Association Between Length of Stay and Incidence of Hospital‐Acquired Anaemia in Critically Ill Patients: A Retrospective Cohort Study

Hospital-acquired anaemia (HAA) is characterised by initially normal haemoglobin levels upon admission that are lowered during the hospital stay. The decreased haemoglobin levels related to the days of intensive care unit (ICU) hospitalisation may explain the effect of other interventions on haemoglobin levels. This study aimed to investigate the association between decreased haemoglobin levels and days of hospitalisation in critically ill patients in the Qassim region by analysing haemoglobin levels within the first 7, 14, and 21 days after ICU admission. A total of 180 patients were admitted during the study period. Patients with gastrointestinal bleeding, transfusion-dependent anaemia, a history of anaemia or bleeding, those with chronic kidney disease or on dialysis, and those who had hematologic or other malignancies were excluded (<i>n</i> = 97). Finally, those who were at least 18 years old, was within the normal range of haemoglobin upon admission to the ICU and had been hospitalized for at least 21 days in the ICU were included (<i>n</i> = 83). The initial average haemoglobin concentration was higher in men (15.24 g/dL) than in women (13.45 g/dL). Both experienced a significant and relatively parallel decline in haemoglobin levels (8.95 g/dL) and (8.66 g/dL), respectively, throughout the 21 day hospitalization period. The <i>p</i> value (< 0.001) suggests that the fixed effects are statistically significant, indicating that time (days) has a significant effect on haemoglobin levels. This study found a consistent decrease in haemoglobin levels over the ICU hospitalisation period, suggesting a progressive condition or treatment effect leading to reduced haemoglobin levels. However, further studies are required to analyse the causes of HAA in ICU.