A marginalized two-part Beta regression model for microbiome compositional data.

In microbiome studies, an important goal is to detect differential abundance of microbes across clinical conditions and treatment options. However, the microbiome compositional data (quantified by relative abundance) are highly skewed, bounded in [0, 1), and often have many zeros. A two-part model is commonly used to separate zeros and positive values explicitly by two submodels: a logistic model for the probability of a specie being present in Part I, and a Beta regression model for the relative abundance conditional on the presence of the specie in Part II.

Importance of Considering the Middle Capillary Plexus on OCT Angiography in Diabetic Retinopathy.

Purpose: To quantify microvasculature changes in the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP) in diabetic retinopathy (DR).

Methods: Retrospective cross-sectional study at a tertiary academic referral center, in which 26 controls (44 eyes), 27 diabetic subjects without retinopathy (44 eyes), 32 subjects with nonproliferative retinopathy (52 eyes), and 27 subjects with proliferative retinopathy (40 eyes) were imaged with optical coherence tomography angiography (OCTA). Outcome measures included parafoveal vessel density (VD), percentage area of nonperfusion (PAN), and adjusted flow index (AFI) at the different plexuses.

Quantifying Microvascular Abnormalities With Increasing Severity of Diabetic Retinopathy Using Optical Coherence Tomography Angiography.

Purpose: We quantified retinal and choriocapillaris microvascular changes in healthy control eyes and different stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).

Methods: This retrospective cross-sectional study included 137 eyes of 86 patients with different stages of DR and 44 eyes of 26 healthy age-matched controls. Participants were imaged with a commercial OCTA device (RTVue-XR Avanti).