Vol. 30, No. 1, pp. 7-13, 1992 Printed in Great Britain. All rights reserved Behm. Rex. Thu.
00057967/92
$5.00 + 0.00
Copyright 0 1991Pergamon Press plc
IS PAIN SENSITIVITY ASSOCIATED DENTAL AVOIDANCE? PETER
WITH
R. GROSS
National Police Research Unit, P.O. Box 370, Marden, SA 5070, Australia (Received
I4 May 1991)
S~a~-~~
present investjgation examined whether pain sensitivity is associated with dental avoidance. Whereas the aim of the first study was to determine whether pain sensitivity can be distinguished from dental fears and health concerns, the aim of the second study was to examine the structure of cognitive aspects of pain sensitivity, and the aim of the third study was to examine the relationships of pain sensitivity to anxiety sensitivity, fear, pain, and avoidance. In the first study (n = 222) a factor analysis performed with items from the Dental Phobia and Pain Sensitivity Inventory distinguished a pain sensitivity factor from factors relating to dental phobia and health concerns. The factor structure of the Pain Sensitivity Index was examined in the second study (n = ISI), and similarly, a pain sensitivity factor was interpreted in the data. The third study (n = 65) found that although pain sensitivity correlated significantly with anxiety sensitivity, these constructs are not identical to each other. For instance, pain sensitivity but not anxiety sensitivity correlated significantly with blood-injury phobia. Pain sensitivity should be taken into account in future studies of dental phobia as pain sensitivity was found to be predictive of pain intensity, and pain intensity was found to be predictive of dental avoidance.
Dental phobia can be distinguished from other specific phobias as persons who avoid dental treatment may perceive that such procedures involve pain. However, pain can be completely controlled in dental practice and this information is frequently presented to the public in educational material on dentistry. For instance, D’Arcy (1990) points out that anaesthetics can be injected into a person’s gums to prevent pain from the drill, and surface anaesthetics can be applied to the gums to prevent pain from the injection. Nevertheless, dental patients may have developed expectations that they will experience pain and the fear of pain may be worse than the actual experience of pain itself (cf. Arntz, van Eck & Heijmans, 1990). In extreme cases, dental treatment is performed when the patient has been admitted to hospital and given general anaesthesia. Persons with non-dental phobias may avoid particular situations because they experience heightened anxiety or panic attacks in those situations (Gross, Oei & Evans, 1989). Persons with dental phobia may avoid dental treatment for these reasons as well as the fear of pain. Indeed, as negative affect may accompany each of these three conditions (Barlow, 1988; Eich, Rachman & Lopatka, 1990), they may interact with each other with the result that negative affect can intensify. However, it is not clear whether the fear of pain, anxiety, or panic is primarily responsible for dental avoidance. A fear expectancy model of avoidance behaviour has been developed by Reiss and McNally (1985). This model incorporates three components: danger expectancy, anxiety expectancy, and anxiety sensitivity. Reiss and McNally (1985) consider that anxiety sensitivity is a personality construct, that is, it is a person-specific factor whereas expectancies are situation-specific factors. Anxiety sensitivity refers to the fear of anxiety, and in this study pain sensitivity refers to the fear of pain, In the study of dental avoidance, pain sensitivity might also be assessed as it could contribute to the learning of avoidance behaviours. For instance, persons who are sensitive to pain may be more likely than persons who are pain tolerant to develop dental phobia. Situational fears are therefore considered to be secondary to the fear of pain. The term pain sensitivity is used to refer to pain thresholds in medical studies; however, the fear of pain is distinct from pain thresholds. For instance, pain thresholds have been found to change over the course of a day (Atrens & Curthoy, 1982), whereas, the fear of pain is considered to be a stable component of personality. Furthermore, anxiety is associated with the fear of pain, although, anxiety is not necessarily associated with low pain thresholds. The term pain sensitivity implies an association between pain and anxiety, although anxiety is not a strong predictor of pain (Arntz, Dreesen & Merckelbach, 1991).
PETER R. GROSS
8
The Reiss-Epstein-Gursky Anxiety Sensitivity Scale was constructed for the purpose of measuring anxiety sensitivity and it can be distinguished from the construct of anxiety (Reiss, Peterson, Gursky & McNally, 1986). Although several instruments have been constructed for the assessment of dental phobia (e.g. Kroeger, 1986; Weiner, Sheehan & Jones, 1986) and responses to pain (Vlaeyen, Geurts, Kale-Snijders, Schuerman, Groenman & van Eek, 1990), the author is not aware of a measure of pain sensitivity that is currently available. Therefore, the present investigation sought to construct a measure of pain sensitivity, and to determine whether pain sensitivity is predictive of dental avoidance. Three studies were conducted in this investigation. The aim of the first study was to determine whether a pain sensitivity dimension could be distinguished from dental fears and health concerns. The aim of the second study was to examine the structure of cognitive aspects of pain sensitivitycognitions may be involved with the maintenance of pain avoidance behaviour (Philips, 1987). The aim of the third study was to determine whether pain sensitivity is different from anxiety sensitivity, and to determine whether pain sensitivity is predictive of dental avoidance and dental pain. STUDY
I-THE
DENTAL
PHOBIAS
AND
PAIN
SENSITIVITY
INVENTORY
Method Subjects. This sample comprised 222 persons who were enrolled in first year psychology courses at James Cook University. The Ss participated in this study on a voluntary basis. The average age of Ss was 23 yr (minimum 17 to maximum 57) and 19% were male. Materials and procedure. The Dental Phobias and Pain Sensitivity Inventory (DPPSI), which was constructed for this study, comprises 33 items relating to dental and medical treatment (see Table 1). Items l-30 are rated by Ss on scales ranging from 0 (no fear) to 7 (severe fear). Items 31-33 relate to avoidance and pain intensity and these are also rated on O-7 scales. Copies of the Table 1. Five-factor solution for dental phobia and pain sensitivity inventory items Factor
I 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34.
