Author ORCID Identifier

0000-0001-7580-4116

Date of Award

Fall 1-8-2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Public Health

First Advisor

Richard Rothenberg

Second Advisor

Heather Bradley

Third Advisor

John McQuiston

Fourth Advisor

Henry Walke

Abstract

Nocardiosis is caused by opportunistic, soil-borne bacteria in the genus Nocardia. The disease is characterized by severe pulmonary and systemic infections, and mild to severe skin infections. People thought to be at risk are older adults and those with underlying comorbidities, particularly immunosuppressive conditions. Treatment duration can be long and may require antimicrobial and surgical interventions. Considered a rare disease, the existing literature and knowledge base regarding the clinical presentation, persons at risk, incidence, and mortality estimates are primarily from case series or limited hospital-based retrospective analyses. Evaluating the disease characteristics from more generalizable data can aid in our understanding of the disease and may aid in identifying persons who may be at greater risk of death.

The purpose of this dissertation is to use population-level administrative data to develop generalizable estimates of the incidence and mortality, and to evaluate risk factors, including identifying a predictive comorbidity measure. The 100% Medicare Fee-For-Service data, and the Healthcare Utilization Project’s State Inpatient Databases and State Ambulatory and Surgery and Services Databases were used to evaluate nocardiosis among Medicare beneficiaries as well as all payer hospitalization and visit discharges. The demographics, costs, visits, and risk factors are described from each data source, and incidence and hospitalization rates are calculated. Comorbidity measures are evaluated for prediction of mortality. Time to death and covariates associated with mortality are calculated from the person-based longitudinal Medicare data and the HCUP hospital visit-based data, respectively.

The findings of this dissertation describe nocardiosis that can be generalized to all Fee-for-Service Medicare beneficiaries and almost half the US population. Nocardiosis cases and nocardiosis-associated visits were more often male, older, and sicker than the general Medicare and US populations. Mortality was associated with disseminated nocardiosis, cerebrovascular disease, and the presence of additional comorbid conditions, when controlling for other factors. Additional findings will be discussed.

These findings can provide additional insight into persons who may be at greater risk of developing nocardiosis and can provide clinicians with factors that are associated with mortality. These findings provide a baseline from which future population-level analyses can be compared.

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