Introduction
What is new?
Key finding- •
There is some conceptual uniformity in measuring functioning of patients in terms of activities of daily living (ADL) but far less uniformity in the operationalization of functional decline.
- •
A decline of 1 point in one study is equivalent to a 2% decrease in ADL functioning, whereas in other studies a decline of 1 point is equal to a 20% decrease in ADL functioning.
What this adds to what was known- •
Functional decline is an often-used outcome measure in older patients.
- •
Of all studies measuring ADL functioning, only four of 28 used the complete original content of the measurement instrument.
- •
Functioning of instrumental activities of daily living was almost never incorporated when operationalizing functional decline.
- •
There is a strong need for standardization of measurement of functioning.
What is the implication; what should change now- •
An expert group should answer several conceptual barriers to achieve uniformity in the process of measurement and operationalization:
- (1)
which activities of daily functioning should be incorporated in the disability continuum;
- (2)
which psychometrically sound instrument(s) should be used to measure the functioning of patients;
- (3)
what should be the optimal time frame in which functional decline is assessed;
- (4)
which clinical and scale score–related statistical definition of functional decline should be used, according to both the medical and patient perspectives.
Acute hospitalization in older patients is not without risk because these patients are more prone to adverse events as compared with younger patients [1], [2]. An important negative health outcome in this population is functional decline. Functional decline can lead to (permanent) disability and may lead to a prolonged hospital stay, institutionalization, and even death [3], [4], [5]. Medical patients are a vulnerable group for functional decline. They often present to the hospital with deterioration in functioning, as a result of an acute exacerbation of chronic multimorbid conditions. Not only in daily practice but also in clinical research, functional decline has become a key outcome after hospitalization in older patients, supported by the working group on functional outcome measures in clinical trails [6]. Activities of daily living (ADL) and instrumental activities of daily living (IADL) are an essential part of patients’ functional status, as is also demonstrated in the International Classification of Functioning from the World Health Organization (WHO) [7]. ADL and IADL functioning are located centrally in this model and affected by disease, impairment, personal factors, and environmental factors.
Many studies focus on functional decline after acute hospitalization in older patients. A review of McCusker et al. [8] already pointed out that there is a large variability in studies on functional decline in terms of study design, analysis, and time of follow-up. In this article, however, relatively little attention has been given to the measurement itself and the applied definitions of functional decline. Uniformity in measuring functional decline is essential for appraising study results and conducting meta-analyses. To achieve this uniformity, researchers should use reliable and valid instruments with clinically comparable item contents. Moreover, it is essential that there be agreement between what level of deterioration should be defined as “decline” and at what time point this should be assessed.
The objective of this systematic review was to study the instruments used to measure (I)ADL functioning and functional decline in acutely hospitalized older medical patients.