Faye Abdellah developed one of the first nursing theories that focused on identifying and addressing patients' health-related problems. She created a model with 21 common nursing problems that could be used as a framework for assessing and caring for patients. Her work emphasized using research and evidence-based practices to improve nursing care. Studies have shown her theoretical approach is still applicable in areas like using problem-focused care, evidence-based practices, and avoiding practices not shown to be beneficial like pre-operative hair removal with razors.