Metformin use despite contraindications in metformin-associated lactic acidosis

Metformin-associated lactic acidosis (MALA) was a rare but important adverse event of metformin therapy and carried a high mortality rate. In most of reported cases, MALA occurred because of one or more patient associated contraindications for the drug were overlooked. The aim of this study was to evaluate the clinical outcome of MALA patients between the avoidable, unpredictable or combined metformin contraindications. During the study period, 91 patients with MALA and admitted to intensive care unit were enrolled in the study. Most patients had combined metformin contraindications (n = 47), followed by groups of unpredictable (n = 36) and avoidable (n = 8). The distribution of most selected outcomes between avoidable, unpredictable, and combined metformin contraindications had no significant statistical difference between these 3 groups. Only patients with vasoactive support presented the significant difference between 3 groups (P = .0149). In addition, the association between each outcome and 3 metformin contraindications groups indicated no statistical difference. In conclusion, for patients with metformin contraindications which were avoidable, unpredictable or combined avoidable and unpredictable, there was no significant difference of clinical outcome. Therefore, MALA prognosis may not be related to the metformin therapy for different types of metformin contraindications.