... Consistent with the Donabedian model, 55 the existing literature examines a wide range of determinants that affect hospital LOS. 11,13,14,[56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74] We illustrate some examples of these determinants in our conceptual framework of Figure 2, which we categorize as: (1) patient characteristics (eg, age, sex, race/ethnicity) 11,13,56-66 ; (2) hospital characteristics (eg, hospital ownership type, volume, region) 11,13,56,58,60-62,67,75 ; (3) clinical caregiver characteristics (eg, specialty, training) 14,57,59,61,66,[68][69][70][71][72][73] ; and (4) social/family environment characteristics (eg, number of people living in household, patients' family preferences). 57,61,63,65 Despite these broad and complex determinants of LOS, however, most studies include controls only for patient characteristics in their models. ...