Aspirin Use Linked to Better Outcomes

Daily low-dose aspirin use after the first trimester was associated with 24% lower rates of preeclampsia and with reductions in adverse preeclampsia outcomes, depending on baseline risk. Absolute risk reductions with aspirin use were 2% to 5% for preeclampsia (relative risk [RR], 0.76; 95% confidence interval [CI], 0.62 - 0.95), 1% to 5% for intrauterine growth restriction (RR, 0.80; 95% CI, 0.65 - 0.99), and 2% to 4% for preterm birth (RR, 0.86; 95% CI, 0.76 - 0.98).

Although the literature review did not detect any significant perinatal or maternal harms, rare harms could not be excluded. Eighteen-month follow-up from the largest trial found no developmental harms, but there were few data regarding long-term outcomes.

Limitations of this systematic review include small-study effects potentially resulting in overestimation of benefits and failure of predictive intervals to achieve statistical significance.

On the basis of these limitations, the reviewers suggest that relative risk reductions closer to 10% for preeclampsia, intrauterine growth restriction, and preterm birth would be a more conservative interpretation of the results.

"Future studies could shift findings toward the null," the reviewers write. "Daily low-dose aspirin beginning as early as the second trimester prevented clinically important health outcomes. No harms were identified, but long-term evidence was limited."

They recommend more primary research to clarify how preeclampsia arising from different risk factors develops and responds to aspirin.

"More robust and consistent tools for preeclampsia risk stratification would support future research and clinical practice," they conclude. "Few trials have been conducted among African American women in the United States, who have the greatest disease burden; clinical research focused on this important subpopulation is urgently needed. For women at high risk for preeclampsia, available evidence indicates modest effects but important benefits of daily low-dose aspirin for prevention of the condition and consequent illness."

The Agency for Healthcare Research and Quality funded this study. Some of the study authors reported having received government or USPSTF contracts.

Ann Intern Med. Published online April 7, 2014.

Source: www.medscape.com