Pain self-efficacy moderates the association between pain and somatization in a community sample

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UEF//eRepository

DSpace https://erepo.uef.fi

Rinnakkaistallenteet Filosofinen tiedekunta

2018

Pain self-efficacy moderates the association between pain and

somatization in a community sample

Karkkola, Petri

Walter de Gruyter GmbH

Tieteelliset aikakauslehtiartikkelit

http://dx.doi.org/10.1515/sjpain-2018-0052

https://erepo.uef.fi/handle/123456789/7003

Downloaded from University of Eastern Finland's eRepository

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PAIN SELF-EFFICACY MODERATES THE ASSOCIATION BETWEEN PAIN AND SOMATIZATION IN A COMMUNITY SAMPLE

Petri Karkkola

School of Educational Sciences and Psychology, University of Eastern Finland

Sanna Sinikallio

Niko Flink

Kirsi Honkalampi

Matti Kuittinen

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PAIN SELF-EFFICACY MODERATES THE ASSOCIATION BETWEEN PAIN AND SOMATIZATION IN A COMMUNITY SAMPLE

1 Introduction

Pain is a common experience. The global mean for one-year prevalence of neck pain is 25% (1) and for low back pain nearly 40% (2). The burden of these conditions, measured in years lived with a disability, is high (3,4). Pain is often related to

psychological symptoms (5) and sleep disturbance (6). In Europe, approximately 19%

of adults experience chronic pain (7), which affects well-being and healthcare use (8).

A minority of people who experience pain develop a debilitating pain condition (9).

Until recently, discussions about the dynamics of recovery and protective factors have been scarce (10,11). Positive affect and optimism have been suggested to prevent pain chronification as they promote the pursuit of subjectively valued life goals (12). In addition to positive affect (13), resilience (14) has moderated associations between pain and emotional outcomes, thus potentially acting as a protective factor. To our knowledge, the only pain-specific moderating factor that has been examined is pain acceptance (15).

Self-efficacy concerns what a person believes they can do with their cognitive, social, emotional and behavioural skills to achieve goals in certain domains or situations (16). Self-efficacy may affect health status, motivation and an adherence to

prescribed regimens (17), thus potentially affecting the ability to achieve goals that

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are otherwise hindered by illness or incapacity. Pain-related self-efficacies have been defined, for example, as a person’s belief in their ability to control pain or associated negative emotions, or to function despite the pain (18). The latter form of self-

efficacy has been particularly associated with low functional impairment (19). For example, it has predicted less avoidance coping (20) and an increased probability of remaining at work despite recurring pain (21). It has been associated with positive change in pain management interventions (22,23) and in primary care (24). Thus, self-efficacy beliefs on functioning despite pain constitute a plausible protective factor that motivates the continuance of the pursuit of valued goals. We aim to examine whether a person’s self-efficacy to function despite their pain attenuates the association between pain and the two non-pain-specific factors of somatization and anxiety in a community sample. Although speculative, it has been suggested that more pain-specific symptoms may only be relevant in chronic pain contexts (25).

Somatization is a tendency to experience and communicate somatic distress and symptoms unaccounted for by pathological findings, to attribute them to physical illness and to seek medical help for them (26). Somatization has been associated with healthcare use (27), fear-avoidance strategies (28) and risk of pain chronicity, and disability (29). It may amplify transient pain sensations, making them more persistent (30). We propose that pain accompanied by low self-efficacy is associated with higher somatization symptoms, whereas high self-efficacy attenuates the association

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as, through the facilitation of goal pursuit, it may decrease somatic distress and the need to communicate symptoms, attribute them to illness, or seek medical help.

Anxiety symptoms are common in people with chronic pain (5). The relationship between pain and anxiety is probably bidirectional (31). Furthermore, anxiety and pain are associated in the general population (32). Pain may disrupt activities by capturing attention and directing it towards new priorities that concern threat

detection, a key factor in anxiety symptomology (33), and choice of behaviour, often characterised by avoidance (34). In the present study, we hypothesise that high pain self-efficacy attenuates the association between pain and anxiety as it promotes goal pursuit and provides counter-evidence for the intrusive effects of pain or directs attention away from pain experiences, thus decreasing the need for threat detection and avoidance.

