Distinctiveness of psychological obstacles to recovery in low back pain patients in primary care
Arthritis Research Campaign National Primary Care Centre, Keele University, UK
Nadine E. Foster: firstname.lastname@example.org
⁎Corresponding author. Address: Arthritis Research Campaign National Primary Care Centre, Primary Care Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK. Tel.: +44 1782 734705; fax: +44 1782 733911. email@example.com
Received 2009 Mar 5; Revised 2009 Oct 6; Accepted 2009 Nov 3.
Copyright © 2010 Elsevier B.V.
This article has been cited by other articles in PMC.
Many psychological factors have been suggested to be important obstacles to recovery from low back pain, yet most studies focus on a limited number of factors. We compared a more comprehensive range of 20 factors in predicting outcome in primary care. Consecutive patients consulting 8 general practices were eligible to take part in a prospective cohort study; 1591 provided data at baseline and 810 at 6 months. Clinical outcome was defined using the Roland and Morris Disability Questionnaire (RMDQ). The relative strength of the baseline psychological measures to predict outcome was investigated using adjusted multiple linear regression techniques. The sample was similar to other primary care cohorts (mean age 44 years, 59% women, mean baseline RMDQ 8.6). The 20 factors each accounted for between 0.04% and 33.3% of the variance in baseline RMDQ score. A multivariate model including all 11 scales that were associated with outcome in the univariate analysis accounted for 47.7% of the variance in 6 months RMDQ score; rising to 55.8% following adjustment. Four scales remained significantly associated with outcome in the multivariate model explaining 56.6% of the variance: perceptions of personal control, acute/chronic timeline, illness identify and pain self-efficacy. When all independent factors were included, depression, catastrophising and fear avoidance were no longer significant. Thus, a small number of psychological factors are strongly predictive of outcome in primary care low back pain patients. There is clear redundancy in the measurement of psychological factors. These findings should help to focus targeted interventions for back pain in the future.
Keywords: Psychological factors, Low back pain, Primary care, Predictors, Prospective cohort
One in four low back pain patients in the United Kingdom (UK) consult their general practitioner  and although most stop consulting within 3 months, 60–80% still have pain or disability a year later [13,29] . Recovery is typically slow and incomplete  and patients who do not make an early recovery are more likely to proceed to long-term disability. Recent reviews [30,35,73] consistently underline the role of psychosocial factors in predicting clinical outcome. The largest body of published studies about predictive factors relates to psychological obstacles to recovery, and, according to Blyth and colleagues  , is flooded with ‘fuzzy’ thinking and confusion.
Guidelines [11,68,71] recommend that health professionals consider, and screen for, psychological factors. Yet many of these may be both important obstacles to recovery as well as potentially modifiable through clinical interventions [34,42] . These include fear avoidance [7,12,40] , catastrophising [23,61,66] or perceptions about risk of persistence  , depression [23,28] , self-efficacy  , expectations [30,72] , beliefs about the future  and patients’ illness perceptions regarding their back problem  . A comprehensive picture of the role of psychosocial factors is lacking  since studies focus only on one or a few factors in isolation. Their relative importance, in terms of explaining outcome, is unknown.
Koes and colleagues  have called for more systematic identification of key psychological obstacles to recovery in primary care back pain patients, and for the development of early, targeted interventions. Maximising the potential for optimally targeted interventions is predicated on better understanding of the prognostic factors that are (a) most predictive of outcome and (b) most likely to be modifiable in primary care  . Only then can we achieve closer matching of treatments to patient characteristics  . Intervention studies are increasingly trying to modify psychological obstacles to recovery [27,67,70] . For example, fear avoidance has been the subject of epidemiological [40,60] and intervention studies [6,22,32] yet a recent review concluded limited evidence to link fear avoidance beliefs with poor prognosis  .
We designed a prospective cohort study of low back pain consulters to determine the psychological factors that: (i) are associated with low back pain at presentation and (ii) most strongly predict clinical outcome 6 months following consultation, to inform targeting of interventions in primary care.
