Psychosocial Variables in Patients With (Sub)Acute Low Back Pain

Transcription

1 Psychosocial Variables in Patients With (Sub)Acute Low Back Pain An Inception Cohort in Primary Care Physical Therapy in the Netherlands Hans Heneweer, MSc,* Geert Aufdemkampe, MSc,* Maurits W. van Tulder, PhD, Henri Kiers, MSc,* Karel H. Stappaerts, PhD, and Luc Vanhees, PhD* SPINE Volume 32, Number 5, pp , Lippincott Williams & Wilkins, Inc. Study Design. A prospective cohort study of patients with episodes of acute or subacute low back pain, seeking physical therapy in primary care, with follow-up at weeks 2, 4, 8, and 12. Objectives. To evaluate the association between psychosocial factors and the transition from acute or subacute low back pain to chronicity. Summary of Background Data. Psychosocial factors have long been thought to be associated with chronic pain only. Recent prospective studies, however, suggest that these factors may also be important in acute or subacute low back pain. Methods. Demographic, psychosocial, and psychological baseline data were collected and analyzed from a sample of 66 acute or subacute patients with low back pain in order to predict the 3-month outcome. Results. After 3 months, response rate was 85% (56 patients). Forty-five percent rated their current status as not recovered. Twelve percent reported work absenteeism. Using multiple regression analyses, baseline scores on the Acute Low Back Pain Screening Questionnaire, Pain Coping Inventory, Fear-Avoidance Beliefs Questionnaire, and Tampa Scale for Kinesiophobia were not significantly associated with nonrecovery at 3 months. The only significant predictor at baseline was the subscale pain of the ALBPSQ, correctly classifying 80% of the patients. The relative risk for not being recovered was 3.72 (95% confidence interval, ) for the subjects with high scores on the subscale for pain. Pain scores and scores on psychosocial variables at 12 weeks were not associated. Conclusions. The study strongly revealed pain-related items to be essential factors in the development of chronicity and long-term disability in primary care physical therapy. Health status at 8 weeks seems crucial in developing chronicity. From the *Research Department Lifestyle and Health and Department of Physical Therapy, University of Professional Education, Utrecht, the Netherlands; Institute for Research in Extramural Medicine, VU University Medical Center, Amsterdam, the Netherlands and Institute for Health Sciences, Faculty of Earth & Life Sciences, Vrije Universiteit, Amsterdam, the Netherlands; and Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, Katholieke Universiteit Leuven, Leuven, Belgium. Acknowledgment date: November 29, First revision date: April 13, Second revision date: June 2, Acceptance date: June 2, The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript. Address correspondence and reprint requests to Hans Heneweer, MSc, University of Professional Education, Department of Physical Therapy, PO Box 85182, 3508 AD Utrecht, the Netherlands; hans. heneweer@hu.nl Key words: inception cohort, acute low back pain, prognostic factors, psychosocial. Spine 2007;32: Low back pain (LBP) continues to be one of the most common and challenging problems in primary care. It is associated with high costs around the western world, both in direct healthcare expenditures and in indirect work and disability-related losses. 1 6 Although LBP is common, explanation of its etiology, particularly its development into chronicity, appears to be substantially hypothetical. Because of considerable variations regarding the definitions of LBP as well as recovery, the course of acute LBP is less identically described. In case of sick absenteeism, most patients return to work within a few weeks. 7 On the other hand, pain and limitations in daily life for more than 1 year after onset are reported Given the serious consequences of chronic LBP, it is important to search for interventions that prevent acute complaints from becoming chronic. 12 Preventive intervention during the acute or subacute stage may be easier to perform and may be more costeffective than rehabilitation of chronicity. 