Abstract
The study aimed to determine whether significant differences exist in blood group type distribution between the elderly population and a younger population. The geriatric group consisted of 2247 patients aged 85 years and older. As for the control group, 2968 individuals aged 20 to 22 years were included. The primary objective was to assess the distribution of ABO and Rh blood group types within each study group and to identify any statistically significant differences between the geriatric and control groups. Analysis considering both ABO and Rh blood types indicated that A Rh(+) was the most common type in both groups. Conversely, AB Rh(‐) was the rarest type in both groups. Additionally, statistical analysis revealed no significant difference in ABO blood group type frequencies between the 2 groups (P = .121). Furthermore, there was no statistically significant difference between the groups in terms of the frequency of Rh positivity: 88.7% in the geriatric patient group and 88.4% in the control group (P = .748). Our findings suggest that ABO/Rh blood type diversity may not be a significant determinant of longevity in individuals aged 85 years and above.
Keywords: ≥85 years of age, ABO, blood group, correlation, longevity, Rh
1. Introduction
Human blood is categorized into various groups based on the presence or absence of specific antigens on the surface of red blood cells. The most fundamental and clinically significant classification system is the ABO and Rh system. This system defines 4 primary blood types: A, B, AB, and O, further classified as Rh-positive (Rh+) or Rh-negative (Rh‐) based on the presence or absence of the RhD antigen. While numerous other antigenic structures contribute to a more granular classification of blood groups,[1] the ABO and Rh system remains the cornerstone of routine hospital practice due to its critical role in ensuring safe blood transfusions.
Population studies have revealed variations in the distribution of blood group types. Research conducted at Çukurova University Balcali Hospital Blood Center by Menziletoğlu Yildiz Ş indicated the following distribution among blood donors: A (38.90%), B (17.00%), O (37.10%), and AB (6.90%), with an 89.90% prevalence of Rh positivity.[2] In a similar manner, a study in Sakarya province by Çekdemir D et al reported a more detailed breakdown: A Rh+ (38.1%), O Rh+ (30.2%), B Rh+ (10.5%), A Rh‐ (6.2%), AB Rh+ (6.2%), O Rh‐ (5.6%), B Rh‐ (2.1%) and AB Rh‐ (1.3%).[3]
The correlation between blood types and aging has been a subject of investigation. Brecher ME and Hay SN, for instance, observed a decline in the frequency of blood type B with advancing age.[4] In contradiction of such findings, Shimizu K et al posit that there could be a potential association between blood type B and longevity in centenarians.[5] However, this correlation was not supported by Vasto S et al in their study of centenarians in Western Sicily, where no significant differences in ABO allele distribution were found between centenarians and a younger control group.[6]
Understanding the distribution of blood groups in older adults has relevance beyond descriptive epidemiology. It may offer further insights into potential genetic or immunological studies associated with age-related disease susceptibility, and contribute to broader population genetics research. Articulating these links can help frame the importance of blood group studies in aging populations more comprehensively.
Motivated by these observations, this study aimed to examine the frequency of ABO and Rh blood types within a geriatric population aged 85 years and older (≥85). We also sought to determine whether significant differences exist in blood group type distribution between this geriatric population and a younger population for any potential interplay between blood group types and aging within this demographic.
2. Materials and methods
This study employed a retrospective design utilizing data extracted from the electronic patient records of Süleyman Demirel University (SDU) Faculty of Medicine Hospital (SDU Research and Training Hospital). The study population comprised 2 distinct groups. The geriatric group consisted of 2247 patients aged 85 years and older (≥85) at their most recent visit (up to and through July 23, 2024), as recorded in the hospital’s electronic patient files. Patients without recorded blood groups were also excluded from the geriatric group.
As for the control group, 2968 individuals aged 20 to 22 years (inclusive) at their most recent visit to SDU Faculty of Medicine Hospital on or before July 23, 2024, as recorded in the hospital’s electronic patient files, were included as controls. Patients who were found to have passed away by their last recorded visit were excluded from the control group. Patients without recorded blood groups were also excluded from the control group. In total, 5215 patients were included in the study, comprising both the geriatric group (≥85 years) and the control group.
To ensure data integrity, strict inclusion and exclusion criteria were applied. Only patients with blood group types registered within the electronic records system were included in the study. Patients lacking blood group data and those under 19 years of age were excluded from the study.
Following the establishment of the study groups, a comparative analysis was undertaken. The primary objective was to assess the distribution of ABO and Rh blood types within each study group and to identify any statistically significant differences between the geriatric and control groups. This involved tabulating the frequencies of each blood type and conducting statistical comparisons, both for the combined ABO and Rh system and for each system independently.
2.1. Statistical analysis
Data analysis was conducted on the SPSS 22 software package (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp.). Frequency tables and descriptive statistics were used to analyze the findings. Categorical data were presented in the form of frequencies and percentages. These data were visually represented in tabular format for clarity and ease of interpretation.
To investigate potential relationships between variables, inferential statistical analyses were performed. For categorical data, the Chi-square test was used to assess the significance of differences between groups. P value < .05 was considered statistically significant.
