Several findings emerge from this study. Firstly, we demonstrated that the BAE number has increased with time. Secondly, our results show that there was a decrease in the number of embolizations during the weekend, and last, we found that there were two seasonal peaks, occurring in April and November.
The increase in the number of BAE could be due to the increased utilization of interventional radiology. The decrease in the number of embolizations during the weekend could be attributable to the fact that at our institution interventional radiologists on duty are on call at home at night and during the weekend.
In our study, hemoptysis requiring BAE peaked in April and November. This finding differs from the results of other studies. Boulay and colleagues, for example, reported an increase in cryptogenic hemoptysis requiring hospitalization in late winter and early spring (peak in March). The same authors, in another article, reported that hemoptysis showed aggregates of clusters in winter.
One possible explanation for the increase in the number of patients with hemoptysis in winter could be due to the association of hemoptysis with acute infection[3, 4]. Smidt reported that patients with cryptogenic hemoptysis often occurred during time periods when influenza or pneumonia were more frequent. Nevertheless, to the best of our knowledge, no study has evaluated how influenza season correlates with hemoptysis.
Apart from infection, environmental triggering factors have been described in the literature as explanation for hemorrhagic events. Principally, a marked increase in hospital attendance due to epistaxis during colder days has been described, although Bray and colleagues, in a larger series found no correlation between temperature, seasonal prevalence and epistaxis.
Apart from epistaxis, seasonal variations in other hemorrhagic situations have been described[16–19]. In some of these cases, an association of bleeding occurrence with meteorologic variations was found[17–19]. Boulay et al. described seasonality of both mortality and hospitalization due to variceal bleeding, with the first one peaking in winter, and the latter in winter-spring. Tahri et al. found a higher risk of esophageal varices rupture during winter. Furthermore, they also found a significant correlation between the risk of bleeding and mean temperature, rainfall and stormy weather. The occurrence of subarachnoid hemorrhage has also been associated with meteorological variations[17, 19]. Lejeune and colleagues found that aneurysmal bleeding was significantly associated with low maximal temperature, and Setzer et al. demonstrated that atmospheric pressure changes of more than 10 hPa within 24 hours were an independent predictor of clustering of patients with subarachnoid hemorrhage.
In respiratory medicine, seasonal pattern of different diseases have been described. Several articles have examined the seasonal pattern of asthma hospitalizations[20–22] and deaths due to asthma[21–23]. Crighton and colleagues found a clear seasonal pattern for asthma hospitalizations, with peaks occurring between September and November and throughout July and August. Fleming et al. found that the seasonal pattern of asthma evolved with age. Other situations in which a seasonal trend has been described are spontaneous pneumothorax or fatal pulmonary embolism.
The main limitation of our study is that we used a therapeutic technique as an indirect indicator of hemoptysis. Thus, not all patients with hemoptysis are included in this study. Those who died due to massive hemoptysis prior to BAE, or those with mild or moderate hemoptysis which did not require BAE were not included in the study.
However the main strength of this report is that all patients included in the study had confirmed severe hemoptysis, and other conditions which could be considered as hemoptysis (such as hematemesis) have been excluded. Another strength is its long follow-up period.