Prevalence of preoperative anemia among adult patients and compliance to rational blood use in a tertiary hospital in a developing country: a cross-sectional study

Introduction

Blood transfusion is a life-saving technique. However, unnecessary transfusions and unsafe transfusion practices expose patients to the risks of serious adverse reactions and transmissible infections. In addition, unnecessary transfusions also increase healthcare costs and reduce the availability of blood products for patients who are in need. Considering the risks associated with blood transfusion and the scarcity of supply, the proper use of blood products is crucial. Rational blood use is defined by the World Health Organization (WHO) as the transfusion of safe blood products only to treat a condition leading to significant morbidity or mortality that cannot be prevented or managed effectively by other means (1).

Guidelines for blood transfusion during the perioperative period are still evolving. The absence of a policy advocating rational blood use as the standard of practice has led to a wide variation in transfusion practices in developing countries, such as the Philippines. A study conducted in Northern Philippines showed differences in transfusion practices among various hospitals, and even among different departments in one hospital setting (2).

The paucity of data on the prevalence of preoperative anemia and compliance with rational blood use hinders the evaluation of optimal utilization of blood products. This study aims to provide insight into the blood transfusion practices in a tertiary hospital in a developing country.

Background

Anemia exists when there is an inadequate number of red blood cells (RBCs) in the body, resulting in a decreased oxygen-carrying capacity of the blood. WHO defines anemia in adult males as hemoglobin less than 130 g/L and anemia in adult females as hemoglobin less than 120 g/L (3).

Anemia is a persistent public health problem in developing countries. In the Philippines, the overall prevalence rate of anemia is 30.9% (4). The highest prevalence of anemia in the Philippine population was observed among infants (56.6%), pregnant women (50.3%), elderly males (49.1%), and lactating women (45.7%) (4). Anemia in the preoperative period is common, ranging from 25% to 40% in large observational studies abroad (5). At present, no data are available on the prevalence of preoperative anemia in surgical patients in the Philippines.

Preoperative anemia is significantly associated with increased morbidity, mortality, intensive care unit length of stay, and hospital length of stay (6,7). Overall, the 30-day risk of mortality is increased, especially in patients with preoperative hemoglobin concentration of less than 60 g/L or in patients with cardiovascular disease with hemoglobin concentration values of 100 g/L or less (8).

Anemia is a major predictor of perioperative blood transfusion (7). The decision to transfuse depends on the concentration of hemoglobin, the amount and speed of ongoing blood loss, the characteristics and clinical condition of the patient, and the risk for inadequate oxygenation (9,10). While the nature of the planned surgery is relevant to blood product management, it actually influences the number of blood products to be prepared for surgery rather than the decision to transfuse before surgery as reflected by the Maximum Surgical Blood Order Schedule (11).

A restrictive transfusion threshold uses a lower hemoglobin threshold for transfusion, commonly 70 to 80 g/L. A liberal transfusion threshold, on the other hand, uses hemoglobin concentration 90 to 100 g/L (12). According to the latest Practice Guidelines for Perioperative Blood Management of the ASA, a restrictive transfusion strategy can be safely employed to minimize blood transfusion. Decisions regarding the need for transfusion at hemoglobin levels between 60 and 100 g/L should consider factors such as potential or ongoing bleeding (including its rate and severity), intravascular volume status, signs of poor oxygen delivery, and the patient’s cardiopulmonary reserve (13). The same is echoed by the Philippine Clinical Practice Guidelines for the Rational Use of Blood and Blood Products and Strategies for Implementation (10). Multiple studies comparing restrictive versus liberal transfusion criteria have demonstrated that restrictive strategies were associated with fewer RBC transfusions; while outcomes such as mortality, cardiac, neurologic, and pulmonary complications, as well as length of hospital stay, remained comparable (13). Recent findings indicate that the transfusion threshold for critically ill patients may be safely reduced, as hemoglobin levels below 70 g/L are not inherently associated with increased mortality or morbidity (14).

Even though blood transfusion is considered essential medicine, the shortage of blood products persists, especially in low- and middle-income countries. Forty-two percent of donated blood is collected in less populous, high-income nations. In contrast, the countries of Southeast Asia, which make up 26% of the world’s population, contribute only 13% of the global blood supply. The scarcity of blood in developing countries is aggravated by logistical constraints in its collection, storage, and distribution (15).

