AB0880 NEUROPATHIC PAIN IN PATIENTS WITH KNEE OSTEOARTHRITIS: PREVALENCE AND RELATED FACTORS

Abstract

Background:Discordance between radiographic and pain severity in osteoarthritis (OA) has led researchers to investigate other pain mechanisms, including neuropathic pain (NP). Recent meta-analysis concluded that NP prevalence in people with knee or hip OA was 23% [1].Objectives:The primary objective of this study was to determine the prevalence of NP in patients with painful knee OA. Secondarily, we evaluated the relationship between NP and pain intensity, function and radiographic severity of knee OA.Methods:This cross-sectional study enrolled patients with knee OA (ACR criteria) from a rheumatology outpatient Hospital over a four-month period. Exclusion criteria were: knee surgery, chronic conditions of the nervous system, cognitive or psychiatric disorders. The patient’s characteristics and pain severity using the Visual Analogue Scale (VAS) were evaluated. The NP was assessed according to the Douleur Neuropathique 4 questionnaire (DN4) (arabic valid version). Functional impairment was estimated using the short form of the Knee injury and Osteoarthritis Outcome Score (KOOS-PS) (KOOS-PS scores to 0 representing no difficulty and 100 representing extreme difficulty). Radiographs were rated using the Kellgren Lawrence (KL) grade classification (I-IV). Statistical analysis was performed to find the factors closely related with NP.Results:Ninety three patients with knee OA were included in the study. The mean age was 65.03±18.5 years with a sex ratio of 0.08. Mean duration of symptoms was 3.5 years [3months-20 years]. Concerning the marital status: 53.8% were married, 34.4% were widow and 10.8% were divorced. The majority of patients were illiterate (65.6%) and only 2.2% went to university. Patients were from low socio-economic class in 37.6% of cases. At least one comorbidity was revealed for 90.3% of patients and their mean BMI was 31.6±6.3 [19.9-52.3]. Concerning the clinical features of the KOA, mean VAS pain was 6.6±1.6 and KOOS-PS was 45.6±18.5. Of the subjects, 22.6% have radiographic at grade II, 57% at grade III and 20.4% at grade IV based on KL grading.The mean (SD) score by the study participants on the DN4 was 4.9± 2.4. The prevalence of NP (DN4≥4) was 71%.A DN4 score≥4 was significantly associated with the VAS pain (p=0.00) and the KOOS-PS (p=0.00) and the presence of comorbidity (p=0.04). However, there was no significant relation between DN4 score and, age, sex, marital status, socio economic class, level of education, BMI and KL grade (p=0.7, p=0.08, p=0.7,p=0.3, p=0.7, p=0.7, p=0.6).Conclusion:Our results highlight the high frequency of NP in patients with knee OA according to the DN4. Knee OA patients with NP encounter clinically relevant functional limitation. Thus, it is important to be aware of this neuropathic component to ensure appropriate management in the treatment of knee OA pain.