers also completed measures of stress-related physical symptoms and coping with pain. We found that the FPQ has excellent internal consistency as well as good concurrent and construct validity indicated by the high correlations between the FPQ subscales and both anxiety and depression but low correlations with anger. There were marked differences between headache sufferers and controls on the FPQ; headache sufferers showed much greater fear of severe and medical pain and lower fear of minor pain. Fear of pain was generally not related to headache characteristics such as frequency, severity, or duration. On the other hand, it was related to headache impact such as disruption of pleasurable activities. These results are consistent with models of chronic pain disorders which emphasize the role of fear of pain over the nociceptive intensity of the pain stimulus. Key Words: Fear of pain, anxiety, depression, anger. Abbreviations:
FPQ Fear of pain questionnaire
(Headache 1992, 32:283-286) Chronic pain disorders are characterized by the persistence of pain and disability with little or no organic pathology to account for them. Models of chronic pain disorders based on learning theory suggest that a reciprocal relationship between avoidance and fear maintains the disability and pain behaviors characteristic of these syndromes.1,2 According to Lethem, for example, avoidance of a pain-related stimulus reduces the state of fear triggered by that stimulus. This reduction in fear reinforces the avoidant response and makes avoidance more probable if the stimulus is encountered again. Over multiple trials avoidance becomes more strongly associated with fear of the stimulus and less associated with the actual nociceptive power of the stimulus. In fact, with successful avoidance the actual properties of the stimulus become largely irrelevant since they are rarely or never experienced. These models of chronic pain and disability strongly resemble learning theory models of anxiety disorders. Successful interventions for pain problems based on these models lend credence to the analogy.3 Learning models of chronic pain disorders such as Lethem's predict that individuals who suffer more frequent pain episodes will demonstrate greater avoidance coping and greater fear of pain than individuals who have less frequent pain episodes.4 In contrast, a traditional biomedical model of pain disorders predicts that greater fear of pain and more avoidance will be associated with greater pain intensity rather than greater frequency.4 Philips found that avoidance is a prominent coping strategy among headache sufferers and is more strongly related to headache chronicity than to headache intensity, consistent with the Fear-Avoidance model of chronic pain disorders.4,5 Unfortunately, Philips did not report any measure of fear in her studies. Thus, while avoidance coping has been convincingly linked to headache and other pain disorders, the role of fear of pain in headache sufferers remains unresolved. Despite the emphasis on fear of pain in various models of chronic pain disorders few measures of fear of pain have appeared. McNeil and his colleagues6 systematically developed and refined the Fear of Pain Questionnaire (FPQ) to fill this need. Based on the work of Lethem2 and to a lesser extent that of Bolles and Fanselow1 the FPQ consists of 30 items briefly describing painful situations and respondents rate how fearful they are of the pain associated with each situation. The FPQ yields three subscale scores (fear of Minor, Severe, and Medical pain) and a total score. Research by the developers supports the validity of the FPQ as a measure of fear of pain in non-clinical subjects exposed to laboratory pain-stimuli. Thus far, however, there has been no research on the FPQ with symptomatic populations. Methods
Overview. In this study we addressed five research problems: 1) The internal consistency of the FPQ in both headache sufferers and nonheadache participants; 2) The relationship of the FPQ to measures of psychological symptoms and somatic complaints in both headache and nonheadache participants; 3) The ability of fear of pain to discriminate headache and nonheadache participants; 4) The relationship between fear of pain and coping in headache sufferers (i.e., does pain-coping strategy predict fear of pain?); and 5) The relationship between fear of pain and headache symptoms (e.g., intensity, duration), headache impact (e.g., disruptiveness, distress), and headache
