The Strain of Care for Delirium Index: a new instrument to assess nurses' strain in caring for patients with delirium.

This study evaluated content validity, internal consistency and construct validity of the Strain of Care for Delirium Index (SCDI), a newly constructed instrument to measure the strain nurses experience in caring for patients with delirium. Content validity, evaluated by eight experts, reduced the initial pool of items from 38 to 28. Using a convenience sample of 190 nurses, Cronbach's alpha for the 28-item version was 0.88. Using non-linear principal components analysis another eight items were eliminated and a four-factor structure was identified. The proportion of variance explained by the remaining 20 items was 61.51%. Preliminary psychometric evaluation of the SCDI supported content validity, internal consistency and construct validity; however additional psychometric evaluation is warranted.