13 Physical therapy in primary care may well play an effective role in identifying patients at risk of developing chronic LBP. During the last decades, explanatory models of back pain adopted by the medical professions have changed from the traditional biomedical and postural model to the biopsychosocial model. 14 In the early 1980s, several authors proposed a fear-avoidance model. Central to the concept of the fear-avoidance model is the idea that fear and avoidance of pain are the most emotive dimensions of pain. 18 This theoretical model was developed in the context of an interdisciplinary back pain clinic and attempted to explain why the majority of people who experience an acute episode of LBP recover spontaneously, whereas a small minority became chronic LBP sufferers. The Fourth International Forum for Primary Care Research on LBP 19 documented the field s emergent new paradigm: a transition from thinking about back pain as a biomedical injury to viewing LBP as a multifactorial biopsychosocial pain syndrome. Although psychosocial factors have long been thought to be associated with chronic pain only, more recent research focuses on psychosocial factors in association with acute or subacute pain. 20 A multitude of 586

2 Psychosocial Variables in Patients With LBP Heneweer et al 587 Table 1. Baseline Characteristics and Scores Dichotomized in Recovered or Not at 12 Weeks (n 56) Recovered at 12 Weeks Not Recovered at 12 Weeks Gender (M/F) (n) 20/11 14/11 Age [Mean (SD)] 40.8 (9.2) 43.1 (9.1) Duration current complaint* (%) 4 weeks 20 (64.5) 9 (36.0) 4 6 weeks 9 (29.0) 6 (24.0) 7 12 weeks 2 (6.5) 10 (40.0) First episode [no. (%)] 1 year 1 (3.2) 3 (12.0) 1 2 years 5 (16.1) 5 (20.0) 3 5 years 10 (32.3) 6 (24.0) 5 years 15 (48.4) 11 (44.0) No. of episodes last 5 years [no. (%)] (51.6) 12 (48.0) (29.0) 8 (32.0) (12.9) 3 (12.0) 10 2 (6.5) 2 (8.0) Previous complaint [no. (%)] 0 3 mo 7 (23.3) 9 (36.0) 4 6 mo 4 (13.3) 4 (16.0) 7 12 mo 9 (30.0) 6 (24.0) 12 mo 10 (33.3) 6 (24.0) Average duration previous episode [no. (%)] 0 4 weeks 18 (60.0) 13 (54.2) 5 6 weeks 6 (20.0) 4 (16.7) 6 weeks 6 (20.0) 7 (29.1) Average interval between episodes [no. (%)] 0 3 mo 3 (10.0) 6 (25.1) 4 6 mo 4 (13.4) 2 (8.3) 7 12 mo 7 (23.3) 5 (20.8) 12 mo 16 (53.3) 11 (45.8) Work absent at 3 mo (yes/no)* (%) 1/30 (3.2/96.8) 6/19 (24.0/76.0) ALBPSQ [Mean (SD)] Total* 67 (26) 81 (25) Subscale function 15 (14) 15 (12) Subscale pain* 17 (5) 23 (5) Subscale psych. factors* 11 (6) 15 (7) Subscale fear avoidance 16 (8) 19 (8) FABQ [Mean (SD)] Total 28 (17) 33 (17) Subscale work 9 (10) 13 (10) Subscale activity 12 (6) 13 (5) TSK [Mean (SD)] 35 (7) 36 (8) PCI [Mean (SD)] Subscale active coping 22 (5) 24 (6) Subscale passive coping 37 (9) 40 (13) *P 0.05 (independent sample t test; 2 tests). ALBPSQ indicates Acute Low Back Pain Screening Questionnaire; FABQ, Fear Avoidance Beliefs Questionnaire; TSK, Tampa Scale for Kinesiophobia; PCI, Pain Coping Inventory. Table 2. Course of Recovery and Work Absenteeism (n 56) 2 Weeks 4 Weeks 8 Weeks 12 Weeks No recovery 44 (78.6) 42 (75.0) 30 (53.6) 25 (44.6) Work absenteeism 19 (43.2) 13 (31.0) 8 (26.7) 6 (24.0) Recovery 12 (21.4) 14 (25.0) 26 (46.4) 31 (55.4) Work absenteeism 4 (33.3) 1 (7.1) 0 (0) 1 (3.2) Values are no. (%). studies indicate that depression/distress, pain-related fear, and fear of movement/(re)injury are potent predictors of observable physical performance and are highly associated with self-reported disability levels in chronic as well as in subacute pain, although others disagree. 28 These theories and models provide directions for future interventions 20,21,29 and support the increasing emphasis on psychological and social factors in current guidelines. To date, the unique contribution of psychological and social factors in the transition from acute presentation to chronicity has not been fully understood. Because of this existing uncertainty, the need of consensus in terms of which factors constitute increased risk and the need for further research in identifying the best screening instruments and strategies for detecting psychosocial problems are still important clinical research questions. This inception cohort