beliefs and expectations (e.g., headache self-efficacy, headache internal locus-of-control) in headache sufferers. Participants. Seventy-six headache sufferers (88% female) and 58 control participants (88% female) were recruited. Headache participants reported frequent and painful headaches consistent with Tension ("muscle-contraction") headaches as described by the Ad Hoc Committee on Diagnosis of Headache.7 These headache sufferers reported five or more at least moderately severe headaches per month; 87% reported one or more headaches per week and 40% reported daily headaches. All headache sufferers reported typical headache severity of 3 or more where 0 = No Headache and 5 = Extremely Painful (completely disabling) Headache on a standard headache intensity scale.8 Among the headache sufferers, 32% reported they were either currently taking prescription medication for headaches or had taken prescription medication for headaches in the past and 84% reported that they were taking Over-the-Counter headache medications once per month or more. Procedures. After receiving an explanation of the experimental procedures all participants provided written informed consent. Participants completed the FPQ, Beck Depression Inventory (BDI), and the state scales of the Spielberger State-Trait Personality Inventory (STPI). Headache sufferers also completed the Wahler Physical Symptoms Inventory (WPSI) and the Coping Strategies Questionnaire9 (CSQ) developed specifically to assess coping with pain. RESULTS
Internal Consistency. The three FPQ subscales and the Total FPQ score all showed moderate to high levels of internal consistency in both groups (Table 1). Fear of medical pain in the non-headache group showed the lowest coefficient alpha. The very high coefficient alphas for the Total FPQ score suggests that the subscales may not be as independent of one another as one might have hoped. Table 1 Internal consistency (Coefficient Alpha) of the FPQ Subscales and Total FPQ Scale Coefficient Alpha Headache Controls FPQ-Minor 0.86 0.71 FPQ-Severe 0.87 0.86 FPQ-Medical 0.87 0.64 FPQ-Total 0.92 0.80 Scale Intercorrelations. Next we correlated the FPQ subscales with one another using all of the participants. As shown in Table 2, fear of medical pain was correlated with both of the other subscales, especially fear of severe pain. This suggests that, at least in our subjects, fear of medical pain and fear of severe pain are very similar constructs.
Severe Medical **p < .001
Table 2 Intercorrelations of the FPQ subscales. Pearson Correlation Coefficients Minor Severe -0.06 0.30** 0.65**
Relationship of Fear of Pain to Measures of Psychological Symptoms and Somatic Complaints. Fear of Severe and Medical pain and total Fear of Pain were correlated with both depression and anxiety but not with anger (see Table 3). The FPQ-Minor scale showed a small but statistically significant correlation with depression only. The FPQ-Severe, Medical, and Total scores were correlated with the average of somatic complaints from the WPSI. The FPQ-Minor score was not correlated with the WPSI, however. Table 3 Correlations of FPQ subscales With Psychological Symptoms and Somatic Complaints Pearson Correlation Coefficients Depression Anxiety Anger Somatic Minor .19* .14 .14 .08 Severe .38** .34** .11 .38** Medical .42** .30** .05 .28** Total .46** .37** .13 .38** * p < .05 **p < .01
Discrimination of Groups. A Multivariate Analysis of Variance (MANOVA) on the FPQ scores by group (Headache versus Control) was significant (F(3,130) = 66.08, p < .001). Followup univariate analyses showed significant differences on all three FPQ subscales (see Table 4). Headache participants were much higher on fear of severe and medical pain and lower on fear of minor pain than the controls. Table 4 MANOVA on FPQ subscales by Group (Headache versus Control) Multivariate F(3,130) = 66.08, p < .001 Fear of Minor Pain Mean SD Univariate F(df = 1,132) Headache 10.88 6.88 9.82 p < .002 Control 14.31 5.38 Fear of Severe Pain Headache Control
28.25 11.33
7.58 8.08
154.83 p < .001
Fear of Medical Pain Headache Control
20.05 11.90
8.52 4.98
42.16 p < .001
Relationship to Pain Coping Strategies. Subscales from the CSQ were used to try to predict FPQ scores with multiple regression analyses. Although one or two coping scales (predictors) loaded significantly on each equation, the largest Adjusted R-Square was only .08 indicating that very little useful prediction could be made. Relationship to Headache Symptoms, Impact, and Beliefs/Expectations. We assessed the relationships between fear of pain and characteristics of the headache sufferers. For these analyses, continuously distributed variables were analyzed with
Pearson's Correlations. Categorical or severely skewed variables were recoded into discrete categories and analyzed using Chi Squares. For the Chi Squares, only the FPQ Total score was analyzed to keep the number of comparisons low. The FPQ-Total score was recorded as High (one standard deviation or more above the mean), Medium (within one standard deviation of the mean), and Low (one standard deviation or more below the mean) for the Chi Square analyses. Fear of minor pain was significantly (though not strongly) correlated with Headache Severity (r = .26, p < .05). Fear of pain was not related to headache frequency or duration, however. In addition, fear of pain was not related to use of either prescription or OTC medications. Chi Squares were highly significant for fear of pain and headache disruptiveness and distress (Table 5). Individuals with greater fear of pain reported more disruption of activities due to headache and more feelings of depression and anxiety associated with their headaches than did individuals with lower fear of pain. Finally, we found no relationship between fear of pain and headache self-efficacy or headache internal locus-of-control. Table 5 Fear of Pain and Headache Impact How much do your headaches: Chi Square Disrupt enjoyable activities 14.76** Cause psychological distress 11.50* Cause you to miss work/activities 7.14 *p < .01 **p < .001 DISCUSSION
