European Journal of Cardiovascular Medicine

Blood donation constitutes an indispensable component of modern healthcare systems, ensuring the continuous availability of safe and adequate blood and blood products for clinical use. These components—red blood cells, plasma, platelets, and cryoprecipitates—are vital for the management of trauma, surgical procedures, obstetric haemorrhage, anaemia, malignancies, and various haematological and genetic disorders. Voluntary, non-remunerated blood donation remains the foundation of an effective and sustainable transfusion service, contributing significantly to both safety and self-sufficiency of national blood supplies.

Although the process of blood donation is considered safe, adverse donor reactions may occasionally occur. The most common among these are vasovagal reactions (VVRs), typically triggered by anxiety, hypovolemia, or transient autonomic imbalance [1,2]. Such reactions may manifest as dizziness, pallor, nausea, sweating, or transient loss of consciousness, and although generally mild, they can adversely influence the donor’s overall experience. Negative donation experiences have been shown to decrease the likelihood of future donations, thereby affecting the retention of voluntary donors—an essential factor for maintaining a stable donor base [3].

Globally, the incidence of donor reactions has been reported to range between 0.5% and 5%, influenced by multiple factors including demographic characteristics, physiological parameters, environmental conditions, and phlebotomy practices [4]. In India, studies have reported higher rates of adverse reactions among first-time and female donors. This increased susceptibility is often attributed to lower blood volume, reduced haemoglobin levels, and greater pre-donation anxiety [5,6]. Understanding such factors is critical for implementing targeted preventive strategies that enhance donor safety and confidence.

Various interventions have been evaluated to minimize the occurrence of donor reactions. Pre-donation hydration protocols have been shown to prevent hypovolemic symptoms; enhanced pre-donation counselling can alleviate anxiety and improve donor preparedness; and optimization of the donation environment—including temperature, privacy, and comfort—has been associated with improved donor tolerance and satisfaction [7–9]. In addition, training of phlebotomists in efficient and minimally traumatic venipuncture techniques further contributes to reducing donor-related adverse events.

The present study was undertaken to compare the incidence and pattern of donor reactions between the years 2023 and 2024 in a tertiary care centre. The study aimed to evaluate the effectiveness of preventive measures implemented in 2024, identify factors associated with donor reactions, and assess the overall impact of these strategies on donor safety and retention. The findings are expected to provide insights into evidence-based practices that can strengthen donor management protocols and promote a safer, more positive donation experience.

Study Design and Setting

A comparative observational study was conducted in the Department of Transfusion Medicine at a tertiary care teaching hospital in South India. The study analyzed and compared blood donor data over two consecutive calendar years—2023 (pre-intervention period) and 2024 (post-intervention period)—to evaluate the impact of newly implemented preventive measures on the incidence and pattern of donor reactions. The study adhered to institutional ethical standards and the principles of the Declaration of Helsinki.

Study Population

All whole blood donations collected during the study period were included in the analysis. Donors were screened and accepted according to the National Blood Transfusion Council (NBTC), India, eligibility criteria.

During the pre-intervention year (2023), a total of 21,607 donors participated in blood donation, of whom 20,516 (94.9%) were males and 1,091 (5.0%) were females. In the post-intervention year (2024), the total number of donors was 20,374, comprising 19,747 (96.9%) males and 627 (3.1%) females. Approximately 35–40% of all donors were repeat donors, while the remaining were first-time donors.

Data Collection and Study Variables

Data were retrieved retrospectively from institutional donor registers, donation records, and adverse donor reaction logs maintained at the blood centre. The following variables were extracted:

• Demographic data: age, gender, and donation status (first-time or repeat).
• Donation-related details: type of donation (voluntary/replacement), phlebotomy details, and donation environment.
• Adverse donor reactions: type, severity, and timing of occurrence.

