R. Moreno P. Morais Validation of the simplified therapeutic intervention scoring system on an independent database* Received: 29 October 1996 Accepted: 27 February 1997 *In collaboration with the Portuguese Se- verity Scoring Systems Study Groups of the Portuguese Intensive Care Society and of the Portuguese Society of Internal Medi- cine (list of authors, see appendix) R. Moreno ( ) ⋅ P. Morais Intensive Care Unit, Hospital de Santo Anto ´ nio dos Capuchos, Alameda de Santo Anto ´ nio dos Capuchos, P-1150 Lisboa, Portugal FAX: + 351 (1) 4844635 e-mail: r.moreno@mail.telepac.pt Abstract Objective: To evaluate the performance of the Simplified Ther- apeutic Intervention Scoring System on an independent database and de- termine its relation with the Thera- peutic Intervention Scoring System in the quantification of nursing workload in intensive care. Design: Analysis of the database of a multicenter prospective Portu- guese study. Setting: 19 intensive care units (ICUs) in Portugal. Patients: Data on 1094 patients con- secutively admitted to the ICUs were collected during a period of 3 months. Methods: Collection of the data necessary for the calculation of the Therapeutic Intervention Scoring System (TISS-76) and the Simplified Therapeutic Intervention Scoring System (TISS-28) during the first 24 h in the ICU. Basic demographic statistics and all the variables neces- sary for the computation of the Sim- plified Acute Physiology Score II were also collected. Vital status at discharge from the hospital was reg- istered. Regression techniques, Pearson’s correlation and paired sample t-test were used. Results are presented as mean ± standard devi- ation except when stated otherwise. Reliability was evaluated by the use of intraclass correlation coefficients in a 5 % random sample. Measurements and results: After ex- clusion of all the patients with miss- ing data, 1080 patients were analy- sed. The overall mean TISS-28 (29.82 ± 10.64) was significantly lower than the mean TISS-76 (31.14 ± 11.95). Both systems showed very significant differences between ICUs (p < 0.001). The cor- relation between the two was good, with TISS-28 explaining 72 % of the variation of TISS-76 (r = 0.85, r 2 = 0.72). The relation between the two systems was TISS- 28 = 6.22 + 0.85 TISS-76. In this cohort, reliability of data col- lection was very high, with intraclass correlation coefficients greater than 0.90 for both systems. Conclusions: TISS-28 was validated on this independent population. The results indicate that TISS-28 can re- place TISS-76 for the measurement of the nursing workload in Portu- guese ICUs Key words Therapeutic Intervention Scoring System ⋅ Simplified Therapeutic Intervention Scoring System ⋅ TISS- 28 ⋅ Intensive care unit ⋅ Nursing workload Intensive Care Med (1997) 23: 640–644  Springer-Verlag 1997 ORIGINAL