INFLUENCE of osteoarthritis genetics may be key to pain sensitivity, according to a recent study following 122 patients with knee osteoarthritis. The research builds on the results of previous work focussing on two genes, COMT and OPRM1, and whether specific alleles within these genes affect pain sensitivity in patients across the range of arthritic diseases.
The study looked at the level of activity and the pain severity of the patients, and considered the variability of knee pain after daily physical exercise. The variability for each individual can be used to gather an idea of whether people in more pain are less active, whilst the variability between participants suggests whether more pain results in less activity. These parameters were measured using an accelerometer for daily activity and a pain questionnaire three-times daily. The researchers also collected genetic data from participants to determine if there were any associations with daily knee pain sensitivity.
This type of research can bring many challenges as Stephanie Wilson, Pennsylvania State University (Penn State), State College, Pennsylvania, USA, stated: “with such a novel study, part of the challenge was trying to make predictions because there is not a lot of other data out there. Previous studies looking at clinical populations compared different people within the arthritis group to each other and to healthy populations to try to associate their genotype with greater severity of pain. However, we were looking at day-to-day pain changes for a single person and its association with their genetics.”
Initially, the researchers predicted that having one or more copies of a specific allele in either COMT or OPRM1 would result in greater variability in pain and more pain following daily activity. However, the findings show that having two copies of a different allele were associated with more pain variability and more pain following activity.
Prof Lynn Matire, Department of Human development and Family Studies, Penn State, concluded that the biggest problem is still getting patients to be active. Genetic data could provide a framework for patient-specific behaviour programs to better match their genotype. However, larger studies are required to confirm this.