Donor reactions were classified according to NBTC (India) guidelines [10] as follows:

• Mild reactions: dizziness, sweating, nausea, pallor, or anxiety.
• Moderate reactions: brief loss of consciousness or vomiting.
• Severe reactions: convulsions or prolonged unconsciousness requiring medical intervention.
• Local reactions: pain at venipuncture site, hematoma formation, or prolonged local bleeding.

Each donor’s reaction, if present, was documented immediately by the attending medical officer and verified through post-donation observation logs.

Preventive Measures Implemented in 2024

Beginning January 2024, a comprehensive set of preventive strategies was introduced to improve donor safety and reduce the frequency of vasovagal and local donor reactions. These included:

1. Pre-donation Hydration: Administration of approximately 300 mL of oral fluids 10–15 minutes prior to donation to prevent hypovolemia and vasovagal episodes [7].
2. Enhanced Counselling: Pre-donation counselling sessions emphasizing the safety of the procedure, relaxation techniques, and reassurance to reduce anticipatory anxiety.
3. Stringent Donor Selection: Exclusion of donors with inadequate rest, recent febrile illness, dehydration, or borderline haemoglobin levels to minimize the risk of adverse events.
4. Experienced Phlebotomy Team: Only trained and experienced phlebotomists were assigned to donor venipuncture to ensure smooth and minimally painful procedures.
5. Comfortable Donation Environment: Maintenance of optimal room temperature, adequate ventilation, soft ambient lighting, and a calm environment to promote donor comfort.
6. Post-donation Observation: Each donor was observed for at least 20 minutes after donation, during which refreshments (snacks and fluids) were provided, and any early reactions were promptly managed.
7. Staff Training: Regular sensitization workshops and simulation-based training programs were conducted for transfusion staff to enhance their ability to recognize, prevent, and manage donor reactions effectively.
8. Follow-up and Feedback: All donors were contacted telephonically within 24–48 hours post-donation to assess recovery, provide reassurance, and encourage future voluntary donations.

Statistical Analysis

All collected data were entered into Microsoft Excel (Microsoft Corporation, USA) and verified for accuracy and completeness. Descriptive statistics were used to summarize donor demographics and reaction profiles. The incidence of donor reactions was expressed as a percentage of total donations. Comparative analysis between 2023 and 2024 was performed to evaluate differences in reaction rates across gender and donation status (first-time versus repeat donors). Statistical significance was assessed using appropriate comparative tests, and results were presented in tabular and graphical formats where applicable.

This comparative observational study assessed the effectiveness of preventive interventions in reducing donor reaction rates by analysing data from two consecutive years—2023 (pre-intervention) and 2024 (post-intervention). A total of 41,981 whole blood donations were included for analysis, comprising 21,607 donations in 2023 and 20,374 in 2024.

Overall Impact of Preventive Measures

Following the implementation of the preventive measures in 2024, a significant reduction in the overall incidence of donor reactions was observed. As depicted in Table 1, the overall donor reaction rate declined from 1.2% in 2023 to 0.6% in 2024, corresponding to a 50% relative reduction and an absolute risk reduction (ARR) of 0.6%. Statistical analysis using the Chi-square (χ²) test confirmed this decrease to be highly significant (p < 0.001).

Donor Reaction Rates by Gender

Gender-wise analysis revealed that female donors experienced a higher frequency of adverse reactions compared to male donors during both study years. Following the introduction of preventive strategies, reaction rates decreased substantially for both groups. Among males, the rate declined from 1.0% to 0.5%, and among females, from 4.2% to 2.3% (p < 0.001 for both). Although female donors continued to show greater susceptibility, the magnitude of reduction in this group demonstrates the effectiveness of the implemented interventions (Table 2).

Reaction Type and Severity

The distribution of donor reaction types remained comparable across both years. Vasovagal reactions (VVRs) were the most frequent, accounting for approximately 90% of all adverse events. Local reactions (such as hematoma and pain at the venipuncture site) represented 8%, while other minor symptoms, including transient anxiety or nausea, comprised 2% of the total. Importantly, no severe or life-threatening reactions such as convulsions or prolonged syncope were reported during either study period, confirming the safety of the donation process following the interventions.

