Background/Purpose: The model of Fear-Avoidance of pain (anxiety, catastrophization and hypervigilance) appears when the pain has maladaptive interpretations, being associated with greater pain and limitations of the activity. Our purpose was to determine the influence of the Fear-Avoidance model in the levels of pain and disability in knee osteoarthritis patients.

Methods:

Patients diagnosed with knee osteoarthritis in the last year of our outpatient clinic who gave their consent completed the evaluation battery and performed the experimental task of hypervigilance. The Wester Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was used to assess pain, stiffness and function of the patient. The variable pain anxiety was measured by the Pain Anxiety Symptoms Scale (PASS-20), catastrophization by the Pain Catastrophizing Scale (PCS), and hypervigilance with an attention task (dot-probe) using E-Prime Software. Secondary variables as sociodemographic (age, sex, work status), clinical (previous knee surgeries and radiological damage with the Kellgren-Lawrence scale [KL] and treatment (analgesic drugs) were also recorded. Descriptive, bivariate and linear regression models (adjusted by secondary variables) were performed to determine the variables of the Fear-Avoidance model associated with pain and disability.

Results:

A total of 33 patients with knee osteoarthritis were included in the study. 70% were women with a mean age of 77.4 ± 10.3 years. 8.5% had previous surgeries. 27.5% were active workers, 44.8% were retired and 25.5% housewives. 82% were on non-opioid drugs, and 11.4% weak opioids. Radiographic disease severity was 51.8% early stage (K/L <2), 48.2% advanced-stage (K/L >2). In bivariate analyses, for global WOMAC, pain anxiety, catastrophization, and work status (active worker) were founded as predictors. For the pain subscale, pain anxiety and age result statistical significant. Finally for physical function subscale pain anxiety catastrophization and work status (active worker) were founded predictors. Regression models adjusted for secondary variables, included all variables that showed significant differences or trend (p=0.1) in the bivariates. In multivariate models, for global WOMAC, the pain anxiety achieved signification (p=0.005). For the pain subscale, active work status was founded a predictor (p=0.04), with a tendency for pain anxiety (p = 0.06). For the physical function subscale, pain anxiety was significant (p=0.002).Hypervigilance showed a tendency to increase the stiffness (p=0.05) and worsen the physical function (p=0.1) and the global WOMAC (p=0.1).

Conclusion:

Variables that integrate the Fear-Avoidance model were the main predictors of the total WOMAC and its subscale, together with the active work status in the pain scale. Identifying these variables in knee osteoarthritis patients will allow us to explain the high levels of pain or disability in patients, which sometimes do not correlate with their damage or injury, and can complicate the prognosis or evolution.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-role-of-fear-avoidance-model-on-pain-and-disability-in-knee-osteoarthritis-patients/