Acute aortic dissection (AAD) is a critical cardiovascular condition that is characterized by tearing of the intimal layer of the aorta wall, with blood entering the middle layer through the intimal tear and then separating along the aorta axis to form true and false lumens (1). AAD has a rapid onset, rapid progression, high complication rate and high fatality rate (2). Population-based studies indicate that the incidence of AAD is 2.6 to 3.5 cases per 100,000 person-years (3), with an obvious upwards trend in recent years. Mortality rates from AAD are as high as 90% in the absence of intervention, with most deaths occurring within 48 h of AAD onset (4). Therefore, the identification of potential risk factors for AAD is critical to addressing this public health issue. Common causes of AAD include uncontrolled hypertension, arteriosclerosis, and hereditary connective tissue diseases (5). Air pollutants are also associated with the incidence of AAD (6, 7).

With the intensification of global climate change, extreme meteorological events (e.g., drought, heat wave, cold wave, and extreme precipitation) continue to occur, and their impact on human health has attracted great attention. A large number of studies have investigated the effects of extreme meteorological factors and acute cardiovascular events, such as AAD, but existing studies have primarily focused on temperature (8–12). There are few studies on the association of other meteorological factors, particularly rainfall, with AAD, and the conclusions are inconsistent. For example, studies in three Chinese cities, Beijing (13), Hong Kong (14), and Urumqi (15), showed that the incidence of AAD was not associated with daily rainfall, but a study in western Japan suggested that rainy days were a risk factor for cardiovascular events in older adults (16). Notably, no studies have examined the risk of extreme precipitation and the incidence of AAD.

Extreme precipitation events have increased across China in recent years, especially in the coastal areas of southern China (17–19). Therefore, the present study was performed in Shantou city, southern China, with the following three objectives: first, to identify the association between extreme precipitation and AAD hospitalizations in Shantou city; second, to identify vulnerable populations with extreme precipitation; and finally, to quantify the burden of AAD hospitalizations due to extreme precipitation. The present study supplements the current limited evidence on the association between extreme precipitation and AAD and provides a reference for relevant authorities to formulate active and effective preventive measures.

Tables 1, 2 display the basic description of daily AAD, weather conditions and pollutant concentrations in Shantou from 2015 to 2020. A total of 3,216 hospitalized cases of AAD were collected during the study period, with a maximum of 9 hospitalized cases per day. Most AAD patients were under 60 years old and accounted for 72.7% of the total number of AAD patients. The number of females admitted to the hospital with AAD was approximately 1.5 times that of males (1985 vs. 1,231). The daily rainfall, sunshine duration, atmospheric pressure, wind speed, relative humidity and mean temperature were 4.2 mm, 5.6 h, 1013.3 hPa, 3.6 m/s, 76.2% and 23.6°C, respectively.

The daily average concentrations of SO₂, PM_2.5 and NO₂ were 11.2 μg/m³, 26.6 μg/m³, and 19.1 μg/m³, respectively. During the study period, 110 days of extreme precipitation events (daily precipitation ≥26.25 mm) occurred. The time series distribution of weather factors is shown in Supplementary Figure A1, which indicates that the meteorological factors had obvious seasonal variation trends.

Figure 2 shows the single-day lag effects of extreme precipitation on hospitalizations for AAD in Shantou, China. The significant adverse effect of extreme precipitation lasted from lag 5 (RR: 1.0318, 95% CI: 1.0067–1.0575) to lag 9 (RR: 1.0297, 95% CI: 1.0045–1.0555) and reached a maximum at lag 7 (RR: 1.0382, 95% CI: 1.0105–1.0665) (Table 3). The significant effects in the male group lasted from lag 4 (RR: 1.0321, 95% CI: 1.0017–1.635) to lag 9 (RR: 1.0382, 95% CI: 1.0079–1.0694) and reached its maximum at lag 7 (RR: 1.0498, 95% CI: 1.0165–1.841). The significant effects in the older adult individuals (≥60 years) lasted from lag 4 (RR: 1.0809, 95% CI: 1.0021–1.1660) to lag 10 (RR: 1.0897, 95% CI: 1.0145–1.1704) and reached its maximum at lag 7 (RR: 1.1481, 95% CI: 1.0566–1.2475). No significant effects of extreme precipitation were found in female and younger individuals (< 60 years). Supplementary Table A3 shows the cumulative lag effects on hospitalizations for AAD in Shantou, China. However, no significant effects of extreme precipitation were found in the total or subgroup AAD population.