2 Method

2.1 Participants and procedure

The participants (N = 217) comprised unpaid volunteers from a Finnish community sample. The inclusion criteria were a minimum age of 18 years and fluency in Finnish. Six participants were excluded due to excessive missing data, most often concerning average pain over the last three months or pain self-efficacy. Four

participants had omitted one item on one of the study measures, and the missing data

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were replaced with the sample mean. Demographic characteristics are presented in Table 1.

INSERT TABLE 1 HERE

The participants were recruited as part of a research methodology course by

undergraduate students of psychology from the School of Educational Sciences and Psychology at the University of Eastern Finland. Data were collected from multiple sites such as workplaces, various public locations, and events. After receiving information about the study and providing their written consent, the participants anonymously completed a background questionnaire and measurements for the study variables and returned the forms to the students in sealed envelopes. The study protocol was approved by the Research Ethics Committee of the University of Eastern Finland.

2.2 Measures

2.2.1 Average pain over the last three months

Average pain over the last three months was measured with one item from the Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) (35,36). The participants were asked to rate their average pain over the last three months using a numerical rating scale (0 = “not at all”, 10 = “very painful”).

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6 2.2.2 Anxiety

Anxiety was assessed using the Anxiety scale (ANX) from the Symptom Checklist- 90 (SCL-90) (37). The participants assessed their anxiety symptoms with 10 items on a scale of 0 (“not at all”) to 4 (“very much”). The mean was used as the scale score, ranging from 0 to 4. Higher scores reflect greater anxiety. The Finnish SCL-90 has been validated in both the general population and for psychiatric patients with adequate psychometric properties (38,39). The internal consistency (Cronbach’s alpha) for the scale in this sample was 0.82.

2.2.3 Somatization

Somatization was assessed using the Somatization scale (SOM) from the SCL-90 (37). The participants reported cardiovascular, gastrointestinal and respiratory symptoms on a scale of 0 (“not at all”) to 4 (“very much”). The scale was scored without the items that referred to pain to prevent pain problems from inflating associations between pain and somatization (40). Somatization scores, calculated as the mean of item scores, can range from 0 to 4. Higher scores reflect greater

somatization. The internal consistency (Cronbach’s alpha) of the scale in this sample was 0.78.

2.2.4 Pain self-efficacy

Pain self-efficacy was assessed using the Pain Self-Efficacy Questionnaire (PSEQ) (41). The PSEQ is a 10-item measure of pain-related self-efficacy. Using a 7-point

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scale from 0 (“not at all confident”) to 6 (“completely confident”), the participants rated their confidence in their ability to perform various activities despite their pain.

Scores can range from 0 to 60, with higher scores indicating stronger self-efficacy beliefs. The Finnish PSEQ has been validated in a sample of rehabilitation

intervention participants with good psychometric properties (42). The internal consistency (Cronbach’s alpha) of the scale in this sample was 0.94.

2.3 Data analysis

The IBM SPSS Statistics 23 program was used for all statistical analyses. The PROCESS macro (43) was used to test for moderator effects. The utilization of PROCESS was based on the availability of heteroscedasticity-consistent standard errors (44).

The number and percentage (for categorical variables) and means and standard deviations (for continuous variables) for the study variables are presented for descriptive purposes. We computed the intercorrelations of the study variables and performed two series of regression analyses. Anxiety and somatization, respectively, were the dependent variables. Average pain over the last three months was entered first. Next, pain self-efficacy was entered. The average pain x pain self-efficacy interaction term was entered at the final step. The scores were all non-centred raw scores. The probability of Type I error was controlled by the Bonferroni correction; a p-value of 0.025 (0.05/2) was chosen as the level of significance in the regression

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analyses. To illustrate significant moderation effects, we present figures with correlations between average pain over the last three months and the independent variable for the lowest and highest quartile of pain self-efficacy.

INSERT TABLE 2 HERE

3 Results

3.1 Sample characteristics

Table 1 displays the demographic characteristics of the sample. The mean age was 38.0 years. There were more women (61%) than men (38%). Most participants were married or in a domestic partnership (55%), and most either worked full time (52%) or were studying (21%).

Participants had experienced, on average, only mild pain over the last three months and mild current anxiety symptoms or somatization. The participants’ pain self- efficacy was high (see Table 2).

