Psoriatic arthritis disease activity tended to improve or stabilize during pregnancy and the first year after giving birth, even outpacing controls, in a small retrospective cohort study.
“The outcome of pregnancy in PsA [psoriatic arthritis] patients is excellent,” investigators from the University of Toronto Psoriatic Arthritis Program reported. They found that “arthritis activity has a favorable course during pregnancy in almost 60% of the pregnancies, while the skin disease shows a favorable course in close to 90% of the pregnancies.”
According to the researchers, led by Ari Polachek, MD, of the Centre for Prognosis Studies in the Rheumatic Diseases at Toronto Western Hospital, previous research has found that rheumatoid arthritis improves in most pregnant women with the condition but then worsens in the year after birth, while most patients with ankylosing spondylitis don’t get better or worse. Limited research suggests psoriasis tends to improve during pregnancy and then flares afterward.
For the new study, researchers tracked 29 pregnant PsA patients with 42 total pregnancies who had a mean age of about 34 years at the beginning of pregnancy and matched them with 67 control patients with PsA who were not pregnant and had an average age of about 35 years. They had all visited the University of Toronto Psoriatic Arthritis Clinic during 1990-2015 ().
Among the 41 pregnancies in women who began follow-up prior to pregnancy, 13 (32%) had an unfavorable course of disease activity marked by worsening during 8 (20%) of the pregnancies or stable high disease activity during 5 (12%). The course of disease activity was more favorable for 24 (59%) pregnancies, in which it improved in 11 (27%) and stayed stable at a low disease level in 13 (32%). Four pregnancies (10%) had a mixed pattern of improvement followed by worsening.
The 1-year postpartum period during 40 pregnancies showed that stable or worsening symptoms were most common: 8 (20%) had improvement and 13 (32.5%) had stable low disease activity, while another 16 (4%) worsened and 3 (8%) had a mixed course of improvement followed by worsening.
After they controlled the results to account for various factors, the researchers found that pregnancy appeared to be especially beneficial for skin-related PsA symptoms. The likelihood of improved skin activity during pregnancy rose significantly (odds ratio, 7.7; 95% confidence interval, 1.8-23.5; P = .004) when compared with a matched period among controls, but this was no longer the case during the year after birth (OR, 0.4; 95% CI, 0.2-1.4; P = .60).
The likelihood of improved joint symptoms during pregnancy also rose, but not to a significant extent (OR, 2.1; 95% CI, 0.8-5.1; P = .10), and the effect on joints was not significant in the year after pregnancy (OR, 1.4; 95% CI, 0.5-3.4; P = .50).
There was a declining use of medications among the patients during pregnancy, particularly in the second and third trimesters, but two-thirds of the patients were treated with medications for PsA during this time, including NSAIDs (41%), disease-modifying antirheumatic drugs (35%), and biologic agents (26%).
The researchers speculated that hormonal changes during pregnancy may explain the improvement in skin activity. However, they noted that women with PsA who have multiple pregnancies don’t tend to have the same experiences each time: “Most of the women with more than one pregnancy had different joint disease course during their own different pregnancies and postpartum periods. Accordingly, this suggests that each woman needs specific evaluation and treatment adjustment during each pregnancy.”
The University of Toronto Psoriatic Arthritis Program is supported by a grant from the Krembil Foundation. Dr. Polachek is supported by an educational grant from Janssen Canada.