Because no significant cumulative effects between extreme precipitation and AAD were found, the maximum single-day lag effect (at lag7) was selected to calculate the disease burden. Table 4 displays the AF and AN of AAD hospitalizations due to extreme precipitation. We found that the AF and AN of AAD hospitalizations were 3.68% (1.04, 6.24%) and 118 (33, 200), respectively. The AF and AN of male patients were 4.74% (1.62, 7.76%) and 58 58 (19, 95), respectively, which were both higher than those of female patients [AF: 1.12% (−4.03, 6.01%), AN: 21 (−80, 119)]. In the older adult group (≥ 60 years), 12.9% (113 cases) of AAD hospitalizations were due to extreme precipitation, and the corresponding AF and AN in the younger group (<60 years) were 0.95% and 22, respectively. These results indicated that extreme precipitation caused a higher disease burden in male and older adult individuals (≥60 years).

After adjusting for the df of time (6–8) and meteorological factors (3–6) in the model, the association between extreme precipitation and AAD did not change significantly (Supplementary Figures A2–A6), which indicated that our results were robust. The estimated effects did not change significantly when pollutants were added to the model (PM_2.5, NO₂ and SO₂) or different cut-off points for extreme precipitation were used (Supplementary Figures A7, A8).

With global climate change, extreme weather events have become more frequent and intense. The present study examined the impacts of extreme precipitation on AAD hospitalizations in Shantou, a coastal city in southern China, and found that the significant adverse effects lasted from lag 5 to lag 9 and reached a maximum at lag 7 (RR: 1.0382, 95% CI: 1.0105–1.0665). Subgroup results showed that males and older adult individuals (≥60 years) were more susceptible to extreme precipitation. The AF and AN of AAD hospitalizations were 3.68% and 118, respectively. Our study adds to the growing but limited evidence of extreme precipitation on acute cardiovascular events.

AAD is an acute critical cardiovascular disease (29). The incidence of AAD has continued to rise in recent decades, which has brought a heavy burden of disease to families and society (30). Studies have shown that targeted intervention measures for risk factors for AAD effectively reduce the morbidity and mortality of the disease (31). Therefore, it is necessary to investigate and identify risk factors associated with AAD. This study is the first to highlight the critical role of extreme precipitation in the progression of AAD.

Our results showed that extreme precipitation was significantly associated with AAD hospitalizations, which is consistent with two published studies on the relationship between extreme precipitation and cardiovascular disease (20, 22). Time series studies in Hefei (22) and Beijing (20) showed that extreme precipitation was significantly associated with ischaemic stroke and acute myocardial infarction admissions, respectively. However, AAD is a serious cardiovascular emergency with a serious prognosis, and it is the most common fatal disease involving the aorta (32). Many scholars have investigated the association between meteorological factors and AAD, but there are few studies involving rainfall, and the conclusions are inconsistent. A Beijing study examined the association between meteorological data and the morbidity of 345 patients with acute aortic dissection and found no significant association between daily average rainfall and AAD (RR: 1.00, 95% CI: 0.99–1.00, p = 0.07) (13). A study in subtropical Hong Kong used linear regression analysis to investigate the effects of meteorological factors on AAD or ruptured aortic aneurysm and found that rainfall was not associated with AAD or aortic aneurysm rupture (14). Another study in Urumqi, Xinjiang divided AAD into “days with AAD” and “days without AAD” and found no significant difference in daily rainfall (15). Two Japanese studies also reported that daily rainfall with AAD was not significantly different from rainfall without AAD (16, 33). However, some studies have shown that rainy days may be a risk factor for cardiovascular disease in the older adult (16, 22). The inconsistencies between the above conclusions may have been due to different study designs, study methods or study populations. More studies with different geographical characteristics are needed in the future to validate our conclusions.

