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Pregnancy and oral contraceptive use do not significantly influence outcome in long term rheumatoid arthritis

K W Drossaers-Bakker¹, A H Zwinderman², D van Zeben³, F C Breedveld⁴, J M W Hazes⁵

¹ Department of Rheumatology, Medisch Spectrum Twente, Enschede, The Netherlands
² Department of Medical Statistics, Leiden University Medical Centre, The Netherlands
³ Department of Rheumatology, Reiner de Graaf Hospital, Delft, The Netherlands
⁴ Department of Rheumatology, Leiden University Medical Centre, The Netherlands
⁵ Department of Rheumatology, Erasmus University of Rotterdam, The Netherlands

Correspondence to:
Correspondence to:
Dr K W Drossaers-Bakker, Polikliniek Reumatologie, Medische Spectrum Twente, Postbus 5000, 7500 KA Enschede, The Netherlands;
wbakker{at}xs4all.nl

Background: Oral contraceptives (OC) and pregnancy are known to have an influence on the risk of onset of rheumatoid arthritis (RA). Pregnancy itself has beneficial effects on the activity of the disease, with relapses post partum. It is not known, however, whether OC and pregnancies influence the ultimate outcome of RA.

Objectives: To explore whether OC use and pregnancies influence the 12 year outcome in RA as measured by radiological damage and disability.

Methods: In a prospective inception cohort of 132 female patients with recent RA according to the 1987 American College of Rheumatology criteria—a cohort initially gathered to study the association between hormonal factors and the onset of RA—outcome was assessed in a follow up after 12 years. The outcome was evaluated in 112 (85%) women by the radiological damage of hands and feet as measured with the Sharp score modification van der Heijde (SHS), the damage of the large joints measured with the Larsen score (LS) of large joints (0–60), and the disability measured with the Health Assessment Questionnaire (HAQ). The median values of each outcome variable were calculated for several subgroups of patients stratified for OC use and pregnancies before and after onset of the disease and the tertiles of the total number of months of OC use and of pregnancies. The association of OC use and pregnancies before and after onset of the disease with the outcome variables was calculated using Spearman's rank correlation (r_s). The combined influence of OC use and pregnancies on the SHS, LS, and HAQ at 12 years was estimated using ordinal polytomous logistic regression.

Results: The median values of the SHS, LS, and HAQ showed a trend towards less radiological joint damage and less disability in women with long term OC use and multiple pregnancies. This difference, however, was not significant, except for the HAQ score in women with three or more pregnancies in life. There was no association between pregnancies, however defined, and any parameter of RA outcome after 12 years (maximum r_s=-0.10). The only significant correlation was found between OC use before symptom onset and the LS (r_s=-0.22, p<0.05). The combination of hormonal variables explained no more than a maximum of 3% of the variance of the 12 year outcome as measured by the SHS.

Conclusion: OC use and pregnancy do not significantly influence outcome in long term RA. There is, however, a trend for patients with multiple pregnancies and long term OC use to have less radiographic joint damage and a better functional level.

Keywords: pregnancy; oral contraceptives; rheumatoid arthritis

Abbreviations: DMARD, disease modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; JSN, joint space narrowing; LS, Larsen score; OR, odds ratio; RA, rheumatoid arthritis; SHS, Sharp score modification van der Heijde score

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