What Does a BIMS Score of 99 Mean?

A BIMS score of 99 does not represent a point value on the scale. The Brief Interview for Mental Status, used in nursing homes across the United States as part of the federally required Minimum Data Set (MDS 3.0), runs on a 0-to-15 scale. A code of 99 means the interview could not be conducted at all, usually because the resident was unable to communicate, was unconscious, or declined to participate. It is a placeholder that tells clinicians and care planners to look elsewhere for information about that person’s cognitive status.

How the BIMS Normally Works

The BIMS is a short, structured interview designed to be given directly to nursing home residents. It asks the person to repeat three words, state the current year, month, and day, and then recall the three words from earlier. Each response earns points, and those points add up to a total between 0 and 15. Validation research confirmed that scores cover the full instrument range of 0 to 15.¹ The scoring breaks down into three tiers: 13 to 15 suggests intact cognition, 8 to 12 indicates moderate impairment, and 0 to 7 points toward severe impairment.

The test was designed to be quick and practical. Most assessors can complete it in just a few minutes. It replaced the older approach where staff members answered questions about a resident’s cognition on the resident’s behalf, and its advantage is that the person being evaluated gets to speak for themselves. But that advantage becomes a limitation when the person cannot speak, cannot hear the questions, or otherwise cannot engage with the interviewer. That is where the 99 code enters the picture.

Why a BIMS Interview Cannot Be Completed

Several situations lead to a 99 code. The most common include residents who are comatose or in a severely reduced state of consciousness, those who have lost the ability to speak and do not use an alternative communication method the assessor can work with, and those who refuse to participate. In each of these cases, the assessor cannot get valid answers to the interview questions, so no numerical score between 0 and 15 can be assigned.

There is sometimes confusion about whether a 99 means the person “failed” the test in the worst possible way. It does not. A resident who attempts the BIMS and cannot answer any question correctly scores a 0, which is a real score at the bottom of the scale reflecting severe cognitive impairment. A 99, by contrast, carries no information about how the person would have performed. A fully alert resident who simply refuses to answer every question and a deeply unconscious resident both receive a 99, even though their cognitive states could be dramatically different. The code communicates an administrative fact about the assessment process, not a clinical finding about the person’s brain.

What Happens When the Code Is 99

The MDS assessment system anticipates that some residents will not be able to complete the BIMS. When a 99 is entered, assessors are directed to use a staff assessment pathway instead. Rather than interviewing the resident, nursing staff evaluate the person’s cognitive function based on their own observations of daily behavior. They look at things like the resident’s ability to make everyday decisions, whether the person can make themselves understood, and how well they recall recent events.

One structured tool that grew out of this need is the Cognitive Performance Scale, which combines five MDS items into a single seven-category ranking of cognitive function.² This scale draws on observable behaviors and clinical indicators rather than direct interview responses, so it can generate a cognitive estimate even for residents who cannot participate in a face-to-face test. The seven categories range from intact cognition down to very severe impairment, giving care planners a workable picture of a person’s functional abilities.

For families who see a 99 on a loved one’s assessment, the practical takeaway is that the care team should have gathered cognitive information through a different channel. If no alternative assessment appears alongside the 99, that is worth asking about. The 99 alone tells you nothing about the person’s mental status, so a care plan built only on a 99 would have a significant gap.

Hearing Loss and Incomplete Cognitive Assessments

One underappreciated reason BIMS interviews go incomplete is hearing impairment. The test is administered verbally. The assessor reads questions aloud, and the resident answers aloud. If a resident has significant hearing loss and no accommodations are made, the interview can break down before it starts.

Research on older adults has shown that hearing impairment is tied to higher rates of missing data on cognitive tests, and not just on tests that require listening. In a large population-based study, moderate-to-severe hearing impairment was associated with roughly 60 to 70 percent higher odds of missing scores on auditory tests like Logical Memory and Digits Backwards, but also on non-auditory tests like Boston Naming and Trail Making B.³ The pattern suggests that hearing loss does not just interfere with the mechanics of a verbal test; it may discourage participation entirely or create frustration that leads to refusal.

In a nursing home setting, this means that some residents coded as 99 on the BIMS may have intact or only mildly impaired cognition but were unable to engage because they could not hear the questions. Hearing aids that are missing, broken, or not inserted before the assessment can turn a routine cognitive screen into an impossible task. If you are a family member and your loved one uses hearing aids, making sure those aids are in and working before a scheduled MDS assessment is one of the simplest things you can do to ensure the BIMS produces a real score rather than a 99.

A 99 Is Not the Same as a 0

This distinction matters more than it might seem. In research and clinical decision-making, BIMS scores drive eligibility for programs, trigger care-planning requirements, and influence reimbursement. A study of nursing home residents with dementia used BIMS scores of 0 to 12 as one of its inclusion criteria for cognitive impairment, and reported an overall mean BIMS score of about 4.3 among its participants.⁴ A score of 4.3 represents severe impairment. Residents with a 99, however, were not included in that calculation at all, because a 99 provides no cognitive data to analyze.

This creates a quiet problem in quality measurement and research. Residents who cannot complete the BIMS often have the most complex conditions: they may be nonverbal due to advanced dementia, or unconscious after a stroke, or dealing with severe psychiatric symptoms that prevent cooperation. These are arguably the people whose cognitive status matters most for care planning, yet they fall into a data gap. The staff assessment pathway catches many of them, but it relies on the observations and judgment of busy nursing staff rather than a standardized interaction with the resident. The quality of that backup assessment varies.