study in Dutch primary care physical therapy attempts to assess the association between psychosocial factors and the transition from acute or subacute LBP to chronicity and long-term disability. Materials and Methods Cohort Selection and Recruitment. The participants in this study were consecutive new referrals consulting their physical therapist for the first time with a first or new episode of LBP. Subjects were enrolled between September 2002 and September 2004, recruited from 20 primary care physical therapy centers in the Netherlands. All subjects were referred by their general practitioner or medical specialist. The main inclusion criterion was a medical referral based on nonspecific LBP preceded by a pain-free period of at least 3 months in which no physical therapist was seen. LBP was defined according to the modified Quebec Taskforce Classification System 7 as pain in an area between the 12th ribs and the gluteal fold (QTFC category 1). Further inclusion criteria were age between 21 and 60 years and sufficient knowledge of the Dutch language to complete the questionnaires. Exclusion criteria were back com- Figure 1. Course of pain intensity on the VAS (means with 95% CI) in patients not recovered (closed markers) and patients recovered.

3 588 Spine Volume 32 Number influencing patients behavior during the course of the treatment. All care was at the discretion of the physical therapist. Procedure. A total of 66 patients met the inclusion criteria and were used for the analysis of baseline data. All participating patients provided written informed consent. The remaining sample of 56 at the 3-month follow-up was used for the analysis of overall outcome. At baseline, subjects were asked to complete a comprehensive set of questionnaires, including sociodemographic characteristics, cause and further development of LBP, fear-avoidance, anxiety, depression, kinesiophobia, and pain-coping behavior. Follow-up questionnaires, administered by post at week 2, 4, 8, and 12, measured pain intensity, disability, and overall improvement (i.e., recovery or not at 12 weeks). Except for the sociodemographic characteristics, all baseline measurements were repeated in week 12. Figure 2. Course of disability according to QBPDS (means with 95% CI) in patients not recovered (closed markers) and patients recovered. plaints with a (suspected) specific cause (e.g., trauma, tumor, rheumatoid arthritis, osteoporosis, infection, nerve root involvement), pregnancy, or coexisting major medical disease. Patients who met the inclusion criteria were given a letter explaining the aim and methods of the study and were asked to participate by completing and returning self-administered questionnaires. None of the patients received financial remuneration for participating in the study. Practitioners were blinded to the aim of the study in order to prevent them from Measurements. Sociodemographic characteristics consisted of age, gender, level of education, profession, employment status, sport participation, duration of current back complaint, occurrence of first episode, number of LBP episodes during the last 5 years, average length of episodes, back surgery, medical specialist consults, radiograph, medication, comorbidity, and judgment of general health. The authorized Dutch version of the Fear-Avoidance Beliefs Questionnaire (FABQ-DLV) 30 was used to measure fearavoidance beliefs about work and physical activity. The FABQ- DLV is a 16-item questionnaire with an internal consistency of Cronbach s alpha 0.70 and an interrater reproducibility (r s )of 0.64 (P 0.01). 31 Two subscales within the FABQ have been identified: a 4-item scale measuring fear-avoidance beliefs about physical activity and a 7-item scale assessing fearavoidance beliefs about work. Kinesiophobia is considered to be an important behavioral factor in the development and continuation of chronic Figure 3. A, Course of score on the PCI active coping behavior (means with 95% CI) in patients not recovered (closed markers) and patients recovered. B, Course of score on the PCI passive coping behavior (means with 95% CI) in patients not recovered (closed markers) and patients recovered.

