Corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are neurodegenerative diseases associated with tau protein abnormalities. CBD is characterized by asymmetric parkinsonism, apraxia, and cognitive and behavioral symptoms. PSP is characterized by supranuclear gaze palsy, postural instability, and cognitive and behavioral changes. Both diseases have heterogeneous clinical presentations and can be difficult to diagnose. There are currently no disease-modifying treatments available for CBD or PSP, but symptomatic relief can be provided through medications and therapy. Research is ongoing to develop biomarkers and therapies for these diseases.

Multivariable analysis is used for four major types of studies: observational studies of etiology, randomized and nonrandomized intervention studies, studies of diagnosis, and studies of prognosis.

For observational studies, whether etiologic or intervention, the most important reason to do multivariable analysis is to eliminate confounding, since in observational studies the groups are not randomly assigned. With randomized studies, multiple analysis is used to adjust for baseline differences that occurred by chance, to identify other independent predictors of outcome besides the randomized group, and x.

With studies of diagnosis, multivariable analysis is used to identify the best combination of diagnostic information to determine whether a person has a particular disease. Multivariable analysis can also be used to predict the prognosis of a group of patients with a particular set of known prognostic factors.