Reaction Rates by Donor Experience

Donor experience was an important determinant of reaction occurrence. First-time donors demonstrated significantly higher reaction rates than repeat donors in both years. Following intervention, the reaction rate among first-time donors decreased from 1.8% to 0.9%, and among repeat donors from 0.4% to 0.2%. These reductions were statistically significant (p < 0.001 for both), indicating a positive effect of pre-donation counselling, hydration, and improved donor handling practices across experience groups (Table 3).

Statistical Summary and Significance

Chi-square (χ²) testing confirmed statistically significant reductions across all evaluated subgroups. Both absolute risk reduction (ARR) and relative risk reduction (RRR) analyses demonstrated consistent trends, with similar magnitude of improvement across gender and donor status categories (Table 4). All p-values were less than the standard alpha level (α = 0.05), supporting the conclusion that observed improvements were unlikely due to chance alone.

Interpretation

The data demonstrate that implementation of structured preventive measures—comprising pre-donation hydration, enhanced counselling, and improved donor management—resulted in a statistically significant and clinically meaningful reduction in donor reactions. The consistent improvement across genders and donor experience categories highlights the robustness of the interventions. No severe or life-threatening reactions occurred during either period, reaffirming the safety and efficacy of the enhanced donor care model.

The present study demonstrates that the implementation of structured preventive measures resulted in a marked and statistically significant reduction in donor reaction rates, reaffirming earlier findings that emphasize the importance of targeted pre-donation interventions to enhance donor safety and retention (2,7,8). Following the introduction of hydration, counselling, and donor comfort optimization strategies, the overall donor reaction rate declined from 1.2% to 0.6%, representing a 50% relative reduction. This trend aligns with global evidence suggesting that donor care protocols substantially mitigate vasovagal events (3,6,9).

Gender Influence

Female donors exhibited a higher predisposition to vasovagal reactions compared with male donors in both study periods, consistent with the observations of Agnihotri et al. (2010) and Newman (1997) (5,9). This increased susceptibility among females is frequently attributed to lower circulating blood volume, reduced haemoglobin concentration, and greater pre-donation anxiety levels (10,11). However, the observed decline in reaction rates among female donors—from 4.2% to 2.3% post-intervention—suggests that hydration and counselling were effective in stabilizing hemodynamic and autonomic responses, reducing anxiety-related triggers, and enhancing overall donor tolerance.

First-Time Donors

First-time donors consistently demonstrated higher reaction rates than repeat donors, a pattern well established in prior studies (4,10,12). Eder et al. (2008) reported that lack of procedural familiarity and psychological apprehension are major contributors to adverse donor responses (4). The present findings corroborate these observations, with first-time donors exhibiting nearly double the reaction rate of repeat donors in the pre-intervention phase. Targeted reassurance, anticipatory guidance, and post-donation feedback appear to have played a significant role in reducing these rates following the intervention.

Effectiveness of Preventive Measures

Among the implemented interventions, pre-donation hydration and structured counselling emerged as the most effective strategies for reducing vasovagal reactions, as previously confirmed by France et al. (2012) and Dhingra et al. (2020) (6,3). Additional measures—such as ensuring a donor-friendly environment, optimizing ambient temperature and posture, and conducting regular staff training—also contributed to the overall improvement in donor safety. These findings reinforce the concept that preventive interventions are most effective when applied as a multifactorial, system-based approach rather than isolated measures (13,14).

Impact on Donor Retention

Minimizing donor reactions is critical not only for ensuring immediate donor safety but also for maintaining long-term donor engagement. The World Health Organization (2020) underscores that donor satisfaction and retention are essential for the sustainability of voluntary blood donation programs (1). In this study, a marginal but notable increase in repeat donor participation following the intervention reflects enhanced confidence and satisfaction, further substantiating the broader public health benefits of donor safety initiatives.

