Data were obtained from InterRAI; a non-profit international multidisciplinary collaboration that aims to improve quality of life of older adults through systematic, accurate and standardized data collection of residents’ physical and psychosocial functioning (16). A specific assessment form was developed for each healthcare setting (17). The RAI Long-Term Care Facilities (LTCF) assessment form is a minimum data set (MDS) which includes nineteen sections, including residents’ nutritional, cognitive and psychosocial status. The assessment form is administered by trained nurses in interaction with the residents, their family members and other health professionals (17). Several studies have shown high validity and reliability of the assessment form (18–20).
Two groups were derived from residents admitted to a LTCF: the ‘newly admitted’ and the ‘existing’ residents. The newly admitted group had their first assessment taken place within one month after admission to a LTCF (‘admission assessment’); thereafter residents were monitored typically with quarterly or semi-annual follow-up assessments.
When a LTCF started using InterRAI, no ‘admission assessment’ was performed for the residents who were already living in that facility (‘existing’ residents). A ‘delayed first assessment’ was then noted as first measurement.
Dutch InterRAI subjects (aged ≥ 65 years) living in LTCF between 2005 and 2020 were included in this study. In total, 4190 residents with an ‘admission assessment’ were available, median time to first assessment was 16 days [IQR: 7–30] after admission. These residents represent ‘newly-admitted’ residents.
In contrast, the ‘existing’ residents are defined by having had their first measure after their initial admission. In total 5592 residents with a ‘delayed first assessment’ were available and this assessment took place with a median time of 345 [IQR: 117–914] days in male and 546 [IQR: 165–1363] days in female residents after their initial admission. Thus, the defining difference between the groups is the time elapsed between their admission and their first assessment, which was shorter in the newly admitted group and longer in the ‘existing’ residents’ group.
Inclusion criteria cross-sectional analyses
For the cross-sectional analyses, only data of ‘admission assessments’ were used (n=4190). Residents were included if data regarding malnutrition status were available. Exclusion criterion was presence of end-stage disease, i.e. terminally ill residents with a life expectancy <6 months as indicated by the treating physician, to exclude residents with incurable malnutrition. After exclusion, 3722 residents were available for analyses.
Inclusion criteria prospective analyses
For the prospective analyses, first assessment data of ‘newly-admitted’ residents as well as first assessment data of ‘existing’ residents and all subsequent follow-up measurements were used. Residents were included when they were not malnourished at their first available measurement and had one or more follow-up measurements where nutrition status was measured. Exclusion criterion was presence of end-stage disease at first or last measurement. After exclusion, 4978 residents were available for analyses.
Figure 1 provides an overview of the in- and exclusion process.
We used the following InterRAI scales for behavior and cognitive problems as independent variables: Communication Scale (SC), Cognitive Performance Scale (CPS), Depression Rating Scale (DRS), Revised Index of Social Engagement (RISE), Aggressive Behavior Scale (ABS) and total number of behavioral-cognitive problems. Malnutrition based on the ESPEN 2015 criteria was used as dependent variable.
Communication Scale (CS)
The CS is a standardized questionnaire that assesses the communication performance of subjects living in a LTCF. It consists of two communication items (understanding others, making oneself self-understood). The scale provides a score ranging from 0 (good communication performance) till 8 (poorest communication performance) (21). No validated cut-off values are available for CS but previous research showed that a cut-off value of ≥3 will identify the 10% most severe cases with communication problems (22). The CS was dichotomized into good communication performance (CS ≤2) or moderate to severe impairment (CS ≥3).
Cognitive Performance Scale (CPS)
The CPS is a standardized and validated questionnaire containing five items (decision making, memory, disordered thinking, change in mental status, change in decision making) to assess cognitive performance of subjects living in a LTCF (23, 24). It provides a total score ranging from 0 (cognitive performance intact) till 6 (very severe cognitive impairment) (24). The CPS has been validated against the MMSE, whereby a CPS score of 2 equals a MMSE score of 19 (24). Therefore, the CPS scale was dichotomized into ≤2 and ≥3.
Depression Rating Scale (DRS)
The DRS is a standardized and validated screening questionnaire to screen for depressive symptoms in subjects living in a LTCF (25, 26). It includes seven depressive mood and behavioral indicators (negative statements, anger, unrealistic fears, health complaints, anxious complaints, sad expressions, crying). All indicators have possible scores of 0 (indicator not present during the past 30 days), 1 (indicator present 1 till 5 times a week) or 2 (indicator present 6 or 7 days a week), resulting in a total maximum score of 14. A total score ≥ 3 indicates a resident is at risk for depression (26). Therefore, this item was dichotomized in low (≤2) or high depression risk (≥3).
