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Pain phenotypes can help predict persistent knee pain in OA
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Researchers have identified four pain susceptibility phenotypes among patients with or at risk for knee osteoarthritis, according to findings published in Arthritis & Rheumatology.
One of the phenotypes, containing the highest proportion of people with pressure pain sensitivity, is associated with developing persistent knee pain within 2 years. Female sex, non-Caucasian race and age 65 years or older are significant predictors for being part of this phenotype, which demonstrates the highest sensitivity to pain.
“Knee osteoarthritis is very common, affecting 302 million adults worldwide, and yet there is no known cure or effective means of managing the pain that accompanies this disease,” Lisa C. Carlesso, BScPT, PhD, of the Université de Montréal, told Healio Rheumatology. “The more persistent pain becomes, the more debilitating the effect on people’s lives. Understanding the factors that contribute to the development of persistent pain is critical in improving our ability to prevent its onset and the transition to more persistent pain.”
To identify pain susceptibility phenotypes and analyze their connection to persistent knee pain after 2 years, Carlesso and colleagues reviewed data from 852 participants of the Multicenter Osteoarthritis Study, a longitudinal cohort of adults aged 50 to 79 years with, or at risk for, knee osteoarthritis. Patients in the original cohort were recruited in Birmingham, Alabama, and Iowa City, Iowa. The researchers focused on patients who attended the 60-month visit, used as their baseline, who were without persistent or frequent knee pain.
Carlesso and colleagues used latent class analysis to determine phenotypes that could contribute to the development of persistent knee pain other than structural pathology. These included widespread pain, poor sleep, psychological factors and quantitative sensory tests, such as pressure pain threshold and temporal summation. In addition, they analyzed the links between sociodemographic characteristics and the relation of pain susceptibility phenotypes to developing persistent knee pain over 2 years.
The researchers identified four pain susceptibility phenotypes, characterized by different proportions of pressure pain sensitivity and facilitated temporal summation. The phenotype with the high proportion of pain pressure sensitivity, plus a moderate proportion of facilitated temporal summation, was twice as likely to develop persistent knee pain over a period of 2 years (OR = 2.11; 95% CI, 1.06-4.22), compared with those with low proportions of sensitivity. In addition, the researchers found that female sex, age and non-Caucasian race were significant predictors of membership of this phenotype, with sex and age demonstrating the highest risk estimates.
“Clinically, our findings lend support to the possibility that one could eventually use tests measuring the sensitivity of the nervous system to pain to identify those at greatest risk of developing persistent knee pain,” Carlesso said. “If and when treatment options become available to target these pathways to help prevent the transition to persistent pain, these tests would be able to identify those appropriate for such treatment. However, there are no such treatments available presently, and such strategies would need to be tested rigorously in clinical trials before they could be implemented in clinical practice.
She added, “Nonetheless, these findings are a first step towards understanding why some people develop persistent knee pain over time while others only have pain with certain activities.” – by Jason Laday
Disclosure: Carlesso reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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