Two underreported temporal limitations in a preschool wheezing cohort

To the Editor,We read with interest the study by Pişkin et al.1, which provides valuable prospective data on viral etiology and clinical risk factors in preschool children presenting with wheezing. The demonstration that rhinovirus and RSV account for the majority of viral detections is consistent with current evidence and has clear clinical relevance. We wish to raise two methodological concerns that, in our view, warrant explicit acknowledgment in the Limitations section, as they directly bear on the strength of the conclusions drawn.First, we wish to raise a concern regarding the epidemiological interpretation of the seasonal RSV data. The authors report a spring predominance for RSV and contextualize this within the framework of regional Mediterranean climatic variability, citing global analyses of shifting RSV seasonality2. While this is a plausible hypothesis, we would argue that it requires more prominent qualification. The study's data collection spanned November 2017 to January 2019, encompassing only a single spring season (Spring 2018). Distinguishing a true geographical shift in RSV seasonality from a year-to-year epidemiological fluctuation requires surveillance across multiple consecutive seasons, as is widely recognized in respiratory virus epidemiology3. The authors do briefly acknowledge the possibility of "year-to-year fluctuations" within the Discussion, but this caveat is presented alongside the climatic hypothesis, risking equal weight being afforded to an inference that single-season data cannot substantiate. Notably, this constraint does not appear in the Limitations section, despite being directly relevant to one of the paper's more novel epidemiological claims.Second, and thematically related, the absence of longitudinal follow-up precludes monitoring of individual wheezing trajectories over time. Although the study is prospective in design, it captures a single clinical episode per child rather than tracking outcomes beyond the index presentation. Given that the study's stated aim explicitly includes "implications for asthma prevention," this represents a meaningful limitation on the paper's central clinical claim. Whether the children who experienced early rhinovirus- or RSV-associated wheezing in this cohort subsequently developed persistent asthma the outcome of greatest preventive interest cannot be determined from the present data4. The authors note in their conclusion that "future multicenter studies with longitudinal follow-up are warranted," which implicitly acknowledges this gap; however, framing it as a future direction rather than a present limitation understates its significance for readers interpreting the current findings.We respectfully suggest that the Limitations section be revised to explicitly acknowledge that (i) the single-season surveillance window precludes definitive conclusions regarding regional RSV seasonality, and (ii) the study design does not permit assessment of long-term wheezing trajectories or asthma progression. Both constraints share a common thread the temporal scope of the study and acknowledging them together would strengthen the paper's methodological transparency without detracting from its substantive clinical contributions.