This is the first study that investigates the relationship between CONUT, albumin and the risk of malnutrition in primary care. The CONUT score, based on three widely used laboratory markers, detected more patients at risk of malnutrition, than albumin alone. The intervention to automatically report the CONUT score when all three necessary laboratory tests were requested was successful, and at a zero cost. The number of patients at risk of malnutrition through the CONUT score increased with patient age. By measuring non-requested albumin and/or total cholesterol tests needed for CONUT calculation when serum was available and lymphocytes counted, it would be possible to assess the risk of malnutrition of all primary care patients undergoing laboratory testing, at a very affordable and reasonable cost, for later to be confirmed/discarded with proven nutritional tools.
When comparing serum albumin levels < 35 g/L as the unique marker for risk malnutrition with CONUT score, it would result in up to 80% of the subjects being misdiagnosed (20), as albumin alone identified every severe case, but missed a significant number of patients at risk of malnutrition (mild and moderate cases) through CONUT score. However, CONUT score identified the risk of malnutrition in 24.1% of the studied patients, figures that may seem too high for a primary care population. It might be explained for two facts. First, the patients with the three involved markers, and consequently evaluated for risk of malnutrition through both methods, had a median (IQR) age of 68. These numbers are not representative of a primary care population but of a primary care elderly population. Second, there could be patients with clinical suspicion of risk of malnutrition, since the GP ordered serum albumin. Consequently, in our study, CONUT score could have been calculated in a primary care elderly population at risk of malnutrition.
Moreover, and to try to explain the differences in the number of patients identified at risk of malnutrition through CONUT and serum albumin, it has been reported that serum albumin cutoff of 35 g/L under-diagnoses malnutrition as defined by validated nutrition screening tools such as Mini Nutritional Assessment (MNA), Nutritional Risk Screening 2002 (NRS-2002), Mini Nutritional Assessment-Short Form (MNA-SF), and Geriatric Nutritional Risk Index (GNRI)) (21). Moreover, the utility of serum albumin and the traditional cutoff (35 g/l) in physically impaired elderly older people has also been reported that is questionable (22). Based on the above, it might be reasonable to replace albumin for CONUT score. It could be a better laboratory indicator to identify patients at risk of malnutrition, especially key in overcrowded primary care. Malnutrition will be confirmed/discarded as soon as possible with proven nutritional assessment tools, to establish the appropriate measures for its correction and subsequent monitoring.
Our study shows that the CONUT score increased with aging, as we detected more subjects at risk of malnutrition in the elderly population. Malnutrition remains a significant and highly prevalent public health problem of developed countries, especially in old population. Earlier identification and appropriate nutrition support may help to reverse or halt the malnutrition trajectory and the negative outcomes associated with poor nutritional status (23). Healthcare professionals should identify the malnutrition risk, and take action, as early as possible (24).
Detecting malnutrition in the general population through traditional tools could be too expensive. Our study results of the potential intervention involving CONUT as a screening tool in all primary care patients who had a laboratory request, by measuring serum albumin and/or total cholesterol when not requested, taking advantage of the serum sample availability and the affordable reagent cost, seems cost-effective. Especially if considering the examined population of more than 70000 primary care patients. The results of our study provide us the opportunity to develop a large-scale opportunistic detection of the risk of malnutrition in the general population, to be subsequently confirmed/discarded through traditional malnutrition evaluation tools.
The study had some limitations. First, patients with CONUT score showing risk of malnutrition were not studied with the nutrition traditional tools, however it has been confirmed in different settings the validity of the CONUT system for early detection and monitoring of clinical undernutrition (25). Second, the calculated economic investments may not apply to other countries or settings, since our laboratory belongs to the Public Health Network, where reagent prices tend to be low.
CONUT score, calculated at no cost when requested involved laboratory markers, detected more patients at risk of malnutrition than albumin, increased with patient age, and could be calculated in all primary care patients by measuring unrequested tests, at a very affordable cost. The early detection of risk of malnutrition at initial stages through the CONUT score, that could be confirmed/discarded through traditional nutritional tools, could greatly improve primary care patient’s outcome.