Acute respiratory infections (IDI) are the most common cause of prescribing antibiotics on an outpatient basis, although most IDIs have a mild viral or bacterial etiology. In many cases, the irrational use of antibiotics not only has a positive effect on the patient's recovery, but also puts them at risk of developing potential side effects. In addition, since there is a cause and effect relationship between the use of antibiotics and the development of antibiotic resistance, reducing the inappropriate use of antibiotics is a key factor in controlling this important problem. Antibiotic resistance has significant negative economic consequences and the risk of ineffective treatment of infections in patients in the future, leading to an increased incidence of infections and their death.

One of the strategies to reduce the frequency of antibiotic use in primary care is to prescribe antibiotic therapy based on the definition of biomarkers. These infectious disease biomarkers are part of the acute phase of the inflammatory response to acute tissue damage, whatever its etiology (infections, trauma, inflammation) and can be used in conjunction with clinical data as a surrogate marker of infection, helping in some cases the doctor to choose the right patient management tactic. with IDP. Several biomarkers, such as CRP, the number of peripheral blood leukocytes and procalcitonin, are proposed as indicators of serious bacterial infection in patients with symptoms of acute respiratory tract infection.

To assess the pros and cons of identifying these infection biomarkers in order to develop certain tactics for the management and prescription of antibiotics for patients with symptoms of acute respiratory infections in primary care, regardless of the age of patients, a meta-analysis and systematic review were performed. The results of this work are published in the November issue of the Cochrane Database of Systematic Reviews.

The research was searched in the CENTRAL (2013, number 12), MEDLINE (from 1946 to January 2014), EMBASE (from 2010 to January 2014), CINAHL (from 1981 to January) 2014), Web of Science ( from 1955 to January 2014) and LILACS (from 1982 to January 2014).

The meta-analysis included randomized controlled trials in patients with IDI that compared the use of biomarkers with standard patient management. The meta-analysis included studies randomizing both individual patients and those using cluster randomization.

Two experts independently assessed the relevance of the studies to be included in a systematic review and extracted the data from the following results:

The only infection biomarker currently available for determination in primary care conditions, identified during the meta-analysis, was the C-reactive protein (CRP). Experts could not find any informative studies in which the number of leukocytes or procalcitonin was determined as markers.

The experts included 6 studies (3284 participants, 130 children) in a meta-analysis which evaluated CRP as a marker of patient management. The information available was obtained from studies with a low or moderate risk of error.

In general, in the group in which CRP was determined, the frequency of antibiotic use decreased (631/1685) compared to standard patient care (785/1599). The combined results of studies in which CRP was determined have shown a 22% reduction in the number of antibiotic prescriptions for acute IDPs compared to conventional patient management.

However, a high level of heterogeneity and a statistically significant test for subgroup differences between three randomized controlled trials and three cluster randomized trials indicate that the results of a meta-analysis on antibiotic use should be interpreted with caution and the combined effect (risk ratio [RR] 0.78, 95% confidence interval [CI] 0.66-0.92, I2 = 68%) may not be as relevant. The heterogeneity observed disappeared in the analysis of the subgroups: RR 0.90, 95% CI 0.80-1.02, I2 = 5% for randomized controlled trials and RR 0.68, 95% CI 0 , 61-0.75, I2 = 0% for cluster randomized controlled trials, indicating that this may be the cause of the observed heterogeneity. No difference was found between using CRP as a regularly accessible and reasonably rapid study and standard patient management tactics for clinical recovery, defined as at least a significant improvement on days 7 and 28 or the need to see a doctor on day 28, as well as the number of patients satisfied with the treatment. However, there was an increase in the frequency of hospitalizations in the group in which CRP was determined in one study, but this was due to several phenomena and could be random results. No patient deaths were recorded in any of the studies included in the meta-analysis. Experts rated the quality of the evidence as moderate.

Regarding the degree of increase in CRP, the researchers did not specifically study the optimal level of CRP to make a particular decision, however, if the duration of symptoms of the disease is more than 24 hours and the level of CRP is less than 20 mg / l, so with high probability it can be said that benefits of antibiotic treatment are not expected and the use of antibiotics can be avoided. T.N. the "gray area", when the CRP level is from 21 to 99 mg / l, is more ambiguous, and we no longer speak of the possibility of dispensing with antibacterial treatment. However, the current level of evidence does not allow specific conclusions to be drawn about the critical level of CRP. Of course, it is important to note that, by the level of CRP, it is impossible to clearly distinguish between the viral and bacterial nature of the infection - it is only a marker of the inflammation that is present in the blood at some point. If the CRP is high, the risk of a serious infection increases and the likelihood of being prescribed antibiotics also increases. Thus, the determination of CRP can be less a diagnostic marker than a prognostic marker.

Thus, the determination of the C-reactive protein to establish the need for prescription of antibiotics can reduce the incidence of antibiotic use, although the degree of reduction remains unclear. This reduction in the frequency of antibiotic use does not affect patient outcomes, including the duration of illness and the rate of onset of full recovery. At the same time, one can only pay attention to a possible increase in the frequency of hospitalizations. More research is needed to more precisely establish the role of CRP as a marker for the prescription of antibiotics, assess the cost of this intervention and compare this biomarker with another strategy to reduce the prescription of antibiotics.