Modified Rankin Scale (mRS) Calculator

How to Use This Calculator

1. Select the mRS grade that best describes the patient's current functional disability level.
2. Disability level, functional independence, and clinical trial context display instantly.
3. Use the Thrombectomy tab to assess pre-stroke mRS eligibility for reperfusion therapy.
4. In the professional tier, enter both current and premorbid mRS for shift analysis.

Formula

Example

Frequently Asked Questions

• What is the Modified Rankin Scale and how is it used in stroke care? ▼
  The Modified Rankin Scale (mRS) is a widely used clinician-reported outcome measure assessing the degree of disability and dependence in daily activities for patients who have suffered a stroke or other neurological condition. It was originally developed by Rankin in 1957 and modified by van Swieten et al. in 1988. The scale consists of seven grades from 0 to 6: 0 (no symptoms at all), 1 (no significant disability despite symptoms — able to carry out all usual duties), 2 (slight disability — unable to perform all previous activities but able to manage personal affairs independently), 3 (moderate disability — requires some help but able to walk without assistance), 4 (moderately severe disability — unable to walk without assistance and unable to attend to own bodily needs without help), 5 (severe disability — bedridden, incontinent, requires constant nursing care), and 6 (death). The mRS is the primary outcome measure in most pivotal stroke clinical trials, including the landmark NINDS tPA trial, the ESCAPE and DAWN thrombectomy trials, and most modern NIHSS-based intervention studies. A 90-day mRS is the standard primary endpoint in stroke reperfusion trials, where mRS 0-1 is typically considered excellent and mRS 0-2 is considered functionally independent.
• How is the mRS score reliably assigned at bedside? ▼
  Reliable mRS assignment requires a structured approach because the scale describes functional state rather than specific neurological deficits, and inter-rater variability can be substantial without standardized assessment. The gold standard is the structured mRS interview developed by Wilson et al. and validated in multiple languages. The clinician should ask the patient and family or caregiver a structured series of questions covering: ability to perform all pre-stroke activities without help (grade 0-1); ability to manage daily personal care — grooming, dressing, cooking, cleaning — without assistance (grade 2 threshold); ability to ambulate independently without aids (grade 3 threshold); ability to perform self-care independently — bathing, toileting, feeding without help (grade 4 threshold); and whether the patient is fully dependent and bedridden (grade 5). Critically, the assessor should determine the grade based on the most restrictive criterion — if a patient can walk but cannot manage personal care independently, they are grade 4, not grade 3. Pre-stroke mRS (premorbid function) is equally important to document, as it defines baseline and is used in eligibility criteria for thrombolysis and thrombectomy. Telephone-based structured interview can achieve reliability comparable to in-person assessment.
• What is the significance of mRS 0-1 vs mRS 0-2 as trial endpoints? ▼
  In stroke reperfusion trials, the distinction between mRS 0-1 and mRS 0-2 as primary endpoints has important clinical and scientific implications. mRS 0-2 (functionally independent) is the most widely used primary endpoint and was used in the ESCAPE, EXTEND-IA, and MR CLEAN thrombectomy trials. It captures patients who have returned to independent living despite some residual disability. mRS 0-1 (excellent outcome — no significant disability) is a stricter endpoint that captures patients with near-complete recovery and is used in some trials to emphasize optimal outcomes. The difference matters because treatment effects can be statistically significant for one endpoint but not the other depending on the severity of the enrolled population. In patients with mild strokes (low NIHSS), mRS 0-2 may be too easy to achieve, making it an insensitive endpoint, while mRS 0-1 better discriminates treatment benefit. Conversely, in severe strokes (high NIHSS or large core infarcts), mRS 0-2 captures meaningful shifts from dependent to independent. Modern trial methodology increasingly uses ordinal shift analysis across the entire mRS distribution (ordinal logistic regression) rather than a binary cutpoint, which captures treatment effects across all levels of outcome and is more statistically efficient.
• How does the mRS relate to eligibility for tPA and mechanical thrombectomy? ▼
  Pre-stroke mRS is an explicit eligibility criterion for both intravenous thrombolysis (tPA) and mechanical thrombectomy in guideline-based clinical practice. For intravenous tPA (alteplase or tenecteplase), the standard eligibility criteria include pre-stroke mRS of 0 or 1, meaning only patients with no prior disability or very mild residual disability are considered for thrombolysis. This restriction reflects the difficulty in attributing new deficits to the acute stroke versus baseline disability, and the lower absolute benefit from reperfusion when baseline function is already compromised. For mechanical thrombectomy, the pivotal trials (ESCAPE, DAWN, DEFUSE-3) all required pre-stroke mRS of 0 or 1 for enrollment. However, contemporary clinical practice guidelines and expert consensus increasingly support considering thrombectomy in selected patients with pre-stroke mRS 2, particularly those with large proximal occlusion and small core infarct, where meaningful functional recovery is achievable. Pre-stroke mRS of 3 or greater generally represents an unfavorable baseline from which major recovery is unlikely even with successful reperfusion, and thrombectomy in this group remains largely outside guideline recommendations. For any individual patient with pre-stroke mRS 2 or higher, the decision requires senior stroke neurology consultation and shared decision-making with the family.
• What is an mRS shift analysis and why is it used in stroke trials? ▼
  mRS shift analysis, also called ordinal shift analysis or ordinal logistic regression, is a statistical approach used in stroke clinical trials to assess the distribution of outcomes across all seven mRS grades rather than dichotomizing outcomes at a single cutpoint such as mRS 0-2. Instead of asking "what proportion of patients achieved mRS 0-2 versus 3-6," shift analysis asks "was the entire distribution of outcomes shifted toward better grades in the treatment group compared to control?" This approach has several important advantages. First, it uses all available information from each patient's outcome rather than collapsing the scale into a binary variable, making it more statistically powerful. Second, it captures benefit even for patients who remain dependent but improve from mRS 5 to mRS 3, which a binary mRS 0-2 endpoint would not count as a success. Third, it is more sensitive to treatment effects in populations where very few patients achieve mRS 0-2 (severe strokes) or where most patients already achieve mRS 0-2 (mild strokes). The common odds ratio is the summary statistic from ordinal shift analysis — a value greater than 1 indicates a shift toward better outcomes across the distribution. Modern stroke trials including DAWN and DEFUSE-3 used both binary mRS 0-2 and ordinal shift as co-primary or sensitivity endpoints. The FDA and ESC/AHA guidelines increasingly endorse shift analysis as the preferred statistical method for stroke reperfusion trials.

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