The Case for the Cognitive Function Scale
- Many nursing facility residents are assessed with the Minimum Data Set (MDS) 3.0 item set. This contains a Brief Interview for Mental Status (BIMS) or a longer staff assessment for mental status.
- The BIMS does not contain questions required for the long-popular Cognitive Performance Scale, but it also cannot be completed in many cases involving varying cognitive impairment severity.
- So, the Cognitive Function Scale for the MDS 3.0 can categorize residents as either cognitively “intact” or as “mildly,” “moderately,” or “severely impaired.” Each category on the Cognitive Function Scale maps to a resident’s scores on the BIMS or CPS.
- Kali Thomas, David Dosa, Andrea Wysocki, and Vincent Mor developed and validated the MDS 3.0 Cognitive Function Scale in a September 2017 publication in Medical Care.
Cognitive function of nursing facility residents should be assessed at admission, and perhaps in all assessments using the Minimum Data Set assessment tool. These assessments are reported by nursing facilities’ staff to the Centers for Medicare and Medicaid Services (CMS) and therefore generate a panel of data for each resident about their condition and planned care in the nursing home.
The MDS is not a research tool, but researchers can use it carefully to better understand nursing facilities and their residents. In particular, researchers can access MDS assessments that are generated during a Medicare-covered short stay (e.g. post-hospital care) and those for Medicaid-covered long stays. These may be from the CMS Integrated Data Repository, from the CMS Chronic Conditions Warehouse, or from the ResDAC’s HRS merged datasets. This past week, my task with Dr. Joanne Lynn, MD, has been to define cohorts of frail Medicare beneficiaries using the Chronic Conditions Warehouse MDS 3.0 records, among other data sources (OASIS assessments for home health, and perhaps Medicare claims for Parts A & B).
Some fields in the MDS are to be filled out for care planning and assessment, but filling them out is not required for payment. Staff fill these fields out less frequently than those tied to payment, but are less incentivized to report the fields to the nursing home. My task this past week has revealed this trade-off: MDS information about cognitive functioning of nursing facility residents is frequently missing; MDS information on physical functioning (ADL deficits) is not often missing, but it may be biased for financial reasons precisely because the pay received depends on assessors’ answers there.
Cognitive Functioning Disrupted by MDS 3.0 Switch
When the MDS changed to a new version, from v2.0 to v3.0, in 2010, researchers faced a problem: a measure used for cognition was no longer consistently available. In the v2.0 era, researchers and CMS alike had drawn on several data fields — most crucially about short-term memory and daily decision making — to compute a Cognitive Performance Scale (CPS) based on MDS 2.0 records. The v3.0 MDS stopped consistently capturing those crucial memory and decision fields, to accommodate faster mental screening. The default MDS workflow instead uses the Brief Instrument for Mental Status (BIMS), which is brief and gives an intuitive ordinal score from 0 (all at issue) to 15 (no issue). The BIMS is not administered to all residents: if the “resident is rarely/never understood,” or if the resident does not complete the BIMS, then the assessors instead fill out a longer section containing the CPS’ requisite memory and decision fields. In that minority of cases, the CPS can be measured. However, not all of these cases necessitate the resident is usually or even currently truly unable to complete the BIMS. In the MDS 3.0’s early years, the BIMS was uncompleted for 17% of cases where a long-stay resident would be eligible — so the lack of a BIMS is a noisy signal of severe cognitive dysfunction. We’d be remiss to use the BIMS alone and to deem all non-BIMS-completers as severely impaired. How, then, do we crosswalk from the BIMS to the CPS?
Resources for Analyses of Frailty and Cognition in the MDS 3.0 and OASIS
The CPS, the Cognitive Performance Scale from MDS 2.0
The Cognitive Performance Score has seven categories, notably “intact” and “borderline intact” and then five escalating categories of “mild impairment” to “very severe impairment.”
The “very severe impairment” class has a coma or has both severely impaired decision making and total dependence for eating. The “mild impairment” class has no severe impairments but has some impairment.
The BIMS, the Brief Interview for Mental Status
The BIMS assesses for three things:
- ability to repeat three words, for
- ability to recall those words from the interview’s start again at its end, and for
- accuracy in recounting the current year, month, and weekday.
The BIMS generates a score from 00 to 15, and this field’s name in the MDS records starts with C0500. It appears this will have the value 99 if BIMS was not conducted. Probable, correct skip patterns are discussed later.
The CFS, the Cognitive Function Scale using either the BIMS or CPS
The Cognitive Function Scale simply provides a crosswalk between the BIMS and CPS patterns in MDS 3.0: it does not try to replicate the CPS’ eight-level structure.
Validation still occurred: its creators analyzed concordance between the scale and BIMS and CPS, and the CFS was validated against MDS 3.0 behavior items that should concord with cognitive status. It was also validated against CPS from MDS 2.0, using 2 records <100 days apart that were 3.0 and 2.0.
At first, I thought that the CFS’ most arguable assumption is that completing the CPS indicates the resident’s cognition cannot be intact. However dubious I felt about the assumption a priori, of all long-stay residents
|CFS Score||CPS Score||BIMS Score|
Calculating the Cognitive Function Score
For constructing the BIMS and CPS without attending to data quality issues, one will need from their Chronic Conditions Warehouse MDS 3.0 extract:
- C0500_BIMS_SCRE_NUM, for BIMS score or indication it was uncompleted.
- If C0500 has the value 99, you will need all of the following.
- C0700 Staff Assessment of Mental Status – Short Term Memory Code, C0700_SHRT_TERM_MEMRY_CD, 1 or 2.
- C1000 Cognitive Skills for Decision Making Code, C1000_DCSN_MKNG_CD, integers 0-3.
- G0110H1 ADL Assistance: Eating Self Performance Code, G0110H1_EATG_SELF_CD, integers 0-4, 7, or 8.
- B0700 Makes Self Understood Code, B0700_SELF_UNDRSTOD_CD, integers 0-3.
- B0100 Comatose Code, B0100_CMTS_CD, integers 0 or 1.
Brief Interview or Staff Assessment? An addendum about data quality.
In the CCW, it seems three patterns for the BIMS or longer staff assessment (here, called SAMS) should exist:
- No BIMS, yes SAMS: In the BIMS section, whether-to-conduct C0100 == 0, then C0200 through C0400C have carrots indicating blank because of skip pattern, and finally C0500 == 99. In the SAMS section, whether-to-conduct C0600 == 1, and then SAMS items C0700 through C1600 have 0s, 1s, or 2s.
- Yes BIMS, no SAMS: In the SAMS section, whether-to-conduct is 0, and SAMS items are blank. In the BIMS section, whether-to-conduct is 0, then BIMS items are filled with integer among 0 through 3, and BIMS score is an integer among 0 through 15.
- Incomplete BIMS, yes SAMS: In the BIMS section, whether-to-conduct is 1, but some BIMS items are blank or incomplete; then, BIMS score is 99. In the SAMS section, whether-to-conduct is 1, and SAMS items C0700 through C1600 have 0s, 1s, or 2s.
A final helpful resource: Example of a state’s instructions for BIMS assessors (Maryland): http://www.foundationsgroup.net/files/126558935.pdf