Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.

Environmental Risk Factors for Psoriatic Arthritis among Patients with PsoriasisA Case-Control Study.

Eder3,  Lihi, Loo3,  Tamryn, Chandran3,  Vinod, Kalman-Lamb3,  Gideon, Shanmugarajah3,  Sutha, Cook1,  Richard, Gladman2,  Dafna D.

Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, ON, Canada
Toronto Western Hospital, Toronto, ON, Canada
University of Toronto Psoriatic Arthritis Clinic, Toronto Western Hospital, Toronto, ON, Canada


To investigate the association between potential environmental exposures and the development of psoriatic arthritis in patients with psoriasis.


In this case-control study, the cases were patients with recent onset psoriatic arthritis (PsA) of less than 7 years since the diagnosis. The control group was composed of psoriasis patients in whom arthritis was excluded after an evaluation by a rheumatologist. Patients and controls were matched by duration of psoriasis. The occurrence of the following environmental exposures was evaluated by a self administered questionnaire: infections, injuries and fractures, physically demanding occupational tasks, stressful life-events and vaccinations. The patients were asked to report any such event that occurred in the past 10 years and a positive exposure was defined as the occurrence of an event prior to the year of diagnosis. Participants in the control group were assigned a reference year corresponding to the year of PsA diagnosis in the matched case. The association between each exposure to environmental events and disease status were assessed through logistic regression after adjustment for age, sex and duration of psoriasis.


There were 159 subjects in each group. There were no differences in age, sex, ethnicity, and severity of psoriasis as measured by PASI score between the 2 groups. The mean duration of PsA was 3.1 ± 2.2 years. The associations between each of the exposure variables and PsA are presented in Table 1 after adjustment for age, sex and duration of psoriasis.

Table 1. Proportion of environmental exposures

ExposureFrequency PsA (%)Frequency Psoriasis (%)Adjusted P value*
Car accidents that required medical consult6 (4%)5 (3%)0.95
Fractures16 (10%)14 (9%)0.73
Any other injury34 (21%)17 (11%)0.01
Infective diarrhea20 (13%)11 (7%)0.23
Infections that required Ab53 (34%)37 (24%)0.05
Infections that required hospitalization11 (7%)0 (0%)0.0006
Vaccination - Hepatitis A3 (3%)4 (4%)0.58
Vaccination - Hepatitis B29 (23%)19 (16%)0.32
Vaccination - Pneumovax30 (24%)20 (17%)0.35
Vaccination - Flu59 (42%)60 (45%)0.92
Vaccination - Rubella4 (3%)5 (4%)0.81
Vaccination - Tetanus6 (5%)4 (4%)0.97
Death in the family41 (27%)44 (29%)0.91
Divorce17 (10.9%)12 (8%)0.33
Movehouse74 (50%)64 (41%)0.62
Changed job70 (47%)56 (40%)0.62
Becoming unemployed34 (23%)35 (23%)0.80
Treated for anxiety/depression21 (14%)26 (17%)0.55
Occupational risk: Prolonged standing95 (65%)85 (58%)0.31
        Squatting45 (31%)32 (22%)0.12
        Lifting heavy weights44 (30%)19 (13%)0.0009
        Pushing heavy weights29 (20%)18 (12%)0.13
        Using vibrating tools7 (5%)8 (6%)0.66
        Repetitive hand movement88 (60%)85 (58%)0.96
        Forceful gripping28 (19%)21 (14%)0.48
        Bending the wrist65 (45%)65 (45%)0.85
Smoking - Current28 (23%)38 (35%)0.05
        Past36 (27%)51 (42%)0.03
*Adjusted for age, sex, Ps duration.

The following exposures remained significantly associated with PsA following multivariate logistic regression: lifting cumulative loads of at least 100 pounds/hr (OR 2.9, p<0.001), infections that required antibiotics (OR 1.8, p=0.04), current smoking (OR 0.5, p=0.03) and past smoking (OR 0.5, p=0.02). Injury was significantly associated with PsA after adjustment for age, sex and duration of psoriasis, however it was no longer significant after inclusion in the full logistic regression model (OR 1.8, p=0.07). No association was found between PsA and vaccination, stressful life events and fractures.


Lifting heavy loads and infections that required antibiotics were associated with the occurrence of arthritis among patients with psoriasis. Smoking and past smoking were negatively associated with PsA. Further studies are necessary to determine whether these and other environmental factors are moderated by predisposing genetic factors.

To cite this abstract, please use the following information:
Eder, Lihi, Loo, Tamryn, Chandran, Vinod, Kalman-Lamb, Gideon, Shanmugarajah, Sutha, Cook, Richard, et al; Environmental Risk Factors for Psoriatic Arthritis among Patients with PsoriasisA Case-Control Study. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1936
DOI: 10.1002/art.29701

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