. Author manuscript; available in PMC: 2014 Dec 9.

Published in final edited form as: Nat Rev Rheumatol. 2014 Apr 1;10(7):403–412. doi: 10.1038/nrrheum.2014.36

Table 1. Examples of risk factor paradoxes in rheumatic disease contexts.

Risk factor	Associations in the general population	Associations in the rheumatic disease (index) population
OA
Bone mineral density	Risk of incident OA	↓ Risk of OA progression⁹
Obesity	Risk of incident OA	↔ Risk of OA progression⁹
Low vitamin C levels	Risk of incident OA	↓ Risk of OA progression⁹
Female sex	Risk of incident OA	↔ Risk of OA progression⁹
RA
Smoking	Risk of incident RA	↓ or ↔ Risk of RA progression^14–16
Smoking	Risk of incident CVD	↔ Risk of CVD among patients with RA^17–18
Obesity	Risk of mortality	↓ Mortality among patients with RA²⁰
*PsA*
Smoking	Risk of psoriasis	↓ Risk of psoriatic arthritis among patients with psoriasis⁴
HLA-Cw*0602	Risk of psoriasis	↓ Risk of psoriatic arthritis among patients with psoriasis^26,27

Abbreviations: CVD, cardiovascular disease; OA, osteoarthritis; PsA, psoriatic arthritis; RA, rheumatoid arthritis.