The following mechanisms may explain extreme precipitation triggering of the onset of AAD. First, as an extreme weather event, extreme precipitation is often accompanied by significant changes in temperature, and low temperatures, diurnal temperature differences, and temperature variations are associated with the occurrence of AAD (34, 35). Second, the body’s perspiration capacity is reduced in a humid environment when extreme precipitation occurs, and the excretion of sodium and chloride ions is blocked, resulting in hypertension, which is the main trigger of AAD (36). Finally, most patients with AAD have comorbid cardiovascular diseases, and extreme precipitation may be an inducement to increase the possibility of AAD in patients with cardiovascular diseases.

Extreme precipitation caused a higher disease burden for males than females, and males seemed to be more susceptible to extreme precipitation. This difference may be because males work outdoors more often and have more direct exposure to extreme precipitation. More males in China smoke, which is associated with AAD (37, 38). Older adult people (≥ 60 years) were more vulnerable to extreme precipitation than younger people (<60 years). This result is consistent with the results of a Japanese study in which the daily precipitation of older adult patients with aortic dissection was significantly higher than that of young patients (16). This difference may be due to the weak body resistance of older adult individuals, who are unable to tolerate the impact of adverse environmental changes (22). Older adult people are more likely to have underlying medical conditions, such as heart disease and hypertension, and more likely to develop AAD under the adverse effects of extreme precipitation (39).

The present study has several advantages. First, as an acute and critical cardiovascular disease, most patients with AAD choose general hospitals with authority and a high medical level. The present study included four top-level general hospitals in Shantou, which basically covered the hospitalized population of AAD patients in Shantou and increased the reliability of the results. Second, to the best of our knowledge, this study may be the first study to investigate the impacts of extreme precipitation on AAD hospitalizations in a coastal city of southeast China using DLNM. Third, previous studies reported that air pollution was correlated with AAD admissions (6, 7). Therefore, we also adjusted for PM_2.5, SO₂, and NO₂ in the sensitivity analysis. Finally, we investigated the association between extreme precipitation and AAD and the lag effects of AAD, which identified the vulnerable population of extreme precipitation and calculated the attributable disease burden. The present study provides a basis for people to better understand the harm of extreme precipitation on AAD and apply more targeted interventions.

Several limitations should not be ignored. First, the present study set extreme precipitation as a categorical variable, which is a method that is used more often in extreme precipitation-related studies (20, 22), and more accurate classification and analysis methods for extreme precipitation are needed in the future. Second, our study was performed only in a coastal city in southeast China, Shantou, and the results may not be applicable to other regions with different climatic characteristics. Third, confounding factors, such as smoking, diet, disease history and socioeconomic status, may also influence AAD hospitalizations (40–42), but these data were not available. Fourth, the environmental data came from fixed monitoring stations, which leads to unavoidable exposure measurement errors. Fifth, this study is an ecological study and cannot explain the causal association between extreme precipitation and AAD. Finally, due to limitations in data sources, we were unable to stratify AAD (e.g., types A and B), and different disease subtypes may differ in sensitivity to extreme precipitation, which will be considered in future studies.

Our results showed that extreme precipitation was significantly associated with AAD hospitalizations. Males and older adult individuals had a higher disease burden and were more susceptible to extreme precipitation. During the study period, 3.68% of AAD hospitalizations in Shantou were due to extreme precipitation. Our study supplements the current limited evidence of the relationship between extreme precipitation and AAD and provides a reference for the relevant governments and medical departments to implement targeted extreme precipitation intervention and control measures.

The data analyzed in this study is subject to the following licenses/restrictions: the data that support the findings of this study are available from the corresponding author, upon reasonable request. Requests to access these datasets should be directed to lpli@stu.edu.cn.

Prior to data collection, the Ethics Committee of Shantou University approved this study. Overall, aggregated data were used in our study, and no information about individual patient privacy was involved in the analysis.

YJ and LL: conceptualization, data curation, investigation, and writing–original draft. JX and ZY: validation and formal analysis. ZY and ZH: conceptualization and writing–review and editing. YJ and JX: writing–review and editing and supervision. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.