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Women with the autoimmune inflammatory myopathies dermatomyositis (DM) and polymyositis (PM) are at increased risk for hypertensive disorders in pregnancy, a nationwide retrospective study found.
In a multivariate analysis that adjusted for factors such as maternal age, race/ethnicity, and diabetes mellitus, a diagnosis of DM/PM was significantly associated with hypertensive disorders such as preeclampsia and eclampsia (OR 2.90, 95% CI 2.0-4.22, P<0.001), according to Lorinda Chung, MD, of Stanford University, and colleagues.
In addition, in a sensitivity analysis that excluded pre-existing hypertension, women with DM/PM again were at increased risk of hypertensive disorders of pregnancy (OR 2.18, 95% CI 1.37-3.46), the researchers reported online in Seminars in Arthritis & Rheumatism.
The inflammatory myopathies, which are more common among women and particularly during the childbearing years, can be associated with potentially serious complications, including cardiovascular, pulmonary, and metabolic disorders, which can have a negative influence on pregnancy outcomes.
Few data are available on adverse outcomes associated with pregnancy among women with DM/PM, although some small studies have suggested that problems such as prematurity, spontaneous abortion, and intrauterine growth restriction may occur with disease flares or active disease.
To address these questions, Chung and colleagues analyzed data for the years 1993 to 2007 from the Nationwide Inpatient Sample Dataset, a publicly available healthcare database that contains information on a 20% sample of U.S. hospitalizations.
Their analysis included 454 patients with DM and 399 with PM who had delivery-associated hospitalizations, along with 101,123 matched controls from the general obstetric population.
Patients with DM/PM more commonly were African-American (37.9% versus 15.1%, P<0.001), had diabetes (4.1% versus 0.9%, P<0.001), and were older (29 versus 28 years, P<0.001).
On univariate analysis, the DM/PM group had a longer mean length of stay in the hospital (4.3 versus 2.5 days, P<0.001) and more often had hypertensive disorders (20.9% versus 7.4%, P<0.001) compared with controls. They also showed a trend toward a greater risk of intrauterine growth restriction (3.1% versus 1.4%, P=0.05).
No differences were seen between patients and controls on rates of Cesarean deliveries or premature rupture of the membranes on the univariate analysis.
On a linear regression analysis, patients with DM/PM had a longer hospital stay compared with controls (β=1.73, 95% CI 1.55-1.92) even after adjustment for the increased risk of hypertensive disorders (β=1.54, 95% CI 1.44-1.65).
On the multivariate analysis, factors associated with a longer length of hospital stay included DM/PM diagnosis (OR 1.87, 95% CI 1.69-2.05), African-American race (OR 0.27, 95% CI 0.23-0.32), age (OR 0.019, 95% CI 0.016-0.022), and diabetes (OR 1.37, 95% CI 1.16-1.58, P<0.001 for all).
For hypertensive disorders, factors other than DM/PM diagnosis that were significantly associated in the multivariate analysis were African-American race (OR 1.38, 95% CI 1.19-1.60) and diabetes (OR 2.94, 95% CI 2.04-4.23, P<0.001 for both).
There also was an increased risk for Cesarean delivery for races other than white or African American (OR 1.10, 95% CI 1.004-1.20, P<0.05), increasing age (OR 1.044, 95% CI 1.038-1.05, P<0.001), and diabetes (OR 1.49, 95% CI 1.11-1.99, P<0.01).
"We found that DM/PM patients are hospitalized longer during delivery and are at increased risk of hypertensive disorders including preeclampsia and eclampsia," Chung and colleagues wrote. They also noted that the hypertension findings remained significant after pre-existing hypertension was excluded. "This is an important point as hypertension is more common in nonpregnant patients with DM/PM compared to the general population," they added.
"Based on our results, preconception counseling, multidisciplinary care with high-risk obstetricians, and blood pressure control are advisable in women with inflammatory myopathies who are pregnant or are planning to become pregnant," they concluded.
Limitations of the analysis included the nature of the National Inpatient Sample database, which may contain coding errors and missing data and which does not contain information on disease activity, previous pregnancy complications, and autoantibody status.