Ethical approval for this research (number 79/2) was granted by the SDU Health Sciences Ethics Committee on September 13, 2024.
3. Results
The study population comprised 5215 participants, with 56.9% (n = 2968) constituting the control group and 43.1% (n = 2247) representing the geriatric cohort (individuals aged ≥ 85). A significant disparity in gender distribution was observed between the 2 groups. In the control group, 71.9% (n = 2134) were female, whereas 55.5% (n = 1248) of the geriatric patients were female (Table 1). This difference in gender distribution between the 2 groups was statistically significant (P = .000) (Table 1).
Table 1.
Comparison of geriatric patients aged ≥ 85 and young controls by gender.
| Groups | Gender | P * | |
|---|---|---|---|
| Male number (≈%) | Female number (≈%) | ||
| People aged 20–22 | 834 (28.1%) | 2134 (71.9%) | .000 |
| People aged ≥ 85 | 999 (44.5%) | 1248 (55.5%) | |
Bold signifies the P value for the whole analysis.
Chi-square test.
Analysis of blood type distributions within the control group revealed that A Rh(+) was the most prevalent, occurring at a frequency of 37.84%. In contrast, AB Rh(‐) was the least common, with an incidence of just 0.91%. The remaining blood types exhibited frequencies between these 2 extremes. In particular, 0 Rh(+) comprised 29.14% of the control group, followed by B Rh(+) at 14.08%, and AB Rh(+) at 7.34%. Rh-negative blood types were less frequent, with A Rh(‐) at 4.45%, 0 Rh(‐) at 3.81%, and B Rh(‐) at 2.43% (Table 2). This distribution underscores the relative rarity of Rh-negative blood types within the study population and highlights the dominance of the A Rh(+) blood type. Further analysis considering both ABO and Rh blood types indicated that A Rh(+) was the most common type in both groups (Table 2). Conversely, AB Rh(‐) was the rarest type in both groups (Table 2). Additionally, statistical analysis confirmed that the overall distribution of ABO Rh blood group types did not differ significantly between the geriatric group and the control group (P > .05).
Table 2.
Distribution of the patients included in the study according to ABO Rh blood group types.
| 0 Rh(‐) | 0 Rh(+) | A Rh(‐) | A Rh(+) | B Rh(+) | B Rh(‐) | AB Rh(+) | AB Rh(‐) | Total | |
|---|---|---|---|---|---|---|---|---|---|
| Control group (N) ≈% | 113 | 865 | 132 | 1123 | 418 | 72 | 218 | 27 | 2968 |
| 3.81% | 29.14% | 4.45% | 37.84% | 14.08% | 2.43% | 7.34% | 0.91% | 100.0% | |
| Geriatric group (N) ≈% | 80 | 640 | 117 | 894 | 284 | 42 | 175 | 15 | 2247 |
| 3.56% | 28.48% | 5.2% | 39.79% | 12.64% | 1.87% | 7.79% | 0.67% | 100.0% |
Bold signifies the P value for the whole analysis.
A comparative analysis of ABO blood type distribution revealed a subtle trend: blood type A appeared more frequently in the geriatric (≥85 years) group with a prevalence of 45.0%, whereas blood type AB was less common at 8.5%. A similar pattern emerged in the control group, where A was again the most prevalent at 42.3%, and AB the least at 8.3%. Despite these parallel trends, statistical analysis revealed no significant difference in ABO blood type frequencies between the 2 groups (P = .121), as detailed in Table 3. This suggests that while certain blood types may be slightly more or less common in individuals of advanced geriatric age, these variations do not deviate significantly from the broader population represented by the control group (Table 3).
Table 3.
Comparison of the geriatric patients and young controls according to ABO blood types.
| Groups | Blood types | P * | |||
|---|---|---|---|---|---|
| Type 0 number (≈%) | Type A number (≈%) | Type B number (≈%) | Type AB number (≈%) | ||
| Control group | 978 (33.0%) | 1255 (42.3%) | 490 (16.5%) | 245 (8.3%) | .121 |
| Geriatric group | 720 (32.0%) | 1011 (45.0%) | 326 (14.5%) | 190 (8.5%) | |
Bold signifies the P value for the whole analysis.
Chi-square test.
Examination of Rh blood type distribution revealed a near-identical prevalence of Rh positivity in both groups: 88.7% in the geriatric patient group and 88.4% in the control group. This minor difference was not statistically significant (P = .748), as shown in Table 4.
Table 4.
Comparison of geriatric patients and young controls according to Rh blood type status.
| Groups | Rh* status | P * | |
|---|---|---|---|
| Rh-negative (‐) number (≈%) | Rh-positive (+) number (≈%) | ||
| Control group | 344 (11.6%) | 2624 (88.4%) | .748 |
| Geriatric group | 254 (11.3%) | 1993 (88.7%) | |
Bold signifies the P value for the whole analysis.
Chi-square test.
