Metformin-associated lactic acidosis (MALA) may occur after acute metformin overdose, or from therapeutic use in patients with renal compromise. The mortality is high, historically 50% and more recently 25%. In many disease states, lactate concentration is strongly associated with mortality. The aim of this systematic review and meta-analysis is to investigate the utility of pH and lactate concentration in predicting mortality in patients with MALA.
We searched PubMed, EMBASE, and Web of Science from their inception to April 2019 for case reports, case series, prospective, and retrospective studies investigating mortality in patients with MALA. Cases and studies were reviewed by all authors and included if they reported data on pH, lactate, and outcome. Where necessary, authors of studies were contacted for patient-level data. Receiver operating characteristic (ROC) curves were generated for pH and lactate for predicting mortality in patients with MALA.
Forty-four studies were included encompassing 170 cases of MALA with median age of 68.5 years old. Median pH and lactate were 7.02 mmol/L and 14.45 mmol/L, respectively. Overall mortality was 36.2% (95% CI 29.6-43.94). Neither lactate nor pH was a good predictor of mortality among patients with MALA. The area under the ROC curve for lactate and pH were 0.59 (0.51-0.68) and 0.43 (0.34-0.52), respectively.
Our review found higher mortality from MALA than seen in recent studies. This may be due to variation in standard medical practice both geographically and across the study interval, sample size, misidentification of MALA for another disease process and vice versa, confounding by selection and reporting biases, and treatment intensity (e.g., hemodialysis) influenced by degree of pH and lactate derangement. The ROC curves showed poor predictive power of either lactate or pH for mortality in MALA. With the exception of patients with acute metformin overdose, patients with MALA usually have coexisting precipitating illnesses such as sepsis or renal failure, though lactate from MALA is generally higher than would be considered survivable for those disease states on their own. It is possible that mortality is more related to that coexisting illness than MALA itself, and many patients die with MALA rather than from MALA. Additional work looking solely at MALA in healthy patients with acute metformin overdose may show a closer relationship between lactate, pH, and mortality.

Do Patients Die with or from Metformin-Associated Lactic Acidosis (MALA)? Systematic Review and Meta-analysis of pH and Lactate as Predictors of Mortality in MALA.

