Pregabalin appears to be more effective than paracetamol for reducing neuropathic pain and improving function in patients with osteoarthritis (OA) of the knee, according to research presented here at the 2017 Annual Congress of the European of League Against Rheumatism (EULAR).
Prior research suggests that a subgroup of patients with knee OA may develop excessive levels of central sensitisation and demonstrate some features of neuropathic pain, explained Priya Chowalloor, MBBS, Royal Perth Hospital, Australia, on June 17.
Dr. Chowalloor and colleagues randomised 90 patients with knee OA who exhibited features of neuropathic pain based on elevated cold pain thresholds (≥15°C) and elevated PainDETECT scores (≥13) to receive 4 weeks of treatment with pregabalin titrated to a maximum dose of 300 mg/day or a standard dose of paracetamol (4,000 mg/day).
The pregabalin (300 mg) group experienced larger reductions than the paracetamol group in Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) pain scores (P = .0001) and PainDETECT scores (P = .0001) at 28 days. They also experienced a larger increase in pressure pain thresholds (reduced tenderness) at the index knee (P = .025).
No significant difference in cold pain thresholds was found between the groups (P = .33).
Pregabalin-treated patients completed the physical tests more quickly than paracetamol-treated patients (sit to stand, P = .05; walk, P = .001; stairs, P = .05).
Pregabalin-treated patients were significantly more likely than paracetamol-treated patients to experience a decrease in PainDETECT scores below the entry value of 13 (odds ratio [OR], 9.20; P = .001), but no significant difference was seen in the likelihood of reducing their cold pain threshold below the entry value of 15°C (OR, 2.26; P = .14).
For years, knee OA has been seen as a nociceptive pain disorder linked to inflammatory or degenerative processes in the joint; however, several studies reported widespread altered sensory and pain thresholds in patients with OA, including significant mechanical and cold hyperalgesia at both the affected joint and distant unaffected areas.
Some patients with OA and widespread cold sensitivity experience multimodality hyperalgesia and increased pain and have more features of neuropathic pain and increased functional impairment than others. Patients with OA may exhibit symptoms normally associated with neuropathic pain, and prior studies indicate that 19% to 22% of patients with OA score in the positive neuropathic category on the PainDETECT questionnaire.