Three Distinct Chronic Pain Phenotypes Identified in Knee Osteoarthritis

woman receiving knee exam, osteoarthritis
woman receiving knee exam, osteoarthritis
Three distinct chronic pain phenotypes were 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.


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