Objectives: to assess the reliability and validity of the 46 items version of the comfort scale for family members of people in critical condition.
Methods: a methodological study, carried out with 278 family members of critically ill patients, admitted to adult and pediatric intensive care units, in a city in the interior of the state of São Paulo, in Brazil. The analyzes were based on the Classical Test Theory and Item Response Theory.
Results: Horn's parallel analysis and exploratory and confirmatory factor analysis did not identify the scale's unidimensionality nor the tridimensionality. The maximum factor loads were positive. The scale proved to be reliable (α=0.93 and Ω=0.63), most item-total correlations were greater than 0.28 and the discrimination coefficients were greater than one.
Conclusions: the scale showed satisfactory reliability and relative construct validity. However, the recommended tridimensional structure for the scale has not been confirmed.