Type A aortic dissection (TAAD) management has significantly improved over the last two decades.1 Advancements in diagnostic techniques, perioperative care strategies and surgical methods have led to a marked reduction in postoperative complications, length of hospital stay and 30-day post-procedural mortality.1–3
The classical published disease incidence measures 30–50 patients per 1 million inhabitants per year, affecting mainly men in their early seventh decade.3,4 However, some recent studies indicated a wider incidence range, 5–30 cases per 1 million persons per year, and a surprising rate of TAAD was discovered in 1–3% of all autopsies in a study from the US.5–6 Aortic dissection is more frequent in African than in Caucasian individuals and is less common in Asian than in Caucasian individuals, according to the same report.5 Another TAAD study from the US found that the age- and sex-adjusted incidence was 77 per 1 million persons per year and increases with age.7 In different hospital types in Berlin, Germany, the emergency department incidences of TAAD varied between 59 and 249 per 1 million inhabitants. Based on autopsy outcomes, approximately 50% of TAAD remains undetected, which actually doubles the reported incidences.8 The peak frequency of an acute event occurs between 8 am and 9 am, with an increased likelihood of pathological events in wintertime.7,9 This is probably due to the natural morning stressors, which feature a surge of corticosteroid levels, and the cold weather adds to the cardiovascular risk by concomitant vasoconstriction, thereby increasing the afterload.9 In addition, a well-described difference is known regarding the point of entry, anatomical extension of dissection, and incidence of myocardial ischaemia between elderly and young patients.10 A marked age-related variation was observed in the presentation and management approaches in the other two acute aortic syndrome pathologies, namely intramural haematoma and penetrating atherosclerotic ulcer.11 The above-mentioned discrepancy was even more prominent between Japanese and European cohort investigations in favour of the Asian country.12 Other confounders in the disease picture, such as lower socioeconomic status (SES), may result in reduced short- and long-term survival after aortic dissection, according to a limited US neighbourhood analysis.13
Furthermore, meteorological changes and geographical relocation can also influence the incidence of TAAD as well, according to an Austrian study.14 Nevertheless, the data presented above are derived from Europe, North America and Japan, countries mainly situated in temperate climates with generic, well-covered healthcare access. Are these numbers valid also globally?
However, our daily experience in the GCC hinted at a different clinical picture that appeared to be resulting from multifactorial influencers. Furthermore, the effect of patient demographics on TAAD presentation and outcomes has not been extensively studied worldwide in the present medical literature. Additionally, the availability of data from the Asian continent, including the Middle East, remains scanty, hampering a comprehensive understanding of the actual burden and disease characteristics of TAAD in this geographical area. At the moment, there is a reliance on extrapolating data on aetiology, diagnosis and management from Western studies, which may not adequately address the specific contextual challenges faced in the region.
Therefore, we investigate patient characteristics, their association with several clinical features, and real-world treatment patterns of individuals with TAAD in a mixed population of the Gulf Cooperation Council (GCC) region.
Methods
Sixty-eight consecutive TAAD cases admitted between 2015 and 2021 were evaluated in a single-centre study. Our hospital is the exclusive medical facility providing acute TAAD care in the Emirate of Abu Dhabi. Patients referred from other Emirates in the reference period were excluded from the analysis. Seasonal variations in the occurrence of TAAD were analysed. Data on patient demographics, past medical history, presenting symptoms, operative techniques, postoperative complications and in-hospital mortality were collected retrospectively and compared between patients with low (n=34) versus high (n=34) SES. SES was defined by the type of employment (given that blue- and white-collar status well delineates the socioeconomic situation in the country of research), and by the health insurance coverage levels, ranging from limited coverage in those with low SES to extended coverage in those with high SES. More complex aortic reconstruction was defined as surgical intervention involving the aortic root, aortic arch or additional requirement for aortic stent grafting. Postoperative ischaemia included any coronary, abdominal or peripheral ischaemia.
Statistical Analysis
All statistical evaluation was performed with JMP Data Analysis Software Version 16 (SAS Institute). Categorical variables are reported as absolute numbers (%), and continuous variables are reported as mean ± SD or median [IQR]. Appropriate parametric testing methods were used, including the t-test for normally distributed continuous variables on the cohort, Mann–Whitney U-test for non-normally distributed continuous variables, and the chi-squared test for categorical variables, respectively. p<0.05 was considered statistically significant.
