ORIGINAL ARTICLE
Pain expectations in neuropathic pain: Is it best to be optimistic? G.P. Bostick1, S.J. Kamper2, T.M. Haanstra3, B.D. Dick4, L.W. Stitt5, P. Morley-Forster6, A.J. Clark7, M.E. Lynch7, 8, A. Gordon9, H. Nathan10, C. Smyth10, M.A. Ware11, C. Toth12, D.E. Moulin13 1 Department of Physical Therapy, University of Alberta, Edmonton, Canada 2 The George Institute for Global Health, University of Sydney, NSW, Australia 3 Department of Orthopedics, VU University Medical Center, Amsterdam, The Netherlands 4 Departments of Anesthesiology and Pain Medicine, Psychiatry and Pediatrics, University of Alberta, Edmonton, Canada 5 LW Stitt Statistical Services, London, ON, Canada 6 Department of Anaesthesiology, Pain Management and Peri-operative Medicine, Western University, London, ON, Canada 7 Department of Anaesthesia, Dalhousie University, Halifax, NS, Canada 8 Departments of Psychiatry and Pharmacology, Dalhousie University, Halifax, NS, Canada 9 Department of Medicine, Division of Neurology, University of Toronto, ON, Canada 10 Department of Anaesthesiology, University of Ottawa, ON, Canada 11 Departments of Family Medicine and Anaesthesia, McGill University, Montreal, QC, Canada 12 Fraser Valley Health Authority, Surrey, BC, Canada 13 Departments of Neurological Sciences and Oncology, Western University, London, ON, Canada
Correspondence Geoff Bostick E-mail:
[email protected] Funding sources This study was funded by grants from Canadian Foundation for Innovation (#7878) and Pfizer Canada. Dr. Moulin has received research funding Phizer Canada and honoraria for continuing education seminars from Merck-Frosst, Purdue Pharma, Lily and Johnson and Johnson. Conflicts of interest Dr. Morley-Forster has received a speaker’s honorarium from Purdue. The remaining authors declare no conflicts.
Accepted for publication 4 September 2016 doi:10.1002/ejp.962
© 2016 European Pain Federation - EFICâ
Abstract Background: Pain expectancy may be an important variable that has been found to influence the effectiveness of treatments for pain. Much of the literature supports a self-fulfilment perspective where expectations for pain relief predict the actual pain experienced. However, in conditions such as neuropathic pain (NeP) where pain relief is difficult to attain, expectations for pain relief could be unrealistic. The objective of this study was to investigate the relationship between realistic/unrealistic expectations and 6-month, post-treatment outcomes. Methods: We performed a retrospective analysis of a large cohort of patients with NeP (n = 789) attending tertiary care centres to determine the association between unrealistic (both positive and negative) and realistic expectations with outcomes after multidisciplinary treatment. An expectation variable with three categories was calculated: realistic expectations were those whose expected reduction in pain was similar to the observed mean group reduction in pain, while optimistic and pessimistic expectations were those who over- or under-estimated the expected response to treatment, respectively. The association between baseline realistic/unrealistic expectations and 6-month pain-related disability, catastrophizing and psychological distress was assessed. Results: Univariable analyses suggested that realistic expectations were associated with lower levels of disability, catastrophizing and psychological distress, compared to unrealistic expectations. However, after adjustment for baseline symptom severity, multivariable analysis revealed that patients with optimistic expectations had lower levels of disability, than those with realistic expectations. Those with pessimistic expectations had higher levels of catastrophizing and psychological distress at follow-up. Conclusions: These findings are largely congruent with the selffulfilment perspective to expectations.
Eur J Pain
(2016)
–
1
Pain expectations in neuropathic pain
G.P. Bostick et al.
Significance: This study defined realistic pain expectations with patient data. Examining the relationship between expectations between pain and disability in a large cohort of patients with neuropathic pain.
