Master Theses UMCG - University of Groningen
 
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The influence of BMI and smoking at disease onset on long-term joint damage measured with the RAAD score in patients with rheumatoid arthritis

(2016) Boes, E.S.

Introduction: after the development of new effective medication and the introduction of “treat-to-target” strategies directed at obtaining remission, the prognosis of RA greatly improved. Remarkably, obesity is named as a predictor of less radiographic progression. The literature is not clear about the relation between body mass index (BMI) and long-term joint damage. Little evidence about the long-term effect of smoking on joint damage is available. Time consuming radiographic scoring methods, such as the Sharp van der Heijde (SHS) and Larsen score, are frequently used in clinical research to evaluate joint damage of hands and feet. In order to have an easy applicable instrument to measure joint damage, Zijlstra et al. developed the RAAD score in 2002. A high correlation between the RAAD score and the SHS has been found. The present study investigated whether BMI and smoking at the moment of diagnosis are related with irreversible joint damage at long-term, measured with the RAAD score.
Patients and methods: the research population consists of all patients who received treatment for RA in the ZGT from January 1996 until December 2015. From this population patients with a RAAD score, determined between 2014 and April the first of 2016, and a disease duration of at least five years at the moment of the RAAD score were included. Baseline data were collected through retrospective record research and through verifying information during an outpatient visit. Smoking at disease onset was categorized in three groups: current smoker, former smoker, non smoker. Mann Whitney U tests, Spearman’s correlations, Kruskal-Wallis tests and multivariate regression analysis were performed.
Results: baseline characteristics study population (n=521): 67.8% woman, mean (SD) age in years 49.0 (13.7), mean (SD) BMI in kg/m2 25.7 (3.9), 79.5% RF positive, 72.6% anti-CCP positive, 36.8% non smoker, 28.4% former smoker, 34.8% smoker. Median [IQR] RAAD score was 2.0 [0-6.0]. A significant, weak correlation between BMI and the RAAD score (correlation coefficient -0.14, p=0.003) was found. No significant difference in RAAD score was found between patients with different smoking status. Obviously, the RAAD score was correlated with disease duration, irreversible damage can only increase. Disease duration was correlated with BMI. There was an increasing trend in BMI at disease during the decades. When corrected for this trend, through adjusting for disease duration, no significant correlation was found between BMI and the RAAD score.
Conclusion: BMI and smoking status at the moment of diagnosis of RA are not related with irreversible joint damage at long-term as measured with the RAAD score, when adjusted for disease duration. For the trend in BMI throughout the decades was corrected with disease duration.




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