Research Statistics Unit, Biomedical Data Sciences, GlaxoSmithKline Pharmaceuticals, Collegeville, PA 19426, USA.
Published: May 2009
AI Article Synopsis
Article Abstract
Dichotomization is the transformation of a continuous outcome (response) to a binary outcome. This approach, while somewhat common, is harmful from the viewpoint of statistical estimation and hypothesis testing. We show that this leads to loss of information, which can be large. For normally distributed data, this loss in terms of Fisher's information is at least 1-2/pi (or 36%). In other words, 100 continuous observations are statistically equivalent to 158 dichotomized observations. The amount of information lost depends greatly on the prior choice of cut points, with the optimal cut point depending upon the unknown parameters. The loss of information leads to loss of power or conversely a sample size increase to maintain power. Only in certain cases, for instance, in estimating a value of the cumulative distribution function and when the assumed model is very different from the true model, can the use of dichotomized outcomes be considered a reasonable approach.
Mesenchymal stem cells (MSCs) are promising candidates for regenerative therapies due to their self-renewal and differentiation capabilities. Pathological microenvironments expose MSCs to senescence-inducing factors such as reactive oxygen species (ROS), resulting in MSC functional decline and loss of stemness. Oxidative stress leads to mitochondrial dysfunction, a hallmark of senescence, and is prevalent in aging tissues characterized by elevated ROS levels.
Creatine monohydrate supplementation (CrM) is a safe and effective intervention for improving certain aspects of sport, exercise performance, and health across the lifespan. Despite its evidence-based pedigree, several questions and misconceptions about CrM remain. To initially address some of these concerns, our group published a narrative review in 2021 discussing the scientific evidence as to whether CrM leads to water retention and fat accumulation, is a steroid, causes hair loss, dehydration or muscle cramping, adversely affects renal and liver function, and if CrM is safe and/or effective for children, adolescents, biological females, and older adults.
Age-related macular degeneration (AMD) is a leading cause of blindness among the elderly worldwide. Anti-vascular endothelial growth factor (anti-VEGF) injections remain the first-line therapy for AMD. However, their high cost and the need for frequent administration pose challenges to long-term adherence, highlighting the need for accessible and cost-effective preventive strategies.
Posterior shoulder instability (PSI) is a shoulder pathology that is challenging to diagnose, leading to treatment delay and exacerbation of symptoms. Etiology can be both traumatic and atraumatic, and a comprehensive clinical history plays a significant role in achieving diagnosis. Imaging in the setting of PSI can reveal a reverse-Bankart lesion, a reverse Hill-Sachs lesion, posterior labral cysts, and potentially glenoid or lesser tuberosity fractures.
Spontaneous hepatic rupture is a rare complication that occurs in pregnant mothers with HELLP syndrome, or preeclampsia with severe features, or eclampsia. The most common symptom of hepatic rupture/hematoma is right upper quadrant pain or epigastric pain, which is similar to the presentation of preeclampsia with severe features. Therefore, the absence of specific signs and symptoms leads to a diagnostic dilemma and a delay in management.
