European Journal of Cardiovascular Medicine

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airway obstruction, primarily resulting from chronic airway inflammation and subsequent destruction of lung parenchyma, ultimately leading to emphysema. This condition ranks among the leading causes of premature mortality and morbidity in adults and accounts for the highest proportion of deaths related to respiratory disorders [1-3].

In addition to significant airway obstruction and reduced functional capacity, COPD is associated with systemic inflammation and numerous comorbid conditions [4]. It is recognized as a chronic systemic inflammatory disorder, marked by elevated levels of inflammatory mediators such as interleukin-1, interleukin-6, and tumor necrosis factor-α [5,6]. The disease's extrapulmonary effects are responsible for several comorbidities, including weight loss, anxiety, depression, skeletal muscle dysfunction, atherosclerosis, coronary artery disease, osteoporosis, and an increased risk of lung cancer [7].

Anemia is another significant comorbidity observed in COPD, similar to other chronic diseases. Although COPD-induced hypoxia often leads to polycythemia, anemia is reported in COPD patients [8–11]. This condition contributes to frequent hospital admissions, increased utilization of healthcare resources, and a decline in quality of life, particularly among older individuals. This study is a retrospective hospital-based investigation aimed at assessing the prevalence of anemia within a study population with COPD.

Retrospective data of COPD patients who were clinically diagnosed and treated as outpatients were collected from the Medical Records Department of the Teaching Hospital under the Medical College in India. Data were retrieved based on ICD coding and subsequently analyzed. 

Patients with coexisting conditions, including bleeding disorders, malignancies, thyroid dysfunction, chronic liver or kidney diseases, heart failure, gastrointestinal bleeding, abnormal uterine bleeding, tuberculosis, connective tissue disorders, diabetes mellitus, or those who had undergone major surgery in the preceding three months, were excluded. 

Anemia was identified using the WHO criteria, defined as hemoglobin (Hb) levels <13 g/dL for males and <12 g/dL for females, or hematocrit (Hct) levels <39% in males and <36% in females. The diagnosis of COPD was determined based on clinical evaluation by the treating physician. 

Out of 567 patient records retrieved, 234 met the inclusion criteria and were analyzed, while the remaining records were excluded due to the presence of coexisting diseases or incomplete documentation. 

Data collected included hospital number, patient name, age, sex, address, hemoglobin levels, red blood cell (RBC) counts, and red cell indices such as hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Statistical analysis was performed using SPSS Version 21.0 and Microsoft Excel 2010. Mean values were compared through ANOVA, while Chi-square tests were used for frequency comparisons.

The study population comprised 234 participants, with a higher proportion of females (148) compared to males (86). The age distribution of the study population, as shown in Table 1, reveals a predominance of participants in the older age groups. The largest cohort was within the 61-70 years age range followed by the 71-80 years range.The total number of participants in the study was distributed across various age groups, including those over 80 years (9 individuals), highlighting the inclusion of older adults in the research.

Table 1: Age distribution of study population

The prevalence of anemia among the COPD patients was further analyzed across these age groups, as presented in Table 2. In total, 139 individuals (79 females and 60 males) were found to have anemia, based on either a hemoglobin (Hb) level of <12 g/dL for females and <13 g/dL for males, or a hematocrit (Hct) level of <36% for females and <39% for males. The highest prevalence of anemia was observed in the 61-70 years age group, with 33 individuals (21 females and 12 males), followed closely by the 71-80 years group, which had 51 anemic patients (26 females and 25 males). Among females, the 71-80 years age group showed the highest number of anemic individuals (26), while in males, the 71-80 years age group also had the largest number (25). The analysis of anemia based on Hb and Hct revealed that these trends were consistent across both measures.

Table 2: Prevalence of Anemia in COPD patients across age groups

A comparison of the mean indices between anemic and non-anemic COPD patients is provided in Table 3. The results show that anemic patients had significantly lower mean levels for hemoglobin (Hb), red blood cell (RBC) count, hematocrit (Hct), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) compared to non-anemic patients, with all these differences being statistically significant. The only parameter that did not show a significant difference was the mean corpuscular hemoglobin concentration (MCHC), with a p-value of 0.43, indicating no significant difference between the two groups in this parameter.

Table 3: Comparison of mean indices among anemic vs non-anemic COPD patients

The gender-based comparison of mean parameters among COPD patients, presented in Table 4, did not show any significant differences between females and males. This suggests that, despite the difference in sample sizes between genders, the hematological parameters in male and female COPD patients were comparable.

Table 4: Gender based comparison of mean parameters among COPD patients

The prevalence of anemia, based on WHO criteria was estimated to be 25.64% in males and 33.76% in females. Previous studies have reported a variation in anemia prevalence among COPD patients, ranging from 10% to 15% [12–14]. For instance, John et al. estimated anemia prevalence at 23.1% [16], while Halpen et al., utilizing Medicare claims data, identified anemia in 21% of COPD patients, which is lower than our findings. Notably, both studies did not differentiate prevalence rates by gender, unlike our analysis. In contrast, Shorr et al. reported a 33% prevalence of anemia, which is comparable to the prevalence observed among females in our study [16].

The mean hemoglobin levels in our study indicated mild anemia consistent with findings from earlier studies [17,18]. Using hematocrit (Hct) values <39% for males and <36% for females to define anemia, we observed anemia in 25.21% of males and 33.76% of females. These rates are higher than those reported by Chambellan et al., where anemia was observed in 13% of males and 8% of females [14]. However, the discrepancy could be attributed to their study focusing solely on patients with severe oxygen-dependent COPD.

It is well-documented that anemia prevalence in the general population increases with age, irrespective of the presence of COPD or other chronic conditions [19]. Some studies suggest that advancing age contributes to the higher prevalence of anemia in COPD patients [16,17,20,21]. In our study, the highest proportion of anemic males was observed in the 71–80-year age group, followed by the 81–90-year group. Among females, the highest prevalence was also in the 71–80-year group, followed by the 61–70-year group.

The study has several limitations. Spirometry was not conducted on all patients, leading to a diagnosis of COPD that was based solely on clinical findings, limiting the ability to fully establish the association between anemia and COPD severity. Additionally, iron and Vitamin B12 levels were not assessed, which could have provided valuable insights into the underlying causes of anemia. The study was conducted over a three-year period; however, a longer duration with a larger sample size and more stringent inclusion criteria to exclude potential confounding factors could have enhanced the reliability and robustness of the findings.

Anemia is recognized as a significant predictor of mortality in individuals with COPD, and addressing this comorbidity in routine clinical practice is crucial. Managing the oxygen deficiency caused by anemia in patients with pulmonary dysfunction could potentially enhance their quality of life. Conducting well-designed prospective studies with rigorous inclusion criteria to minimize confounding factors would provide a clearer understanding of the pathophysiology of anemia in COPD. This, in turn, could aid clinicians in optimizing treatment approaches, thereby reducing the morbidity and mortality associated with COPD.

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