4 Psychosocial Variables in Patients With LBP Heneweer et al 589 Table 3. Logistic Regression Model of the ALBPSQ, FABQ, TSK, and PCI on the Dependent Variable Recovered or Not at 12 Weeks 95% CI for Exp(B) B SE Wald Significance Exp(B) Lower Upper ALBPSQ FABQ FABQ-work FABQ-activity TSK PCI-active PCI-passive Constant pain. 15,32 36 The Dutch version of the Tampa Scale for Kinesiophobia (TSK-DLV) 37 was used. The TSK is a 17-item questionnaire quantifying excessive fear in pain patients of (re)injury induced by movement. The TSK-DLV has an internal consistency ( ) of 0.70 and an interrater reproducibility (r s )of 0.76 (P 0.01). 31 To measure pain-coping behavior the Pain Coping- Inventory 41 (PCI) was used. The PCI exists of a 2-factor model. This 2-factor solution supports the distinction between so-called active and passive coping behavior, as made by Brown and Nicassio. 42 The PCI has an internal consistency ( ) of 0.64 to 0.78 and an interrater reproducibility (r p ) of 0.42 to 0.82 (P 0.05). 41 The Dutch translation 43 of the Acute Low Back Pain Screening Questionnaire (ALBPSQ) of Linton and Halldén 44 was used to screen for a compilation of psychosocial variables. This questionnaire has been specifically constructed as a selfadministered screening instrument, based on variables that have been suggested as risk factors in the literature. To increase validity and reproducibility, most of the items in this questionnaire were taken from questionnaires previously shown to be reproducible and valid. Variables are grouped in several subscales according to items dealing with function, pain, psychological factors and fear avoidance, with sick leave as dependent variable. The separate discriminant analyses for the various groups are highly significant (P 0.001) as well as the subsequent total score analysis on the dependent variable (P ). 44,45 Outcomes. Evolution of pain and functional disability were measured during weeks 2, 4, 8, and 12 by a Visual Analogue Scale for pain (horizontal mm) 46,47 and the Quebec Back Pain Disability Scale (DLV) 48,49 (QBPDS). The main outcome of the study, recovery at 12 weeks, was assessed by an overall improvement questionnaire. This questionnaire consisted of 2 dichotomized questions: recovery: yes/no; work absenteeism: yes/no. Within the scope of this study, recovery reflects the patient s individual perception of well-being within the current health state. One should realize that the perception of being better is highly contextualized by the experience of the individual. 50 Data Analysis. Sample size was based on the principle of a minimum of 10 patients per variable, as recommended for multiple regression analysis by Dawson-Saunders and Trapp. 51 Data analysis was conducted by dichotomizing the sample into self-rated recovered and nonrecovered groups. All data were tested for normality by means of a one-sample Kolmogorov-Smirnov goodness-of-fit. Scores of the ALBPSQ, FABQ, TSK, and PCI were analyzed as continuous variables. Baseline scores of the recovered and nonrecovered groups were compared by means of independent sample t tests or 2 tests. The effect of the predictor variables on the risk of nonrecovery was assessed in logistic regression models. All the variables were studied one at a time in a base model, followed by stepwise approaches (p in 0.05, p out 0.10). Separate subscales of the ALBPSQ were tested via multivariate logistic regression and relative risk calculation. A receiver operating characteristic curve (ROC) was used to compare the accuracy of the models without the use of a specific cutoff point. All analyses were performed in SPSS, (version 12.01). All P values are 2-sided and the level of significance was set at Results During the study, 10 patients (15%) of a total of 66 patients dropped out for various personal reasons. The main reason for dropout was inconvenience by the study requiring too much time (60%), patient effort (10%), or a combination of reasons (30%). Patients who dropped out did not differ significantly on baseline sociodemo- Table 4. Logistic Regression Model of the Subscales Function, Pain, Psychological Factors, and Fear-Avoidance Beliefs of the ALBPSQ on the Dependent Variable Recovered or Not at 12 Weeks 95% CI for Exp(B) B SE Wald Significance Exp(B) Lower Upper ALBPSQ-function ALBPSQ-pain ALBPSQ-psychological factors ALBPSQ-fear-avoidance Constant

