according to a large, population-based, nested case-control study of older adults, spanning two decades.
The findings, published online in JAMA, “underscore the importance of judicious prescribing, with preferential use of antibiotics associated with a lower risk when clinically appropriate,” noted senior author David Juurlink, MD, PhD, professor of medicine; pediatrics; and health policy, management and evaluation at the University of Toronto, and head of the Clinical Pharmacology and Toxicology Division at Sunnybrook Health Sciences Centre, also in Toronto, Ontario, Canada, and coauthors.
“We hope our study raises awareness about the importance of drug allergy and gains support for future studies to improve drug allergy care,” lead author Erika Lee, MD, clinical immunology and allergy lecturer at the University of Toronto’s Drug Allergy Clinic, Sunnybrook Health Sciences Centre, said in an interview. “It is important to recognize symptoms and signs of a severe drug rash and promptly stop culprit drugs to prevent worsening reaction.”
Serious cADRs are “a group of rare but potentially life-threatening drug hypersensitivity reactions involving the skin and, frequently, internal organs,” the authors wrote. “Typically delayed in onset, these reactions include drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) — the most severe cADR, which has a reported mortality of 20%-40%,” they noted.
Speculation Without Data
Although it has been speculated that some oral antibiotics are more likely than others to be associated with serious cADRs, there have been no population-based studies examining this, they added.
The study included adults aged 66 years or older and used administrative health databases in Ontario, spanning from April 1, 2002, to March 31, 2022. Data on antibiotic use were taken from the Ontario Drug Benefit database. The Canadian Institute for Health Information (CIHI) National Ambulatory Care Reporting System was used to obtain data on emergency department (ED) visits for cADRs, while the CIHI Discharge Abstract Database was used to identify hospitalizations for cADRs. Finally, demographic information and outpatient healthcare utilization data were obtained from the Registered Persons Database and the Ontario Health Insurance Plan database, respectively.
A cohort of 21,758 older adults (median age, 75 years; 64.1% women) who had an ED visit or hospitalization for serious cADRs within 60 days of receiving antibiotic therapy was matched by age and sex with 87,025 antibiotic-treated controls who did not have a cutaneous reaction.
The median duration of antibiotic prescription was 7 days among cases and controls, and among the cases, the median latency period between antibiotic prescriptions and hospital visits for cADRs was 14 days. Most of the case patients went to the ED only (86.9%), and the rest were hospitalized.
The most commonly prescribed antibiotic class was penicillins (28.9%), followed by cephalosporins (18.2%), fluoroquinolones (16.5%), macrolides (14.8%), nitrofurantoin (8.6%), and sulfonamides (6.2%). Less commonly used antibiotics (“other” antibiotics) accounted for 6.9%.
Macrolide antibiotics were used as the reference because they are rarely associated with serious cADRs, noted the authors, and the multivariable analysis, adjusted for risk factors associated with serious cADRs, including malignancy, chronic liver disease, chronic kidney disease, and HIV.
After multivariable adjustment, relative to macrolides, sulfonamides were most strongly associated with serious cADRs (adjusted odds ratio [aOR], 2.9) but so were all other antibiotic classes, including cephalosporins (aOR, 2.6), “other” antibiotics (aOR, 2.3), nitrofurantoin (aOR, 2.2), penicillins (aOR, 1.4), and fluoroquinolones (aOR,1.3).
In the secondary analysis, the crude rate of ED visits or hospitalizations for cADRs was highest for cephalosporins (4.92 per 1000 prescriptions), followed by sulfonamides (3.22 per 1000 prescriptions). Among hospitalized patients, the median length of stay was 6 days, with 9.6% requiring transfer to a critical care unit and 5.3% dying in the hospital.