A Study of Lactic Acidosis Associated with the Use of Metformin in Nakhonpathom Hospital

Abstract

          Objective: To study the characteristics of patients with metformin associated lactic acidosis (MALA) and to study relationship among factors affecting occurrence of metformin associated lactic acidosis at Nakhonpathom Hospital.

            Methods: A descriptive study was conducted by collecting retrospective data from inpatients who developed lactic acidosis and received metformin from October 1, 2020, to September 30, 2023. The chi-square test, t test, and Fisher's exact test were used to analyze the relationship among factors affecting the occurrence of lactic acidosis.

            Results: A review of the medical records of 325 patients who developed acidosis revealed that 261 patients (80.3%) received metformin. Among them, 73 patients developed lactic acidosis associated with metformin use (MALA). There were 32 males (43.8%), 41 females (56.2%); 49 (67.1%) were older than or equal to 60 years, and 24 (32.9%) were younger than 60 years. The factors contributing to the development of lactic acidosis included:

1. Renal function: When admitted, glomerular filtration rate (GFR) was less than 60 mL/min/1.73 m² in 59 patients (80.8%), with an odds ratio (OR) of 5.64 (95% CI = 2.86–11.11); relative risk (RR) of 3.26 (95% CI = 2.26–4.70); and p < .05.
2. Serum creatinine levels: Creatinine levels were higher than 1.02 mg/dL in 58 patients (79.4%), with an OR of 4.16 (95% CI = 2.15–8.08); RR of 2.66 (95% CI = 1.86–3.79); and p < .05.
3. Liver function: Aspartate transaminase (AST) levels were above the normal range (greater than 35 IU/L in females and greater than 40 IU/L in males) in 39 patients (53.4%), with an OR of 2.68 (95% CI = 1.37–5.23); RR of 1.81 (95% CI = 1.35–2.44); and p = .003.

Factors associated with the development of acidosis included:

• Acute renal failure: 57 patients (78.1%), with an OR of 30.28 (95% CI = 13.83–66.30); RR of 1.67 (95% CI = 1.18–2.34); and p < .05;

• Septic shock: 22 patients (30.1%), with an OR of 6.74 (95% CI = 2.81–16.12); RR of 1.82 (95% CI = 1.21–2.73); and p < .05;
• Bacteremia: 17 patients (23.3%), with an OR of 2.80 (95% CI = 1.27–6.16); RR of 6.77 (95% CI = 4.82–9.50); and p = .009; and
• Hypoxia: 14 patients (19.2%), with an OR of 15.54 (95% CI = 3.42–70.57); RR of 2.53 (95% CI = 2.01–3.17); and p < .05.

The most common primary diagnoses upon hospital admission included infectious diseases in 13 patients (17.8%), followed by septic shock in 7 patients (9.6%), and bacteremia in 4 patients (5.5%).

The primary diagnosis most strongly associated with the development of lactic acidosis was heart failure in 3 patients (4.11%), with an OR of 0.90 (95% CI = 0.27–2.95), RR of 1.42 (95% CI = 0.69–2.90), and p < .01.

            Conclusions: This study found that factors associated with the occurrence of metformin-associated lactic acidosis in patients at Nakhonpathom Hospital included kidney function on the day of hospitalization, serum creatinine levels, liver function, acute kidney failure, septic shock, bacteremia, and heart failure. If there is a guideline to screen patients from these factors, it will reduce the mortality rate of patients from this condition.