Results
Patient Demographics and Seasonal Variation in Presentation
For the 68 TAAD patients, mean age at presentation was 48.2 ± 15.6 years (median: 45 years [total range: 22–87]), and 79.4% were male. The median incidence for the reference period was 5.2 cases per 1 million inhabitants per year [IQR: 4.7–6.5]. Admissions for TAAD peaked in spring with 25 cases, contrasting with the lowest number of 12 events in summer (36.8% versus 17.6%; RR 2.1; p=0.03), while only 16 cases (23.5%) arose in winter, and 15 (22.1%) in autumn (Figure 1). A total of 75% of patients were non-GCC nationals, of whom 31.4% were natives of Western Asia/Levant, 25.5% were from Southeast Asia, and 23.5% from the Indian subcontinent (Figure 2).


Group Comparison According to Socioeconomic Status
Half of the patients belonged to the low-SES group. No differences were recorded between the low-SES versus high-SES groups in age (49.7 ± 16.3 years versus 46.6 ± 15.0 years; p=0.2), male gender (82.3% versus 76.5%; p=0.7), history of hypertension (79.4% versus 76.5%; p=0.8) or diabetes (11.7% versus 17.6%; p=0.7; Table 1). Although it did not reach statistical significance, patients with low SES had a lower rate of previously diagnosed connective tissue disease than the high SES group (0 versus 11.76%; p=0.1), were numerically more likely to present with syncope (17.6% versus 2.9%; p=0.1), and featured a notable trend toward requiring more complex aortic reconstruction (88.2% versus 67.6%; p=0.08). In addition, the low-SES patients had more prolonged intensive care unit (ICU; 5 [IQR: 3–13] versus 4 [IQR: 2–7] days; p=0.17) and hospital (22 [IQR: 9–54] versus 12 [IQR: 7–24] days; p=0.14) length of stay. Nevertheless, rates of in-hospital mortality (17.6% versus 14.7%; p=0.95), postoperative complications including acute kidney injury (35.3% versus 26.5%; p=0.6), ischaemia (14.7% versus 14.7%; p=1) and sepsis (21.2% versus 14.7%; p=0.5) were comparable between the low- and high-SES groups, respectively (Table 1).

Discussion
The first striking outcomes of our investigations are the significantly younger mean age at presentation of 48.2 years, and the even more pronounced male predominance of nearly 80%, compared with the Western data. Nevertheless, the country’s population features a unique characteristic: only 11.5% of the inhabitants are local citizens, and the rest are expatriates living and usually working in the short term to mid-term in the region. A total of 53.9% of the expatriates come from countries of the Indian subcontinent, 5.6% from the Philippines, 4.8% have Iranian origin, and 18.1% are natives of other Arabic-speaking countries, mainly from Western Asia and the Levant.15,16 Another interesting attribute of the population statistics is that in the largest, active working age group of 25–55 years, 63.5–68.8% are male.15,16
Supporting our findings, a recent Malaysian study noted a mean age of 51.6 ± 12.7 years with a 72.4% male predominance and a distinct ethnic difference, which the SES might partially influence, although data were unavailable on this aspect.17 In their series, 90% of the patients presented with chest, back or abdominal pain and 22.3% had malperfusion syndrome. In-hospital mortality was 17.9%, the median length of ICU stay was 5 [IQR: 3–8] days, and the hospital stay was 8 [IQR: 6–14] days.17
In contrast to the winter predominance of TAAD in the temperate climate region, we have registered a significant increase in cases in the springtime. This time of the year results in the most marked meteorological changes, with an abrupt rise in temperature within weeks, usually in April.18 The sudden temperature alteration may lead to tachycardia, dehydration or hypertensive excess, especially in a disease that is not well-controlled, providing a plausible meteorological reason for the increased seasonal incidence of TAAD. Schachner et al. also described, in their study on recreational alpine skiers, that swift, complex environmental changes may impact the incidence of TAAD.14 However, they found that the perioperative outcome of TAAD in recreational skiers temporarily relocating from low altitudes was favourable, showing low mortality. This might be explained by the good physical condition of skiers who regularly train in other sports throughout the year and who usually have a healthy diet. They also belong mainly to high SES, which supports our findings regarding the positive effect of high SES on TAAD outcomes. Nevertheless, recreational skiing associated with TAAD affects persons who perform an unusual physical activity not practised for the rest of the year that temporarily increases intrathoracic and systolic blood pressure at a high altitude, with concomitant lower atmospheric pressure, and a sudden significant drop in external temperature. Interestingly, skiing-associated TAAD usually does not result from sport-related trauma and is spontaneous in nature.14
The health insurance structure in the country of our study is similar to the system in the US, consisting of different insurance service levels. Nevertheless, even uninsured individuals are fully covered for any type of emergency patient care by the mandate provided by the government.19 Despite the equal access opportunities for high-quality emergency care in a high-income country, the lower SES group had a higher rate of syncope on presentation and a pronounced trend towards requiring more complex aortic reconstruction. In addition, a lower rate of previously diagnosed connective tissue disease was observed in this group.