2.1. Design and setting
We conducted a prospective cohort study of consecutive patients consulting with low back pain in 8 general practices in North Staffordshire and Central Cheshire in England. The practices cover a heterogeneous population, both socio-economically and geographically, and conduct regular audits of their coding practices as part of the Keele General Practice Research Partnership  . In the UK, approximately 98% of the population is registered with a National Health Service (NHS) general practitioner  . Ethical approval for the study was obtained from the North Staffordshire and Central Cheshire Research Ethics Committees and permission was given by each general practice. All participants received usual care from their general practitioner.
2.2. Patients and recruitment
Contact information for all patients aged 18–60 years consulting their general practitioner with low back pain from September 2004 to April 2006 was downloaded each week from practice databases. In the week following consultation, invitation letters were posted from each general practice with an information sheet and questionnaire. The last page of the questionnaire was a consent form and, on return, these were detached from the questionnaire to maintain anonymity. For non-responders, a reminder postcard was sent after 2 weeks and a reminder questionnaire after 4 weeks. Patients consulting more than once during the study were only invited to participate after their first consultation.
Computerized primary care records in the UK are recorded using the Read Code classification system, and patients were identified through the use of Read Codes indicating a consultation about low back pain. A range of codes was used since most patients with low back pain are not given a specific diagnosis when seen in primary care and the codes selected were intended to include all cases of non-specific low back pain. Codes indicating a red flag diagnosis (e.g. cauda equina syndrome, significant trauma, ankylosing spondylitis, cancers) were excluded. The validity of Read Codes in electronic patient records in the UK has been established  and the Read Codes used were a subset of those used in a previous study  .
Patients were sent postal questionnaires at baseline and 6 months, which covered sociodemographics, low back pain information, and psychological factors suggested to be risk factors for poor prognosis.
This included information on gender, age, employment status, and job title to determine the individual’s socio-economic classification [49,50] .
2.3.2. Low back pain information
The Roland and Morris Disability Questionnaire (RMDQ)  was used to measure self-reported disability from low back pain and asks patients to think of themselves “today”. It includes 24 items and is scored from 0 (no disability) to 24 (highest disability). Low back pain symptom duration was determined through the duration of current episode [15,18] and recent radiating symptoms were defined as pain, numbness or pins and needles below the knee in the last 2 weeks.
2.3.3. Psychological obstacles to recovery
We identified potential psychological obstacles to recovery using six different tools that, in total, provided data on 20 psychological constructs.
184.108.40.206. Illness perceptions
Illness perceptions are purported to influence clinical outcome within the ‘common-sense’ or self-regulation model  which suggests that people develop personal representations about their illness and these influence their behaviour and thus, outcome  . Illness perceptions predict outcomes in many conditions [1,8,24,31,52] and have been shown to predict outcome in low back pain patients  . We used the Revised Illness Perception Questionnaire (IPQ-R)  to measure 12 sub-scales; 8 measured patients’ illness perceptions (illness identity, consequences, timeline – acute/chronic, timeline – cyclical, illness coherence, treatment control, personal control, emotional representations) and 4 captured patients’ views of the causes of their back problem (psychological cause, risk factors, immunity and accident/chance). Items were coded as per the guidance of the developers of the tool so that high scores represent strong perceptions on a particular dimension (for example, the individual perceives their back problem to have serious consequences on their life and that it will last a long time). For illness identity, the number of symptoms reported as related to the individual’s back problem was summed giving a possible range of values from 0 to 14.
220.127.116.11. Fear avoidance beliefs
Fear avoidance is a belief that certain activities should be avoided due to fear of causing pain or re-injury and has been suggested to predict future disability  . Fear of movement related to pain (labeled fear avoidance) was measured using the Tampa Scale of Kinesiophobia (TSK)  . This is based on 17 items each with a four-point Likert scale with scoring alternatives ranking from ‘strongly disagree’ to ‘strongly agree’ (range in scores: 17–68); higher scores indicate greater level of fear avoidance. Early factor analysis suggested four factors in the scale but more recent research suggested two factors: somatic focus and activity avoidance  . These two factors are reflective of the higher order construct, namely fear of movement and (re)injury  and the total score has been recommended to study the role of general levels of fear of movement and re-injury [56,69] .