1. Introduction Pain expectations are broadly defined as patient’s individual predictions regarding a future pain outcome (Janzen et al., 2006). Pain expectations are expectations about the future intensity of pain and have been cited as an important construct in contributing to the experience of pain (Mondloch et al., 2001; Cormier et al., 2016). The manner in which expectations influence behaviour is commonly conceptualized using response expectancy theory, which is rooted in social-cognitive theory (Maddux, 1994). Response expectancy is an expectation for a nonvolitional response (e.g. pain) and is related to one’s beliefs about their own reactions to pain (Maddux, 1994). A key tenant of response expectancy is the self-fulfilment perspective where expected outcomes are more likely to occur for a variety of reasons including changes in behaviour that result from cognitive expectations and biases (Logan and Rose, 2005). For example, negative pain expectations (i.e. expecting that pain intensity will worsen or fail to improve) tend to be associated with poor future outcomes, while positive pain expectations tend to be associated with more positive outcomes (Goossens et al., 2005; Smeets et al., 2008; Bialosky et al., 2011; Bishop et al., 2011, 2013). Some data suggest that it is more important to set expectations that are likely to be fulfilled (realistic). For example, fulfilled expectations have been shown to be more strongly related to outcome than the expectation itself (Mannion et al., 2009). Moreover, since chronic pain is often refractory to treatments aimed at reducing pain intensity it can be difficult to fulfil expectations for pain relief. Thus, facilitating realistic expectations is a common management recommendation (Husain and Lee, 2015). Unrealistic expectations may generate negative consequences such as disappointment and disillusionment when they are not met (Armor and Taylor, 1998). Disillusionment or “the pathology of high expectations” tends to occur when an individual’s high expectations persist for long periods of time despite unsatisfactory outcomes (Janoff-Bulman and Brickman, 1982). The implications of this could include reduced self-efficacy or the perseverance of ineffective problem-solving and over-looking valid alternatives to manage pain. 2 Eur J Pain (2016) –
Expectations is a complex construct (Haanstra et al., 2015); an expectation for little or no pain relief could be viewed as either maladaptive or adaptive (realistic). A patient who does not expect their pain to change may not have adequate self-efficacy to engage in a proposed treatment aimed at reducing pain intensity and suffer an undesirable outcome (Jackson et al., 2014). On the other hand, the expectation could be viewed as realistic and an adaptive adjustment to living well despite chronic pain (Ramirez-Maestre et al., 2012). Thus, self-fulfilling expectations may not tell the full story. The majority of studies in the pain literature argue from a self-fulfilment perspective and consequently, there is little data that critiques common clinical practices where realistic expectations are encouraged, instead of positive expectations. The objective of this study was to investigate the association of realistic expectations with the 6-month outcomes of self-reported disability, catastrophizing and psychological distress. We hypothesized that patients with neuropathic pain (NeP) with unrealistically optimistic expectations for pain relief would have poorer outcomes compared to patients with NeP with realistic expectations. Poorer outcomes were defined as higher levels of self-reported disability, pain catastrophizing and psychological distress at 6-month follow-up. A secondary objective was to explore potential demographic and baseline clinical characteristics associated with those with realistic and unrealistic expectations for pain relief.
2. Methods 2.1 Participants A retrospective study was performed on patients originally included in the Canadian Neuropathic Pain Database (NePDAT) which was established in 2008 and records data from patients with NeP seen in academic tertiary care pain centres across Canada. Probable NeP was diagnosed if there was clinical evidence of a lesion or disease affecting the somatosensory system (Treede et al., 2008). Clinical evidence included the DN4 questionnaire (Bouhassira et al., 2005) and bedside sensory examination. Inclusion criteria were the presence of NeP of at least © 2016 European Pain Federation - EFICâ
G.P. Bostick et al.
3 months duration and an estimated life expectancy of at least 2 years. Patients were excluded if they did not have primarily NeP were diagnosed with fibromyalgia, had a personality disorder, cognitive impairment or history of substance abuse, had a significant language barrier or presented with active cancer or tumour infiltration of nerve. NePDAT consists of 789 patients with varied NeP diagnoses assessed at baseline and follow-up visits at 3, 6, 12, 18 and 24 months. Treatment for these patients were consistent with standard guidelines for the management of neuropathic pain (O’Connor and Dworkin, 2009; Attal et al., 2010; Moulin et al., 2014) and may have consisted of pharmacotherapy and other approaches including; physical therapy, occupational therapy, kinesiology, psychology and invasive pain reduction procedures such as lidocaine infusions, spinal cord stimulation and nerve ablation. Treatment was individualized for each patient as determined by the treating clinician. Outcome measures administered at baseline and at each follow-up visit were consistent with Initiatives on Methods Measurement and Pain Assessment in Clinical Trials (IMMPACT) guidelines (Dworkin et al., 2005). Measures used in this study are described below. Institutional ethics review board approval was obtained at each tertiary care pain centre and informed consent was acquired from all study participants.
