Introduction and short history

Malnutrition in older adults is a really important problem, occurs 40% more often in the older ones; and is identified in 1 of 3 older adults in the hospital, and in 1 of 2 rehabilitation patients (1). Subjects intake is often poor from lack of appetite, most adults in the hospital eat less than 50% of the served food at each meal and the proportion of patients with malnutrition increases during hospital stay (2,3).

A tool to assess nutritional status in older persons was really needed. It is why in 1989 at my first IAGG conference in Acapulco, I spoke about the MNA® idea with Yves Guigoz, from the Nestle International Research Center in Lausanne. I told him we must design and validate a tool for assessing nutritional status in the elderly analogous following the MMSE tool for assessing cognitive functions. Because already most physician know that a total score of 30 is the maximum for cognitive functions our total score for the MNA® must be also at 30.

Validation of the MNA® full form, short form and self-management form (fig. 1)

It took us 5 years (1994) to convince our colleagues, to design the tool, to complete the first validations studies both in France and in the U.S. and to publish it (4,5). We would like to acknowledge Werner Bauer, former director of the Nestlé Research Center who took the decision to fund the study, Phill Garry Ph.D., W.C Cameron Chumlea Ph.D., from the University of New Mexico Aging Process Study, Albuquerque, NM, USA and our team at the Gerontopole, including Sylvie Lauque RD. We validated the MNA® screening versus the results from 2 physicians with all the current nutritional assessment including nutritional intake, anthropometric measurement, and biological biomarkers (e.g. albumin, prealbumin, CRP, αl-acid glycoprotein, cholesterol, triglycerides, vitamins A, D, E, B1, B2, B6, and B12, folate, copper, zinc, haemoglobin, and blood cell count). We did it in two different populations in Toulouse area, France and in Albuquerque, NM, USA. Subjects were classified using principal component and discriminant analysis. Principal component analysis indicated that the MNA® can be used without clinical biochemistry. Threshold value ranges for risk of malnutrition and malnutrition were 22–24 points and 16–18 points, respectively, on a maximum of 30 points. Exact threshold values were then set by cross-tabulation of cut-off values for serum albumin without the presence of inflammation. We have been able to observe that those with an MNA® score less than 17.5 have usually protein-calorie undernutrition, those between 17 and 23 are at risk for malnutrition but have not yet protein-calorie undernutrition and those > 23 have in general an adequate nutritional status (57).

Figure 1
figure 1

MNA®: History & Development

Figure 2
figure 2

The MNA® forms

In 2001, With Larry Rubenstein, from U.C.L.A we developed validated the MNA® Short-form (8). The MNA® short form includes 6 items to do a first steps to screen those at risk for malnutrition. After completing the MNA® short form it is still useful if the subjects are scored at risk for malnutrition to complete the full MNA®. Carefully looking at the full MNA® items to determine where the subjects lose point can help to guide the nutrition intervention. For e.g. if we observe that a patient doesn’t eat on the evening we can propose something, them if some subjects need help to eat… it takes few minutes to do the MNA® SF and it is already a very common used tool.

In 2009 a Revised MNA® short-form (9) has been developed & validated as a stand-alone screening tool; it includes option for substituting calf circumference (CC) for BMI, and takes less than 5 minutes. The MNA®-SF is available in 42 languages, The validity of substituting CC for BMI has been further validated (1012).

In 2012 the Self-MNA® was developed (13) and validated in community-dwelling older adults, results shared with their family medicine (14). It takes 3–5 minutes. If we want to, improve the health of older persons self-management and participative care are very useful underlining the importance of such tool (15,16).

