ITL: Physician Reviews of HM-Relevant Research

Study design: Retrospective cohort study.

Setting: Kaiser Permanente Colorado.

Synopsis: Using clinical and administrative databases, 442 patients who presented with GI bleeding while receiving warfarin therapy were identified. Patients were grouped by whether they resumed warfarin (n=260, including 41 patients in whom anticoagulation was never interrupted), or did not resume warfarin therapy (n=182) in the 90 days following index GI bleed. Patients with prosthetic heart valves or GI bleeding localized to the rectum/anus were more commonly restarted on warfarin, whereas older patients and those in whom the source of bleeding was not identified were less likely to be restarted on warfarin therapy.

Restarting warfarin therapy after index GI bleed was associated with lower risk of thrombosis (HR 0.05, 95% CI 0.01-0.58) and death from any cause (HR 0.31, 95% CI 0.15-0.62), and it was not associated with a significant increase in risk for recurrent GI bleed (HR 1.32, 95% CI 0.50-3.57).

The authors concluded that for many patients who experience a warfarin-associated GI bleed, the benefits of restarting warfarin therapy outweigh the risks. No conclusions were made regarding the optimal timing of resuming therapy. Limitations included the use of administrative data and inability to determine the potential influence of aspirin use on outcomes.

Bottom line: Resuming warfarin in the 90 days following a warfarin-associated GI bleed is associated with decreased risk of thrombosis and death without increased risk for recurrent GI bleed.

Citation: Witt DM, Delate T, Garcia DA, et al. Risk of thromboembolism, recurrent hemorrhage, and death after warfarin therapy interruption for gastrointestinal tract bleeding. Arch Intern Med. 2012 Sep 12. doi:10.1001/archinternmed.2012.4261.

Preoperative Hyponatremia Associated with Increased Risk for Perioperative Complications and Mortality

Clinical question: Is preoperative hyponatremia an indicator of perioperative morbidity and mortality?

Background: Hyponatremia is a common diagnosis in the hospital setting and is associated with adverse outcomes, even in mild cases. However, it is unclear if this association exists in surgical patients when detected preoperatively.

Study design: Retrospective cohort study.

Setting: Academic and community hospitals participating in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP).

Synopsis: A total of 75,423 adult patients with hyponatremia (sodium <135 mEq/L) who were undergoing major surgery were compared to 888,840 patients with normal preoperative sodium levels over a six-year period. The primary outcome was 30-day mortality. Secondary outcomes included postoperative major coronary events, stroke, wound infection, pneumonia, and length of stay (LOS).

Compared to patients with normal sodium levels, those with preoperative hyponatremia had higher rates of perioperative mortality (5.2% vs. 1.3%; adjusted odds ratio 1.44, 95% CI 1.38-1.50), with increased risk that correlated with increasing severity of hyponatremia. Association with postoperative mortality was particularly strong among hyponatremic patients with ASA scores of 1 or 2 and those undergoing nonemergency surgery.

Patients with preoperative hyponatremia were also found to have increased risk for all postoperative complications evaluated, with the exception of stroke. Limitations included the potential for unmeasured confounders and not being able to account for the role of medications used perioperatively. Research is needed to determine whether correcting preoperative hyponatremia lessens the risk of mortality and other postoperative complications.

Bottom line: Among patients undergoing major surgery, preoperative hyponatremia is a predictor of postoperative 30-day mortality and morbidity.

Citation: Leung AA, McAlister FA, Rogers SO, et al. Preoperative hyponatremia and perioperative complications. Arch Intern Med. 2012;172:1-8.