2.2 Measures The three dependent variables were measured 6months after treatment was initiated. The 6-month follow-up was chosen because the pain expectations item (described below) referenced expected pain in 6-months. Disability was self-reported using the Pain Disability Index (PDI) (Pollard et al., 1984). The PDI scores the extent of pain interference with typical activities of daily living on a scale from 0 to 70. Higher PDI scores indicate higher levels of selfreported disability. The PDI has acceptable internal consistency (a = 0.86) and test–retest reliability (r = 0.44) (Tait et al., 1987). The validity evidence of the PDI is supported insofar as scores are significantly related to pain intensity, psychological distress and other disability measures (Tait et al., 1990). Pain catastrophizing was measured with the Pain Catastrophizing Scale (PCS), a 13-item instrument that measures the extent of exaggerated negative mental thoughts during actual or anticipated painful experience on a 0–52 point scale (Sullivan et al., 1995). Higher PCS scores indicate higher levels of painrelated catastrophizing. The PCS has acceptable © 2016 European Pain Federation - EFICâ
Pain expectations in neuropathic pain
internal consistency (a = 0.87), test–retest reliability (r = 0.75) (Sullivan et al., 1995), substantial validity evidence and is one of the most consistent predictors of persistent disability (Quartana et al., 2009). Psychological distress was measured using the Profile of Mood States (POMS), a 30-item scale used to assess six mood states (including depression, anxiety and anger) as well as a total mood disturbance score (McNair et al., 1971). For the total score, possible scores range from 20 to 100 with higher total scores indicating greater mood disturbance. The POMS has acceptable internal consistency (a = 0.63– 0.93), test–retest reliability (r = 0.65–0.74) (Curran et al., 1995) and is sensitive to detecting relationships between pain and emotional functioning (Jensen et al., 2007). All of these measures are widely used and have been recommended for use in chronic pain research (Dworkin et al., 2005; Taylor et al., 2016). Expected pain was measured with 1-item specifically constructed for this database and similar to other 1-item measures of expectations (Ebrahim et al., 2015): ‘Given the treatment plan, what do you expect your pain to be in 6 months?’ Participants circled a number from 0 (no pain) to 10 (pain as bad as you can imagine). In the context of this study, pain expectations reflect outcome or probability expectations (Kravitz, 1996; Janzen et al., 2006; Haanstra et al., 2013). Realistic expectations were defined in reference to the observed mean improvement in pain intensity from baseline to 6 months post-treatment for the cohort. In this case, the mean improvement (standard deviation) was 0.89 (2.09), rounded to 1.0 (2.0), on an 11-point numeric rating scale. Thus, a realistic expectation would be one that is similar to the observed mean improvement in pain intensity for the cohort. Based on the observed mean improvement in pain, realistic expectations for pain intensity reduction at 6-months (baseline pain intensity – expected pain) were defined as those that fell within the mean improvement (1.0) 1 standard deviation (2.0) (≥ 1 and ≤ +3). Accordingly, unrealistic, optimistic expectations were calculated as baseline pain intensity – pain expectations > +3. Unrealistic, pessimistic expectations were calculated as baseline pain intensity – pain expectations < 1. Pain intensity was measured on an 11-point numeric rating scale anchored with 0 (no pain) and 10 (worst imaginable pain) averaged over the past 2 weeks. Other descriptive variables included age (years), gender, pain duration (months), hope for pain relief in 6 months (0–10 numeric pain scale: “Given the treatment plan, what do you hope your Eur J Pain
(2016)
–
3
Pain expectations in neuropathic pain
pain level will be in 6 months from now?”) and selfreported opioid use at baseline and prescribed opioid use at 6-month follow-up. These measures were not included in the main analyses but are presented to describe the sample and explore potential associations with realistic/unrealistic expectancy at baseline.
2.3 Analysis Descriptive statistics for the entire sample and for each expectancy group at baseline and 6-months were calculated as means and standard deviations or, when appropriate, medians and interquartile ranges (IQR) for continuous variables and percentages for dichotomous variables. One-way analysis of variance was used to determine statistical differences in clinical variables among expectancy group at baseline and 6 months follow-up. For each of the three dependent variables (6 month disability, catastrophizing and psychological distress) linear regressions were used to evaluate differences among expectancy groups adjusting for baseline pain, disability, catastrophizing, psychological distress and pain duration. Only participants with complete predictor (baseline) and outcome (6 months) data were used in the analyses, participants included and excluded on this basis were compared with respect to clinical measures at baseline. SAS 9.3â software (Cary, NC, USA) was used to perform all analyses. p-values
