The relationship between oral contraceptive use and functional outcome in women with recent-onset inflammatory polyarthritis: results from the Norfolk Arthritis Register.

ABSTRACT

OBJECTIVE: Use of oral contraceptives (OCs) may prevent the development of rheumatoid arthritis, but the influence of OC use on disease outcome is unresolved. The purpose of this study was to examine functional outcome and OC use in women with inflammatory polyarthritis (IP). METHODS: The Norfolk Arthritis Register (NOAR) is an inception cohort of patients with recent-onset IP. We studied patient-reported history of OC use in 663 women who were born after 1945 and who had not used OCs during followup. OC use during followup was additionally investigated in 265 women who were <50 years old and had not undergone menopause or hysterectomy during followup. All patients were recruited to the NOAR between 1990 and 2004. Functional ability was assessed using the Health Assessment Questionnaire (HAQ), with adjustment for age at symptom onset. RESULTS: The median followup was 4.9 years. In the investigation analyzing OC use before symptom onset, patients who had used OCs before symptom onset had lower HAQ scores throughout followup than patients who had not taken OCs before symptom onset (difference in score at 5-year followup -0.35; 95% confidence interval [95% CI] -0.51, -0.19). Patients who were taking OCs at baseline had lower HAQ scores over time than women who were not taking OCs at baseline but had previously done so (mean difference -0.21; 95% CI -0.40, -0.02). In the investigation analyzing OC use during followup, OC use during followup was associated with lower HAQ scores over time than no OC use during followup (mean difference -0.06; 95% CI -0.16, 0.03); however, this was only significant for women with moderate or severe functional disability at the previous assessment (mean difference -0.23; 95% CI -0.40, -0.07). Further adjustment for potential confounders and exclusion of hormone replacement therapy users had little impact. CONCLUSION: OC use is generally associated with a beneficial functional outcome in IP, and use before and at symptom onset appeared to have the most consistent benefit.