Researchers find small benefit from antibiotics for patients with respiratory infections

Physicians would have to prescribe antibiotics to more than 12,000 patients diagnosed with common colds to prevent one hospital admission for pneumonia, according to a study published in a recent issue of the Annals of Family Medicine.

“Common colds are extremely unlikely to progress to more serious bacterial infections,” said the study's lead author, Sharon B. Meropol, MD, PhD, of Case Western Reserve University School of Medicine, Rainbow Babies and Children’s Hospital, Cleveland, Ohio. “This should reassure doctors and patients that antibiotics are usually not needed or helpful.

“Doctors frequently prescribe antibiotics for nonspecific respiratory infections, or common colds, which are almost always caused by viruses,” Meropol continued. “Presumably they and/or their patients feel that antibiotics are likely to prevent progression to a serious bacterial illness. We wanted to further explore the real risks to enable more informed decision-making about antibiotic use in the future.”

In addition, when an adverse event is reported after medication use, it is frequently blamed on the drug, when it might have occurred with or without the drug, either by chance alone or because of the patient’s underlying medical condition, said Meropol.

“We wanted to get a better estimate of the true risks of antibiotic use, comparing similar groups of patients who were treated vs. those who were not treated with antibiotics,” she said.

The study

Using anonymous data from electronic medical records in the United Kingdom, Meropol, an assistant professor of pediatrics and epidemiology and biostatistics, and colleagues found a group of patients who had been diagnosed with nonspecific respiratory tract infections - common colds - during visits to their primary care doctors.

Approximately two-thirds (65%) of the patients received antibiotic prescriptions, and the rest did not.

“For these patients, we checked for hospital admissions within two weeks after the visit, for pneumonia and for certain severe reactions often attributed to drug side effects,” said Meropol. “We compared risks of hospital admission for these diagnoses between people who received antibiotics to risks of hospital admission for people who did not receive them.”

The adjusted risk difference for treated vs. untreated patients per 100,000 visits was 1.07 fewer adverse events and 8.16 fewer pneumonia hospitalizations within 15 days following the visit.

“Comparing similar patients exposed vs. not exposed to antibiotics, we did not find a significant risk of severe side effects,” Meropol said. “We did find a risk of less severe side effects that did not result in hospital admission.”

Drug-resistant bugs

Bacteria that cause diseases are becoming increasingly resistant to antibiotics, and doing so more quickly than effective drugs can be developed to treat infections.

“The more we use antibiotics, the faster bacteria in our environment become resistant to them, and the less well they work,” Meropol said.

In the United States, almost half of patients diagnosed with common colds are prescribed antibiotics.

“This is more harmful than helpful, as almost all common colds are caused by viruses that don’t respond to antibiotic treatment,” Meropol said. “Avoiding unnecessary antibiotic use, slowing the development of resistance, and preserving antibiotics’ effectiveness as long as possible is an urgent public health issue. Results of this study will help guide decision-making about antibiotic prescribing, reassuring us that we can safely avoid using antibiotics where they are unlikely to be of benefit, especially for the common cold, and will help us target them to where they will be the most effective.”

Although any drug can cause side effects, reports of a side effect after drug use should be considered carefully to assess whether it was actually caused by the drug or whether there is a different explanation, Meropol said.

“While any drug can have risks, it is best to use caution when attributing an adverse health event to a drug side effect, if that event could instead have been caused by chance alone or by the patient’s underlying medical condition. Comparison with an unexposed control group can help elucidate true drug risks,” she said.