Many in the lower SES population of our study originate from low GDP (gross domestic product) regions in Asia, receiving insufficient medical care during upbringing, including limited diagnostic accessibility and general medical follow-up. Therefore, chronic diseases, such as diabetes and hypertension, are not sufficiently controlled.20–22 Cerebrovascular events and ischaemic heart disease (IHD) are the two leading causes of disability globally. The burden of IHD is disproportionally higher in low- and middle-income countries in contrast to high-income ones, and more than 80% of IHD-related deaths occur in low- and middle-income regions.23,24 In addition, IHD significantly affects the working-age populations in low- and middle-income countries.25 However, the research is fairly challenging in this area; hence the number and quality of available studies are generally low. A further limitation of these papers is that reporting transparency, especially for funding, cost data sources and outcomes, is not entirely reliable. Gheorghe et al. undertook a comprehensive review of 83 studies on this topic and found that most were single-centre retrospective investigations conducted in secondary care settings. They concluded that in most low- and middle-income countries, the cost of an acute cardiovascular episode and the annual cost of care exceed several-fold the total health expenditure per capita.26
Furthermore, genetic investigations are not covered by insurance in many regions. The required tests are expensive and may not be physically available locally, therefore, following up on familiar aortopathies or syndromic traits is limited.
In addition, we found that in patients with low SES, the median ICU and hospital stays were longer by 25% and 75%, respectively, than in those with high SES. In fact, more severe symptoms on presentation and increased hospital resource usage, including more complex surgical approaches and extended hospital stays in patients with low SES, probably result from multifactorial influences. A lower nutritional status, more progressed chronic disease burden, lower educational background delaying the seeking of medical attention, and fear of the financial consequences of being ill might be some of the impactful factors in this trend. A US rich–poor neighbourhood comparison study by Kabbani et al. demonstrated a similar demographic pattern in this regard.13 Differences in outcome for patients originating from diverse regions might be additionally influenced by environmental and cultural factors, including family structure, but we did not observe any impact of major race groups of East Asian, African, or Indo-European background on disease characteristics or postoperative outcomes in our study.
Limitations
This is a single-centre, retrospective study involving a limited number of patients, and the small sample size might have precluded definitive conclusions regarding differences in demographics, presenting symptoms or clinical outcomes. However, our centre is the exclusive medical facility providing acute TAAD care in a 67,340 km2 geographical area. Therefore, pain-to-table time was not analysed due to the transport time variances, even though the in-hospital admission-related procedural times are standardised and constantly monitored. Genetic analysis was unavailable due to financial restrictions to evaluate the eventual influence of familiar aortopathies and syndromic aortic disease in both of the SES groups.
Conclusion
In this study from the GCC region, we have identified a significantly younger age at presentation with TAAD compared with western data, with considerable seasonal variation in incidence. In addition, patients with low SES presenting with TAAD appeared to have increased resource usage during hospitalisation. The present study may facilitate a better understanding of the influence of SES, especially in the context of geoeconomic origin, on outcomes of TAAD. However, due to the limited scale of the study, further research is required to refine the picture in this segment of the aortic literature. Nevertheless, the present outcomes may have some immediate impact on clinical practice. For example, knowing the patient’s SES, the first-line clinical treatment team may be better prepared at the diagnosis of TAAD to face additional challenges emerging during intra- and postoperative care, and expect a more extensive procedure and longer postoperative recovery. Indirectly, focused health promotion in low- and middle-income societies and thorough screening programs for underlying chronic diseases may be initiated in view of the above findings.
Clinical Perspective
- The effect of patient demographics on type A aortic dissection (TAAD) presentation and outcomes has not been extensively studied worldwide; the data in the literature are mainly from Europe and North America.
- Patients from diverse regions of Asia are significantly younger at presentation with TAAD compared with Western data, with considerable seasonal variation in incidence; springtime represents the peak season in the Gulf Cooperation Council region.
- Low socioeconomic status (SES) is associated with a more likely presentation with syncope and a notable trend toward requiring more complex aortic reconstruction.
- Patients with low SES appear to have increased resource utilisation during hospitalisation, prolonged intensive care unit and hospital length of stay, and a lower rate of previously diagnosed connective tissue disease.
- With awareness about the patient’s SES on admission, the first-line clinical treatment team may be better prepared at the diagnosis of TAAD to face additional challenges during intra- and postoperative care, expect a more extensive procedure and longer postoperative recovery.
- Focused health promotion in low- and middle-income societies and thorough screening programs for underlying chronic diseases may improve the TAAD burden of Asian countries.