A dentist scraping my teeth The sight of someone else’s blood The sight of a syringe Headache The sight of a dental drill A painfui wound to myseh” Dentists Doctor’s surgeries Nurses Stomach ache A dentist holding a syringe Colds An injection into my gums Minor aches and pains Toothache Medical doctors Having a sample of blood taken Painful dental procedures Muscular pain The sight of my own blood Dental surgeries Having dental fillings Dental checkups An injection into my arm Medical operations A drill being used on my teeth Hospitals Pain in my gums A dentist holding a drill Severe pain Having dental X-rays The sucker placed on my tongue Do yott avoid going to the dentist? How much pain do you usually experience whilst having an mjcetion into your gums? __ . 35. How much pam do you usually expenence whilst having your teeth drtlted7
Only loadings 10.35 are shown.
2
3
4
0.54
0.46 0.76
5
0.74
0.68 0.76 0.49
0.37
0.82 0.72 0.73 0.76 0.62 0.71 0.48
0.48 0.48
0.76 0.44
0.46 0.37
0.78 0.76 0.52
0.63 0.66 0.53
0.76 0.80
0.36
0.86 0.79 0.54 0.78 0.67 0.63 0.82
0.43 0.43
0.41
0.53 0.44 0.72 0.60 _ __ U./U
0.38
0.42 -0.44 -0.43
Assessment of pain sensitivity
9
questionnaire were distributed to students during lectures and tutorials. The completed questionnaires were then collected by University staff and returned to the author for analysis. Results
To investigate the structure of aspects of dental pain and fear, a factor analysis was performed with 33 DPPSI items using the programme Statview (Abacus Concepts, 1986). As the factors produced by the analysis did not correlate highly with each other an orthogonal transformation solution employing varimax procedures was selected. Five factors were extracted using standard default parameters. The proportion of variance accounted for by each factor is as follows: 1, 38%; 2, 9%; 3, 7%; 4, 6%; and 5, 4%. Correlations between individual items and factors can be seen in Table 1. On the basis of these correlations, the first factor can be interpreted as a dental phobia factor. For instance, the items that correlated highest with the first factor were fears relating to dental checkups, a dentist holding a drill, and dental fillings. The second factor was interpreted as a health concerns factor as fears relating to stomach ache, minor aches and pains, and colds correlated highest with this factor. The third factor was interpreted as a medical phobia as fears relating to medical doctors, nurses, and hospitals correlated highest with this factor. The items that correlated highest with factor four were injections into an arm, the sight of a syringe, and having a blood sample taken. Therefore, the fourth factor was interpreted as relating to injections/venipuncture phobia. The fifth factor was interpreted as a pain sensitivity factor as fears relating to painful dental procedures, injections into one’s gums, and severe pain correlated highest and positively with this factor. The two items that were found to correlate negatively with this factor are described as ‘having dental X-rays’ and ‘the sucker placed on one’s tongue’. It can be seen that the fear of severe pain loaded on several factors-which suggests that the fear of pain is a generalized and trans-situational fear. Items characterized by severe pain tended to correlate higher with the pain sensitivity factor than items characterized by moderate pain (the cutoff for factor loadings was lowered from > 0.40 to >0.35 to show the associations of moderate pain items with the fifth factor). STUDY
2-THE
PAIN
SENSITIVITY
INDEX
Method Subjects. This sample comprised 181 persons who were enrolled in first-year psychology courses at James Cook University. The Ss participated in this study on a voluntary basis. The average age of Ss was 27 yr and 24% were male. Materials and procedure. The Pain Sensitivity Index (PSI) was constructed for the purpose of measuring pain sensitivity. The PSI is based on the Anxiety Sensitivity Scale (Reiss & McNally, 1985). Although the PSI initially comprised 18 items, the final 16 items on the form are shown in Table 2. Items are rated by Ss on scales ranging from 0 (very little) to 7 (very much). Copies of the questionnaire were distributed to students during lectures and tutorials. The completed questionnaires were then collected by University staff and returned to the author for analysis. Results
The programme Statview (Abacus Concepts, 1986) was used to perform a factor analysis with PSI items. Three cases with missing data were deleted. Initially, the programme indicated that singularity was present in the data. The computer output was checked and extreme factor loadings were noted for the following two items: “It scares me when I think about painful experiences I have had” and “I experience more pain than other people”. When these items were deleted, a non-singular solution was obtained. An orthogonal transformation solution using varimax procedures extracted 5 factors. The proportion of variance accounted for by each factor is as follows: 1, 32%; 2, 9%; 3, 8%; 4, 7%; and 5, 7%. Table 2 presents the correlations between individual items and factors. The first factor was interpreted as a pain sensitivity factor as items described as ‘when I detect pain I worry that I might be seriously ill’ and ‘it scares me when pain persists’ correlated highest with this factor. In particular, the item ‘I am more sensitive to pain than other people’ correlated highly with the first factor.
PETERR. Gms
10 Table 2. Five-factor
solution
for Pain Sensitivity
Index items Factor
1
1. It is important to me not to appear in pain 2. I cannot keep my mind on a task when I am experiencing pain 3. It scares me when my blood vessels throb 4. It is important to me to avoid pain 5. When I notice that my heart is beating rapidly, I worry that I might experience severe pain 6. I do not like it when other people talk about their distressing emotional experiences 7. It scares me when I am in pain 8. When I am in pain I become short of breath 9. When I detect pain, I worry that I might be seriously ill 10. It scares me when I am unable to keep my mind off pain 11.Other people notice when I experience pain 12. I am more sensitive to pain than other people 13. I worry about pain 14. It scares me when pain persists 15, I have painful memories 16. I do not like it when other people talk about their painful injuries Only loadings
>0.40
2
3
4
5
0.81 0.79 0.56 0.47 0.60 0.88 0.43
0.64 0.52
0.49
0.79 0.69 0.44 0.58 0.6 I 0.72
0.55 0.43
0.80 0.85
are shown.
