Three Distinct Chronic Pain Phenotypes Identified in Knee Osteoarthritis

Among patients with knee osteoarthritis (OA), a study identified 3 distinct chronic pain phenotypes (PPs). These findings were published in Pain Medicine.

Adults (N=343) with knee OA were recruited from 5 major academic hospitals in Montreal, Canada. Motivated by the Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT) recommendations, knee PPs were evaluated using multiple patient-reported measures which assessed pain, catastrophizing, phycological effects, and sleep as well as quantitative testing of sensory, pressure, mechanical, and performance status. These variables were combined using a Bayesian method.

Considering all data, a 3-class PP solution was determined to be best fit with a classification probability >91 and entropy of 0.85.

Participants in class 1 (49%), 2 (40%), and 3 (11%) were aged mean 66.7, 62.6, and 62.3 years; 52.1%, 74.6%, and 77.8% were women; body mass index (BMI) was 29.7, 32.7, and 31.3 kg/m²; they had 1.1, 1.4, and 1.9 comorbidities on average; and chronic pain self-efficacy scores were 44.2, 34.3, and 33.4 points, respectively.

Class 1 was associated with the lowest pain severity and quantitative sensory test (QST) values, indicating little nervous system sensitivity. Those in class 2 had mild pain scores but high pain variability with mixed QST values depending on individual. Those in class 3 had the highest pain values which were not variable, indicating sustained severe pain with greater nervous system sensitivity.

Compared with those in class 1, those in class 2 and 3 performed poorer in self-reported function (2: β, -15.9; 3: β, -29.7), chair stand (2: β, 0.9; 3: β, 0.8), stair climb (2: β, 2.6; 3: β, 5.6), and 40-meter walk (2: β, 3.2; 3: β, 8.4) assessments.

Similar results were observed in a sensitivity analysis.

This study was limited by not confirming these PPs among an independent cohort, a validation study is needed.

This study identified 3 multidimensional PPs, guided by IMMPACT recommendations, among patients with knee OA. Considering distinct PPs may enhance knee OA prognosis and targeted treatment.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.

Reference

Carlesso LC, Feldmann DE, Vendittoli P-A, et al. Use of IMMPACT recommendations to explore pain phenotypes in people with knee osteoarthritis. Pain Med. 2022;pnac044. doi:10.1093/pm/pnac044