Clinical Edge

Summaries of Must-Read Clinical Literature, Guidelines, and FDA Actions

Smoking Paradox Among People with PsA, Psoriasis

Ann Rheum Dis; ePub 2017 Nov 4; Nguyen, et al

Smoking was positively associated with psoriatic arthritis (PsA) risk in the general population, but negatively associated among patients with psoriasis, a recent study found. Conditioning on a causal intermediate variable (psoriasis) may even reverse the association between smoking and PsA, potentially explaining the smoking paradox for the risk of PsA among patients with psoriasis. Using 1995–2015 data, researchers performed survival analysis to examine the association between smoking and incident PsA in the general population and among patients with psoriasis. They clarified the paradox using mediation analysis and conducted bias sensitivity analyses to evaluate the potential impact of index event bias and quantify its magnitude from uncontrolled/unmeasured confounders. They found:

  • Of 6.65 million subjects without PsA at baseline, 225,213 participants had psoriasis and 7,057 developed incident PsA.
  • Smoking was associated with an increased risk of PsA in the general population, but with a decreased risk among patients with psoriasis.
  • Mediation analysis showed that the effect of smoking on the risk of PsA was mediated almost entirely through its effect on psoriasis.


Nguyen U-S D, Zhang Y, Lu N, et al. Smoking paradox in the development of psoriatic arthritis among patients with psoriasis: A population-based study. [Published online ahead of print November 4, 2017]. Ann Rheum Dis. doi:10.1136/annrheumdis-2017-211625.

This Week's Must Reads

SLE, Cognitive Impairment, and Lower Income, Lupus, ePub 2018 Feb 21; Meara, Davidson, et al

Understanding Native American Patients with SLE , Lupus Sci Med; ePub 2018 Feb 27; Kheir, et al

RA Linked with Post-Op Surgical Complications, Spine; 2018 ePub Feb 23; Horowitz, et al

Low Muscle Density, Greater Disability Linked in RA, Arthritis Care Res; ePub 2018 Feb 26; Baker, et al

Sputum Antibody Reactivity Is a Marker for RA, Arthritis Rheumatol; ePub 2018 Mar 2; Demoruelle, et al

Must Reads in Psoriatic arthritis

FDA Approves Xeljanz/Xeljanz XR for Adult PsA, Pfizer news release; 2017 Dec 14

FDA Approves New Pfizer Biosimilar Ixifi, Pfizer news release; 2017 Dec 13

FDA Approves Taltz for Adult Psoriatic Arthritis, FirstWord Pharma news release; 2017 Dec 1

US Arthritis Prevalence Has Been Underestimated, Arthritis Rheumatol; ePub 2017 Nov 27; Jafarzadeh, et al

Geographic Distance Affects DMARD Use for Veterans, J Rheumatol; ePub 2017 Nov 15; Walsh, Pei, et al