Given the limited availability of blood and the potential risks of transfusion, the judicious use of blood products is essential. Rational blood use—a component of patient blood management—has been shown to improve patient outcomes, key program indicators, and reduce blood product utilization. It has significantly led to product-related cost savings (16). Despite existing evidence, the rational use of blood has been met with many challenges in the Philippines, as reported by several unpublished studies. One study showed that among internal medicine residents, there is an inadequacy in the knowledge of transfusion medicine as applied to adult patients (17). Another study showed that while there is actually awareness among respondents regarding restrictive transfusion, translation to everyday clinical practice is still a challenge. Existing protocols, guidelines, and medico-legal implications of transfusion neither encouraged nor discouraged the decisions made regarding anemia management (18). The gaps in knowledge and poor insight into long-standing patterns of practices may have resulted in the weak adoption of restrictive blood transfusion in the Philippine setting. Indeed, a study showed that 14.5% of requests for packed RBC transfusions in pediatric patients were inappropriate (19), while another showed that almost half of the blood transfusions in surgical and obstetric patients could have been avoided (2). Hence, there is a need to determine the baseline compliance with rational blood use among physicians in a high-volume hospital.

Rationale and knowledge gap

Search of several online databases (Scopus, PubMed, Web of Science, ERIC, ScienceDirect, Directory of Open Access Journals, and JSTOR) showed no local study that reported the prevalence of anemia in the preoperative period and the factors associated with preoperative blood transfusion. Inquiry from the research office of a national university also did not yield any articles. Hence, this study was conducted to determine the prevalence of anemia in a tertiary hospital in the Philippines, the characteristics of patients associated with transfusion, and the compliance rate of different services to rational blood use. The results of this study will not only guide perioperative physicians in managing anemia but also inform hospital administrators in developing policies that promote the rational use of the already scarce supply of blood products.

Objectives

This study aimed to determine the compliance with rational blood use in the preoperative management of anemia among adult patients. Specific goals of the study included the determination of the prevalence of preoperative anemia, the prevalence of preoperative hemoglobin level below 100 g/L, the frequency of preoperative blood transfusion in patients with hemoglobin level between 60 to 99 g/L, the characteristics of patients associated with preoperative blood transfusion, and the compliance rate to a restrictive transfusion threshold in patients with no other compelling condition for transfusion except for hemoglobin levels less than 60 g/L. In addition, surgical services were to be ranked according to compliance rate. We present this article in accordance with the STROBE reporting checklist (available at https://aob.amegroups.com/article/view/10.21037/aob-25-25/rc).

Methods

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study protocol was approved by the University of the Philippines Manila Research Ethics Board with code UPMREB 2023-0484-01. Since this was a chart review, the request to waive the requirement of obtaining consent to participate from the subjects was approved.

Study design and setting

This cross-sectional study reviewed electronic medical records of adult patients who underwent elective, inpatient, noncardiac surgery between January and December 2023 at the University of the Philippines-Philippine General Hospital (UP-PGH), a tertiary, state-owned referral center in the capital city of the Philippines, where more than 10,000 surgical procedures are performed annually.

Sample size calculation

There is no local data on the proportion of surgical patients who are anemic or need transfusion. Using a 95% confidence level, a 5% margin of error, a population size of 9,000, and a population proportion of 50%, the calculated sample size is 369. A proportional, stratified, random sampling method was employed, with strata defined by the primary surgical services of UP-PGH: gynecology, orthopedics, hepatobiliary and pancreatic surgery, head and neck, breast, esophagus and soft tissue surgery, otolaryngology, urology, neurosurgery, colorectal surgery, ophthalmology, plastic surgery, burn, and dentistry. The proportion of patients in each stratum relative to the overall surgical population was calculated, and the sample size per stratum was obtained by multiplying the total sample size by the corresponding proportion. Samples per stratum were selected using a random number generator. A total of 500 patients who met the inclusion and exclusion criteria were included in the study. A flow diagram of the selection process is provided in Figure S1.

Inclusion criteria

Patients aged 19 to 65 years old, with American Society of Anesthesiologists-Physical Status Classification (ASA-PS) classification I to III, who underwent elective surgery from January 1, 2023 to December 31, 2023 were included in the study. A normal, healthy patient is classified as ASA-PS class 1. A patient with mild systemic disease is classified as ASA-PS class 2. A patient with severe systemic disease that does not threaten life is classified as ASA-PS class 3 (20). Since anemia is multifactorial and prevalent, especially in developing countries, an anemic patient may present to any surgical service in the preoperative period. Hence, all services were included in the study.