Medications with anticholinergic properties are commonly prescribed to older adults. The cumulative anticholinergic effect of all the medications a person takes is referred to as the 'anticholinergic burden' because of its potential to cause adverse effects. It is possible that high anticholinergic burden may be a risk factor for development of cognitive decline or dementia. There are various scales available to measure anticholinergic burden but agreement between them is often poor.
To assess whether anticholinergic burden, as defined at the level of each individual scale, is a prognostic factor for future cognitive decline or dementia in cognitively unimpaired older adults.
We searched the following databases from inception to 24 March 2021: MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), CINAHL (EBSCOhost), and ISI Web of Science Core Collection (ISI Web of Science).
We included prospective and retrospective longitudinal cohort and case-control observational studies with a minimum of one year' follow-up that examined the association between an anticholinergic burden measurement scale and future cognitive decline or dementia in cognitively unimpaired older adults.
Two review authors independently assessed studies for inclusion, and undertook data extraction, assessment of risk of bias, and GRADE assessment. We extracted odds ratios (OR) and hazard ratios, with 95% confidence intervals (CI), and linear data on the association between anticholinergic burden and cognitive decline or dementia. We intended to pool each metric separately; however, only OR-based data were suitable for pooling via a random-effects meta-analysis. We initially established adjusted and unadjusted pooled rates for each available anticholinergic scale; then, as an exploratory analysis, established pooled rates on the prespecified association across scales. We examined variability based on severity of anticholinergic burden.
We identified 25 studies that met our inclusion criteria (968,428 older adults). Twenty studies were conducted in the community care setting, two in primary care clinics, and three in secondary care settings. Eight studies (320,906 participants) provided suitable data for meta-analysis. The Anticholinergic Cognitive Burden scale (ACB scale) was the only scale with sufficient data for 'scale-based' meta-analysis. Unadjusted ORs suggested an increased risk for cognitive decline or dementia in older adults with an anticholinergic burden (OR 1.47, 95% CI 1.09 to 1.96) and adjusted ORs similarly suggested an increased risk for anticholinergic burden, defined according to the ACB scale (OR 2.63, 95% CI 1.09 to 6.29). Exploratory analysis combining adjusted ORs across available scales supported these results (OR 2.16, 95% CI 1.38 to 3.38), and there was evidence of variability in risk based on severity of anticholinergic burden (ACB scale 1: OR 2.18, 95% CI 1.11 to 4.29; ACB scale 2: OR 2.71, 95% CI 2.01 to 3.56; ACB scale 3: OR 3.27, 95% CI 1.41 to 7.61); however, overall GRADE evaluation of certainty of the evidence was low.
There is low-certainty evidence that older adults without cognitive impairment who take medications with anticholinergic effects may be at increased risk of cognitive decline or dementia.
A los adultos mayores se les prescriben con frecuencia fármacos con propiedades anticolinérgicas. El efecto anticolinérgico acumulado de todos los fármacos que toma una persona se denomina "carga anticolinérgica" por su potencial para causar efectos adversos. Es posible que una alta carga anticolinérgica sea un factor de riesgo para la aparición de un deterioro cognitivo o la demencia. Existen varias escalas para medir la carga anticolinérgica, pero la concordancia entre ellas suele ser mala.
Evaluar si la carga anticolinérgica, definida a nivel de cada escala individual, es un factor pronóstico de un futuro deterioro cognitivo o demencia en adultos mayores sin deterioro cognitivo. MÉTODOS DE BÚSQUEDA: Se realizaron búsquedas en las siguientes bases de datos desde su creación hasta el 24 de marzo de 2021: MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), CINAHL (EBSCOhost) e ISI Web of Science Core Collection (ISI Web of Science). CRITERIOS DE SELECCIÓN: Se incluyeron los estudios observacionales de cohortes y de casos y controles longitudinales prospectivos y retrospectivos con un seguimiento mínimo de un año, que examinaron la asociación entre una escala de medición de la carga anticolinérgica y el futuro deterioro cognitivo o demencia en adultos mayores sin deterioro cognitivo. OBTENCIÓN Y ANÁLISIS DE LOS DATOS: Dos autores de la revisión, de forma independiente, evaluaron los estudios para su inclusión y realizaron la extracción de los datos, la evaluación del riesgo de sesgo y la evaluación GRADE. Se extrajeron los odds ratios (OR) y los cociente de riesgos instantáneos, con intervalos de confianza (IC) del 95%, y los datos lineales sobre la asociación entre la carga anticolinérgica y el deterioro cognitivo o la demencia. La intención fue agrupar cada métrica por separado; sin embargo, sólo los datos basados en el OR fueron aptos para agruparlos mediante un metanálisis de efectos aleatorios. Inicialmente se establecieron las tasas agrupadas ajustadas y no ajustadas para cada escala anticolinérgica disponible; luego, como un análisis exploratorio, se establecieron las tasas agrupadas sobre la asociación predeterminada entre las escalas. Se examinó la variabilidad según la intensidad de la carga anticolinérgica.
Se identificaron 25 estudios que cumplían los criterios de inclusión (968 428 adultos mayores). Veinte estudios se realizaron en ámbitos de atención comunitaria, dos en centros de atención primaria y tres en ámbitos de atención secundaria. Ocho estudios (320 906 participantes) proporcionaron datos adecuados para el metanálisis. La escala Anticholinergic Cognitive Burden (escala ACB) fue la única escala con datos suficientes para un metanálisis "basado en la escala". Los OR no ajustados indicaron un aumento en el riesgo de deterioro cognitivo o demencia en los adultos mayores con sobrecarga anticolinérgica (OR 1,47; IC del 95%: 1,09 a 1,96) y los OR ajustados indicaron igualmente un aumento en el riesgo de sobrecarga anticolinérgica, definida según la escala ACB (OR 2,63; IC del 95%: 1,09 a 6,29). El análisis exploratorio que combina los OR ajustados entre las escalas disponibles apoyó estos resultados (OR 2,16; IC del 95%: 1,38 a 3,38) y hubo evidencia de variabilidad en el riesgo según la intensidad de la carga anticolinérgica (1 en escala ACB): OR 2,18; IC del 95%: 1,11 a 4,29; 2 en escala ACB: OR 2,71; IC del 95%: 2,01 a 3,56; 3 en escala ACB: OR 3,27; IC del 95%: 1,41 a 7,61); sin embargo, la evaluación global de la certeza de la evidencia con el método GRADE fue baja.
Existe evidencia de certeza baja de que los adultos mayores sin deterioro cognitivo que toman fármacos con efectos anticolinérgicos podrían tener un mayor riesgo de deterioro cognitivo o demencia.

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