5 590 Spine Volume 32 Number Figure 4. Receiver operating characteristic curve (ROC) analyses from different logistic regression models using the ALBPSQ. Upper line: subscales function/pain/psychological factors and fearavoidance beliefs; middle line: subscale pain; lower line: ALBPSQ total. graphic characteristics from patients who completed the study. The main baseline characteristics of the study population are presented in Table 1. In total, the number of LBP episodes during the last 5 years varied between none (5%) and more than 10 (7%) with a majority of 1 to 3 episodes (62%). Seventy-five percent experienced their first episode of LBP more than 2 years ago, of whom about 27% more than 10 years ago. In a major part of the sample (52%), the current complaint lasted less than 4 weeks. At week 12, 25 patients (45%) judged their status as not recovered of whom 6 (24%) reported work absenteeism (Table 2). LBP history did not statistically significantly differ between recovered and nonrecovered patients at 12 weeks. Baseline scores of the ALBPSQ, the course of pain intensity, and disability according to the QBPDS differed significantly between both groups. Scores on the course of pain intensity (Figure 1) and disability (Figure 2) tend to stabilize or even increase at week 8 up to week 12. Differences between recovered and nonrecovered patients on the active and passive coping behavior scales of the PCI decreased during the observed period of 3 months (Figure 3). A multivariate regression analysis of baseline scores of the ALBPSQ, FABQ, TSK, and the PCI resulted in a not significant model (Table 3). Additional stepwise backward analysis showed the ALBPSQ to be the only factor of borderline significance (P 0.056). Logistic regression analysis of the subscales of the ALBPSQ (i.e., function, pain, psychological factors, and fear-avoidance beliefs) yielded the subscale pain to be a significant predictor of recovery versus nonrecovery (Table 4). In predicting recovery or not at 12 weeks, the subscale pain of the ALBPSQ was dichotomized by equal to or lower versus higher than the mean score. 19 This resulted in a relative risk for not being recovered at 12 weeks of 3.72 (95% confidence interval, ). The accuracy of the different subscales of the ALBPSQ, as shown in the areas under the ROC curves (Figure 4), varied between poor (0.64) and good (0.86) (Table 5). Additional correlation analyses between pain scores at 12 weeks and scores on fear-avoidance beliefs about work and physical activity, kinesiophobia, and paincoping behavior, revealed no significant associations (r p between 0.12 and 0.26). Discussion The hypothesis of this study in primary care physical therapy was that early identification of patients at risk for chronicity may prevent long-term disability. Although people with acute LBP experience improvements in pain, disability, and return to work within 1 month, 52 the overall level of recovery tends to be overestimated and the long-term course of LBP seems less favorable than generally assumed. 8 Literature 52 states that levels of initial pain continue to decrease in a smaller extent until about 3 months. In our study, 45% of the patients considered their condition as not recovered at 3 months. The course of pain intensity and disability showed improvement up to 8 weeks and stabilization between week 8 and 12. The first 8 weeks seem crucial in preventing chronicity. This finding is consistent with conclusions of earlier studies and reports in which the health status at 4 to 6 weeks was predictive in detecting patients with LBP at risk of developing persistent problems. 53,54 The report of a Clinical Standards Advisory Group on back pain 55 even indicated the first 6 weeks as crucial in terms of preventing chronicity. Once back pain has Table 5. Area Under the Curve of the ALBPSQ and Subscales Test Result Variable Area SE Asymptotic Significance (B) Lower Asymptotic 95% CI Upper ALBPSQ total score Subscales function/pain/psychology and fear-avoidance beliefs Subscale pain