3.2 Moderating effects of pain self-efficacy

Intercorrelations between the study variables are listed in Table 3. Average pain was moderately associated with anxiety and somatization, but not significantly with pain self-efficacy. Anxiety and somatization were strongly associated, and both had a statistically significant association with pain self-efficacy.

INSERT TABLE 3 HERE

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The results of the regression analyses are presented in Table 4. Using anxiety as the dependent variable, the results show a direct effect of average pain over the last three months on anxiety in the first step (t = 4.08, p < 0.025) and a direct negative effect of pain self-efficacy over and above average pain in the second step (t = –2.37,

p < 0.025). In the third step, the interaction term was not statistically significant.

INSERT TABLE 4 HERE

Using somatization as the dependent variable, average pain over the last three months had a direct effect on somatization in the first step (t = 4.92, p < 0.025). Pain self- efficacy had a direct negative effect on somatization over and above average pain in the second step (t = –3.49, p < 0.025). In the third step, the average pain x pain self- efficacy interaction term was statistically significant (F(1,207) = 5.65, p < 0.025), indicating moderation. The interaction explained 3% of the variance in somatization, over and above average pain and self-efficacy. Among those in the bottom quartile of pain self-efficacy, the association between average pain over the last three months and somatization was moderate or strong (r = 0.62, p < 0.01). For those in the top quartile of pain self-efficacy, the association was modest and statistically non- significant (r = 0.11, p > 0.05). This interaction is presented in Figure 1.

INSERT FIGURE 1 HERE

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10 4 Discussion

The findings were partially consistent with the hypothesis that high pain self-efficacy moderates the negative effects of average pain over the last three months, even in a relatively healthy community sample. We observed a moderator effect, suggesting that high pain self-efficacy attenuates the association between perceived pain and somatization.

4.1 Moderating effect on somatization

To our knowledge, this is the first study to examine the moderating effect of pain self-efficacy on the association between pain and somatization. Furthermore, the effect was observed in a community sample. As somatization is consistently elevated in chronic pain samples (5), increases the risk of low back pain chronicity (29), and is associated with seeking health care (27), the result is interesting from both a scientific and a clinical perspective.

It has been suggested that pain interference in day-to-day activities could trigger the adverse responses regarding affects, disability and chronicity (10). However, factors that contribute to the pursuit of valued goals may protect against pain chronification and subsequent disability (11, 12). Pain self-efficacy, defined as the confidence to function despite pain, is negatively associated especially with functional impairment (19). As a motivational factor, pain self-efficacy could, via goal-setting and other active self-regulatory strategies (16), decrease somatic distress and the need to

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communicate symptoms, attribute them to illness, or seek medical help, as pain self- efficacy predicts better outcomes related to pain management interventions (23), work (21), and coping (20).

Pain self-efficacy is not the only potential pain-related factor that promotes goal pursuit. For example, pain acceptance has been found to moderate the relationship of pain and negative affect in a chronic pain sample (15). It is noteworthy that the most common pain acceptance measure comprises subscales that assess the degree of engagement in activities regardless of pain, and the willingness to experience pain (45,46). It appears that engagement in activity despite pain (component of pain acceptance) and the confidence to function despite pain (pain self-efficacy) are related but not identical phenomena that should be studied together as potential protective factors.

The interaction explained 3% percent of additional variance over and above average pain over the last three months and self-efficacy. It is expected that in a community sample displaying mild pain symptoms, the possible effect would be of modest magnitude. For example, in a sample suffering from chronic pain, interactions

including pain intensity and positive affect contributed an additional variance of up to 9%, depending on the outcome variables (13).

If future studies were to support the moderating effect, the role of self-efficacy as a protective factor should be explicated. Further research, preferably longitudinal, in

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both the general population and in chronic pain samples is necessary to establish the moderating effect.

The findings have some clinical implications. Supporting and promoting the patient’s confidence in their functioning despite pain is recommended, including in acute and sub-acute pain conditions. This may be especially important with individuals who are prone to somatization. However, although pain self-efficacy can be increased during interventions for people suffering from chronic pain (47,48), more research on supporting pain self-efficacy in non-chronic pain populations is needed.

4.2 Lack of a moderating effect on anxiety

The lack of a moderating effect of pain self-efficacy on the association between pain intensity and anxiety may initially seem surprising. Several factors have buffered the effects of pain on depression (14) or on negative affect (13). However, previous studies have examined people suffering from chronic pain.

