Objectives: To evaluate the performance of the Simplified Therapeutic Intervention Scoring System (TISS 28) on an independent database and to determine its relation to the original Therapeutic Intervention Scoring System (TISS 76).
Design: Analysis of the database of the Spanish prospective multicenter study PAEEC (Project for the Epidemiological Analysis of Critical Care Patients).
Setting: 86 intensive care units (ICUs) in Spain.
Patients: Data on 8838 patients admitted to the ICUs.
Measurements and results: Administrative data, main diagnostic category, severity score [Acute Physiology and Chronic Health Evaluation (APACHE) II and III] and data for the calculation of the TISS 76 and TISS 28 were collected during the first 24 h after the patient's ICU admission. TISS 76 and TISS 28 scores were calculated and analyzed on how they varied according to other variables (diagnostic group, severity level, hospital size and age). The association between TISS 76 and TISS 28 was studied. The TISS 76 score was 21 +/- 10.5 points and the TISS 28 score 23.3 +/- 8.8 points. There was a good correlation between TISS 76 and TISS 28 (r = 0.85). The regression equation was: TISS 28 = 8.35 + (0.712 x TISS 76). The TISS 28 score behaved similarly to the TISS 76 score in relation to the other variables, with a positive correlation between the therapeutic and the severity level (APACHE II and III) and a negative correlation between therapeutic activity and age, with very similar correlation coefficients. Both TISS 28 and TISS 76 scores were higher in larger hospitals.
Conclusions: There is a strong correlation between TISS 28 and TISS 76 scores in the PAEEC database and TISS 28 works correctly in our setting.