Featured CDSI Research of Dr. Cosby Stone

Dr. Cosby Stone focuses on the “right amount of testing,” which has involved identifying and delabeling low-risk penicillin allergies in the hospital and clinic. His efforts have saved lives and allowed patients to receive the “right drug at the right time.” 

Cosby Allen Stone, Jr., MD, MPH, is an Assistant Professor of Medicine in the Division of Allergy, Pulmonology, and Critical Care Medicine within the Department of Medicine at Vanderbilt University Medical Center.

Expertise: 

Dr. Stone has expertise in epidemiology, clinical drug allergy, and translational mechanistic projects in drug and vaccine allergy. He is engaged in pioneering clinical/translational research on beta-lactam antibiotic allergies with a secondary interest in immediate excipient allergies to alpha-gal and polyethylene glycols/polysorbates.   

Current Focus: 

At CDSI, Dr. Stone’s work is currently culminating in a study on understanding and monitoring drug-induced anaphylaxis. Dr. Stone and CDSI researchers are collecting DNA information from individuals who have anaphylactic reactions from medications and/or foods to determine if certain genetic sequences are predisposed to certain reactions. This study, defined below, utilizes the knowledge and information Dr. Stone and his colleagues have developed through their research on beta-lactam allergies and their previous work identifying and delabeling low-risk penicillin allergies at VUMC. 

Learn more about Dr. Stone's research projects below. 


Dr. Stone has developed and validated risk stratification tools utilizing data from patients tested for penicillin allergy to identify patients with low-risk penicillin allergy labels. Patients qualifying as having low-risk penicillin allergy labels include more than 60% to 70% of patients. The tools utilized by Dr. Stone, Dr. Elizabeth Phillips, and their colleagues have a 99% negative predictive value (NPV 95% CI, 96.4-99.9) for excluding true penicillin allergy. These diagnostic tools have been successfully administered to inpatients at Vanderbilt University Medical Center (VUMC) and to outpatients at the Vanderbilt Asthma, Sinus, and Allergy Program (VASAP) to safely remove their penicillin allergy label via amoxicillin challenge without preceding skin testing. 

Penicillin Allergy Risk Stratification*


This schema has been retrospectively and prospectively validated to have a >99% NPV for any symptoms after a challenge when the patient has been assessed as having a low-risk history. The main observed risk in low-risk patients who are challenged is a 0.5% chance of mild-moderate delayed onset rash (typically morbilliform type) 

* Koo G, Stollings JL, Lindsell C, Dear ML, Kripalani S, Nelson GE, McCoy AB, Rice TW, Phillips EJ, Stone CA Jr; Vanderbilt University Medical Center Learning Healthcare System. "Low-risk penicillin allergy delabeling through a direct oral challenge in immunocompromised and/or multiple drug allergy labeled patients in a critical care setting." J Allergy Clin Immunol Pract. 2022 Jun;10(6): PMID: 35131513; PMCID: PMC9188986.

Cephalosporin allergy risk stratification**



This schema has been retrospectively validated to have (so far) 100% NPV for any symptoms after a challenge when the patient is assessed as having a low-risk cephalosporin allergy history. 

** Koo G, Yu R, Phillips EJ, Stone CA Jr. "Retrospective stratification of cephalosporin allergy label risk using validated penicillin allergy frameworks." J Allergy Clin Immunol Pract. 2022 Sep;10(9):2472-2475.e1. doi: 10.1016/j.jaip.2022.05.032. Epub 2022 Jun 9. PMID: 35690369.