The most basic explanation is that while pain is common in the general population, pain-related self-efficacy is not an important protective factor in relation to anxiety symptoms. Moderate or severe anxiety symptomology is also associated with many non-pain-related life events (49) and personality traits (50). In contrast, it is likely that somatization has a more direct connection to common pain experiences. Anxiety is perhaps too broad an outcome measure compared to more pain-specific factors such

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as pain catastrophizing or fear of pain. The hypothesised buffering effect in the chronic pain population remains an open question and warrants further research.

However, it is also possible that despite high intercorrelations, anxiety and

somatization have fundamental differences regarding the dynamics of pain and pain- self-efficacy. Somatization directs attention to somatic distress and motivates a person to seek medical help (26), whereas anxiety is about threat detection and avoidance (33). It is possible that the avoidance motivated by anxiety directs a person’s efforts towards goals that are not particularly facilitated by pain self- efficacy, thus making it impossible for self-efficacy to provide counter-evidence of the intrusive effects of pain regarding the avoided or abandoned goals now being associated with pain. Nevertheless, all these hypothetical mechanisms need to be further studied.

4.3 Study limitations

The study has some limitations. Firstly, the cross-sectional design rules out causal conclusions. The results are partially consistent with the buffering hypothesis but do not refute alternative interpretations. Secondly, in our sample, anxiety, somatization, and pain intensity were all low. This makes the detection of moderator effects more difficult, although this is more or less inevitable in a community sample. Thirdly, anxiety and somatization are related both conceptually and empirically (26). As they correlate strongly and have virtually identical associations with pain and pain self-

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efficacy in the present study, it may be doubtful whether one provides any

incremental information over the other. However, they may have different dynamics regarding pain and pain self-efficacy, and their moderating roles differed.

Nevertheless, in further studies the potential protective role of pain self-efficacy should be examined with more variable risk factors, including pain-specific measures.

Fourthly, our sample was not representative, but was a convenience sample. The generalisability of our results is unknown. This calls for replications using different kinds of participants, both with and without pronounced pain. Finally, it is not known how stable pain self-efficacy is in the transitions between different pain conditions (e.g. from acute pain to sub-acute pain). If pain self-efficacy is unstable, it may not be a reliable protective factor.

4.4 Conclusions

Interestingly, pain self-efficacy moderated the association between pain intensity and somatization in a community sample. Attempts at replications should be made with samples of different pain conditions. Providing that the effect is observed and the person’s pain self-efficacy is found to be at least moderately stable, pain self-efficacy should be considered a protective factor in the process of pain chronification.

5 Authors’ statements 5.1 Research funding

There was no funding for this study.

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15 5.2 Conflict of interest

The authors declare no potential conflicts of interest.

5.3 Informed consent

After receiving information about the study, the participants provided written consent.

5.4 Ethical approval

The study protocol was approved by the Research Ethics Committee of the University of Eastern Finland.

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16 References

(1) Hoy DG, Protani M, De R, Buchbinder R. The epidemiology of neck pain. Best Pract Res Clin Rheumatol 2010;24:783–92.

(2) Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, Woolf A, Vos T, Buchbinder R. A systematic review of the global prevalence of low back pain.

Arthritis Rheum 2012;64:2028–37.

(3) Hoy D, March L, Brooks P, Blyth F, Woolf A, Bain C, Williams G, Smith E, Vos T, Barendregt J, Murray C, Burstein R, Buchbinder R. The global burden of low back pain: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014;73:968–74.

(4) Hoy D, March L, Woolf A, Blyth F, Brooks P, Smith E, Vos T, Barendregt J, Blore J, Murray C, Burstein R, Buchbinder R. The global burden of neck pain:

estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis 2014;73:1309–15.

(5) Burke ALJ, Mathias JL, Denson LA. Psychological functioning of people living with chronic pain: a meta‐analytic review. Brit J Clin Psychol 2015;5:345–60.

(6) Kelly GA, Blake C, Power CK, O'Keeffe D, Fullen BM. The association between chronic low back pain and sleep: a systematic review. Clin J Pain 2011;27:169–81.

(7) Breivik H, Collett B, Ventafridda V, Cohen R, Gallacher D. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Eur J Pain

2006;10:287–333.