The FPQ is an appropriate instrument for measuring fear of pain in symptomatic populations. In addition to being brief and easy to complete, it has good internal consistency, construct validity, and concurrent validity. In a broader sense, these results support Lethem's model and underscore the importance of fear in chronic and recurrent pain disorders. On the other hand, several areas where revisions are needed were identified as well. Our results showed that the FPQ is a reliable and valid measure of fear of pain. The very high alpha coefficients indicate that the FPQ subscales demonstrate excellent internal consistency. Intercorrelations among the FPQ subscales suggest that these scales are meaningfully related but also provide independent information about fear of pain. On the other hand, the high intersubscale correlations of the FPQ suggests that the individual subscales may not be as distinct as they should be. Further research can clarify the components of fear of pain. The concurrent and construct validity of the FPQ was indicated by the high correlations between the FPQ subscales and measures of anxiety and depression while there were low correlations with anger. Finally, the marked differences between headache sufferers and controls supports the ecological validity of the FPQ. A second goal of this study was to investigate the applicability of fear of pain as conceptualized in Lethem's Fear-Avoidance model to chronic headache disorders. The lower fear of minor pain among headache sufferers is consistent with Lethem's prediction of decreased fear following exposure to less severe pain episodes. Exposure allows greater synchronization between actual nociceptive intensity and affective reaction which become desynchronized in chronic pain disorders, according to Lethem.2 These headache sufferers presumably experience more overall episodes of pain than the control participants and thus report less fear. On the other hand, the much greater fear of both severe and medical pain among headache participants appears to conflict with these same predictions. Lethem does suggest that acute episodes of severe pain may sensitize individuals to fear of pain and in fact we did find a small but significant correlation between fear of minor pain and the typical headache severity reported by our headache sufferers. There was no such correlation with fear of severe or medical pain, however. It appears that headache sufferers make sharp distinctions among types of potentially painful situations (e.g., minor versus severe or medical) that nonheadache people do not. Headache sufferers showed much greater variability between the FPQ subscales than did the control participants. For example, the latter group showed nearly identical means across all three FPQ subscales. We were only able to account for small amounts of variance in fear of pain with pain-coping strategies. This appears to conflict with the predictions of Lethem's Fear-Avoidance theory. Other studies have found avoidance coping more prominent in headache sufferers, however4, so our inability to show such a relationship may be due to the coping measure we employed or to characteristics of our sample. We are currently investigating avoidance and fear of pain in headache sufferers using a more controlled laboratory manipulation (the cold pressor task). Fear of pain had a greater relationship to headache impact than to headache symptoms. Fear of pain was generally not related to headache characteristics such as frequency, severity, and duration. On the other hand, fear of pain was related to the impact of headaches such as disruption of pleasurable activities. This supports Lethem's model which emphasizes the greater importance of fear of pain in pain-related disability over the actual nociceptive intensity of the pain stimulus. We should note that the results of the current
study are consistent with a variety of psychological models of chronic pain disorders in addition to Lethem's model.1,10 A case in point is the Gate-Control model advanced by Melzack and Wall10 which was among the first to suggest that affective and cognitive ("evaluative") aspects of pain are important. While the current study does not address the relative merits of these models, our results suggest that future research on the role of fear in pain disorders will be advanced by the use of reliable and valid measures of pain-related fearfulness such as the FPQ. Acknowledgement. The authors wish to acknowledge Michelle Woehr and James Wilfer for assisting with some of the data collection for this study. REFERENCES
1.
