Pittsburgh, PA—Preoperative metformin prescriptions show promise for decreasing postoperative mortality and readmission for diabetes patients undergoing surgery, a new study finds.
The report in JAMA Surgery notes that adults with comorbidity have less physiological reserve and an increased rate of postoperative mortality and readmission after a major surgical intervention, which can stress their systems.
University of Pittsburgh School of Medicine–led researchers sought to assess postoperative mortality and readmission among diabetes patients, comparing those who were prescribed metformin preoperatively to those who were not.
The cohort study obtained data from the electronic health record of a multicenter, single health care system in Pennsylvania and included adult patients with diabetes who underwent a major operation with hospital admission from January, 1, 2010, to January 1, 2016, at 15 community and academic hospitals within the system. Follow-up continued until December 18, 2018.
Preoperative metformin exposure was defined as one or more prescription for metformin in the 180 days before the surgical procedure. Excluded were those surgical patients without a clinical indication for metformin therapy.
About 59% of the 10,088 diabetes patients undergoing a major surgical intervention had preoperative metformin prescriptions. Researchers propensity-score matched 5,460 patients with a mean (SD) age of 67.7 (12.2) years. Most, 53%, were women.
The study team compared all-cause postoperative mortality, hospital readmission within 90 days of discharge, and preoperative inflammation measured by the neutrophil-to-leukocyte ratio between those with and without preoperative prescriptions for metformin.
Results from the propensity score–matched cohort indicate that preoperative metformin prescriptions were associated with a reduced hazard for 90-day mortality (adjusted HR, 0.72 [95% CI, 0.55-0.95]; absolute risk reduction [ARR], 1.28%; [95% CI, 0.26-2.31]) and hazard of readmission, with mortality as a competing risk at both 30 days (ARR, 2.09% [95% CI, 0.35-3.82]; sub-HR, 0.84 [95% CI, 0.72-0.98]) and 90 days (ARR, 2.78% [95% CI, 0.62-4.95]; sub-HR, 0.86 [95% CI, 0.77-0.97]).
In addition, preoperative inflammation was reduced in those with metformin prescriptions compared with those without (mean neutrophil-to-leukocyte ratio, 4.5 [95% CI, 4.3-4.6] versus 5.0 [95% CI, 4.8-5.3]; P < .001), according to the study.
“This study found an association between metformin prescriptions provided to individuals with type 2 diabetes before a major surgical procedure and reduced risk-adjusted mortality and readmission after the operation. This association warrants further investigation,” the authors write.
Metformin is the most commonly prescribed noninsulin medication for type 2 diabetes and has anti-inflammatory properties independent of its role in glycemic control. It also appears to reduce cardiovascular disease in individuals with diabetes or prediabetes, according to background information in the article, as well as decreasing chronic inflammation.
“Therefore, we sought to understand the association between metformin and risk-adjusted surgical outcomes. We hypothesized that preoperative metformin ameliorates the physiological stress of a surgical intervention and improves postoperative mortality and readmission in this patient population,” the researchers explain.
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The report in JAMA Surgery notes that adults with comorbidity have less physiological reserve and an increased rate of postoperative mortality and readmission after a major surgical intervention, which can stress their systems.
University of Pittsburgh School of Medicine–led researchers sought to assess postoperative mortality and readmission among diabetes patients, comparing those who were prescribed metformin preoperatively to those who were not.
The cohort study obtained data from the electronic health record of a multicenter, single health care system in Pennsylvania and included adult patients with diabetes who underwent a major operation with hospital admission from January, 1, 2010, to January 1, 2016, at 15 community and academic hospitals within the system. Follow-up continued until December 18, 2018.
Preoperative metformin exposure was defined as one or more prescription for metformin in the 180 days before the surgical procedure. Excluded were those surgical patients without a clinical indication for metformin therapy.
About 59% of the 10,088 diabetes patients undergoing a major surgical intervention had preoperative metformin prescriptions. Researchers propensity-score matched 5,460 patients with a mean (SD) age of 67.7 (12.2) years. Most, 53%, were women.
The study team compared all-cause postoperative mortality, hospital readmission within 90 days of discharge, and preoperative inflammation measured by the neutrophil-to-leukocyte ratio between those with and without preoperative prescriptions for metformin.
Results from the propensity score–matched cohort indicate that preoperative metformin prescriptions were associated with a reduced hazard for 90-day mortality (adjusted HR, 0.72 [95% CI, 0.55-0.95]; absolute risk reduction [ARR], 1.28%; [95% CI, 0.26-2.31]) and hazard of readmission, with mortality as a competing risk at both 30 days (ARR, 2.09% [95% CI, 0.35-3.82]; sub-HR, 0.84 [95% CI, 0.72-0.98]) and 90 days (ARR, 2.78% [95% CI, 0.62-4.95]; sub-HR, 0.86 [95% CI, 0.77-0.97]).
In addition, preoperative inflammation was reduced in those with metformin prescriptions compared with those without (mean neutrophil-to-leukocyte ratio, 4.5 [95% CI, 4.3-4.6] versus 5.0 [95% CI, 4.8-5.3]; P < .001), according to the study.
“This study found an association between metformin prescriptions provided to individuals with type 2 diabetes before a major surgical procedure and reduced risk-adjusted mortality and readmission after the operation. This association warrants further investigation,” the authors write.
Metformin is the most commonly prescribed noninsulin medication for type 2 diabetes and has anti-inflammatory properties independent of its role in glycemic control. It also appears to reduce cardiovascular disease in individuals with diabetes or prediabetes, according to background information in the article, as well as decreasing chronic inflammation.
“Therefore, we sought to understand the association between metformin and risk-adjusted surgical outcomes. We hypothesized that preoperative metformin ameliorates the physiological stress of a surgical intervention and improves postoperative mortality and readmission in this patient population,” the researchers explain.
« Click here to return to Weekly News Update.
