Clinical perspectives and stewardship imperatives in the study of acute exacerbations of chronic obstructive pulmonary disease

The article by Kasundra et al.[1] was of great interest to us. Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a significant burden to the healthcare system and economy, especially in rural areas where the infrastructure for diagnosis and antibiotic treatment may be limited. The authors are to be commended on their efforts in creating regional microbiological data, which is obviously of great importance. However, some aspects of the article require clarification. One of the important methodological issues is the time frame of the study. It has been mentioned in the manuscript that patient recruitment took place from January 2021 to December 2023, which means that the recruitment process took 3 years. However, in another part of the manuscript, it is mentioned that 150 patients were recruited in 15 months. Seasonal variations have a major impact on respiratory infections and their exacerbations. Reliable information about the duration of patient recruitment is essential for the reader to understand the data in its seasonal context. Another problem is related to the testing of procalcitonin (PCT). In the study of 150 patients, only 80 (53.3%) had their PCT tested, and the reason for selective testing is not clear. The risk of selection bias is higher in studies that test the biomarker in a particular subset of patients, and the relationship between PCT and positive sputum culture may not be generalizable to the entire population. It would have been helpful to understand the reasons for selective testing, whether due to availability or certain indications, in the context of the current evidence regarding the role of PCT in guiding antibiotic therapy for lower respiratory tract infections.[2] Moreover, more robust conclusions would have been obtained by employing multivariate regression analysis. Moreover, the statistical reporting requires more specificity. Confidence intervals and effect size are not given, although the P values for the correlation between sputum purulence and inflammatory markers are highly significant. Clinical predictability does not always relate to statistical significance. Factors such as previous use of antibiotics, the severity of chronic obstructive pulmonary disease (COPD) (based on GOLD criteria), other underlying conditions, and previous hospitalization may influence inflammatory markers and microbiological results.[3] It becomes difficult to analyze the predictive value if these factors are not taken into consideration. In microbiology, only 40% of sputum samples yielded positive cultures. However, it seems that bacterial pathogens are understood to be the main causes of exacerbations in the discussion section. The airway is frequently colonized by Pseudomonas aeruginosa in chronic COPD patients, and this does not always imply an acute infection in such cases.[4] Distinguishing colonization from pathogenic infection typically necessitates clinical interpretation and, preferably, quantitative culture results or knowledge of previous colonization status. Furthermore, viral infections are recognized as key triggers of AECOPD and often occur alongside bacterial pathogens.[3] The results of antibiotic sensitivity tests hold great significance. Nevertheless, the recommendations regarding the prompt administration of drugs, such as amikacin or meropenem, should be approached with care. Current recommendations suggest choosing antibiotics according to the seriousness of the exacerbation, assessing risk factors, and considering microbiological history, rather than relying on the old approach of empiric treatment with broad-spectrum or reserve antibiotics.[3] In rural areas, where data on antimicrobial resistance can change rapidly, the uncritical increase in carbapenem use may ironically affect resistance levels. A stepwise therapeutic approach that is stewardship-friendly and based on international antimicrobial classification systems would be more suitable.[5] Moreover, the essential clinical predictors, such as spirometric classification, exacerbation frequency, prior antibiotic use, and hospitalization records, were excluded from the analytical framework. These elements are significant in the spread of pathogens and resistance, and they play a vital role in improving the external validity of microbiological research in COPD. The mean value of CRP (88.3) also needs explanation regarding its units. Elevated CRP levels might indicate significant systemic inflammation or sepsis instead of exacerbation. Finally, given that the study is a single-center rural observational study using consecutive sampling, it is most likely that the results are representative of the microbial ecology of that particular region. Although such information is extremely useful for the region, care must be taken when extrapolating such information to the general population. In conclusion, the study by Kasundra et al.[1] is pertinent to a clinically relevant question and provides useful regional microbiological information. Improved clarity in terms of the duration of the study, more detailed statistical modeling, incorporation of viral testing, and interpretation of antibiotic recommendations in a stewardship-minded fashion would improve the rigor and relevance of the study. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.