Bolles RC, Fanselow MS: A perceptual-defensive-recuperative model of fear and pain. Behav and Brain Sciences 1980; 3:291-323.
2.
Lethem J, Slade PD, Troup JDG, Bentley G: Outline of a fear-avoidance model of exaggerated pain perception-I. Behav Research and Ther 1983; 21:401-408.
3.
Fordyce WE: Behavioral Methods in Chronic Pain and Illness. St. Louis, C.V. Mosby, 1976.
4.
Philips C, Jahanshahi M: Chronic pain: An experimental analysis of the effects of exposure. Behav Research and Ther 1985; 23:281-290.
5.
Philips C, Jahanshahi M: The components of pain behavior report. Behav Research and Ther 1986; 24:17-125.
6.
McNeil DW, Rainwater AJ, Aljazireh L: Development of a methodology to measure fear of pain. Proceedings of the Annual Meeting of the Association for Advancement of Behavior Therapy. 1986.
7.
Ad Hoc Committee on Classification of Headache. JAMA 1962; 179:127-128.
8.
Holroyd KA, Penzien DB, Hursey KG, Tobin DL, Rogers L, Holm JE, Marcille PJ, Hall JR, Chila AG: Change mechanisms in EMG biofeedback training: Cognitive changes underlying improvements in tension headache. J Consulting and Clin Psychology 1984; 52:1039-1053.
9.
Rosenstiel, AK Keefe, F: The use of coping strategies in chronic low back pain patients: Relationship to patient characteristics and current adjustment. Pain 1983; 17:33-44.
10.
Melzack, R, Wall, PD: Pain mechanisms: A new theory. Science 1965; 150:971-979.
Karl G. Hursey, Ph.D. and S. Daniel Jacks, M.S.
Reprint requests to: Dr. K. G. Hursey, Department of Psychology, Texas A&M University, College Station TX 77843. Accepted For Publication: March 29, 1992 SYNOPSIS
We investigated the role of fear of pain in headache sufferers using the Fear of Pain Questionnaire (FPQ). Seventy-six headache sufferers and 58 controls completed the FPQ and measures of depression, anxiety, and anger. Headache sufferers also completed measures of stress-related physical symptoms and coping with pain. We found that the FPQ has excellent internal consistency as well as good concurrent and construct validity indicated by the high correlations between the FPQ subscales and both anxiety and depression but low correlations with anger. There were marked differences between headache sufferers and controls on the FPQ; headache sufferers showed much greater fear of severe and medical pain and lower fear of minor pain. Fear of pain was generally not related to headache characteristics such as frequency, severity, or duration. On the other hand, it was related to headache impact such as disruption of pleasurable activities. These results are consistent with models of chronic pain disorders which emphasize the role of fear of pain over the nociceptive intensity of the pain stimulus. Key Words: Fear of pain, anxiety, depression, anger. Abbreviations:
FPQ Fear of pain questionnaire
(Headache 1992, 32:283-286) Chronic pain disorders are characterized by the persistence of pain and disability with little or no organic pathology to account for them. Models of chronic pain disorders based on learning theory suggest that a reciprocal relationship between avoidance and fear maintains the disability and pain behaviors characteristic of these syndromes.1,2 According to Lethem, for example, avoidance of a pain-related stimulus reduces the state of fear triggered by that stimulus. This reduction in fear reinforces the avoidant response and makes avoidance more probable if the stimulus is encountered again. Over multiple trials avoidance becomes more strongly associated with fear of the stimulus and less associated with the actual nociceptive power of the stimulus. In fact, with successful avoidance the actual properties of the stimulus become largely irrelevant since they are rarely or never experienced. These models of chronic pain and disability strongly resemble learning theory models of anxiety disorders. Successful interventions for pain problems based on these models lend credence to the analogy.3 Learning models of chronic pain disorders such as Lethem's predict that individuals who suffer more frequent pain episodes will demonstrate greater avoidance coping and greater fear of pain than individuals who have less frequent pain episodes.4 In contrast, a traditional biomedical model of pain disorders predicts that greater fear of pain and more avoidance will be associated with greater pain intensity rather than greater frequency.4 Philips found that