The remaining factors were difficult to interpret as few items correlated with each of these factors. As the first factor accounted for most of the variance, it is considered to be the most important factor in this solution. The second factor was characterized by feeling uncomfortable when other people discuss their painful experiences. The third factor was characterized by concerns about appearing in pain to other people. Whereas the fourth factor was characterized by cognitive interference due to pain, the fifth factor was characterized by painful memories. STUDY
3-THE
RELATIONSHIP DENTAL
BETWEEN PAIN AVOIDANCE
SENSITIVITY
AND
method Subjects. This sample comprised one group of 40 second-year psychology students and their acquaintances, and one group of 25 dental patients. The average age of persons in the first group was 34, whereas the average age of dental patients was 29. The percentage of males in the first group was 22, whereas the percentage of males in the second group was 30. As the dental patients group was relatively small in number, it was decided to combine the two groups in some of the analyses in the third study. All of the Ss participated in the study on a voluntary basis. Materials and procedure. The DPPSI items relating to dental avoidance, intensity of injection pain, and intensity of drill pain (items 31-33) were used in the third study. These items were found to correlate highly with the dental phobia factor in study 1. The nine items of the PSI which constitute the pain sensitivity factor, as shown in study 2, were summed to provide a pain sensitivity score for each S. The Fear Questionnaire (FQ; Marks & Mathews, 1979) comprises four subscales for the assessment of agoraphobia, blood-injury phobia, social phobia, and anxiety-depression. The Reiss-Epstein-Gursky Anxiety Sensitivity Scale (ASS; Reiss & McNally, 1985) is a 16-item instrument for assessing anxiety sensitivity. Items are rated on scales which range from 0 (very little) to 4 (very much). A panic scale comprising four items relating to panic attacks, pain, and anxiety was included in this study. This form provides a definition of a panic attack and the first item requests subjects to indicate whether they have previously experienced a panic attack during dental treatment. For the remaining items, Ss rate the extent to which they avoid the dentist due to fears relating to pain, panic attacks, and anxiety on scales ranging from 0 (never) to 7 (always). Students completed the forms in class and they were asked to give a set of questionnaires to one of their acquaintances. Dental patients completed the forms in the waiting room of a suburban dental practice which had
Assessment of pain sensitivity
11
Table 3. Correlations of Pain Sensitivity Index and Anxiety Sensitivity Scale with fear and panic Scale a
PSI ASS
Ag
Bi
So
An
Pain
Panic
Anxiety
0.42’. 0.25
0.36* 0.18
0.32* 0.14
0.35’ 0.49**
0.02 0.06
0.13 0.35’
0.17 0.25
lP < 0.05; l*P < 0.01. Ag = FQ agoraphobia; Bi = FQ blood-injury social phobia; An = FQ anxiety-depression; due to pain; Panic= avoidance due to avoidance due to anxiety.
phobia; So = FQ Pain = avoidance panic; Anxiety =
agreed to participate in the study, although a total of five dental practices in the Cairns region were invited to participate in this study. Whereas the first group of Ss completed the DPPSI, PSI, FQ, AS1 and the panic scale, dental patients completed only the DPPSI and the PSI. Results
To investigate the relationships of pain sensitivity with dental avoidance and pain intensity, correlations between the PSI (pain sensitivity dimension) and DPPSI items were calculated (n = 65). Although pain sensitivity did not correlate significantly with avoidance (r = 0.15, P > 0.05), it did correlate with injection pain (Y = 0.30, P c 0.05) and drill pain (r = 0.47, P < 0.01). Injection pain did not correlate significantly with avoidance (r = 0.18, P > 0.05); however, drill pain did correlate significantly with avoidance (r = 0.44, P < 0.01). Table 3 presents the correlations of the PSI (pain sensitivity dimension) and the ASS with agoraphobia, blood-injury phobia, social phobia, anxiety, and the panic scale items (n = 40). It can be seen that the PSI correlated significantly with agoraphobia, blood-injury phobia, social phobia, and anxiety, whereas the ASS correlated significantly with anxiety and avoidance due to panic. The PSI was found to correlate highly with the ASS (r = 0.60, P < 0.01). Twelve persons in this sample (30%) indicated that they had experienced panic attacks during dental treatmenthowever, not all of these attacks may fulfil criteria for DSM-III-R panic attacks (cf. Gross & Eifert, 1990). DISCUSSION
The findings from the first study indicate that pain sensitivity can be distinguished from dental phobia and health concerns. For instance, the item described as ‘having dental X-rays’ correlated positively with the dental phobia factor, whereas it correlated negatively with the pain sensitivity factor (X-rays are not usually painful). The first factor analysis also indicates that dental phobia is independent of medical and injection phobias. This finding is supported by a case study with an adolescent who demonstrated multiple phobias of injections, and dental and medical procedures as each phobia had to be treated individually (Sanders & Jones, 1990). As the pain sensitivity factor accounted for a small proportion of the variance in the solution, a subsequent study was conducted with the aim of developing a more useful measure of pain sensitivity. The findings from the second study also showed that a pain sensitivity dimension could be interpreted in the data. Although five factors were produced by the analysis, the pain sensitivity factor explained a substantial proportion of the variance in the solution. This factor resembles the pain impact factor identified in the study by (Vlaeyen et al., 1990). The relationships of this dimension with anxiety sensitivity and dental pain were investigated in the third study. The third study showed that pain sensitivity did not correlate significantly with self-reported avoidance of dental treatment. However, it was predictive of drill pain, and drill pain was predictive of avoidance behaviour. Although the PSI and the ASS correlated significantly with each other, they did not correlate equally with measures of fear, anxiety, and panic. In support of the view that the construct of pain sensitivity is different from that of anxiety sensitivity, the PSI but not the ASS was found to correlate significantly with blood-injury phobia (many of the situations described by items on this subscale of the Fear Questionnaire, such as having minor surgery, often involve pain). In contrast, the ASS correlated higher than the PSI with anxiety-depression. Nevertheless, both of these constructs may be linked to negative affect. It is not clear why the PSI
12
PETERR. GROSS
