Even a small change can make a big difference: the case of in-hospital cognitive decline and new IADL dependency.

Background: post-hospitalisation functional decline is a widely described phenomenon, yet factors related to new disability in instrumental activities of daily living (IADL) in previously independently functioning older adults are rarely studied.
Objective: to test whether change in cognitive status from admission to discharge during short-term acute-care hospitalisation is associated with the incidence of medium-term post-hospitalisation IADL dependency.
Design: prospective cohort study.
Setting: internal medicine wards in two Israeli medical centres.
Subjects: two hundred and seventy-two hospitalised older adults (≥70) who were independent in self-care and mobility activities at admission, at discharge and 1 month after discharge, and who were independent in IADL pre-admission.
Methods: cognitive status was evaluated at admission and at discharge using Pfeiffer's Short Portable Mental Status Questionnaire (SPMSQ). One-month post-discharge, IADL was assessed using Lawton and Brody's scale by telephone.
Results: incidence of IADL dependency was 74/272 (27.2%). Controlling for length of stay, co-morbidities, re-hospitalisation and age, a one-unit decrease in SPMSQ score during hospital stay was associated with 1.57 higher odds (95% CI, 1.14-2.15) of post-hospitalisation new IADL dependency. The odds of new IADL dependency were also significantly higher in participants who were rehospitalised within the previous month (odds ratio = 2.65; 95% CI, 1.25-5.62).
Conclusions: decline in SPMSQ score during acute hospitalisation has a detrimental effect on functional decline after acute hospitalisation, defined by incidence IADL dependency. This finding emphasises the need to identify cognitive decline during hospitalisation to allow timely intervention to prevent post-discharge functional decline in this population.
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