How BIMS Fits Among Other Cognitive Screens

People who encounter the BIMS for the first time sometimes wonder how it compares to more widely known cognitive tests. The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) are two screening tools that come up frequently in clinical settings outside of nursing homes. Both are scored on different scales: the MMSE out of 30 and the MoCA also out of 30. Neither uses a 99 code for incomplete interviews in the same formalized way the MDS system does.

The BIMS was not designed to replace these broader tools. It was built specifically for the nursing home MDS assessment, where brevity and ease of administration matter. The MMSE and MoCA cover more cognitive domains, including visuospatial abilities, executive function, and language tasks that go beyond what the BIMS measures. Research comparing the MoCA and MMSE has found that the MoCA tends to be more sensitive at detecting early cognitive changes. In a study of genetic frontotemporal dementia, the MoCA could distinguish between people with no symptoms and those in the presymptomatic stage, while the MMSE could not, and the MoCA showed better overall discriminative ability.⁵

None of this means the BIMS is a poor test. Within its intended setting, its simplicity is a strength. It takes far less time than a MoCA or MMSE, it requires no pen-and-paper tasks (which matter for residents with motor impairments), and it feeds directly into the MDS system that drives nursing home care planning. But if a family member sees a 99 on a BIMS and wants a fuller picture of their loved one’s cognition, asking about a more comprehensive assessment like a MoCA or a formal neuropsychological evaluation is reasonable, provided the person can participate in such testing.

What Families Should Know When They See a 99

If you are reviewing a nursing home resident’s MDS assessment and see a BIMS score of 99, here is what to keep in mind:

It means “not tested”: The resident did not complete the interview. It says nothing about whether the person is cognitively intact or severely impaired.
Ask about the backup: The care team should have completed a staff assessment of cognition. If you do not see any cognitive evaluation at all, that is a gap worth raising.
Check for fixable barriers: Hearing aids, language barriers, pain, sedation, or timing of the assessment can all prevent a resident from completing the BIMS. Some of these can be addressed before the next quarterly assessment.
Request a reassessment if things change: If the 99 was coded during a period when the resident was acutely ill or recovering from a procedure, a follow-up BIMS once the person is more stable may produce a real score.

A 99 can also persist across multiple assessments for residents with conditions that permanently prevent verbal communication. In those cases, the staff assessment pathway becomes the ongoing source of cognitive information, and the BIMS will continue to show 99 each quarter. This is expected and not a sign of neglect, but it does mean the care plan’s cognitive picture depends entirely on staff observation rather than direct interaction with the resident.

Coding Quirks in the MDS System

The 99 code is part of a broader set of special codes used throughout the MDS 3.0, not just in the BIMS section. Across many items in the MDS, a dash or a specific number like 99 signals that the data could not be collected for a given resident. These codes exist because nursing homes serve people in an enormous range of conditions, from someone recovering from a hip replacement who is fully alert and oriented to someone in the late stages of a terminal illness who has not been conscious for weeks. A single assessment instrument cannot force every person into a numerical box, so the system needs escape valves.

For the BIMS specifically, the 99 triggers a branching pathway in the MDS software. Instead of calculating a cognitive summary from the BIMS score, the system pulls from the staff assessment items to generate a cognitive classification. This branching is automatic in most electronic health record systems used by nursing homes. The practical effect is that a resident with a 99 still ends up with some form of cognitive rating in their record; it just comes from a different source than the interview. How accurately that staff-derived rating reflects the person’s true cognitive state is an open question that varies by facility, by the training of the staff completing the assessment, and by how well the staff know the individual resident.

Understanding this coding system helps explain why a 99 can look alarming to someone unfamiliar with MDS conventions. Seeing a number that high next to the word “cognitive” naturally triggers concern, especially if you assume higher numbers mean worse outcomes. In reality, the number sits entirely outside the scoring scale and functions more like a flag than a measurement. If anything, the appropriate reaction to a 99 is curiosity about what came next in the assessment process, not alarm about the number itself.

When the Same Resident Scores Differently Over Time

It is not unusual for a nursing home resident to have a mix of real BIMS scores and 99 codes across successive quarterly assessments. A resident recovering from a severe infection might be too drowsy or confused to complete the BIMS during one assessment period, score a 99, and then score an 11 three months later after the infection resolves. Another resident might score 6 on one assessment and 99 on the next because they developed a condition that temporarily or permanently prevents verbal communication.

These fluctuations do not necessarily mean the person’s cognition is yo-yoing. They often reflect changes in the person’s ability to participate in the test rather than changes in their underlying brain function. Delirium, medication changes, acute illness, pain, and fatigue can all temporarily make the BIMS impossible to complete or dramatically lower the score even when the person’s baseline cognitive ability has not changed. For family members tracking a loved one’s trajectory, looking at patterns across multiple assessments and paying attention to the reasons behind any 99 codes gives a much clearer picture than any single data point.

Nurses and social workers who work in long-term care deal with these coding realities daily, but the scores are increasingly visible to families through patient portals and discharge paperwork. A number that is routine to clinical staff can be mystifying or frightening to a family member who encounters it with no context. If you are in that situation, the simplest move is to ask the director of nursing or the MDS coordinator at the facility to walk you through the assessment. They can explain not just what the 99 means, but what cognitive information was gathered through other channels and how it is shaping the care plan.