Exclusion criteria

Patients who underwent ambulatory, cardiac, vascular, thoracic, and repeat surgery were excluded. Patients who were pregnant or with any of the following: critical, end-organ ischemia (including but not limited to coronary artery disease, heart failure and cerebrovascular disease), low ejection fraction (<50%), active blood loss (any recorded clinical sign of bleeding like hemoptysis, hematemesis, melena, hematochezia, etc.), and clinical indications of hypovolemia [urine output <0.5 mL/kg/h, tachycardia (heart rate >100 beats per minute), and hypotension (blood pressure <90/60 mmHg)], tissue hypoxia (SpO₂ <95%), ischemia (ST depression, T wave changes), and lactic acidosis (lactate >2 mmol/L), were also excluded from the study.

Data collection

Data collection commenced after the University of the Philippines Manila Research Ethics Board approved the study protocol. Pertinent data from 500 eligible cases were collected through a review of electronic medical records and subsequently encoded. All identifying patient information was kept anonymous and confidential. A numeric code was assigned for each case number to conceal the information.

Variables

Data collected from the electronic medical records included age, sex, ASA-PS classification, primary service, baseline preoperative hemoglobin, and number of units of packed RBCs transfused preoperatively. Age was classified into three categories: young adult (19–39 years old), middle-aged adult (40–59 years old), and senior adult (60 years old and above). Baseline hemoglobin was the latest hemoglobin taken at most one month before surgery, and before any blood transfusion was done. Hemoglobin levels were classified as <60, 60–69, 70–79, 80–89, 90–99, and ≥100 g/L based on previously published transfusion thresholds. The number of units transfused was counted after the time the baseline hemoglobin was taken up to before the start of surgery. The prevalence of preoperative anemia, frequency of blood transfusion, patient characteristics associated with blood transfusion, utilization rate, and compliance rates to a restrictive transfusion threshold were determined from the collected data.

Statistical analysis

No missing data was encountered. Descriptive statistics, such as frequency and percentage, were used to present the clinico-demographic variables. A series of Z-tests for proportions, chi-square, or Fisher’s exact tests were used to compare the patient characteristics between comparison groups (i.e., those who received versus those who did not receive transfusion, and compliance rates). The level of significance for all sets of analysis was set at a P value less than 0.05 using two-tailed comparisons. The statistical software, JASP version 0.16.4, was used.

Results

Five hundred patients were selected from 6,604 patients who were deemed eligible based on the predefined inclusion and exclusion criteria. The overall prevalence of anemia in adult patients during the preoperative period was 38% [95% confidence interval (CI): 33.73–42.42%]. The prevalence of preoperative baseline hemoglobin less than 120 g/L in adult females was 40.13% (95% CI: 34.62–45.83%), while the prevalence of preoperative baseline hemoglobin less than 130 g/L in adult males was 34.55% (95% CI: 27.84–41.76%). There was no notable difference between these two proportions (P=0.21). Table 1 shows the rate of anemia per service.

The incidence of blood transfusion in anemic patients is 23.16% (95% CI: 17.2–29.2%), while it is 8.8% (95% CI: 6.3–11.3%) among all surgical patients. Table 2 breaks down the incidence among services.

Incidence in anemic patients is the number of patients who were transfused divided by the number of anemic patients per service (see Table 1). Incidence in all patients is the number of patients who were transfused divided by the number of all patients per service (see Table 1).

The prevalence of preoperative baseline hemoglobin levels less than 100 g/L in adult patients is 12.6% (95% CI: 9.82–15.83%). Among the 56 patients with hemoglobin levels 60 to 99 g/L, 35 received blood transfusions (see Table 3). The proportion of patients with hemoglobin levels 60 to 99 g/L who received blood transfusions is 62.5% (95% CI: 48.55–75.08%).

Table 3 shows a comparative analysis of patients who did not receive blood transfusions versus those who did. There were no differences in the two groups in terms of age and sex. Half of the patients who received preoperative blood transfusion were classified as ASA-PS 3 than otherwise (P<0.01). Based on the data, patients of gynecology, colorectal surgery, and orthopedics appeared to receive blood transfusions preoperatively than other services (P<0.01). As expected, patients with low levels of hemoglobin received blood transfusions more often than otherwise (P<0.01). Notably, transfusions were administered to two patients with hemoglobin levels greater than 100 g/L, which may reflect limited awareness of the restrictive approach or the lack of an established policy on rational blood use.

