Do genetics influence knee osteoarthritis patient's sensitivity to pain?
According to a new study, people with knee osteoarthritis may experience different levels of knee pain based on their genetics and specifically examined its impact on mood and interaction with each other. According to Lynn Martire, professor of human development and family studies, Penn State, "This work was part of a larger study focused on the daily lives of couples in which one person has arthritis."
"The biggest problem in arthritis is that a person becomes physically inactive because they are in pain, but if they don't move, then it makes them hurt more," she added. "As a supplement to the larger study, we collected genetic data from those who were willing to participate to determine if there were any associations with daily knee pain sensitivity."
Previous research suggests that patients with knee osteoarthritis who have two specific genes such as catechol-O-methyltransferase (COMT) and mu-opioid receptor (OPRM1), experience more variability in their day-to-day pain and pain severity increases after daily physical activity. This study has been published in Scandinavian Journal of Pain. According to Martire, within-person variability looks at whether patients who have more pain are less active, whereas between-person variability looks at whether patients are less active on those days when they have more pain.
The researchers recruited 120 knee osteoarthritis patients who went through a 22-day assessment protocol in which they wore a device "accelerometer" to measure daily physical activity and reported on their pain, three times a day using a questionnaire and found greater pain variability throughout the day reflected increased sensitivity to pain after physical activity.
According to Martire, "Our results showed that the genotypes that had increased pain sensitivity were the opposite of what we predicted, but the context and the design of our experiment are different from previous work." The team predicted that patients with one or more copies of a certain allele in either COMT or OPRM1 would have greater pain variability and more pain after daily physical activity, but in fact the greater pain results were seen among those patients who having two copies of a different allele. "With such a novel study, part of the challenge was trying to make predictions because there's not a lot of other data out there," told Stephanie Wilson, graduate student in human development and family studies, Penn State. "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."
Martire concluded that the biggest problem is still getting patients to be active. However, larger studies are required to confirm these preliminary findings and it could lead to the development of tailored behavioral programs based on a person's genotype.