(8) Reid KJ, Harker J, Bala MM, Truyers C, Kellen E, Bekkering GE, Kleinen J.

Epidemiology of chronic non-cancer pain in Europe: narrative review of prevalence, pain treatments and pain impact. Curr Med Res Opin 2011;27:449–62.

(9) Boersma K, Carstens-Söderstrand J, Linton SJ. From acute pain to chronic

disability: psychosocial processes in the development of chronic musculoskeletal pain and disability. In: Gatchel RJ, Schultz IZ, editors. Handbook of musculoskeletal pain and disability disorders in the workplace. New York: Springer, 2014:205–17.

(10) Crombez G, Eccleston C, Van Damme S, Vlaeyen J, Karoly P. Fear-Avoidance model of chronic pain: the next generation. Clin J Pain 2012;28:475–83.

(18)

17

(11) Boselie JJL, Vlaeyen JWS. Broadening the fear-avoidance model of chronic pain? Scand J Pain 2017;17:176–7.

(12) Vlaeyen JWS, Crombez G, Linton SJ. The fear-avoidance model of pain. Pain 2016;157:1588–9.

(13) Thong ISK, Tan G, Jensen MP. The buffering role of positive affect on the association between pain intensity and pain related outcomes. Scand J Pain 2017;14:91–7.

(14) Bauer H, Emeny RT, Baumert J, Ladwig K. Resilience moderates the association between chronic pain and depressive symptoms in the elderly. Eur J Pain

2016;20:1253–65.

(15) Kratz A, Davis M, Zautra A. Pain acceptance moderates the relation between pain and negative affect in female osteoarthritis and fibromyalgia patients. Ann Behav Med 2007;33:291–301.

(16) Bandura A. Self-efficacy: the exercise of control. New York: Freeman, 1997:604.

(17) Marks R, Allegrante JP, Lorig K. A review and synthesis of research evidence for self-efficacy-enhancing interventions for reducing chronic disability: implications for health education practice (part I). Health Promot Pract 2005;6:37–43.

(18) Miles CL, Pincus T, Carnes D, Taylor SJC, Underwood M. Measuring pain self- efficacy. Clin J Pain 2011;27:461–70.

(19) Jackson T, Wang Y, Wang Y, Fan H. Self-efficacy and chronic pain outcomes: a meta-analytic review. J Pain 2014;15:800–14.

(20) Asghari A, Nicholas MK. Pain self-efficacy beliefs and pain behaviour. A prospective study. Pain 2001;94:85–100.

(21) de Vries HJ, Reneman MF, Groothoff JW, Geertzen JHB, Brouwer S. Workers who stay at work despite chronic nonspecific musculoskeletal pain: do they differ from workers with sick leave? J Occup Rehabil 2012;22:489–502.

(22) Kowal J, Wilson KG, Geck CM, Henderson PR, D'Eon JL. Changes in perceived pain severity during interdisciplinary treatment for chronic pain. Pain Res Manag 2011;16:451–6.

(19)

18

(23) Nicholas MK, Asghari A, Corbett M, Smeets RJ, Wood BM, Overton S, Perry C, Tonkin, LE, Beeston L. Is adherence to pain self-management strategies associated with improved pain, depression and disability in those with disabling chronic pain?

Eur J Pain 2012;16:93–104.

(24) Campbell P, Foster NE, Thomas E, Dunn KM. Prognostic indicators of low back pain in primary care: five-year prospective study. J Pain 2013;14:873–83.

(25) Mounce C, Keogh E, Eccleston C. A principal components analysis of negative affect-related constructs relevant to pain: evidence for a three component structure. J Pain 2010;11:710–7.

(26) Lipowski ZJ. Somatization: the concept and its clinical application. Am J Psychiat 1988;145:1358–68.

(27) Jensen JC, Haahr JP, Frost P, Hviid Andersen J. The significance of health anxiety and somatization in care-seeking for back and upper extremity pain. Fam Pract 2012;29:86–95.

(28) Chou R, Shekelle P. Will this patient develop persistent disabling low back pain?

JAMA 2010;303:1295–302.

(29) Pincus T, Burton AK, Vogel S, Field AP. A systematic review of psychological factors as predictors of chronic/disability in prospective cohorts of low back pain.

Spine 2002;27:E109–20.

