Page 28 - THE EVOLUTION OF EARLY ARTHRITIS AND CARDIOVASCULAR RISK Samina A. Turk
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CHAPTER 2
 Fig. 1. The evolution of RA from health to disease.
ACPA, anti–citrullinated protein antibody; RF, rheumatoid factor, anti-CarP, anti-carbamylated protein antibodies
RISK FACTORS: THE BUILDING BLOCKS OF PREDICTION
The current evidence on risk factors for RA is summarized in Table 1. Besides the factors reported in the table, many others have been investigated for their association with the risk of RA, but these studies have led to negative, inconclusive, or conflicting results. Among these are variables such as silicone implants(7-9); consumption of coffee, tea,(10-13) or red meat(13-16); geographic area(17-22); and socioeconomic status.(23- 28)
In contrast, some of the factors that have statistically significant associations with RA show opposite directions of risk in different studies. Examples of such cases are age at menarche, breastfeeding, and parity. This uncertainty makes the value of such variables questionable, even if they have been included in prediction models, as is the case with parity and breastfeeding in the model by Lahiri and colleagues.(29)
In conclusion, there are not many risk factors with strong and confirmed associations with RA. Among these are family history of RA, high birth weight, smoking, silica exposure, alcohol nonuse, obesity, diabetes mellitus, rheumatoid factor (RF), anti– citrullinated protein antibody (ACPA), and genetic variants such as the shared epitope (SE) and protein tyrosine phosphatase nonreceptor type 22 (PTPN22).
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