correlated significantly with agoraphobia. Although persons who experience panic attacks often report chest pain (cf. Barlow, 1988) they appear to have normal pain threshold levels (Roy-Byrne, 1985). These findings can contribute to an understanding of the fear pathways leading from pain sensitivity to pain intensity and from pain intensity to dental avoidance. Firstly, although Ss in this investigation reported fears of dentists, it seems that they also had an underlying fear of pain. Indeed, personality may influence the learning of abnormal behaviour (Staats, 1990). For instance, consistent with Reiss and McNally’s model, pain sensitivity in persons could interact with pain expectancies in dental situations-which could have an effect on avoidance behaviour. Pain sensitivity appears to have explanatory value as it has been previously noted that dental pain can be controlled by dentists, yet persons may develop dental phobias because inaccurate pain expectations (cf. Arntz & Lousberg, 1990) could interact with the pain sensitivity aspect of personality. Despite the association of fear with dentists and dental treatment in normal persons, most persons do not avoid dental treatment as they have also learned-and may tell themselvesthat such treatment is necessary. Appropriate language behaviours may therefore counteract negative self-verbalizations in relation to dental avoidance. Secondly, it is interesting to note that ‘a dentist holding a drill’ correlated marginally higher than ‘the sight of a dental drill’ with the dental phobia factor. In regard to the treatment of dental phobia, it may be important to target fearful composite images (Lohr & Hamberger, 1990) or fearful action-oriented images as well as images of a dentist or a drill on their own. Thirdly, in regard to the theoretical understanding of pain sensitivity, this construct may predict the number of fears associated with dental treatment as well as the intensity of such fears. In an epidemiologic study, Dworkin, Von Korff and LeResche (1990) found that the number of pain conditions reported by members of a community sample was a better predictor of emotional problems than were pain severity and pain persistence. In addition, social-evaluative fears may contribute to dental avoidance (cf. Moore, Brodsgaard & Birn, 1991). For instance, study 2 showed that persons are concerned about their appearance when they are in pain. When anxious persons attend their dentist, they may perceive that the dentist is evaluating them. To help reduce fear in patients, dentists could indicate their sensitivity to their patient’s pain sensitivity by explaining the various options available to them for pain relief. The present findings suggest that pain intensity and pain sensitivity are important components of dental avoidance. In other words, perceived pain is different to reactions to pain; however, pain sensitivity is only one of the reactions that people may experience in relation to pain. As cognitions can influence the ways in which individuals react to pain experiences (Heyneman, Fremouw, Gano, Kirkland & Heiden, 1990) cognitions may influence the relationship between pain and dental avoidance. It is possible that genetic factors contribute to individual differences in pain thresholds, but they may not be directly involved with pain sensitivity. For instance, Castellano, Puglisi, Renzi and Oliverio (1985) reported genetic differences in daily rhythms of pain thresholds in mice. Numerous studies have shown that endogenous biological factors are involved with pain thresholds (e.g. Janal, Colt, Clark & Glusman, 1984). Cognitions may interact with biological factors, for instance, pain sensitive persons may interpret physical arousal as pain cues. Interestingly, pain but not anxiety has been found to correlate with circulatory and biochemical variables after dental surgery (Goldstein, 1982). In seeking a comprehensive understanding of pain behaviour, Turk and Rudy (1987) have pointed to the need to assess and relate biological and psychological information. Some caution should be exercised in regard to these interpretations of the present findings as the psychometric properties of the PSI have not yet been fully determined. However, the construct of pain sensitivity could be relevant to a comprehensive understanding of various pain behaviours. For instance, a study that is currently being conducted examines the predictions that persons with cardiophobia score highly on both the ASS and the PSI, persons with panic disorder score highly on the ASS, and persons with chronic pain score highly on the PSI. As pain sensitivity is regarded as a stable personality component, it could contribute to an understanding of chronic and multiple pains which are accompanied by anxiety. It is argued that the expectancy model of fear could be expanded to include pain sensitivity and pain expectations; furthermore, in seeking an understanding of tourist approach behaviours, Gross (1991) has suggested that this model needs to include both negative and positive affect.
Assessment
of pain sensitivity
13
REFERENCES Abacus Concepts (1986). Stafuiew (Computer program). Calabasas, Calif.: Brain Power Inc. Arntz, A., Dreesen, L. & Merckelbach, H. (1971). Attention, not anxiety, influences pain. Behauiour Research and Therapy, 29, 41-50. Arntz, A. & Lousberg, R. (1990). The effects of underestimated pain and their relationship to habituation. Behaviour Research and Therapy, 28, 15-28. Arntz, A., van Eck, M. & Heijmans, M. (1990). Predictions of dental pain: The fear of any expected evil is worse than the evil itself. Behaviour Research and Therapy, 28, 29941. Atrens, D. & Curthoys, I. (1982). The neurosciences and behaviour. Sydney: Academic Press. Barlow, D. H. (1988). Anxiety and its disorders. New York: Guildford Press. Castellano, C., Puglisi-Allegra, S., Renzi, P. & Oliverio, A. (1985). Genetic differences in daily rhythms of pain sensitivity in mice. Pharmacology, Biochemistry and Behaviour, 23, 91-92. D’Arcy, R. (1990). Low stress dentistry. Family Circle. December, 105. Dworkin, S. F., Von Korff, M. V. & LeResche, L. (1990). Multiple pains and psychiatric disturbance. Archives of General Psychiatry, 47, 239-244. Eich, E., Rachman, S. & Lopatka, C. (1990). Affect, pain, and autobiographical memory. Journal of Abnormal Psychology, 99, 1744178. Goldstein, D. S. (1982). Circulatory, plasma catecholamine, cortisol, lipid, and psychological responses to a real-life stress (third molar extractions): Effects of diazepam sedation and of inclusion of epinephrine with the local anesthetic. Psychosomatic Medicine, 44, 259-272. Gross, P. R. (1991). How IO approach crocodiles: Be calm, be very calm! Manuscript submitted for publication. Gross, P. R. & Eifert G. H. (1990). Components of generalized anxiety: The role of intrusive thoughts vs worry. Behaviour Research and Therapy, 28, 421-428. Gross, P. R., Oei, T. P. & Evans, L. (1989). Generalized anxiety symptoms in phobic disorders and anxiety states: A test of the worry hypothesis. Journal of Anxiety Disorders, 3, 159-169. Heyneman, N. E., Fremouw, W. J., Gano, D., Kirkland, F. 8c Heiden, L. (1990). Individual differences and the effectiveness of different