MNA® use in clinical research

As we can see in table 1, more than 2000 clinical research have used the MNA® all over the world on many topics from frailty to hip fractures, from community care to hospital (see recent publications 2018–2020 (1,14226) and MNA® and MNA®-SF tables Identifying the elderly at risk of malnutrition (Tables 213). We observed a prevalence of malnutrition of 5% (SE 0.1) and 4.3% (SE 0.1) in the community for MNA® and MNA®-SF respectively; of 11% (SE 0.2) and 11.0% (SE 0.3) for the frail elderly (outpatients and home care) respectively. A Higher prevalence of malnutrition is observed in hospitals, 22% (SE 0.2) and 29% (SE 0.3) for MNA® and MNA®-SF; and for institutionalized elderly 18% (SE 0.3) and 22% (SE 0.4) respectively. Cognitively impaired elderly and Parkinson’s disease patients have similar prevalence to the frail elderly, 14% (SE 0.4), and 6.3 (SE 0.9) for MNA®. (see Table 14: Prevalence of malnutrition and risk of malnutrition in different settings).

Table 1 MNA®: Publications
Table 2 MNA®-SF Clinical practice: Community-dwelling elderly — Identifying the elderly/adults at risk of malnutrition
Table 3 MNA® -SF Clinical practice: elderly — Hospial Settings — Identifying the elderly/adults at risk of malnutrition
Table 4 MNA® -SF Clinical practice — Frail elderly (Outpatient/Home Care) — Identifying the elderly/adults at risk of malnutrition
Table 5 MNA® -SF Clinical practice — Institution — Identifying the elderly/adults at risk of malnutrition
Table 6 MNA® -SF Clinical practice- Cognitively impaired elderly/elderly-adults with Parkinson’s disease — Identifying the elderly/adults at risk of malnutrition
Table 7 MNA® Clinical practice- Community-living elderly — Identifying the elderly/adults at risk of malnutrition
Table 8 MNA® Clinical practice- Hospital Settings — Identifying the elderly/adults at risk of malnutrition
Table 9 MNA® Clinical practice — Frail elderly (Outpatient/Home Care) — Identifying the elderly/adults at risk of malnutrition
Table 10 MNA® Clinical practice: elderly — Institution — Identifying the elderly/adults at risk of malnutrition
Table 11 MNA® Clinical practice: elderly — Cognitively impaired elderly — Identifying the elderly/adults at risk of malnutrition
Table 12 MNA® Clinical practice: elderly/adults with Parkinson’s disease — Institution — Identifying the elderly/adults at risk of malnutrition
Table 13 Self-MNA® Clinical practice: elderly — Identifying the elderly/adults at risk of malnutrition
Table 14 Prevalence of malnutrition and risk of malnutrition in different settings MNA®

The MNA® and MNA®-SF have been validated in many studies, used as reference standard to validate other screening tools and compared to following screening tools: MUST, NRS-2002, GNRI, SGA, PG-SGA, NRI, SNAQ, MST, and NUTRI score, in different settings, community, home care, nursing homes and hospitals (20, 30, 34, 42; 47, 53, 123, 181, 227258). The sensitivity and specificity of the MNA® are 80% (SD 13) and 68% (SD 22), respectively, against a wide range of criteria in 40 studies (see table 15: MNA® Sensitivity/Specificity against Nutritional assessment parameters & other parameters) (140, 222, 227, 228, 235, 241, 246, 248, 259287). The same is true for the MNA®-SF with a sensitivity of 87% (SD 10) and a specificity of 85% (SD 15) against the MNA®, and a sensitivity of 81% (SD 18) and a specificity of 63% (SD 20) against a wide range of criteria in 43 studies (Tables 16 & 17) (8, 12, 20, 41, 54, 67, 140, 222, 227, 228, 230, 234, 235, 240, 247, 266, 270, 278, 282, 284, 286, 288307). In general, it can be observed that MNA®-SF and MNA® are the most used tools to evaluate the risk of malnutrition in the elderly, independent of the setting, with high sensitivity, ≥ 80%, and a good specificity, ≥ 60% (Tables 1517), and see meta-analysis/systematic review, reviews, and content validity (1, 43, 47, 149, 182, 221, 308320). MNA®-SF and MNA® are appropriate screening and assessment tools for use in community-dwelling elderly (321), and all other geriatric settings (205,322329). Further the MNA®s are the only tools to evaluate the intake of nutrient-rich food groups, which allow for implementation of nutritional intervention. Discrepancies with other screening tools come mainly from the dietary assessment and the difference in weight loss evaluation. It is the only assessment tool assessing two «functional concept» related to muscle and cognitive function. MNA® can be improved by the addition of inflammatory factors or other biological nutritional biomarkers when needed.

