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.


Seasonal Variation in Vitamin D Levels in Patients with Psoriatic Arthritis from Northern and Southern Latitudes and Its Association with Clinical Outcomes.

Touma5,  Zahi, Eder4,  Lihi, Zisman1,  Devy, Field1,  Joy, Chandran5,  Vinod, Rosen5,  Cheryl, Shen2,  Hua

"Lin" Medical Centre, Clalit Health Service, Carmel Medical Centre, Haifa, Israel
Division of Biostatistics, University of Waterloo, Waterloo, ON, Canada
Toronto Western Hospital, Toronto, ON, Canada
University of Toronto Psoriatic Arthritis Clinic, Toronto Western Hospital, Torotn, ON, Canada
University of Toronto Psoriatic Arthritis Clinic, Toronto Western Hospital, Toronto, ON, Canada

Background:

Vitamin D has emerged as an important factor in the pathogenesis of several autoimmune diseases including psoriasis and inflammatory arthritis. Hypovitaminosis-D seems to be a pandemic problem. Studies showed that it is more common in inhabitants of high latitude compared to low latitude areas.

Objective:

We aimed to determine the prevalence of vitamin D deficiency/insufficiency in patients with psoriatic arthritis (PsA), its seasonal and geographic variation, association with demographic and lifestyle characteristics, and with disease activity.

Methods:

This study was conducted in a center in a northern geographic area (N;North) and a center in a subtropical region (S;South), from March 2009 to August 2009. Most subjects were assessed in both winter and summer. Patients completed a vitamin D questionnaire developed to assess lifestyle determinants of vitamin D levels. Demographic, clinical data, skin type (Fitzpatrick classification), serum 25(OH) vitamin D, creatinine, calcium, phosphorus and liver enzymes were determined. Vitamin D levels were categorized as deficient < 30, insufficient 30– 74 and adequate >75 ng/ml.

A multivariate linear mixed model that included demographic/lifestyle and clinical variables, latitude, season as covariates, was used to assess the relationship with vitamin D levels.

Results:

302 PsA patients were enrolled: 258 winter (201 in N/57 in S), 214 summer (140 N/74 S). Vitamin D levels (winter/summer) were adequate (N: 41.3/41.4%; S: 42.1/35.1%), insufficient (N: 55.7/58.6%; S: 50.9/62.2%) and deficient (N: 3/0%; S: 3.8/0.9%) among patients (Table 1).

Table 1. Patients' characteristics and vitamin D level distribution

Variables/SitesNorth n = 201South n = 101SeasonVitamin DNorth n = 201South n = 101North and South n = 302
Age at visit51.8 ± 12.556.4 ± 13.4WinterAdequate41.3%42.1%41.5%
    Insufficient55.7%50.9%54.7%
    Deficient3%7%3.8%
Age at onset of Psoriasis28.2 ± 14.637.1 ± 16.0SummerAdequate41.4%35.1%39.3%
    Insufficient58.6%62.2%59.8%
    Deficient0%2.7%0.9%
Age at onset of PsA36.5 ± 12.946.4 ± 14.4     
Sex
  M128 (63.7%)59 (58.4%)     
  F73 (36.3%)42 (41.6%)     
Race
  Caucasians189 (95.0%)101 (100%)     
  South Asian1 (0.5%)      
  Chinese4 (2.0%)      
  Filipino2 (1.0%)      
  Others3 (1.5%)      
Skin classification
  112 (6.2%)11 (13.8%)     
  258 (30.1%)40 (50.0%)     
  367 (34.7%)15 (18.8%)     
  439 (20.2%)13 (16.2%)     
  517 (8.8%)1 (1.2%)     

Multivariate regression showed that subjects who had suntanned and received phototherapy, in the past three months, has significantly higher vitamin D levels (p=0.012 and p=0.030 respectively). Taking multivitamins increased vitamin D levels (p=0.014) and vitamin D supplementation was independently associated with higher vitamin D levels p<0.001. Fish oil supplementation was also associated with higher levels of vitamin D (p=0.036). Males were more likely to have lower vitamin D levels p=0.02. There was no association between vitamin D levels, geographic and seasonal interaction, race, employment status and skin type, and disease activity as measured by PASI score for psoriasis and active joint count, dactylitis and inflammatory spinal pain for PsA in both seasons. No association between disease activity in summer and vitamin D levels in winter could be found.

Conclusion:

A high prevalence of vitamin D insufficiency among PsA patients was found. There is no seasonal variation in vitamin D level among PsA patients in the southern and northern sites. No association could be established between disease activity and vitamin D level. However, lifestyle and demographic determinants such as having a suntan and intake of vitamin D supplements did have an effect on vitamin D level.

To cite this abstract, please use the following information:
Touma, Zahi, Eder, Lihi, Zisman, Devy, Field, Joy, Chandran, Vinod, Rosen, Cheryl, et al; Seasonal Variation in Vitamin D Levels in Patients with Psoriatic Arthritis from Northern and Southern Latitudes and Its Association with Clinical Outcomes. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :783
DOI: 10.1002/art.28551

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