Can an early diagnostic procedure of metformin-associated lactic acidosis in an emergency unit reduce mortality?

Summary Objective Metformin-associated lactic acidosis (MALA) is a rare but serious adverse reaction with a mortality rate of up to 50%. Unfortunately, diagnosis and care management are often delayed. The objective was to assess the impact on the mortality rate and length of hospital stay of a MALA early diagnosis procedure in diabetic patients with metformin at emergency department (ED) admission. Method From 1/7/2012, a new MALA diagnosis procedure (pH, lactate, metformin) was implemented in all diabetic patients with metformin just after their admission to the ED. The pharmacovigilance staff confirmed the MALA cases (defined as pH ≤ 7.35, lactate concentration > 5 mmol/L) in patients exposed to metformin and after a causality assessment to eliminate other common causes of lactic acidosis. To assess the impact of this new diagnosis procedure, a before-after study was conducted between two groups: a series of cases with intervention (IG; 1/7/2012-30/6/2013) and a control series of past cases without intervention (CG; 1/1/2011–30/6/2012). The main outcome was the relative reduction of mortality rate and length of hospital stay between the two groups. Results Thirty-four MALA cases were confirmed in 745 subjects admitted with lactic acidosis, (IG: 12; CG: 22). A higher illness severity score in the IG vs. CG was observed: respectively arterial lactate (14.2 ± 6.9 vs. 8.8 ± 5.8 mmol/L, P vs. 14.3 ± 6.3 mmol/L, P Conclusion While the results were not significant, the study suggests that the implementation of a MALA early diagnosis procedure in all patients with metformin admitted to an ED tends to decrease mortality, especially for serious MALA cases detected earlier.