avoidance is a prominent coping strategy among headache sufferers and is more strongly related to headache chronicity than to headache intensity, consistent with the Fear-Avoidance model of chronic pain disorders.4,5 Unfortunately, Philips did not report any measure of fear in her studies. Thus, while avoidance coping has been convincingly linked to headache and other pain disorders, the role of fear of pain in headache sufferers remains unresolved. Despite the emphasis on fear of pain in various models of chronic pain disorders few measures of fear of pain have appeared. McNeil and his colleagues6 systematically developed and refined the Fear of Pain Questionnaire (FPQ) to fill this need. Based on the work of Lethem2 and to a lesser extent that of Bolles and Fanselow1 the FPQ consists of 30 items briefly describing painful situations and respondents rate how fearful they are of the pain associated with each situation. The FPQ yields three subscale scores (fear of Minor, Severe, and Medical pain) and a total score. Research by the developers supports the validity of the FPQ as a measure of fear of pain in non-clinical subjects exposed to laboratory pain-stimuli. Thus far, however, there has been no research on the FPQ with symptomatic populations. Methods
Overview. In this study we addressed five research problems: 1) The internal consistency of the FPQ in both headache sufferers and nonheadache participants; 2) The relationship of the FPQ to measures of psychological symptoms and somatic complaints in both headache and nonheadache participants; 3) The ability of fear of pain to discriminate headache and nonheadache participants; 4) The relationship between fear of pain and coping in headache sufferers (i.e., does pain-coping strategy predict fear of pain?); and 5) The relationship between fear of pain and headache symptoms (e.g., intensity, duration), headache impact (e.g., disruptiveness, distress), and headache
beliefs and expectations (e.g., headache self-efficacy, headache internal locus-of-control) in headache sufferers. Participants. Seventy-six headache sufferers (88% female) and 58 control participants (88% female) were recruited. Headache participants reported frequent and painful headaches consistent with Tension ("muscle-contraction") headaches as described by the Ad Hoc Committee on Diagnosis of Headache.7 These headache sufferers reported five or more at least moderately severe headaches per month; 87% reported one or more headaches per week and 40% reported daily headaches. All headache sufferers reported typical headache severity of 3 or more where 0 = No Headache and 5 = Extremely Painful (completely disabling) Headache on a standard headache intensity scale.8 Among the headache sufferers, 32% reported they were either currently taking prescription medication for headaches or had taken prescription medication for headaches in the past and 84% reported that they were taking Over-the-Counter headache medications once per month or more. Procedures. After receiving an explanation of the experimental procedures all participants provided written informed consent. Participants completed the FPQ, Beck Depression Inventory (BDI), and the state scales of the Spielberger State-Trait Personality Inventory (STPI). Headache sufferers also completed the Wahler Physical Symptoms Inventory (WPSI) and the Coping Strategies Questionnaire9 (CSQ) developed specifically to assess coping with pain. RESULTS
Internal Consistency. The three FPQ subscales and the Total FPQ score all showed moderate to high levels of internal consistency in both groups (Table 1). Fear of medical pain in the non-headache group showed the lowest coefficient alpha. The very high coefficient alphas for the Total FPQ score suggests that the subscales may not be as independent of one another as one might have hoped. Table 1 Internal consistency (Coefficient Alpha) of the FPQ Subscales and Total FPQ Scale Coefficient Alpha Headache Controls FPQ-Minor 0.86 0.71 FPQ-Severe 0.87 0.86 FPQ-Medical 0.87 0.64 FPQ-Total 0.92 0.80 Scale Intercorrelations. Next we correlated the FPQ subscales with one another using all of the participants. As shown in Table 2, fear of medical pain was correlated with both of the other subscales, especially fear of severe pain. This suggests that, at least in our subjects, fear of medical pain and fear of severe pain are very similar constructs.