Table 4 presents the utilization rate and compliance rates of the various services. Among patients who received blood transfusions, patients under gynecology, colorectal surgery, and orthopedics utilized packed RBCs the most. No patient in ophthalmology, otolaryngology, head and neck surgery, or dentistry received a blood transfusion. Among patients who received blood transfusions, only the neurosurgery service was compliant with rational blood use. Compliance entails adopting a restrictive transfusion strategy, wherein transfusion is indicated only for patients with hemoglobin levels below 60 g/L, provided that none of the following conditions are present: critical end-organ ischemia, limited cardiopulmonary reserve, active hemorrhage, clinical evidence of hypovolemia, inadequate oxygen delivery, or tissue hypoxia. On the other hand, most of the transfusions done by other services were noncompliant, with less than 17% of the patients who received blood transfusions having hemoglobin values less than 60 g/L. As such, services may be arranged according to compliance rate in descending order as follows: neurosurgery, gynecology, colorectal surgery, orthopedics, and hepatobiliary and pancreatic surgery. All cases of transfusion in head and neck, breast, esophagus, soft tissue surgery, plastics, urology, and burn were noncompliant. There is no statistically significant difference in compliance rate among the services. However, the sample size may not have been enough to detect an effect, and there are cells that are unfilled. The result may still be likely due to chance.

Utilization rate is the number of units transfused by the service divided by the total number of units transfused across all services (98 units). The compliance rate is the number of patients in the service with hemoglobin levels lower than 60 g/L who were transfused preoperatively, divided by the total number of patients in the service who received preoperative transfusions (see Table 3).

Discussion

Key findings

Among 500 patients, the prevalence of preoperative anemia was 38%. In particular, the prevalence of preoperative hemoglobin less than 100 g/L was 12.6%. Out of the 56 patients with hemoglobin levels of 60 to 99 g/L who could have benefited from a restrictive approach, 62.5% received blood transfusions that may have been potentially unnecessary. Patients classified as ASA-PS 3, who were under the services of gynecology, colorectal, and orthopedics, and those with low hemoglobin levels were more likely to receive blood transfusion preoperatively than otherwise. There was no statistically significant difference in the compliance rate to a restrictive transfusion threshold among services, but this may still be due to chance.

Strengths and limitations

No missing data were encountered in this study. The prevalence of preoperative anemia among patients admitted to a hospital in a developing country was reported, together with the characteristics associated with blood transfusion. The results of this study are limited by biases related to inaccuracies in the data gathered from electronic medical records, which may be due to human error and/or the lack of an automated system that prevents the skipping of required data in health information systems. Results may only be applied to the specific institution where the study was conducted, as the sample size was computed using an institution-specific population. The disparate distribution of patients and the small number of cases that received blood transfusion also limits the conclusions from this study. No causation was established since this is a cross-sectional study.

Comparison with similar research

The prevalence of anemia in adult patients presenting for surgery (38%) is similar to those reported by other studies that investigated anemia in the general population (30.9%) (5) and among preoperative patients (25–40%) (4,21). The incidence of preoperative blood transfusion in patients with hemoglobin levels of 60–99 g/L in this study (62.5%) lies between values reported in previous studies. One study described the incidence of preoperative blood transfusion according to hematocrit levels. Estimation of hemoglobin levels from the cited hematocrit values revealed that the incidence of preoperative blood transfusion is 16% among patients with hemoglobin levels of 80–99 g/L, and 42% in those with hemoglobin levels lower than 80 g/L (22). Another study reported that among patients who received preoperative blood transfusions, 89.1% had hemoglobin levels above 70 g/L, and 71.8% had levels above 80 g/L (21). If the overall rate of blood transfusion is considered, the result of this study (8.8%) is higher than that of a previous retrospective study (5.16%) (21).

