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Validation of a clinical prediction rule to reduce preoperative type and screen procedures
W A van Klei1, K G M Moons, A T Rheineck-Leyssius
1Department of Peri-operative Care, Anaesthesia and Pain Management, Julius Centre for General Practice and Patient Oriented Research, University Medical Centre Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands.
Background:
We have developed a prediction rule for the occurrence of perioperative red blood cell transfusion to help to reduce the number of unnecessary preoperative type and screen procedures. We evaluated the robustness of this prediction rule in patients from another hospital.
Methods:
The rule was retrospectively applied to 1282 consecutive patients ('validation set') who underwent similar surgical procedures to the patients in the derivation study. The outcome was similarly defined as any allogeneic transfusion on the day of surgery or during the first postoperative day. The predictive value of the rule was assessed using a Receiver Operating Characteristic curve (ROC) and compared with the results of the derivation study. Subsequently, the number of correctly predicted transfusions was compared.
Results:
The patient characteristics did not differ between the two sets, except for the incidence of transfusion (derivation study: 18%; present study: 8%). In the validation set, the ROC area of the prediction rule was 0.78 (95% confidence intervals [CI]: 0.73-0.82), which was within the CI of the ROC area found in the derivation study (0.75; 95% CI: 0.72-0.79). In total, 35% of the type and screen procedures could be omitted (derivation study: 50%), with 13% missed transfused patients (derivation study: 20%).
Conclusions:
After comparing the results of this validation study with that of the derivation study, the prediction rule was robust and may work in other clinics as well.