Severe Medical **p < .001
Table 2 Intercorrelations of the FPQ subscales. Pearson Correlation Coefficients Minor Severe -0.06 0.30** 0.65**
Relationship of Fear of Pain to Measures of Psychological Symptoms and Somatic Complaints. Fear of Severe and Medical pain and total Fear of Pain were correlated with both depression and anxiety but not with anger (see Table 3). The FPQ-Minor scale showed a small but statistically significant correlation with depression only. The FPQ-Severe, Medical, and Total scores were correlated with the average of somatic complaints from the WPSI. The FPQ-Minor score was not correlated with the WPSI, however. Table 3 Correlations of FPQ subscales With Psychological Symptoms and Somatic Complaints Pearson Correlation Coefficients Depression Anxiety Anger Somatic Minor .19* .14 .14 .08 Severe .38** .34** .11 .38** Medical .42** .30** .05 .28** Total .46** .37** .13 .38** * p < .05 **p < .01
Discrimination of Groups. A Multivariate Analysis of Variance (MANOVA) on the FPQ scores by group (Headache versus Control) was significant (F(3,130) = 66.08, p < .001). Followup univariate analyses showed significant differences on all three FPQ subscales (see Table 4). Headache participants were much higher on fear of severe and medical pain and lower on fear of minor pain than the controls. Table 4 MANOVA on FPQ subscales by Group (Headache versus Control) Multivariate F(3,130) = 66.08, p < .001 Fear of Minor Pain Mean SD Univariate F(df = 1,132) Headache 10.88 6.88 9.82 p < .002 Control 14.31 5.38 Fear of Severe Pain Headache Control
28.25 11.33
7.58 8.08
154.83 p < .001
Fear of Medical Pain Headache Control
20.05 11.90
8.52 4.98
42.16 p < .001
Relationship to Pain Coping Strategies. Subscales from the CSQ were used to try to predict FPQ scores with multiple regression analyses. Although one or two coping scales (predictors) loaded significantly on each equation, the largest Adjusted R-Square was only .08 indicating that very little useful prediction could be made. Relationship to Headache Symptoms, Impact, and Beliefs/Expectations. We assessed the relationships between fear of pain and characteristics of the headache sufferers. For these analyses, continuously distributed variables were analyzed with
Pearson's Correlations. Categorical or severely skewed variables were recoded into discrete categories and analyzed using Chi Squares. For the Chi Squares, only the FPQ Total score was analyzed to keep the number of comparisons low. The FPQ-Total score was recorded as High (one standard deviation or more above the mean), Medium (within one standard deviation of the mean), and Low (one standard deviation or more below the mean) for the Chi Square analyses. Fear of minor pain was significantly (though not strongly) correlated with Headache Severity (r = .26, p < .05). Fear of pain was not related to headache frequency or duration, however. In addition, fear of pain was not related to use of either prescription or OTC medications. Chi Squares were highly significant for fear of pain and headache disruptiveness and distress (Table 5). Individuals with greater fear of pain reported more disruption of activities due to headache and more feelings of depression and anxiety associated with their headaches than did individuals with lower fear of pain. Finally, we found no relationship between fear of pain and headache self-efficacy or headache internal locus-of-control. Table 5 Fear of Pain and Headache Impact How much do your headaches: Chi Square Disrupt enjoyable activities 14.76** Cause psychological distress 11.50* Cause you to miss work/activities 7.14 *p < .01 **p < .001 DISCUSSION
The FPQ is an appropriate instrument for measuring fear of pain in symptomatic populations. In addition to being brief and easy to complete, it has good internal consistency, construct validity, and concurrent validity. In a broader sense, these results support Lethem's model and underscore the importance of fear in chronic and recurrent pain disorders. On the other hand, several areas where revisions are needed were identified as well. Our results showed that the FPQ is a reliable and valid measure of fear of pain. The very high alpha coefficients indicate that the FPQ subscales demonstrate excellent internal consistency. Intercorrelations among the FPQ subscales suggest that these scales are meaningfully related but also provide independent information about fear of pain. On the other hand, the high intersubscale correlations of the FPQ suggests that the individual subscales may not be as distinct as they should be. Further research can clarify the components of fear of pain. The concurrent and construct validity of the FPQ was indicated by the high correlations between the FPQ subscales and measures of anxiety and depression while there were low correlations with