Assessing functional status after intensive care unit stay: the Barthel Index and the Katz Index

To assess the functional status of post-ICU patients using the Barthel Index (BI) and the Katz Index (KI) and to assess which is more suitable for this population.

Retrospective longitudinal study.

Public tertiary hospital in São Paulo (Brazil).

Patients aged ≥18 years old, admitted to ICU, who were treated with mechanical ventilation (MV) ≥ 24 h and were discharged to ward.

Inability to answer the BI and the KI; limiting neurological or orthopaedic conditions; ICU stay ≥90 days. Patients transferred to or from other hospitals or who died in the wards were not analysed.

BI and KI were scored pre-ICU and post-ICU and the variation was calculated.

BI and KI scores were compared using analysis based on item response theory (IRT), using degree of difficulty and discriminating items as parameters.

Median age was 52 years old, median APACHE II score was 15. Median ICU stay was 11 days and median MV duration was 4 days. BI variation was 44% and KI variation was 55%. In IRT analysis, BI considered a larger number of items with different levels of difficulty.

Both the BI and the KI revealed significant deterioration of functional status after ICU discharge. The IRT analysis suggested that the Barthel Index might be a better scale than the Katz Index for the assessment of functional status of patients discharged from ICU, since it presented better discrimination of the ability to carry out the tasks.