Through the work of authors such as Lazarus and Folkman  , the concept of psychological coping has developed and some studies have suggested the adoption of passive coping strategies, and specifically holding maladaptive catastrophic thoughts, is associated with disability in back pain patients  . Coping was measured using the 4 sub-scales of the Coping Strategies Questionnaire (CSQ24) for which higher scores on each sub-scale indicate higher frequency of the specific coping style (0 = never use it, 6 = always): catastrophising (6 items; sub-scale score: 0–36), diversion (6 items; 0–36), re-interpretation (6 items; 0–36) and cognitive coping (5 items; 0–30)  .
18.104.22.168. Anxiety and depression
Depression, usually thought to be associated with catastrophising cognitions, has been a reasonably consistent obstacle to recovery in previous studies [16,53,76] . We measured anxiety and depression using the Hospital Anxiety and Depression Scale (HADS) (7 items each for anxiety and depression; item scores range from 0 to 3; sub-scale scores range from 0 to 21) on which higher scores indicate greater levels of distress  .
22.214.171.124. Self-efficacy beliefs
A concept developed by Bandura  , self-efficacy is a personal belief about how successfully one can cope with difficult situations, in this case, the degree of confidence a patient has in performing normal activities and tasks (such as household chores and increasing activity levels) despite their pain. Previous prospective studies have shown self-efficacy beliefs to be important determinants of pain behaviour and disability [2,14] . We used the Pain Self-Efficacy Questionnaire (PSEQ) that measures both the strength and generality of a patient’s beliefs about their ability to accomplish a range of activities despite their pain. It has 10 items each with a six-point Likert scale (scale score: 0–60) and higher scores indicate stronger self-efficacy beliefs [47,48] .
2.4. Statistical analysis
Scores for each of the psychological constructs were calculated according to the methods specified by the questionnaire developers. The baseline sociodemographic, back pain specific and psychological scales (20 psychological constructs) are presented using simple descriptive statistics. The direct relationships between each of the psychological constructs and RMDQ scores at baseline are presented as Pearson correlation coefficients (with associated 95% confidence intervals) and the variance explained (expressed as %R2).
A multi-stage linear regression modeling procedure was applied to determine the distinctiveness of the psychological obstacles to recovery as predictors of RMDQ score at 6 months follow-up.
Stage 1 assessed the importance of each of the individual psychological constructs in predicting outcome after adjusting for important baseline data (univariate models). For each of the 20 psychological constructs, three models were computed. Model 1 contained only the baseline RMDQ scores; Model 2 added the demographic data (gender, age group) and low back pain specific data (baseline data on average pain severity, duration of back pain and radiation of symptoms into the legs) to Model 1; Model 3 added the baseline psychological construct score to Model 2. The coefficients of interest were: (i) %R2 and adjusted %R2 for the overall linear regression models as the index of the percentage of the variance explained (Models 1–3), (ii) change (Δ) in %R2 and associated p-value (from an F-test) for the comparisons of the models (Model 1 vs Model 2; Model 2 vs Model 3) to examine the additional percentage of the variance explained, and (iii) regression coefficient (B) and associated 95% confidence interval for the psychological construct for each individual model (Model 3).
The objective of Stage 2 was to develop a model (“initial multivariate model”) that included multiple psychological constructs that were found to be statistically significant at Stage 1. The statistical significance of each of the psychological constructs in Stage 1 was assessed by the F-test associated with the change in %R2 from Model 2 to Model 3. As a large number of constructs were being examined, only constructs that were individually significant (p-value of F-test 0.01. This simpler multivariate model (“reduced multivariate model”) was then fitted.
Finally, in Stage 3 we investigated whether the power of the psychological constructs was influenced by baseline symptom duration (acute: