The Association of Osteoarthritis Knee Pain with Cardiac and Metabolic Risk Factors
Over the past several decades rates of obesity and diabetes in the United States have been rising. In 2015 the Centers for Disease Control estimated that 30.3 million Americans were living with diabetes, a figure representing 9.5% of the population. A well- established link exists between obesity and osteoarthritis and recent research has implicated diabetes and hyperglycemia as the potential cause of cartilage degeneration. Other medical conditions associated with knee pain include dyslipidemia and hypertension.
The National Health and Nutrition Examination survey (NHANES) database has been carefully studied to elucidate the relationship between cardiometabolic risk factors and osteoarthritis. Examples include obesity and diabetes. However, it is unknown to what extent these factors are associated with knee pain as opposed to radiographs. A prior study showed that 50% of people in the general population with radiographic findings of osteoarthritis do not have knee pain and 50% of the people with knee pain who are older than age 54 do not have radiographic findings of osteoarthritis.
The purpose of this investigation was to understand the relationship between modifiable cardiac and metabolic risk factors (such as obesity, hemoglobin A1c and smoking) and self-reported knee pain. An additional goal was to determine if there are different risk factors in patients with bilateral knee pain compared to unilateral knee pain.
A cross-sectional, retrospective study of the NHANES database from 1999 to 2004 was done. The specific outcomes were any degree of knee pain and bilateral knee pain. Effects of interest were BMI (Body Mass Index) and hemoglobin A1c. Investigators additionally assessed certain patient factors such as race, age, gender, poverty and smoking status. Multivariable logistic regression models and interaction terms were investigated.
Twelve thousand nine-hundred patients provided data for the study. The modifiable risk factors associated with any knee pain were obesity, glycemic control (blood sugar) and smoking. The same factors were associated with bilateral knee pain. Subgroup analysis demonstrated that patients less than 65 years old have a 5% increase in the risk of having any knee pain as their BMI increases whereas patients older than 65 years have a 10% increase in risk.
This report confirms the association of knee pain with increased weight, poor blood sugar control, current smoking, and increased age.