6 Psychosocial Variables in Patients With LBP Heneweer et al 591 lasted for 6 weeks, it is increasingly likely to become chronic, and at 6 months there is only a 50% chance of return to work. 56 Several studies 20,24,25,27,35,53 have emphasized the relevance of pain-related fear, as being one of the strongest predictors of observable physical performance, being highly correlated with self-reported disability levels in (sub)acute and chronic pain. The results of our study did not confirm this evidence. Baseline scores on the FABQ, TSK, and PCI did not predict recovery at 12 weeks. Only the subscale pain of the ALBPSQ appeared to be predictive for recovery. The predictive strength of pain-related items, such as the extension of back pain, duration of the current complaint, intensity and frequency of pain, and rating of the current pain in the (sub)acute stage of LBP suggests a role of these items in the process of developing pain-related fear. However, regression analyses of pain scores and scores of the FABQ and TSK over the course of 12 weeks did not support this suggestion. The main outcome of our study is supported by recent studies, also emphasizing the predictive value of LBP history and pain intensity. 57,58 Conversely, the lack of the predictive value of psychosocial variables, as found in this study, is not supported by other studies. 59,60 These conflicting results emphasize the importance of the analysis and estimation of the health status of acute and subacute patients with LBP in full extent, without presuppositions of certain associations. The development of chronicity can be considered as a dynamic system of health-related items. As with other complex dynamic systems, small differences in the initial state of the host and in the intensity, quality, and meaning of the nociceptive stimulus can produce major differences in the detailed manner in which this process unfolds. 61 These processes might explain the differences in psychosocial outcome variables between studies with different or heterogeneous groups of patients. LBP is still to be considered as a multifactorial biopsychosocial pain syndrome because the contribution of the sensory and emotional components of pain remains unclear, even in the acute stage of LBP. However, this study emphasizes the importance of the biological components (pain-related variables) within the biopsychosocial model of back pain. Nevertheless, some limitations of the current study should be considered. The study consisted of a relatively small sample. Furthermore, treatment was at the discretion of the therapist with the probability of a diversity of interventions. Recent research of physical therapy management of LBP by Dutch physical therapists showed that treatment mainly consisted of manual interventions (massage or manual manipulation) and exercise therapy. 62 Given the serious consequences of chronicity, there is a need for more research on screening methods and interventions aimed at meeting the needs of accurately defined groups of patients with an increased risk of developing chronicity and long-term disability. Conclusion About 45% of the back pain patients in primary care physical therapy continued to experience longstanding back pain complaints. Pain, and not psychosocial variables, was the strongest predictor for chronicity. Key Points This study found 45% of the patients with acute and subacute low back pain, consulting primary care physical therapy, not recovered at the 3-month follow-up. Scores on pain-related items showed to be far more predictive than scores on psychosocial items, such as kinesiophobia, fear-avoidance beliefs, and pain-coping behavior. Pain scores and scores on psychosocial variables at 12 weeks were not associated. Health status at 8 weeks turns out to be crucial in developing chronicity. Acknowledgments The authors thank Harriet Wittink, PhD, Kees Arens, MSc, and Eric Stutterheim, MSc, for their efforts toward this study. References 1. Deyo RA, Cherkin D, Conrad D, et al. Cost, controversy, crisis: low back pain and the health of the public. Annu Rev Public Health 1991;12: Frymoyer JW, Cats-Baril WL. An overview of the incidences and costs of low back pain. Orthop Clin North Am 1991;22: Nachemson AL. Spinal disorders: overall impact on society and the need for orthopedic resources. Acta Orthop Scand 1991;62: Webster BS, Snook SH. The cost of compensable low-back pain. J Occup Environ Med 1990;32: van Tulder MW, Koes BW, Bouter LM. 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