coping strategies for pain. Cognitive Therapy and Research, 14, 63-77. Janal, M., Colt, E. W., Clark. W. C. & Glusman. M. (1984). Pain sensitivitv. mood. and ulasma endocrine levels in man * following long-distance running: Effects of naloxone. Pain, 19, 13-25. _’ Kroeger, R. F. (1986). The management of dental phobia: The use of fear-screening questionnaires. International Journal of Psychosomatics, 33, 92-95. Lohr, K. M. & Hamberger, L. K. (1990). Verbal and emotional repertoires in the regulation of dysfunctional behaviour: An integrative conceptual framework for cognitive-behavioural disorders. In Eifert, G. H. & Evans, I. M. (Eds), Unifving behaviour therapy: Contributions of paradigmatic behaviourism. New York: Springer. Marks, I. M. & Mathews, A. M. (1979). Brief standard self-rating for phobic patients. Behaviour Research and Therapy, 17, 263-267. Moore, R., Brodsgaard, I. & Birn, H. (1991). Manifestations, acquisition and diagnostic categories of dental fear in a self-referred population. Behaviour Research and Therapy, 29, 5 l-60. Philips, H. C. (1987). Avoidance behaviour and its role in sustaining chronic pain. Behauiour Research and Therapy, 25, 273-279. Reiss, S. & McNally, R. J. (1985). Expectancy model of fear. In Reiss, S. & Bootzin, R. R. (Eds), Theoretical issues in behaviour therapy. Orlando: Academic Press. Reiss, S., Peterson, R. A., Gursky, D. M. & McNally, R. J. (1986). Anxiety sensitivity, anxiety frequency, and the prediction of fearfulness. Behaviour Research and Therapy, 24, 108. Roy-Byrne, P. (1985). Normal pain sensitivity in patients with panic disorder. Psychiafry Research, 14, 77-84. Sanders, M. R. & Jones, L. (1990). Behavioural treatment of injection, dental, and medical phobias in adolescents-A case study. Behavioural Psychotherapy, 18, 3 11-3 16. Staats, A. W. (1990). Paradigmatic Behaviour Therapy: A unified framework for theory, research, and practice. In Eifert, G. H. & Evans, I. M. (Eds), Unifving behaviour therapy: Contributions of paradigmatic behaviourism. New York: Springer. Turk, D. C. & Ruddy, T. E. (1987). Towards a comprehensive assessment of chronic pain patients. Behaviour Research and Therapy, 25, 237-249. Vlaeyen, J. W. S., Geurts, S. M., Kole-Snijders, A. M. J., Schuerman, J. A., Groenman, N. H. & van Eek, H. (1990). What do chronic pain patients think of their pain? Towards a pain cognition questionnaire. British Journal of Clinical Psychology, 29, 3833394. Weiner, A. A., Sheehan, D. V. & Jones, K. J. (1986). Dental anxiety-the development of a measurement model. Acta Psychiatrica Scandanavia, 73, 559-565.
00057967/92
$5.00 + 0.00
Copyright 0 1991Pergamon Press plc
IS PAIN SENSITIVITY ASSOCIATED DENTAL AVOIDANCE? PETER
WITH
R. GROSS
National Police Research Unit, P.O. Box 370, Marden, SA 5070, Australia (Received
I4 May 1991)
S~a~-~~
present investjgation examined whether pain sensitivity is associated with dental avoidance. Whereas the aim of the first study was to determine whether pain sensitivity can be distinguished from dental fears and health concerns, the aim of the second study was to examine the structure of cognitive aspects of pain sensitivity, and the aim of the third study was to examine the relationships of pain sensitivity to anxiety sensitivity, fear, pain, and avoidance. In the first study (n = 222) a factor analysis performed with items from the Dental Phobia and Pain Sensitivity Inventory distinguished a pain sensitivity factor from factors relating to dental phobia and health concerns. The factor structure of the Pain Sensitivity Index was examined in the second study (n = ISI), and similarly, a pain sensitivity factor was interpreted in the data. The third study (n = 65) found that although pain sensitivity correlated significantly with anxiety sensitivity, these constructs are not identical to each other. For instance, pain sensitivity but not anxiety sensitivity correlated significantly with blood-injury phobia. Pain sensitivity should be taken into account in future studies of dental phobia as pain sensitivity was found to be predictive of pain intensity, and pain intensity was found to be predictive of dental avoidance.
Dental phobia can be distinguished from other specific phobias as persons who avoid dental treatment may perceive that such procedures involve pain. However, pain can be completely controlled in dental practice and this information is frequently presented to the public in educational material on dentistry. For instance, D’Arcy (1990) points out that anaesthetics can be injected into a person’s gums to prevent pain from the drill, and surface anaesthetics can be applied to the gums to prevent pain from the injection. Nevertheless, dental patients may have developed expectations that they will experience pain and the fear of pain may be worse than the actual experience of pain itself (cf. Arntz, van Eck & Heijmans, 1990). In extreme cases, dental treatment is performed when the patient has been admitted to hospital and given general anaesthesia. Persons with non-dental phobias may avoid particular situations because they experience heightened anxiety or panic attacks in those situations (Gross, Oei & Evans, 1989). Persons with dental phobia may avoid dental treatment for these reasons as well as the fear of pain. Indeed, as negative affect may accompany each of these three conditions (Barlow, 1988; Eich, Rachman & Lopatka, 1990), they may interact with each other with the result that negative affect can intensify. However, it is not clear whether the fear of pain, anxiety, or panic is primarily responsible for dental avoidance. A fear expectancy model of avoidance behaviour has been developed by Reiss and McNally (1985). This model incorporates three components: danger expectancy, anxiety expectancy, and anxiety sensitivity. Reiss and McNally (1985) consider that anxiety sensitivity is a personality construct, that is, it is a person-specific factor whereas expectancies are situation-specific factors. Anxiety sensitivity refers to the fear of anxiety, and in this study pain sensitivity refers to the fear of pain, In the study of dental avoidance, pain sensitivity might also be assessed as it could contribute to the learning of avoidance behaviours. For instance, persons who are sensitive to pain may be more likely than persons who are pain tolerant to develop dental phobia. Situational fears are therefore considered to be secondary to the fear of pain. The term pain sensitivity is used to refer to pain thresholds in medical studies; however, the fear of pain is distinct from pain thresholds. For instance, pain thresholds have been found to change over the course of a day (Atrens & Curthoy, 1982), whereas, the fear of pain is considered to be a stable component of personality. Furthermore, anxiety is associated with the fear of pain, although, anxiety is not necessarily associated with low pain thresholds. The term pain sensitivity implies an association between pain and anxiety, although anxiety is not a strong predictor of pain (Arntz, Dreesen & Merckelbach, 1991).