Revised Index of Social Engagement (RISE)
The RISE is a standardized and validated measure of social engagement of subjects living in a LTCF (27). It includes six dichotomous indicators of social engagement (initiating social interaction, accepting social interaction, activity participation, accepting invitations and facility involvement). The scale provides a score ranging from 0 (poor social engagement) till 6 (high social engagement) (27). Based on the original validation paper of RISE, a cut-off of ≤2 reflects a division between low- and high functioning people (28). Therefore, the RISE was dichotomized into low social engagement (RISE score ≤2) and high social engagement (RISE score ≥3). The high social engagement group (RISE score ≥3) was chosen as reference group in our analysis.
Aggressive behavior scale (ABS)
The ABS is a validated four-item scale based on the following items: verbal abuse, physical abuse, socially inappropriate behavior and resisting care (29). These items are coded as: not present (0), present in last three days (1), happened once or twice in three days (2) or daily (3). Based on the four items, scores range from 0–12, and higher scores indicate aggressive behavior. The ABS was dichotomized into no aggressive behavior (ABS=0) or aggressive behavior present (ABS ≥1) (29).
Total number of behavior and cognitive problems
Based on the dichotomized scores of the scales mentioned above, a sum score of CS, CPS, DRS, RISE, ABS was created, which indicated on how many of the behavioral-cognitive scales problems were identified (range 0–5).
The primary end point of this study was malnutrition based on the ESPEN 2015 criteria; Body Mass Index (BMI) < 18.5 kg/m2, or weight loss (5% during last month or 10% in six months), in combination with a reduced age-specific BMI (< 20 kg/m2 < 70 years or < 22 kg/m2 ≥ 70 years) (30).
Data on age, gender, living status before admission (together vs. alone) and number of underlying diseases were obtained from the RAI-LTCF Assessment Form.
InterRAI assessments are performed for clinical purposes as part of routine care. Data is de-identified and thereafter transferred to the InterRAI database at the Amsterdam University Medical Centres — Location VUmc. Residents are informed (by their practice nurse, through newsletters, posters and website) in general terms that their data can be used for research purposes. Residents can object against use of their data and an opt-out procedure is available therefore. The Ethical committee of VUmc approved the use of data for research in this way.
All statistical analyses were performed in SPSS version 25 (IBM Corp., Armonk, New York, USA). Descriptive statistics were stratified by nutritional status and gender. Normality was checked by QQ-plots and stem-and-leaf plots. Means with standard deviations were used to describe continuous variables and numbers and percentages for categorical data. Logistic regression analyses were used to study the associations between CPS, CS, DRS, RISE, ABS and total number of behavior and cognitive problems (independent variables), and malnutrition (dependent variable). Kaplan-Meier curves and Cox Proportional Hazard regression analyses were performed with malnutrition as event and CPS, CS, DRS, RISE, ABS, and total number of behavior and cognitive problems as independent variables. Time to event was defined as days between first available assessment and the first follow-up assessment where malnutrition occurred. If someone was categorized as malnourished, all further follow-up measurements were removed. Residents who stayed well-nourished during their total follow-up period were censored and event time ended at their latest available measurement. Kaplan-Meier curves provided a graphical evaluation of the proportional hazard assumption. As these assumptions were met, Cox Proportional Hazard regression analyses were performed.
Stratification for gender was based on the significance of interaction terms (behavior-cognitive problem * gender). In the cross-sectional analyses this interaction term was significant (p<0.10) (31) for RISE, CPS and total number of behavior-cognitive problems. In the prospective analyses, interaction terms for DRS and total number of behavior-cognitive problems were statistically significant.
Thereafter, we tested whether there was effect modification by type of first assessment in the prospective analyses (behavior-cognitive problem * type of first assessment). Significant interaction terms (p<0.10) (31) were seen for male gender (CS, DRS, ABS, CPS and total number of behavior-cognitive problems). Based on this number of significant interaction terms and the large differences in effect sizes between men/women and newly-admitted/existing residents, we decided to present four different strata (for illustration, see appendix 1 for additional Kaplan-Meier curves on CS).
As previous studies showed that malnutrition is related to very old age (≤ 90 years vs. ≥ 91 years) (32), number of comorbidities (≤1 vs. ≥2) (33, 34) and living status before admission (alone vs. together) (35), all regression analyses were adjusted for these variables (model 1). As most behavioral-cognitive problems are associated with each other, a full model was created which included in addition all five determinants (CS, DRS, RISE, ABS and CPS) (full model).