A Clinical Prediction Model for Inadequate Hemoglobin Response After Red Blood Cell Transfusion

Transfusion of one unit of packed red blood cells is traditionally expected to increase hemoglobin concentration by approximately 1 g/dL in adults. However, substantial variability in hemoglobin response is frequently observed in clinical practice. Smaller-than-expected increments may raise concerns regarding ongoing bleeding, hemodilution, or altered erythrocyte distribution. Understanding predictors of inadequate hemoglobin response may help clinicians interpret post-transfusion laboratory values and avoid unnecessary repeat transfusion.

We conducted a prospective observational cohort study of 518 hemodynamically stable hospitalized adults receiving a single unit of red blood cell transfusion. Hemoglobin concentrations were measured at baseline and at 12, 24, and 48 h after transfusion. Inadequate hemoglobin response was defined a priori as a 24-h hemoglobin increment (ΔHb24) < 1 g/dL. Multivariable logistic regression was used to identify predictors of inadequate response. Model discrimination and calibration were evaluated using receiver operating characteristic analysis and calibration plots. A simplified clinical prediction score and nomogram were derived from the regression model.

The mean 24-h hemoglobin increment was 1.41 ± 0.37 g/dL. Inadequate hemoglobin response occurred in 106 patients (20.5%). Patients with inadequate response had higher baseline hemoglobin levels and a greater prevalence of splenomegaly. In multivariable analysis, higher baseline hemoglobin (OR 1.35 per 1 g/dL increase, 95% CI 1.18-1.54) and splenomegaly (OR 1.70, 95% CI 1.10-2.65) were independently associated with inadequate hemoglobin response. The prediction model demonstrated moderate discrimination (AUC 0.64; 95% CI 0.58-0.70) and acceptable calibration. A simplified clinical score stratified patients into low-, intermediate-, and high-risk categories for inadequate response. Decision curve analysis demonstrated modest clinical utility across a range of threshold probabilities.

Inadequate hemoglobin response after single-unit red blood cell transfusion occurs in approximately one fifth of patients and appears to be influenced primarily by recipient physiological factors rather than donor unit characteristics. A simple clinical prediction model may assist clinicians in interpreting post-transfusion hemoglobin changes and reduce unnecessary repeat transfusions.