Explanation of findings

The similarity of the prevalence of anemia in this study to that of other published studies may be due to parallels in existing factors that influence the prevalence of anemia, such as nutritional deficiencies, infections, chronic diseases, and socioeconomic conditions. The higher overall rate of blood transfusion among anemic patients who might have otherwise benefited from a restrictive approach may be attributed to persistent resistance arising from conflicting beliefs and practices, limited knowledge and skills in managing anemia through alternatives to transfusion, the absence or weakness of patient blood management programs and local transfusion protocols, as well as a defensive approach to clinical decision-making. Patients under gynecology, colorectal, and orthopedics were more likely to receive blood transfusions than others, probably due to physicians’ anticipation of expected intraoperative blood loss.

Implications and actions needed

The findings of this study reinforce anemia as a significant public health problem, especially in developing countries like the Philippines. Given that anemia has been shown to be significantly associated with increased morbidity, mortality, intensive care unit length of stay (6,7), hospital length of stay, diagnostics tests and treatment options for anemia in the preoperative period should be made available and affordable. Since anemia is a major predictor of perioperative blood transfusion, strategies aimed at minimizing or avoiding transfusion should be actively promoted. Avoidance of unnecessary blood transfusions reduces exposure of patients to severe adverse reactions and transfusion-transmissible infections, conserves the limited supply of blood products in healthcare facilities, and contributes to cost savings.

Patients classified as ASA-PS 3, who underwent gynecologic, colorectal, or orthopedic surgeries, and who have low hemoglobin levels (less than 100 g/L), appear to receive blood transfusions preoperatively than others. More vigilant investigation and management of anemia may be employed for these patients preoperatively. These patients may be asked to prepare blood products for possible transfusion. Most services still did not comply with a 60-g/L threshold for blood transfusions in patients with no critical, end-organ ischemia, low cardiopulmonary reserve, active blood loss, clinical indication of hypovolemia, inadequate oxygen delivery, and tissue hypoxia. If the threshold is increased to 80 g/L, six out of nine services still transfused patients who had hemoglobin levels above 80 g/L. The results call for the espousal of a restrictive blood transfusion strategy among surgeons. A restrictive blood transfusion strategy has been shown to improve patient outcomes and key program indicators, reduce blood product utilization (23), and generate product-related cost savings (16,24).

Studies have identified the common barriers to compliance with a restrictive blood transfusion strategy. These barriers included knowledge and beliefs about the intervention, access to information, and resistance to change (17,18,25). Given that this study revealed most transfusions could have been avoided under a restrictive strategy, addressing barriers through educational materials, training programs, audits with feedback, and local consensus discussions may help improve this prevailing practice (25,26). To reduce unnecessary use of blood products, institution-specific, evidence-based transfusion practice guidelines for each blood component must be developed, ratified, and communicated to all medical staff (23,24,27). A governance body must be established to ensure the appropriate use of blood products, monitor, audit, and analyze transfusion ordering practices and transfusion-related events, and implement necessary corrective measures (24,28). A study focusing on the population of patients who received blood transfusions preoperatively may give more insight into the risk factors for transfusion. Examining the barriers to restrictive blood transfusion practices can inform the development of more effective policies and interventions.

Conclusions

The prevalence of preoperative anemia among adults in a tertiary hospital in the Philippines was 38%, with 12.6% of patients presenting with baseline hemoglobin levels below 100 g/L. Blood transfusion could have been avoided in 62.5% of patients in this subgroup, yet it was still administered. Patients who had severe systemic diseases, under the services of gynecology, colorectal and orthopedics, and had low levels of hemoglobin were more likely to receive blood transfusion compared to others. Overall, compliance with a restrictive transfusion strategy remained suboptimal across most surgical services. The high prevalence of preoperative anemia, coupled with low adherence to recommended transfusion thresholds, underscores the importance of optimizing patient blood management strategies and addressing barriers to compliance.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://aob.amegroups.com/article/view/10.21037/aob-25-25/rc

Data Sharing Statement: Available at https://aob.amegroups.com/article/view/10.21037/aob-25-25/dss

Peer Review File: Available at https://aob.amegroups.com/article/view/10.21037/aob-25-25/prf

Funding: The implementation of this study was supported by the 2024 University of the Philippines-Philippine General Hospital Regular Research Grant (No. 2024-C1).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aob.amegroups.com/article/view/10.21037/aob-25-25/coif). M.T.B.A. received payments from the 2024 University of the Philippines - Philippine General Hospital Regular Research Grant. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study protocol was approved by the University of the Philippines Manila Research Ethics Board with code UPMREB 2023-0484-01. Since this was a chart review, the request to waive the requirement of obtaining consent to participate from the subjects was approved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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