RESEARCH - Postpartum onset of RA and other chronic arthritides

September 9, 2009

Ann Rheum Dis. 2009 Aug 27.

Post partum onset of rheumatoid arthritis and other chronic

arthritides: results from a patient register linked to a medical birth

registry.

Wallenius M, Skomsvoll JF, Irgens L, Salvesen KA, Koldingsnes W,

Mikkelsen K, Kaufmann C, Kvien TK.

Norwegian University of Science and Technology, Norway.

OBJECTIVE: It is known that onset of rheumatoid arthritis (RA) is

increased post partum. We wanted to compare incidence rates between RA

and other chronic arthritides (OCA) 0-24 months after delivery, and to

compare the incidence rates within each group 0-24 versus 25-48 months

post partum.

METHODS: Premenopausal women from a Norwegian patient register were

linked with the Medical Birth Registry of Norway to study the interval

between delivery and time of diagnosis. regression analysis with

adjustments for age at delivery and birth order was applied to compare

proportions of incident cases of RA and OCA with onset 0-24 months

post partum. Poisson regression analysis with adjustment for

population at risk was applied to estimate incidence rate ratio (IRR)

0-24 versus 25-48 months post partum.

RESULTS: Out of 183 RA and 110 OCA patients diagnosed after delivery,

69 (37.7 %) had RA and 31 (28.2 %) OCA during the first 24 months post

partum (p=0.09). The IRR (95 % CI) for diagnosis during 0-24 months

versus 25-48 months was 1.73 (1.11, 2.70) (p=0.01) for RA, 1.05 (0.59,

1.84) (p=0.86) for OCA. The IRR was 2.23 (1.06, 4.70) and 1.87 (0.67,

5.21), respectively, when only considering diagnoses after 1st

pregnancy. Clinical characteristics were similar within each

diagnostic group.

CONCLUSION: The proportions of incident cases with onset 0-24 months

after delivery were not different between RA and OCA. A peak in

incidence during 0-24 months was seen in the RA group, both when

considering all pregnancies and only the first pregnancy.

PMID: 19717397

Not an MD

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