4. Discussion
Hirani et al’s Australian study revealed a distribution of blood group types among patients as follows: O RhD+ (38.4%), A RhD+ (32%), B RhD+ (11.8%), O RhD‐ (6.5%), A RhD‐ (5.6%), AB RhD+ (3.7%), B RhD‐ (1.5%), and AB RhD‐ (0.5%).[7] In the study of Hirani et al, the prevalence of Rh positivity was reported as 85.9%, while Rh negativity as 14.1%.[7] On the other hand, our study conducted in Isparta Province, Anatolia found A Rh+ as the most prevalent blood type. However, similar to the study conducted by Hirani R et al,[7] the rarest blood group in our study conducted in Isparta Province was AB Rh‐. In addition, Ekinci et al’s research on healthy blood donors in eastern Turkey reported A blood type prevalence at 44%, O at 31.2%, B at 16.2%, and AB at 8.6%.[8] Kader Ç et al documented comparable frequencies in Yozgat, Anatolia: A at 44.3%, O at 31.7%, B at 15.9%, and AB at 8.1%.[9] Torun YA et al’s study in Kayseri, Anatolia, yielded an Rh positivity rate of 88.2% and an Rh negativity rate of 11.8%.[10] Their analysis of blood type frequencies showed A at 44%, O at 33.3%, B at 16.2%, and AB at 6.5%.[10] Our Isparta study corroborated these trends, with A, 0, B, and AB blood types observed in descending order of frequency. Notably, within the geriatric patient group aged 85 years and older, the distribution of A (45%), 0 (32%), B (14.5%), and AB (8.5%) closely aligned with the patterns observed in the aforementioned Turkish regions.[3,8–10] Furthermore, our analysis of Rh positivity among geriatric patients in Isparta Province (88.7%) showed consistent findings with the study of Torun YA et al.[10]
The potential relationship between blood group type and disease susceptibility, particularly for leading causes of mortality like cancer and cardiovascular disease, has been garnering considerable scientific interest. This connection, if established, could indirectly shed light on the question of whether there is an association between blood group types and longevity. A meta-analysis by He M et al reported a significantly elevated risk of coronary heart disease in individuals with non-O blood types as compared to those with blood type O.[11] In a similar vein, Urun Y et al concluded that there was an increased risk of lung cancer in individuals with non-O blood types and Rh negativity.[12] Focusing on gastric cancer, Yu H et al observed a higher 5-year survival rate among patients with blood type O and a heightened risk of developing the disease in those with blood type A.[13]
There are conflicting data in the literature regarding whether there is a relationship between blood group type and longevity.[4–6,14,15] Mengoli C et al noted a higher prevalence of blood type O (70%) among individuals aged over 99 years, although this finding lacked statistical significance.[14] They also observed a decline in the frequency of blood group type B with increasing age. Conversely, a study by Zhu Y et al in China found no association between ABO blood group type and longevity.[15] Our own investigation, focusing on individuals aged 85 years and older, similarly failed to establish a correlation between ABO/Rh blood group types and longevity.
5. Limitations and future prospects
While this study provides valuable insights, several limitations must be acknowledged. First, the sample size and demographic diversity. The groups in our study refer to people who were admitted to our hospital and whose blood group was studied. This situation may constrain the generalizability of the findings. Second, the study did not account for (specific variables, e.g., long-term effects, environmental factors, cultural differences, and specific comorbidities), which could influence the outcomes. Additionally, retrospective design might have affected data accuracy. To address these limitations and expand upon the current findings, future research should prioritize longitudinal studies to track over time. Expanding the sample size and diversity, particularly incorporating underrepresented populations (e.g., varying cultural, geographic, or socioeconomic groups), would enhance the robustness and applicability of the results.
6. Conclusion
While numerous environmental and genetic factors contribute to longevity, our findings, along with the conflicting evidence presented in the literature, suggest that ABO/Rh blood type diversity may not be a significant determinant of longevity in individuals aged 85 years and above. Further multicenter studies with larger participant pools are warranted to definitively address this complex issue and resolve the existing discrepancies.
Acknowledgments
The authors want to thank Erman Zengin, MD for his support in statistical analyses. In addition, Alparslan Merdin is the main author of this study.
Author contributions
Conceptualization: Alparslan Merdin.
Data curation: Alparslan Merdin.
Formal analysis: Alparslan Merdin.
Investigation: Alparslan Merdin, Ümit Aydin.
Methodology: Alparslan Merdin, Ümit Aydin.
Project administration: Alparslan Merdin.
Software: Ümit Aydin.
Supervision: Alparslan Merdin.
Validation: Alparslan Merdin.
Visualization: Alparslan Merdin.
Writing – original draft: Alparslan Merdin, Ümit Aydin.
Writing – review & editing: Alparslan Merdin, Ümit Aydin.
Abbreviation:
- SDU
- Süleyman Demirel University
The authors have no funding and conflicts of interest to disclose.
The data that support the findings of this study are available from a third party, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are available from the authors upon reasonable request and with permission of the third party.
How to cite this article: Merdin A, Aydin Ü. Evaluation of the distribution of ABO and Rh blood groups in geriatric patients aged ≥85 years: A retrospective single-center study. Medicine 2025;104:27(e43154).
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