Overall, this study demonstrates that comprehensive preventive strategies—including hydration, counselling, donor comfort optimization, and trained phlebotomy practices—are effective in substantially reducing adverse donor reactions. The consistency of improvement across all demographic and experiential categories highlights the robustness of the implemented protocol. Sustained adherence to such preventive frameworks is recommended to improve donor experiences, encourage repeat donations, and ensure a stable, safe, and self-sufficient blood supply

The present comparative study demonstrates that structured preventive interventions—specifically pre-donation hydration, enhanced counselling, optimized donor comfort, and trained phlebotomy practices—significantly reduced donor reaction rates. The 50% relative decline in overall reaction incidence, consistent across gender and donor categories, underscores the value of systematic donor care in enhancing safety and confidence. These findings highlight the importance of a proactive, evidence-based donor management framework in ensuring safe and sustainable blood donation practices.

Limitations

This study was conducted at a single tertiary care centre, which may limit generalizability to other institutional or community-based donation settings. The reliance on donor self-reporting and routine documentation may have led to underestimation of minor or delayed reactions. Additionally, individual psychological and physiological parameters such as baseline anxiety, hydration status, and haemodynamic variability were not quantitatively assessed. Future multicentric studies incorporating standardized stress and volume markers, as well as longitudinal follow-up, are warranted to strengthen these findings and refine preventive protocols.

Recommendations

Based on the findings, it is recommended that blood transfusion centres integrate pre-donation hydration and structured counselling as standard components of donor care. Regular staff training, environmental optimization, and post-donation observation should be institutionalized to further minimize adverse events. Establishing a national donor safety and follow-up registry could enhance surveillance, improve donor retention, and contribute to a more resilient and self-sufficient blood supply system.

1. World Health Organization. Blood Safety and Availability. WHO; 2020.
2. Eder AF, et al. Adverse reactions to allogeneic whole blood donation by 16- and 17-year-olds. JAMA. 2008;299(19):2279–2286.
3. Dhingra S, et al. Analysis of donor adverse reactions at a tertiary care hospital. Asian J Transfus Sci. 2020;14(1):35–39.
4. Eder AF, Hillyer CD, Dy BA. Adverse reactions to blood donation: risk factors and interventions. Transfusion. 2008;48(2):295–300.
5. Agnihotri N. Whole blood donor adverse reactions at a tertiary care hospital. Asian J Transfus Sci. 2010;4(1):31–35.
6. France CR, et al. Vasovagal reactions in blood donors: a review. Transfus Med Rev. 2012;26(2):94–101.
7. Wiltbank TB, et al. Effect of pre-donation hydration on vasovagal reaction rates. Transfusion. 2008;48(3):562–568.
8. Newman BH. Blood donor reactions and injuries: evaluation and prevention. Transfus Med Rev. 1997;11(1):64–75.
9. Dhingra KR, et al. Predictors of adverse donor reactions in Indian blood donors. Indian J Hematol Blood Transfus. 2018;34(2):291–298.
10. National Blood Transfusion Council (NBTC). Guidelines for Blood Donor Selection and Reaction Management. Ministry of Health, Government of India; 2021.
11. Singh S, et al. Adverse donor reactions in blood donation: experience from a tertiary care hospital in India. Transfus Apher Sci. 2019;58(1):89–93.
12. Yamada T, et al. Gender differences in blood donation reactions and related factors. Transfus Med. 2017;27(5):365–72.
13. Eder AF, Notari EP, Dodd RY. Do reactions to blood donation affect donor return? 2012;52(2):372–4.
14. Bravo M, et al. Comprehensive donor care models in transfusion services: impact on donor health outcomes. Blood Transfus. 2019;17(3):229–36.
15. Zervou EK, et al. Prevention and management of vasovagal reactions in blood donors: an evidence-based approach. Vox Sang. 2018;113(8):e93–e102.