STONE Score: A Predictor for Need of Blood Transfusion in Percutaneous Nephrolithotomy.

Objective: To determine if the STONE score is a predictor of blood transfusion and if patient-related factors, i.e., the presence of comorbidities such as urinary tract infection and obesity, can predict blood transfusion post-percutaneous nephrolithotomy.

Study Design:  A cross-sectional descriptive study.  Place and Duration of the Study: Department of Urology, The Aga Khan University Hospital, Karachi, Pakistan, between March 2022 and 2023.

Methodology: All patients admitted for percutaneous nephrolithotomy (PNCL) were included in the study. STONE score and patient related factors were assessed. Chi-square or Fisher's exact test was applied to check the association between the dependent variables (blood transfusion) and the independent variables. Logistic regression analysis was applied to compare the variables responsible for the outcome.  Results: During the study period, 150 patients underwent PCNL. After exclusion, 89 patients were included in the study. The mean STONE score was 7.87, and the total number of transfusions was 8 (8.9%). BMI (body mass index) >25kg/m2 and STONE score were found to be significant factors predicting the need for transfusion with p-values of 0.02 and 0.03, respectively. On multivariate analysis, only BMI was found to be a significant contributing factor for blood transfusion.

Conclusion:  High BMI and STONE score are significant predictive factors for blood transfusion post-PCNL. Blood product arrangements should be restricted to obese patients.

Key Words: STONE score, Body mass index, Blood transfusion.