PETER R. GROSS
8
The Reiss-Epstein-Gursky Anxiety Sensitivity Scale was constructed for the purpose of measuring anxiety sensitivity and it can be distinguished from the construct of anxiety (Reiss, Peterson, Gursky & McNally, 1986). Although several instruments have been constructed for the assessment of dental phobia (e.g. Kroeger, 1986; Weiner, Sheehan & Jones, 1986) and responses to pain (Vlaeyen, Geurts, Kale-Snijders, Schuerman, Groenman & van Eek, 1990), the author is not aware of a measure of pain sensitivity that is currently available. Therefore, the present investigation sought to construct a measure of pain sensitivity, and to determine whether pain sensitivity is predictive of dental avoidance. Three studies were conducted in this investigation. The aim of the first study was to determine whether a pain sensitivity dimension could be distinguished from dental fears and health concerns. The aim of the second study was to examine the structure of cognitive aspects of pain sensitivitycognitions may be involved with the maintenance of pain avoidance behaviour (Philips, 1987). The aim of the third study was to determine whether pain sensitivity is different from anxiety sensitivity, and to determine whether pain sensitivity is predictive of dental avoidance and dental pain. STUDY
I-THE
DENTAL
PHOBIAS
AND
PAIN
SENSITIVITY
INVENTORY
Method Subjects. This sample comprised 222 persons who were enrolled in first year psychology courses at James Cook University. The Ss participated in this study on a voluntary basis. The average age of Ss was 23 yr (minimum 17 to maximum 57) and 19% were male. Materials and procedure. The Dental Phobias and Pain Sensitivity Inventory (DPPSI), which was constructed for this study, comprises 33 items relating to dental and medical treatment (see Table 1). Items l-30 are rated by Ss on scales ranging from 0 (no fear) to 7 (severe fear). Items 31-33 relate to avoidance and pain intensity and these are also rated on O-7 scales. Copies of the Table 1. Five-factor solution for dental phobia and pain sensitivity inventory items Factor
I 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34.
A dentist scraping my teeth The sight of someone else’s blood The sight of a syringe Headache The sight of a dental drill A painfui wound to myseh” Dentists Doctor’s surgeries Nurses Stomach ache A dentist holding a syringe Colds An injection into my gums Minor aches and pains Toothache Medical doctors Having a sample of blood taken Painful dental procedures Muscular pain The sight of my own blood Dental surgeries Having dental fillings Dental checkups An injection into my arm Medical operations A drill being used on my teeth Hospitals Pain in my gums A dentist holding a drill Severe pain Having dental X-rays The sucker placed on my tongue Do yott avoid going to the dentist? How much pain do you usually experience whilst having an mjcetion into your gums? __ . 35. How much pam do you usually expenence whilst having your teeth drtlted7
Only loadings 10.35 are shown.
2
3
4
0.54
0.46 0.76
5
0.74
0.68 0.76 0.49
0.37
0.82 0.72 0.73 0.76 0.62 0.71 0.48
0.48 0.48
0.76 0.44
0.46 0.37
0.78 0.76 0.52
0.63 0.66 0.53
0.76 0.80
0.36
0.86 0.79 0.54 0.78 0.67 0.63 0.82
0.43 0.43
0.41
0.53 0.44 0.72 0.60 _ __ U./U
0.38
0.42 -0.44 -0.43
Assessment of pain sensitivity
9
questionnaire were distributed to students during lectures and tutorials. The completed questionnaires were then collected by University staff and returned to the author for analysis. Results
To investigate the structure of aspects of dental pain and fear, a factor analysis was performed with 33 DPPSI items using the programme Statview (Abacus Concepts, 1986). As the factors produced by the analysis did not correlate highly with each other an orthogonal transformation solution employing varimax procedures was selected. Five factors were extracted using standard default parameters. The proportion of variance accounted for by each factor is as follows: 1, 38%; 2, 9%; 3, 7%; 4, 6%; and 5, 4%. Correlations between individual items and factors can be seen in Table 1. On the basis of these correlations, the first factor can be interpreted as a dental phobia factor. For instance, the items that correlated highest with the first factor were fears relating to dental checkups, a dentist holding a drill, and dental fillings. The second factor was interpreted as a health concerns factor as fears relating to stomach ache, minor aches and pains, and colds correlated highest with this factor. The third factor was interpreted as a medical phobia as fears relating to medical doctors, nurses, and hospitals correlated highest with this factor. The items that correlated highest with factor four were injections into an arm, the sight of a syringe, and having a blood sample taken. Therefore, the fourth factor was interpreted as relating to injections/venipuncture phobia. The fifth factor was interpreted as a pain sensitivity factor as fears relating to painful dental procedures, injections into one’s gums, and severe pain correlated highest and positively with this factor. The two items that were found to correlate negatively with this factor are described as ‘having dental X-rays’ and ‘the sucker placed on one’s tongue’. It can be seen that the fear of severe pain loaded on several factors-which suggests that the fear of pain is a generalized and trans-situational fear. Items characterized by severe pain tended to correlate higher with the pain sensitivity factor than items characterized by moderate pain (the cutoff for factor loadings was lowered from > 0.40 to >0.35 to show the associations of moderate pain items with the fifth factor). STUDY
2-THE
PAIN
SENSITIVITY
INDEX
Method Subjects. This sample comprised 181 persons who were enrolled in first-year psychology courses at James Cook University. The Ss participated in this study on a voluntary basis. The average age of Ss was 27 yr and 24% were male. Materials and procedure. The Pain Sensitivity Index (PSI) was constructed for the purpose of measuring pain sensitivity. The PSI is based on the Anxiety Sensitivity Scale (Reiss & McNally, 1985). Although the PSI initially comprised 18 items, the final 16 items on the form are shown in Table 2. Items are rated by Ss on scales ranging from 0 (very little) to 7 (very much). Copies of the questionnaire were distributed to students during lectures and tutorials. The completed questionnaires were then collected by University staff and returned to the author for analysis. Results
The programme Statview (Abacus Concepts, 1986) was used to perform a factor analysis with PSI items. Three cases with missing data were deleted. Initially, the programme indicated that singularity was present in the data. The computer output was checked and extreme factor loadings were noted for the following two items: “It scares me when I think about painful experiences I have had” and “I experience more pain than other people”. When these items were deleted, a non-singular solution was obtained. An orthogonal transformation solution using varimax procedures extracted 5 factors. The proportion of variance accounted for by each factor is as follows: 1, 32%; 2, 9%; 3, 8%; 4, 7%; and 5, 7%. Table 2 presents the correlations between individual items and factors. The first factor was interpreted as a pain sensitivity factor as items described as ‘when I detect pain I worry that I might be seriously ill’ and ‘it scares me when pain persists’ correlated highest with this factor. In particular, the item ‘I am more sensitive to pain than other people’ correlated highly with the first factor.
