SAN FRANCISCO – The incidence of severe sepsis was nearly five times lower and the risk of death from severe sepsis was 43% lower during pregnancy, compared with nonpregnant women, in a large retrospective study of data on more than 47 million pregnancy-related discharges.
The decreased mortality rate in pregnancy remained after investigators controlled for the effects of age, comorbidities, and severity of illness, Dr. Gagan Kumar reported.
The incidence of sepsis in pregnancy increased fourfold from 2000 to 2009 – from 0.01% to 0.04% – and tripled in nonpregnant women – from 0.06% to 0.18% – while the U.S. pregnancy rate and the rate of hospitalizations during pregnancy remained relatively stable during that period, he said at the Critical Care Congress, sponsored by the Society for Critical Care Medicine.
In-hospital mortality from severe sepsis decreased gradually for nonpregnant patients from about 30% in 2000 to approximately 18% in 2009, but remained relatively stable in pregnant patients, increasing from approximately 3% in 2000 to 10% in 2009, he said.
The investigators studied claims data from 2000 to 2009 from the Nationwide Inpatient Sample for 47,027,806 pregnancy-related discharges of women aged 15-44 years. Of these, 0.03% had a diagnosis of severe sepsis. Among all cases of severe sepsis in the cohort, 2.4% were during pregnancy (643,417 cases).
Eight percent of pregnant women with severe sepsis died, compared with 22% of nonpregnant women with severe sepsis, a significant difference. The median time to death was significantly longer in pregnancy (10 days) than without pregnancy (8.5 days). The median length of stay was significantly shorter in pregnant women who survived severe sepsis (8 days), compared with nonpregnant survivors (11 days). Pregnant survivors were more likely to be discharged home and less likely to go to a skilled nursing facility or have home care compared with nonpregnant survivors, reported Dr. Kumar of the Medical College of Wisconsin, Milwaukee.
Compared with nonpregnant women, pregnant women were significantly less likely to have three or more organs fail (16% vs. 22%) or to have cardiac, renal, hepatic, hematologic, metabolic, or neurologic failure. Pregnant women were significantly more likely to have respiratory failure than were nonpregnant women.
The likelihood of dying of severe sepsis was 62% lower in pregnant women, compared with nonpregnant women, in an unadjusted analysis and 41%-43% lower than in nonpregnant women under three separate analyses that adjusted for various risk factors or incorporated matched data, Dr. Kumar said.
Although the rate of in-hospital mortality decreased in nonpregnant women from approximately 30% in 2000 to approximately 18% in 2009, the rate increased in pregnant women from approximately 4% in 2000 to 10% in 2009.
Published data are limited and suggested that sepsis in pregnancy is rare, affecting approximately 0.1% of pregnancies, with septic shock in approximately 0.01%-0.001%. These studies relied predominantly on single centers, and used varying definitions of severe sepsis; most were conducted before the year 2000. Since then, the average age of mothers in pregnancy has risen, invasive tests are more common, the rate of cesarean deliveries increased by 7% per year between 1996 and 2011, and the rates of comorbidities such as obesity and diabetes during pregnancy have increased, he said.
Pregnant patients with severe sepsis were 7 years younger on average (27 years of age), compared with nonpregnant women with severe sepsis (age 34 years). Severe sepsis in pregnancy was significantly more common in Hispanics (17%) and Asians (4%), compared with nonpregnant patients (9% and 2%, respectively). Pregnant patients with severe sepsis also had less comorbidity, obesity, and atrial fibrillation, compared with nonpregnant patients with severe sepsis.
Previously Dr. Kumar and his associates reported that the rate of hospitalizations for severe sepsis increased from 143/100,000 persons in 2000 to 343/100,000 in 2007, while mortality rates from severe sepsis decreased from 39% to 27% (Chest 2011;40:1223-31).
The findings of the current study raise questions worth pursuing in future studies, he said, such as the reasons for rising rates of severe sepsis in pregnancy despite no increase in pregnancies or hospitalizations during pregnancy. Pregnancy is considered an immunocompromised state, so why are incidence and mortality rates for severe sepsis lower in pregnancy? he asked. And why has mortality from severe sepsis in pregnancy not improved over the past 10 years?
Dr. Kumar reported having no financial disclosures.
On Twitter @sherryboschert