Table 15 MNA® Sensitivity/Specificity against Nutritional assessment parameters & other parameters
Table 16 MNA® -SF Sensitivity/Specificity against Nutritional assessment parameters & other parameters
Table 17 MNA® -SF Sensitivity/Specificity against MNA®

The MNA® appears also to be useful as primary criteria for intervention studies, and move positively in several major studies (56,89,98,330334).

Further, the MNA® appears useful to measure frail older persons, especially when the MNA® is between 17 and 23.5 (27,286,303,335,336). Malnutrition and physical frailty seem to be strongly related, however, they should be assessed separately within the geriatric assessment (313,317,326,337341).

MNA® use in clinical practice

At least 22 Expert groups included the MNA® in new clinical practice guidelines, national or international registries (113, 116, 131, 132, 136, 151, 189, 190, 319, 324, 342377). New Global Leadership in Malnutrition (132) consensus publication outlines the diagnostic criteria for malnutrition, for application in clinical settings (131,151). GLIM Committee involved major global clinical nutrition societies: ASPEN, ESPEN, FELANPE, PENSA representatives (Tables 18). 42 Electronic Health Record Software Companies have incorporated MNA® in software, 22 APPS for Smartphones, tablets have incorporated MNA® (Table 19).

Table 18 MNA®: Practicalities
Table 19 MNA®: Incorporation of the MNA® into electronic and applications software

Notably, the MNA® screening tool evaluates items that are similar to relevant criteria that GLIM established for the diagnosis of malnutrition (202,378). Furthermore for the evaluation of malnutrition in the elderly, the MNA® with its two step procedure a) screening with MNA®-SF and b) nutritional status evaluation with the MNA® full form can be completed with evaluation of nutritional makers (e.g. as serum C-reactive protein and transthyretin (prealbumin) (379386)) or the GLIM criteria (131,206,207,223,376,387). This is of importance to separate malnutrition from inflammation, when undernutrition is due to disease related cachexia (174,380,383,388391). MNA® fulfill the two steps, screening followed by assessment, required by the GLIM criteria procedure for the diagnosis of protein-energy malnutrition in elderly (376,377), and provides guidance for nutritional intervention. Elderly with malnutrition or at risk of malnutrition should have a nutritional intervention with multidisciplinary team in order to support adequate dietary intake, maintain or increase body weight and/or improve functional and clinical outcome (184,189,190,363,392).

MNA® and Healthy aging

For the W.H.O Healthy aging is the capacity to maintain function, to be able to do what we value. The ICOPE step 1 includes some nutrition assessment (weight loss, poor appetite), and MNA® is part of the ICOPE program step 2, Integrated care of older persons (figure 3) to maintain functions in older adults (393395). Our practice needs really to move to prevention and ambulatory care. We need to provide good nutrition to the senior citizen and monitor their nutritional status, the aims of ICOPE Monitor apps part of the Inspire program is to monitor the main function including nutrition in older adults. The links between Nutrition and Geroscience for a healthy aging have to be studied (396,397).

Figure 3
figure 3

W.H.O Icope Pogram

Perspective for the future have of course to treat undernutrition in sick old adults; however, the urgent need is to target the frail older adults more likely to have weight loss and poor appetite. To do it, program for early detection of the risk of malnutrition should be implemented as it is in development in Netherlands (80,81,115,184), the NUDAD (Nutrition, the unrecognized determinant in Alzheimer’s disease) study (139,398) and within the Integrated Care for Older People (ICOPE) with the implementation of the INSPIRE study (213,394,399). Further the geriatric assessment to be comprehensive should include the MNA®-SF as nutrition parameters and all the elderly detected at risk of malnutrition or malnourished should be further evaluated with GLIM criteria, and MNA® to be able to implement a nutritional intervention. The best MNA® score to predict healthy aging is still to be determined