PETERR. Gms
10 Table 2. Five-factor
solution
for Pain Sensitivity
Index items Factor
1
1. It is important to me not to appear in pain 2. I cannot keep my mind on a task when I am experiencing pain 3. It scares me when my blood vessels throb 4. It is important to me to avoid pain 5. When I notice that my heart is beating rapidly, I worry that I might experience severe pain 6. I do not like it when other people talk about their distressing emotional experiences 7. It scares me when I am in pain 8. When I am in pain I become short of breath 9. When I detect pain, I worry that I might be seriously ill 10. It scares me when I am unable to keep my mind off pain 11.Other people notice when I experience pain 12. I am more sensitive to pain than other people 13. I worry about pain 14. It scares me when pain persists 15, I have painful memories 16. I do not like it when other people talk about their painful injuries Only loadings
>0.40
2
3
4
5
0.81 0.79 0.56 0.47 0.60 0.88 0.43
0.64 0.52
0.49
0.79 0.69 0.44 0.58 0.6 I 0.72
0.55 0.43
0.80 0.85
are shown.
The remaining factors were difficult to interpret as few items correlated with each of these factors. As the first factor accounted for most of the variance, it is considered to be the most important factor in this solution. The second factor was characterized by feeling uncomfortable when other people discuss their painful experiences. The third factor was characterized by concerns about appearing in pain to other people. Whereas the fourth factor was characterized by cognitive interference due to pain, the fifth factor was characterized by painful memories. STUDY
3-THE
RELATIONSHIP DENTAL
BETWEEN PAIN AVOIDANCE
SENSITIVITY
AND
method Subjects. This sample comprised one group of 40 second-year psychology students and their acquaintances, and one group of 25 dental patients. The average age of persons in the first group was 34, whereas the average age of dental patients was 29. The percentage of males in the first group was 22, whereas the percentage of males in the second group was 30. As the dental patients group was relatively small in number, it was decided to combine the two groups in some of the analyses in the third study. All of the Ss participated in the study on a voluntary basis. Materials and procedure. The DPPSI items relating to dental avoidance, intensity of injection pain, and intensity of drill pain (items 31-33) were used in the third study. These items were found to correlate highly with the dental phobia factor in study 1. The nine items of the PSI which constitute the pain sensitivity factor, as shown in study 2, were summed to provide a pain sensitivity score for each S. The Fear Questionnaire (FQ; Marks & Mathews, 1979) comprises four subscales for the assessment of agoraphobia, blood-injury phobia, social phobia, and anxiety-depression. The Reiss-Epstein-Gursky Anxiety Sensitivity Scale (ASS; Reiss & McNally, 1985) is a 16-item instrument for assessing anxiety sensitivity. Items are rated on scales which range from 0 (very little) to 4 (very much). A panic scale comprising four items relating to panic attacks, pain, and anxiety was included in this study. This form provides a definition of a panic attack and the first item requests subjects to indicate whether they have previously experienced a panic attack during dental treatment. For the remaining items, Ss rate the extent to which they avoid the dentist due to fears relating to pain, panic attacks, and anxiety on scales ranging from 0 (never) to 7 (always). Students completed the forms in class and they were asked to give a set of questionnaires to one of their acquaintances. Dental patients completed the forms in the waiting room of a suburban dental practice which had
Assessment of pain sensitivity
11
Table 3. Correlations of Pain Sensitivity Index and Anxiety Sensitivity Scale with fear and panic Scale a
PSI ASS
Ag
Bi
So
An
Pain
Panic
Anxiety
0.42’. 0.25
0.36* 0.18
0.32* 0.14
0.35’ 0.49**
0.02 0.06
0.13 0.35’
0.17 0.25
lP < 0.05; l*P < 0.01. Ag = FQ agoraphobia; Bi = FQ blood-injury social phobia; An = FQ anxiety-depression; due to pain; Panic= avoidance due to avoidance due to anxiety.
