The hospitalizations of patients with a record of allergy to penicillin are associated with worse clinical outcomes and higher economic costs, which has a negative impact on patients and health systems. According to a recent study, a correct diagnosis of allergy to penicillins would allow a reduction of 3,863 days of hospitalization and a saving of around 1.5 million euros per year in Portugal.
In fact, only a minority of these possible allergies to penicillins – including amoxicillin, the first-line antibiotic for a large number of infections – was duly confirmed. After a proper diagnostic study, only one in ten of the patients is actually allergic.
This is the conclusion of a study authored by several researchers from CINTESIS – Center for Health Technology and Services Research, namely Bernardo Sousa Pinto (first author), António Cardoso-Fernandes, João Fonseca, Alberto Freitas, Luís Araújo and Luís Delgado. The article was published this year in the prestigious Annals of Allergy, Asthma & Immunology, an official body of the American College of Allergy, Asthma & Immunology.
The study analyzed data from the Central Administration of the Health System regarding all hospitalizations occurred in Portuguese public hospitals from 2000 to 2014, comparing all the episodes in patients with a record of allergy to penicillin (102,872 hospitalizations) to an equal number of patients with similar demographic and clinical features, but with no record of allergy to penicillin. The objective was to see whether there were differences, for example, in the duration and cost of the hospitalization.
The results indicate that patients suspected to be allergic to penicillin represent a significantly higher mean cost of hospitalization. In total, hospitalizations in these patients exceeded 325 million euros, which is 9% more than the costs of the same number of patients without indication of allergy. In some of those patients, particularly severely ill younger patients, costs were 27% higher. Over a period of 15 years, the hospitalizations of patients with an indication of allergy to penicillin cost an additional 27 million euros.
In addition, the hospitalization time of patients with a record of allergy to penicillin is almost 10% longer, adding up to 64,000 days over the 15-year period. In severely ill patients, this classification resulted in an increase of almost a quarter to half of the hospital stay duration, depending on whether they were older than 30 years of age or younger.
Patients who are registered as allergic to penicillin also have a higher number of infections due to drug-resistant agents, presenting a significantly higher frequency of urinary tract and skin infections.
According to Bernardo Sousa Pinto, “clearly, there are many people with false diagnoses of allergy to antibiotics of the penicillin family. This can have serious consequences, clinically and for health services. These patients are treated with second-line antibiotics, which are less effective and have a higher risk of resistance than penicillins. In addition, they involve a higher cost, which is also related to a higher number of readmissions”.
Assuming that only one in 10 of the patients registered as allergic to penicillin is indeed allergic, the researcher estimates that “withdrawing this label from the other hospitalized patients would result in an annual reduction of an additional 3,863 days of hospitalization and a saving of more than 1.5 million euros in hospital expenses”.
Bernardo Sousa Pinto, who has several studies in this area, therefore advocates for the need to obtain a structured clinical history and, whenever possible, confirmatory tests, such as provocation tests, to establish the diagnosis of allergy to penicillins.