Page 31 - Fertility in Women with Rheumatoid Arthritis Vruchtbaarheid van vrouwen met reumatoïde artritis

Rheumatoid factors (RF) were measured by commercial ELISA (HYCOR Biomedical,
Garden Grove, California, USA) or by the EliA RF IgM method on the ImmunoCAP 250
(Phadia, Uppsala, Sweden). For RF, the level above which only 5% of healthy controls
were tested as positive was de ned as positive. The presence of anti-citrullinated 2 protein antibodies (ACPA) was tested by fluoroenzyme immunoassay using EliA CCP
Fertility in RA – clinical factors
on the ImmunoCAP 250. A level >10 U/mL was considered positive.14
Statistics
Values are given as mean±SD, number (percentage), or median (IQR). We calculated inter-group differences using the Student t test or Mann-Whitney U test for continuous variables and Fisher’s exact test for categorical variables. Differences between different time points were calculated by a paired t test or the Wilcoxon signed-ranks test.
Differences in TTP per categorised variable were studied using Kaplan-Meier curves. The signi cance of differences between curves was tested using the log-rank test. A multivariable analysis was performed by Cox regression analysis including age, nulliparity, smoking, disease duration, RF, ACPA, DAS28, non-steroidal anti- inflammatory drug (NSAID) use, prednisone use, sulfasalazine use and previous MTX use. If the patient had not become pregnant at the last time of contact, the TTP was considered censored at the date of the last visit or contact.
A two-sided p-value of <0.05 was considered signi cant. The statistical package Stata/ SE V.12.0 for Windows (StataCorp LP, College Station, TX, USA) was used.
RESULTS
Patients
Of 475 patients recruited from May 2002 to August 2008, 369 were enrolled in the PARA study, and 245 of these were available for the present analyses ( gure 1). There were no statistical differences in general characteristics between included and excluded subjects.
Study population details are shown in table 1. During the study period, 205 women (84%) conceived, 64 of whom (31%) had a TTP longer than 12 months. These 64 women together with the 40 women who did not become pregnant during follow-up, formed the subfertile group in this cohort (subfertility 42%). In the women who got pregnant, the
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