It is increasingly widely recognized that hospitalized patients are undernourished and that circa 30% of patients are at nutritional risk on admission to hospital.1–3 Chronic Obstructive Pulmonary Disease (COPD),4–6 lung cancer7,8 and tuberculosis9 are pathologies that tend to be associated with undernutrition. Although the frequency of undernutrition risk in these pathologies has been studied, the data on the nutritional status of patients admitted to Pulmonology departments in very limited. A multicenter study conducted recently by Fang et al. in China revealed a frequency of 55.9% of undernutrition risk in a Pulmonology unit,10 which justified the need to clarify whether the extent of this problem is confirmed in Portugal.

Some of the factors that increase undernutrition risk have already been mentioned, namely female gender and advanced age.11,8 The presence of the disease is critical since it is associated with increased risk of infection, organ dysfunction and pharmacological therapy.3,8,12,13 In the past not enough attention was given to the importance of evaluating and monitoring parameters related to nutritional status, however the need to conduct undernutrition screening has now been widely recognized.11,8

Screening for undernutrition is justified by the fact that undernutrition is associated with adverse consequences for health as it increases predisposition to disease and inhibits recovery.11 It has been reported that undernourished patients stay in hospital approximately 1.5-1.7 times longer than normal weight patients.10,14,15 Undernutrition also increases the risk of infections and multiorgan dysfunction, the pressure on health care facilities and mortality, all of which have strong economic consequences.3,13,16–18

To the best of our knowledge, the association between undernutrition risk and hospital admission pathology, time of admission and clinical outcomes has not been quantified for pulmonology patients, hence the need to conduct this research to improve our understanding of the extent of the problem and to confirm whether the associations already described for other classes of diseases can be confirmed in Pulmonology patients. The present study aims to contribute to the characterization of the risk of undernutrition of patients admitted to Pulmonology units and to quantify the possible associations between undernutrition risk, assessed by the Malnutrition Universal Screening Tool (MUST) and admission pathology, length of hospital stay and discharge destination.

This sample was composed of 323 patients (220 male and 103 female), with 18.3% showing high risk of undernutrition and 15.5% moderate risk. The pathology that most frequently led to hospitalization in patients at moderate and high undernutrition risk was, respectively, COPD (22% and 27.1%) and lung cancer (26% and 23.7%) (Table 1). The patients at high risk of undernutrition were those who had a weight loss of often more than 10% (p < 0.001) (Table 2). There were no statistically significant differences in hospital length of stay according to undernutrition risk classes (p=0.765).

Undernutrition risk and hospital discharge destination were not independent (p<0.001). A higher proportion of patients with low risk of undernutrition were found to be discharged home, while the proportion of deaths was higher in patients with a high risk of undernutrition (25.4%) (Table 1). Stratifying patients by BMI categorization,22 revealed that 66.7% of patients with high risk of undernutrition had low weight (p<0.001). In the remaining classes of undernutrition risk, the majority of patients had normal–weight (Table 2).

In multivariate analysis, males showed a higher undernutrition risk compared to females (OR=1.79, 95% CI: 1.06-3.01). COPD was the pathology associated with a higher risk of undernutrition (OR=4.04, 95% CI: 1.83–8.90). It was also observed that pneumonia (OR=2.31, 95% CI: 1.15-4.64) and lung cancer were associated with high undernutrition risk (OR=2.12, 95% CI: 1.01-4.47). Moreover, patients at moderate/high risk of undernutrition are 2.72 times more likely to die during hospitalization (OR=2.72 95% CI: 1.48-4.97) (Table 3).

The frequency of Pulmonology patients at high (18.3%) and moderate undernutrition risk (15.5%) at the time of hospital admission was shown to be relevant; one in three patients admitted to this unit is at risk of undernutrition. Fang et al. using the Nutritional Risk Screening 2002 reported recently on 440 patients admitted to a Chinese Pulmonology unit who had a higher risk of undernutrition (55.9%) than found in this present study.10 Using the same method, Lucchini et al. reported on a sample of 35 patients admitted to an Italian Pulmonology Department of whom 40.0% were at risk of undernutrition.23

Previous studies evaluating the frequency of risk of undernutrition using the MUST have been conducted among patients from other medical departments. In one Internal Medical unit, 25.4% of patients showed a high risk of undernutrition, higher than that found in the present sample.24 Similarly, 47.5% of surgery patients were at high risk.25 These differences may be explained by the characteristics of the sample and the methodology used.

Diseases such as COPD,4–6 lung cancer7,8 and pneumonia stood out26 among the conditions which led to hospitalization of patients at high risk of undernutrition. It has been reported that pneumonia patients have a higher prevalence of weight loss and biochemical changes related to nutritional status such as hypoalbuminemia.26 These changes may explain high frequency of undernutrition in these patients.

According to the literature, tumours are associated with high rates of undernutrition.8 A study by Zhang et al. conducted in patients hospitalized with a diagnosis of lung cancer, showed that 33% had undernutrition risk.27 Although a different undernutrition screening tool (the Mini Nutritional Assessment) was used from the one in the present study, a significant frequency of patients with lung cancer at undernutrition risk (23.7%) was identified. The fact that some patients with lung cancer had previously received nutritional advice, may have contributed to a lower frequency of undernutrition risk than previously reported.

Gupta et al. conducted a study amongst hospitalized patients with COPD which showed that 83.0% were undernourished.5 In the present study, a high proportion of COPD patients (27.1%) were at a high risk for undernutrition. It is not known if the previous study of the association between the reason for admission and risk of undernutrition was in an environment similar to this study, so comparisons cannot be made.

When comparing the frequencies of the outcomes of hospitalization according to risks of undernutrition it was found that the majority of patients with low risk were released home and the number of deaths was higher in patients who were at risk of undernutrition (25.4%). These results are consistent with indications that undernutrition is associated with increased risk of mortality.26

Contrary to what has been previously described, it was found that males are more likely to be at medium/high undernutrition risk11,8 and no differences were found in length of hospital stay according with undernutrition risk classes.14,15

This research has some strengths; it is heterogeneous as it is composed of patients with different reasons for hospital admission and covers the full spectrum of diseases treated in a department of pulmonology. The study used MUST as the undernutrition screening tool as it is recommended for this purpose and has been validated for use in hospital.14,16 The fact that all the data was collected by the same investigator reduces the possibility of inter-observer variations and the possibility of misclassification in undernutrition risk classification.

The limitations of the present study include those inherent to its design. Patients admitted to the department studied may not represent the full spectrum of nutritionally relevant Pulmonology diagnoses and stages, especially those which are seasonal, although a relevant consecutive sample was obtained. Also, the small sample size obtained in some diagnostic groups compromised the statistical analyses and the inference for some types of patients.

We can conclude that patients in the Pulmonology Department showed a significant rate of undernutrition risk and patients with COPD or lung cancer were those with the highest risk of undernutrition. Patients at undernutrition risk were more likely to die during hospitalization. These results reinforce the need to screen all patients in pulmonology hospital care for undernutrition risk.

The authors have no conflicts of interest to declare.