The fear-avoidance model is a theoretical framework proposed to explain why some patients develop persistent disability following an experience of acute low back or sciatic pain.1 A central concept of this framework is fear of pain. It suggests that pain-related fear may lead to avoidance of physical activity or movements that aggravate or provoke the pain, trapping patients into a downward spiral of increasing disability and dysfunction.2,3 In contrast, if the pain experience is perceived in a nonthreatening manner, patients will confront and deal with it adaptively, thereby leading to recovery.4 However, the fear-avoidance model does not fully explain which mechanisms are involved when patients recover and exactly what forms of confrontation might be adaptive.3 Little attention has been given to what happens to pain-related fear in patients who recover from pain disability. From a clinical standpoint, it is reasonable to expect that when pain disability improves, either spontaneously or due to effective treatment, pain-related fear will diminish. However, few studies have explored pain-related fear over time, and almost no data exist on patients who recover. Grotle et al5 followed an acute (3 months) cohort of patients with low back pain who reported similar levels of pain-related fear at baseline. In the acute cohort, in which pain and disability rapidly improved, pain-related fear diminished. In the chronic cohort, levels of pain and disability remained high, and pain-related fear did not diminish. Generally, pain-related fear has been shown to be more strongly related to self-reported disability than to pain intensity.6,7 Among patients with low back pain, those with radiating pain in the leg, ie, sciatica, report more disability than those without radiating pain.8,9 Prospective studies indicate that a substantial number of patients with sciatica will improve within 1–2 years.10,11 Thus, sciatica might be a useful condition to study the associations of pain-related fear with disability and self-perceived recovery. To our knowledge, no longitudinal studies on pain-related fear have been performed in sciatica. A challenge in investigating the mechanisms involved in the fear-avoidance model is how to assess pain-related fear. Several questionnaires exist, all measuring somewhat different aspects, but it is not known whether one is more suitable than the others.12 The two most commonly used are the Tampa Scale for Kinesiophobia (TSK)13 and the Fear-Avoidance Beliefs Questionnaire (FABQ).14 The TSK aims to measure kinesiophobia, meaning fear of movement and (re)injury; the FABQ includes one subscale to measure fear regarding physical activity (FABQ-PA). The purpose of the present study was to follow up patients with sciatica for 2 years in order to explore how pain-related fear evolves over time and its relationship with both pain disability and self-perceived recovery. We hypothesized that pain-related fear would decrease in patients improving from their sciatica and remain high or would increase in those who did not improve. Due to the uncertainty as to measuring pain-related fear, we applied both the FABQ-PA and the TSK.
This was a 2-year follow-up study of patients with sciatica and disk herniation who had been referred to a back clinic in four hospitals in southeast Norway. Details have been presented elsewhere.15,16 The inclusion criteria were age >18 years and radiating pain in the leg below the knee or paresis caused by a magnetic resonance imaging- or computed tomography-verified disk herniation at the corresponding level and side. The exclusion criteria included pregnancy, tumor, infection, prior surgery at the affected disk level, and inability to communicate in written Norwegian. Patients were invited to participate in the study by the clinical staff and received treatment as usual. The consultation included information about the condition and general advice to stay active and use pain medication if necessary. No specific interventions regarding pain-related fear were given. In patients with severe symptoms, surgery was performed at the discretion of the individual surgeon. At inclusion, patients completed a comprehensive questionnaire. Patients were followed up by questionnaires sent by mail at 1 year and 2 years. Pain-related fear was measured using the TSK and the FABQ-PA. A validated Norwegian TSK version containing 13 items and four response categories (strongly disagree, disagree, agree, and strongly agree) was used.17 The sum score ranges from 13 to 52; higher scores indicate a greater degree of kinesiophobia. In this study, we subtracted 13 from the sum giving a total score range of 0–39. The FABQ-PA comprises four items, each of which is rated on a 7-point scale using verbal responses ranging from completely disagree (0) to completely agree (6). This gives a possible score of 0–24; a higher score indicates more fear-avoidance beliefs.18 Pain-related disability was measured by the Maine–Seattle Back Questionnaire. The Maine–Seattle Back Questionnaire is an abbreviated version of the Patrick-modified 23-item Roland–Morris Disability Questionnaire designed for patients with sciatica and lumbar spinal stenosis.19,20 It contains 12 items of impairment and activity limitations due to leg or back pain within the same day. Each item is scored as yes (1) or no (0), yielding a possible score of 0–12; higher scores indicate greater disability. At 2 years, patients reported their sciatica/back problem on a global change scale of seven possible verbal responses (completely gone, much better, better, a little better, no change, a little worse, and much worse). Those who reported completely gone were categorized as recovered, and those who reported no change, a little worse, and much worse were categorized as no change/worse. The associations between pain-related fear and disability were analyzed by standardized response means (SRMs), correlation (Pearson’s r), and multivariate linear regression. The change scores of the variables were calculated as the scores at 2 years subtracted from the scores at baseline. SRMs were calculated by dividing the change scores by the SD of the change.21 Linear regression models were performed using changes in the TSK and the FABQ-PA as dependent variables and change in disability as the independent variable. The models were adjusted for age, sex, smoking, educational level, baseline pain-related fear, and baseline disability. Collinearity was assessed by the variance inflation factor; values