Rising Anemia Rates Amidst the COVID-19 Pandemic: Is There A Connection?

Rationale: This study aims to analyze data from patients who developed anemia during the COVID-19 pandemic and assess the risk of developing different types of anemia among patients diagnosed with COVID-19.

Methods: This retrospective cohort study used the National Inpatient Sample (2020–2021). We included males and females of various ethnicities (White, Black, Hispanic, Asian/Pacific Islander, Native American, and others) with ICD-10 codes D50–D64. The data was weighted with hospital strata. Data analysis was performed using IBM SPSS Statistics™ 25.0, applying inferential statistics.

Results: This study encompassed a cohort of 136,636,051 with a mean age of 49.93 years (+/- 27.26), of whom 75,904,558 (55.6%) were females. The mortality rate was 2.4% (3,316,244), with a mean length of stay of 4.77 days (± 26.322). Of all patients, 24.9% (16,382,561) had anemia, whereas 75.1% (49,306,986) did not. Compared with 2018, when 8,257,430 patients (23.2%) had anemia, the figure rose during the COVID-19 pandemic in 2021 to 8,398,512 (25.2%), a significant increase (p<0.001). Further analysis showed that this increase is not associated with the COVID-19 pandemic, as COVID-19 patients were 13% less likely to have anemia RR= 0.874 [95% CI 0.872-0.876]. Further analysis by subgrouping anemia types reveals that COVID-19 patients were less likely to develop most types of anemia except for other aplastic anemias and bone marrow failure syndromes RR= 1.209 [95% CI 1.201-1.217] and other anemias RR=1.095 [95% CI 1.092-1.099] which is ambiguous diagnosis.

Conclusions: While anemia rates rose during the pandemic, COVID-19 was not a major driver except for specific anemia subtypes. Further research is needed to understand these associations.

Keywords: Anemia, COVID-19, National Inpatient Sample, Temporal trends, Hospitalized patients, Hematologic abnormalities, Aplastic anemia, Bone marrow failure syndromes