Antibiotics may be effective in reducing infection-related hospital admissions, but their use could reduce the future effectiveness of the prescribed antibiotic in the patient, researchers have warned.
A population-based cohort study, published in BMC Medicine
on 2 March 2020, analysed electronic health records from primary care linked to hospital admission records. The study population included 1.8 million patients prescribed a systemic antibiotic, with a recent record of selected infections and no history of COPD.
The researchers matched the groups with different histories of antibiotic use by propensity score to adjust for underlying differences in patient risks and to make sure that the comparison group was of a similar age and sex, with similar levels of comorbidity.
They found that a significant number of patients received antibiotics frequently and intermittently in general practice. Patients with larger histories of antibiotic use had risks of infection-related hospital admission that remained elevated compared to patients with minimal prior use.
Tjeerd van Staa, a professor in health e-research from the University of Manchester and lead author of the study told The Pharmaceutical Journal that their findings were “unexpected”, but that after replicating the analyses in another dataset, they found similar results.
“Frequent intermittent antibiotic use is prevalent in primary care, but there is very little or no evidence from randomised trials that this type of antibiotic use is effective — our research found that this type of antibiotic use may have limited benefit,” he said.
“Other research has found that use of antibiotics can lead to a patient developing resistance to that antibiotic.”
The researchers said that a “potential mechanism” for the reduced effectiveness was antibiotic resistance and that antibiotics may disrupt the intestinal microbiota contributing to colonisation with resistant bacteria. Antibiotic guardianship may have to consider reviews of patients who frequently and intermittently receive antibiotics, they added.
Jacqueline Sneddon, an antimicrobial pharmacist and project lead for the Scottish Antimicrobial Prescribing Group said the results highlighted the importance of prescribing antibiotics on an individual patient basis.
“When a patient presents with an infection, it is important to look at their medical history and if they’ve had any antibiotics previously. The standard might be to look back three months and see if they’ve had one for the same complaint or another complaint [in that time],” she said.
“There is evidence to show that if you’ve had even one course of antibiotic, your chance of getting a resistant infection in the next three months is significantly higher [and that risk] continues for the following year.”
Sneddon said that community pharmacists have an important role to play by flagging up prescriptions when a patient’s record shows that they have been prescribed repeated courses of antibiotics.
“It should be ringing alarm bells,” she said.
The study’s research team has also submitted research grant proposals for the development of a tool for GPs to enable them to calculate the risks for their patients associated with taking multiple courses of antibiotics.
“GPs are using electronic health records and such a decision support system can be built into the main electronic health record systems, as currently used in primary care,” said van Staa.