(30) Vargas-Prada S, Coggon D. Psychological and psychosocial determinants of musculoskeletal pain and associated disability. Best Pract Res Clin Rheumatol 2015;29:374–90.

(31) van Hecke O, Torrance N, Smith BH. Chronic pain epidemiology and its clinical relevance. Brit J Anaesth 2013;111:13–8.

(32) Hinz A, Ernst J, Glaesmer H, Brähler E, Rauscher FG, Petrowski K, Kocalevent RD. Frequency of somatic symptoms in the general population: normative values for the Patient Health Questionnaire-15 (PHQ-15). J Psychosom Res 2017;96:27–31.

(33) Ouimet AJ, Gawronski B, Dozois DJA. Cognitive vulnerability to anxiety: a review and an integrative model. Clin Psychol Rev 2009;29:459–70.

(20)

19

(34) Attridge N, Crombez G, Van Ryckeghem D, Keogh E, Eccleston C. The experience of cognitive intrusion of pain: scale development and validation. Pain 2015;156:1978–90.

(35) Linton S, Boersma K. Early identification of patients at risk of developing a persistent back problem: the predictive validity of the Örebro Musculoskeletal Pain Questionnaire. Clin J Pain 2003;19:80–6.

(36) Ruokolainen O, Haapea M, Linton S, Korniloff K, Häkkinen A, Paananen M, Karppinen J. Construct validity and reliability of Finnish version of Örebro

Musculoskeletal Pain Screening Questionnaire. Scand J Pain 2016;13:148–53.

(37) Derogatis LR, Cleary PA. Confirmation of the dimensional structure of the SCL- 90: a study in construct validation. J Clin Psychol 1977;33:981–9.

(38) Holi MM, Sammallahti PR, Aalberg VA. A Finnish validation study of the SCL- 90. Acta Psychiat Scandinavica 1998;97:42–6.

(39) Holi MM, Marttunen M, Aalberg V. Comparison of the GHQ-36, the GHQ-12 and the SCL-90 as psychiatric screening instruments in the Finnish population. Nord J Psychiat 2003;57:233–8.

(40) Turner JA, Holtzman S, Mancl L. Mediators, moderators, and predictors of therapeutic change in cognitive–behavioral therapy for chronic pain. Pain 2007;127:276–86.

(41) Nicholas MK. The pain self-efficacy questionnaire: taking pain into account.

Europ J Pain 2007;11:153–63.

(42) Karkkola P, Kuittinen M. [Psychometric properties of the Finnish Pain-Self- Efficacy Questionnaire in musculoskeletal rehabilitees]. Psykologia 2017;52:276–92.

Finnish.

(43) Hayes AF. Introduction to mediation, moderation, and conditional process analysis. New York: The Guilford Press, 2013:507.

(44) Hayes AF, Cai L. Using heteroscedasticity-consistent standard error estimators in OLS regression: an introduction and software implementation. Behav Res Methods 2007;39:709–22.

(45) McCracken LM, Vowles KE, Eccleston C. Acceptance of chronic pain:

component analysis and a revised assessment method. Pain 2004;107:159–66.

(21)

20

(46) Ojala T, Piirainen A, Sipilä K, Suutama T, Häkkinen A. Reliability and validity study of the Finnish version of the Chronic Pain Acceptance Questionnaire (CPAQ).

Disabil Rehabil 2013;35:306–14.

(47) Nash VR, Ponto J, Townsend C, Nelson P, Bretz MN. Cognitive behavioral therapy, self-efficacy, and depression in persons with chronic pain. Pain Manag Nurs 2013;14:e236–43.

(48) Tse MM, Vong SK, Tang SK. Motivational interviewing and exercise

programme for community‐dwelling older persons with chronic pain: a randomised controlled study. J Clin Nurs 2013;22:1843–56.

(49) Spinhoven P, Elzinga BM, Hovens JG, Roelofs K, Zitman FG, van Oppen P, Penninx BW. The specificity of childhood adversities and negative life events across the life span to anxiety and depressive disorders. J Affect Disorders 2010;126:103–

12.

(50) Kotov R, Gamez W, Schmidt F, Watson D. Linking "big" personality traits to anxiety, depressive, and substance use disorders. Psychol Bull 2010;136:768–821.

(22)

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Figure 1. Associations of pain with somatization for different levels of pain self- efficacy.