On 15 June at 14:00 will Raili Müller defend her doctoral thesis „Cardiometabolic risk profile and body composition in early rheumatoid arthritis“.
Senior Research Fellow in Rheumatology Riina Kallikorm cand (Medicine), Institute of Clinical Medicine, Unversity of Tartu
Professor of Propaedeutics of Internal Medicine Margus Lember (dr. med., Institute of Clinical Medicine, Unversity of Tartu
Senior Research Fellow in Internal Medicine Kaja Põlluste (PhD (Public Health), Institute of Clinical Medicine, Unversity of Tartu
Markku Jaakko Kauppi (PhD), University of Helsinki, Finland
Rheumatoid arthritis is a chronic progressive autoimmune disease that affects about 1% of population. The inflammatory process begins long time before the onset of symptoms of arthritis, damage to joints is only a tip of the iceberg, systemic inflammation has an effect on the whole body. Joint deformations and specific damage to internal organs is preventable with adequate treatment but people suffering from the disease are still at elevated risk of having cardiovascular disease and premature death as a consequence due to reasons not completely understood.
In general population increased risk of cardiovascular disease is associated with overweight and obesity, in rheumatoid arthritis the opposite is evident- patients with higher body mass are at lower risk of getting heart disease.
Obesity induced elevated cardiovascular risk is associated with metabolic disturbances. The co- occurrence of hypertension, diabetes, high cholesterol and triglyceride levels and abdominal obesity is called metabolic syndrome. The syndrome is associated with another important metabolic alteration called insulin resistance that presents as low sensitivity in muscle, fat and liver cells to insulin- a hormone responsible for regulation of blood sugar.
In established rheumatoid arthritis a change in body composition called sarcopenic obesity (high fat percentage and low proportion of muscle tissue) has been described. This phenomenon increases the risk of cardiovascular disease at a higher extent than regular obesity. A change in body composition can be one of the reasons behind increased risk for heart disease in rheumatoid arthritis, metabolic disturbances caused by altered body composition can remain undetected on routine evaluation.
Most of the previous studies looking into metabolic risk factors and body composition in rheumatoid arthritis have focused on data of patients with long disease duration. Some authors have hypothesized that the change in body composition may already start in the early or even preclinical stage of the disease.
This study investigated the presence of metabolic syndrome, insulin resistance and changes in body composition in early rheumatoid arthritis. Additionally, we tried to find lifestyle and disease- associated factors explaining the development of body composition alterations.
This project is based on a study of 92 patients with early rheumatoid arthritis with an average time from diagnosis one month. The data was compared to Estonian general population using patients from family doctors practice lists as control subjects.
We found that metabolic factors associated with elevated cardiovascular risk can be detected in patients with rheumatoid arthritis in the first months after the disease onset. Normal weight patients with rheumatoid arthritis had hypertension, hyperglycemia and metabolic syndrome significantly more often than the control subjects with similar weight status, 17% of arthritis patients with normal weight had metabolic syndrome and only 2% of the controls. There was no difference between the groups in the presence of assessed cardiovascular risk factors or metabolic syndrome among overweight/obese subjects. Having rheumatoid arthritis was associated with higher blood pressure but only 31% of the rheumatoid patients with hypertension used anti-hypertensive medications, at the same time more than 50% of control subjects with hypertension received treatment.
Low sensitivity to insulin was almost 5 times more common among arthritis patients. Insulin resistance was present more often in men and patients with high inflammatory markers. We found that insulin sensitivity could not be predicted by body mass index, reduced insulin sensitivity in rheumatoid arthritis group was associated with low lean mass.
There was a significant difference in body fat and muscle composition between control subjects and early rheumatoid arthritis group. 42% of patients with arthritis had low muscle mass, 68% had high body fat percentage and 26% had both reduced muscle mass and excess fat (sarcopenic obesity). Only 16% of the patients did not have any abnormal components of body composition, at the same time 43% of the control subjects had healthy body composition with both normal fat percentage and muscle mass. Looking into the factors associated with low muscle mass we found a difference between rheumatoid arthritis and control group. In arthritis group low lean mass was associated with higher levels of inflammatory markers, glucocorticosteroid therapy and reduced protein intake in diet. In the control group the most important factors were older age, inactivity and smoking.
Results of the study show that all patients with early rheumatoid arthritis should be screened for risk factors of cardiovascular disease regardless of their weight status. The development of metabolic risk factors in rheumatoid arthritis is independent of body weight and can appear in the initial stage of the disease. These differences should be taken into account when evaluating cardiovascular risk in patients with rheumatoid arthritis. Timely screening and treatment could postpone the progression of cardiovascular disease and avoid premature death.