phobia; So = FQ Pain = avoidance panic; Anxiety =
agreed to participate in the study, although a total of five dental practices in the Cairns region were invited to participate in this study. Whereas the first group of Ss completed the DPPSI, PSI, FQ, AS1 and the panic scale, dental patients completed only the DPPSI and the PSI. Results
To investigate the relationships of pain sensitivity with dental avoidance and pain intensity, correlations between the PSI (pain sensitivity dimension) and DPPSI items were calculated (n = 65). Although pain sensitivity did not correlate significantly with avoidance (r = 0.15, P > 0.05), it did correlate with injection pain (Y = 0.30, P c 0.05) and drill pain (r = 0.47, P < 0.01). Injection pain did not correlate significantly with avoidance (r = 0.18, P > 0.05); however, drill pain did correlate significantly with avoidance (r = 0.44, P < 0.01). Table 3 presents the correlations of the PSI (pain sensitivity dimension) and the ASS with agoraphobia, blood-injury phobia, social phobia, anxiety, and the panic scale items (n = 40). It can be seen that the PSI correlated significantly with agoraphobia, blood-injury phobia, social phobia, and anxiety, whereas the ASS correlated significantly with anxiety and avoidance due to panic. The PSI was found to correlate highly with the ASS (r = 0.60, P < 0.01). Twelve persons in this sample (30%) indicated that they had experienced panic attacks during dental treatmenthowever, not all of these attacks may fulfil criteria for DSM-III-R panic attacks (cf. Gross & Eifert, 1990). DISCUSSION
The findings from the first study indicate that pain sensitivity can be distinguished from dental phobia and health concerns. For instance, the item described as ‘having dental X-rays’ correlated positively with the dental phobia factor, whereas it correlated negatively with the pain sensitivity factor (X-rays are not usually painful). The first factor analysis also indicates that dental phobia is independent of medical and injection phobias. This finding is supported by a case study with an adolescent who demonstrated multiple phobias of injections, and dental and medical procedures as each phobia had to be treated individually (Sanders & Jones, 1990). As the pain sensitivity factor accounted for a small proportion of the variance in the solution, a subsequent study was conducted with the aim of developing a more useful measure of pain sensitivity. The findings from the second study also showed that a pain sensitivity dimension could be interpreted in the data. Although five factors were produced by the analysis, the pain sensitivity factor explained a substantial proportion of the variance in the solution. This factor resembles the pain impact factor identified in the study by (Vlaeyen et al., 1990). The relationships of this dimension with anxiety sensitivity and dental pain were investigated in the third study. The third study showed that pain sensitivity did not correlate significantly with self-reported avoidance of dental treatment. However, it was predictive of drill pain, and drill pain was predictive of avoidance behaviour. Although the PSI and the ASS correlated significantly with each other, they did not correlate equally with measures of fear, anxiety, and panic. In support of the view that the construct of pain sensitivity is different from that of anxiety sensitivity, the PSI but not the ASS was found to correlate significantly with blood-injury phobia (many of the situations described by items on this subscale of the Fear Questionnaire, such as having minor surgery, often involve pain). In contrast, the ASS correlated higher than the PSI with anxiety-depression. Nevertheless, both of these constructs may be linked to negative affect. It is not clear why the PSI
12
PETERR. GROSS
correlated significantly with agoraphobia. Although persons who experience panic attacks often report chest pain (cf. Barlow, 1988) they appear to have normal pain threshold levels (Roy-Byrne, 1985). These findings can contribute to an understanding of the fear pathways leading from pain sensitivity to pain intensity and from pain intensity to dental avoidance. Firstly, although Ss in this investigation reported fears of dentists, it seems that they also had an underlying fear of pain. Indeed, personality may influence the learning of abnormal behaviour (Staats, 1990). For instance, consistent with Reiss and McNally’s model, pain sensitivity in persons could interact with pain expectancies in dental situations-which could have an effect on avoidance behaviour. Pain sensitivity appears to have explanatory value as it has been previously noted that dental pain can be controlled by dentists, yet persons may develop dental phobias because inaccurate pain expectations (cf. Arntz & Lousberg, 1990) could interact with the pain sensitivity aspect of personality. Despite the association of fear with dentists and dental treatment in normal persons, most persons do not avoid dental treatment as they have also learned-and may tell themselvesthat such treatment is necessary. Appropriate language behaviours may therefore counteract negative self-verbalizations in relation to dental avoidance. Secondly, it is interesting to note that ‘a dentist holding a drill’ correlated marginally higher than ‘the sight of a dental drill’ with the dental phobia factor. In regard to the treatment of dental phobia, it may be important to target fearful composite images (Lohr & Hamberger, 1990) or fearful action-oriented images as well as images of a dentist or a drill on their own. Thirdly, in regard to the theoretical understanding of pain sensitivity, this construct may predict the number of fears associated with dental treatment as well as the intensity of such fears. In an epidemiologic study, Dworkin, Von Korff and LeResche (1990) found that the number of pain conditions reported by members of a community sample was a better predictor of emotional problems than were pain severity and pain persistence. In addition, social-evaluative fears may contribute to dental avoidance (cf. Moore, Brodsgaard & Birn, 1991). For instance, study 2 showed that persons are concerned about their appearance when they are in pain. When anxious persons attend their dentist, they may perceive that the dentist is evaluating them. To help reduce fear in patients, dentists could indicate their sensitivity to their patient’s pain sensitivity by explaining the various options available to them for pain relief. The present findings suggest that pain intensity and pain sensitivity are important components of dental avoidance. In other words, perceived pain is different to reactions to pain; however, pain sensitivity is only one of the reactions that people may experience in relation to pain. As cognitions can influence the ways in which individuals react to pain experiences (Heyneman, Fremouw, Gano, Kirkland & Heiden, 1990) cognitions may influence the relationship between pain and dental avoidance. It is possible that genetic factors contribute to individual differences in pain thresholds, but they may not be directly involved with pain sensitivity. For instance, Castellano, Puglisi, Renzi and Oliverio (1985) reported genetic differences in daily rhythms of pain thresholds in mice. Numerous studies have shown that endogenous biological factors are involved with pain thresholds (e.g. Janal, Colt, Clark & Glusman, 1984). Cognitions may interact with biological factors, for instance, pain sensitive persons may interpret physical arousal as pain cues. Interestingly, pain but not anxiety has been found to correlate with circulatory and biochemical variables after dental surgery (Goldstein, 1982). In seeking a comprehensive understanding of pain behaviour, Turk and Rudy (1987) have pointed to the need to assess and relate biological and psychological information. Some caution should be exercised in regard to these interpretations of the present findings as the psychometric properties of the PSI have not yet been fully determined. However, the construct of pain sensitivity could be relevant to a comprehensive understanding of various pain behaviours. For instance, a study that is currently being conducted examines the predictions that persons with cardiophobia score highly on both the ASS and the PSI, persons with panic disorder score highly on the ASS, and persons with chronic pain score highly on the PSI. As pain sensitivity is regarded as a stable personality component, it could contribute to an understanding of chronic and multiple pains which are accompanied by anxiety. It is argued that the expectancy model of fear could be expanded to include pain sensitivity and pain expectations; furthermore, in seeking an understanding of tourist approach behaviours, Gross (1991) has suggested that this model needs to include both negative and positive affect.
Assessment
of pain sensitivity
13
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