anger. Finally, the marked differences between headache sufferers and controls supports the ecological validity of the FPQ. A second goal of this study was to investigate the applicability of fear of pain as conceptualized in Lethem's Fear-Avoidance model to chronic headache disorders. The lower fear of minor pain among headache sufferers is consistent with Lethem's prediction of decreased fear following exposure to less severe pain episodes. Exposure allows greater synchronization between actual nociceptive intensity and affective reaction which become desynchronized in chronic pain disorders, according to Lethem.2 These headache sufferers presumably experience more overall episodes of pain than the control participants and thus report less fear. On the other hand, the much greater fear of both severe and medical pain among headache participants appears to conflict with these same predictions. Lethem does suggest that acute episodes of severe pain may sensitize individuals to fear of pain and in fact we did find a small but significant correlation between fear of minor pain and the typical headache severity reported by our headache sufferers. There was no such correlation with fear of severe or medical pain, however. It appears that headache sufferers make sharp distinctions among types of potentially painful situations (e.g., minor versus severe or medical) that nonheadache people do not. Headache sufferers showed much greater variability between the FPQ subscales than did the control participants. For example, the latter group showed nearly identical means across all three FPQ subscales. We were only able to account for small amounts of variance in fear of pain with pain-coping strategies. This appears to conflict with the predictions of Lethem's Fear-Avoidance theory. Other studies have found avoidance coping more prominent in headache sufferers, however4, so our inability to show such a relationship may be due to the coping measure we employed or to characteristics of our sample. We are currently investigating avoidance and fear of pain in headache sufferers using a more controlled laboratory manipulation (the cold pressor task). Fear of pain had a greater relationship to headache impact than to headache symptoms. Fear of pain was generally not related to headache characteristics such as frequency, severity, and duration. On the other hand, fear of pain was related to the impact of headaches such as disruption of pleasurable activities. This supports Lethem's model which emphasizes the greater importance of fear of pain in pain-related disability over the actual nociceptive intensity of the pain stimulus. We should note that the results of the current
study are consistent with a variety of psychological models of chronic pain disorders in addition to Lethem's model.1,10 A case in point is the Gate-Control model advanced by Melzack and Wall10 which was among the first to suggest that affective and cognitive ("evaluative") aspects of pain are important. While the current study does not address the relative merits of these models, our results suggest that future research on the role of fear in pain disorders will be advanced by the use of reliable and valid measures of pain-related fearfulness such as the FPQ. Acknowledgement. The authors wish to acknowledge Michelle Woehr and James Wilfer for assisting with some of the data collection for this study. REFERENCES
1.
Bolles RC, Fanselow MS: A perceptual-defensive-recuperative model of fear and pain. Behav and Brain Sciences 1980; 3:291-323.
2.
Lethem J, Slade PD, Troup JDG, Bentley G: Outline of a fear-avoidance model of exaggerated pain perception-I. Behav Research and Ther 1983; 21:401-408.
3.
Fordyce WE: Behavioral Methods in Chronic Pain and Illness. St. Louis, C.V. Mosby, 1976.
4.
Philips C, Jahanshahi M: Chronic pain: An experimental analysis of the effects of exposure. Behav Research and Ther 1985; 23:281-290.
5.
Philips C, Jahanshahi M: The components of pain behavior report. Behav Research and Ther 1986; 24:17-125.
6.
McNeil DW, Rainwater AJ, Aljazireh L: Development of a methodology to measure fear of pain. Proceedings of the Annual Meeting of the Association for Advancement of Behavior Therapy. 1986.
7.
Ad Hoc Committee on Classification of Headache. JAMA 1962; 179:127-128.
8.
Holroyd KA, Penzien DB, Hursey KG, Tobin DL, Rogers L, Holm JE, Marcille PJ, Hall JR, Chila AG: Change mechanisms in EMG biofeedback training: Cognitive changes underlying improvements in tension headache. J Consulting and Clin Psychology 1984; 52:1039-1053.
9.
Rosenstiel, AK Keefe, F: The use of coping strategies in chronic low back pain patients: Relationship to patient characteristics and current adjustment. Pain 1983; 17:33-44.
10.
Melzack, R, Wall, PD: Pain mechanisms: A new theory. Science 1965; 150:971-979.
