SWALLOWING, NUTRITIONAL STATUS AND HYDRATION IN ACUTE AND SUB-ACUTE CARE SETTINGS: IMPLICATIONS ON SURVIVAL AND ASPIRATION PNEUMONIA

Introduction: malnourishment, dehydration and dysphagia are common in hospitalized patients both in Acute and Sub-acute care settings. However, the relationships among these conditions have been poorly studied and with divergent results. In the absence of these information it appears very difficult to appropriate manage health-care resources in order to early identify the population at risk of developing negative outcomes and to develop a prevention program. This research project was design in order to improve the clinical management of dysphagic, malnourished and dehydrated patients admitted to the Acute and Sub-acute care Units. In particular, the project was structured into 3 different phases. In the first one the prevalence of malnutrition, dysphagia and dehydration at admission in Acute and Sub-acute care settings was analyzed. In the second phase the association between malnutrition, critical weight loss, dysphagia and dehydration and negative clinical outcomes was studied. Finally, in the third phase a statistically-based exploratory analysis (using an unsupervised clustering method) was used in order to identify the presence of similar phenotypic subgroups of patients according to objective criteria. In addition, the ability of this classification in predicting negative clinical outcomes was also assessed. Materials and methods: a total of 686 patients were recruited, 483 of them were admitted to the Acute care Unit (Stroke-Unit), while 203 were admitted to the Sub-acute care Unit. Information regarding age, gender, weight, height, presence of aphasia and dysarthria, severity of stroke (only in patients admitted to the Acute care Unit), data on functional status activity of daily living, data on oral intake, data on serum analysis (known or suspected to be related to the presence of dysphagia, dehydration and malnutrition), presence of swallowing disorders, data on hydration level, presence of undernutrition were collected at admission in all the patients. Student t test and Chi-square test were used to compare the distribution of continuous and categorical data among patients according to gender and presence of dysphagia. Correlation analysis was performed in order to evaluate the presence of significant correlations among the collected variables. Kaplan-Meier curves and Cox’s proportional hazard models were used to assess the impact of malnutrition, critical weight loss, dysphagia and dehydration on clinical outcomes. Finally, Ward’s minimum-variance hierarchical method was used in order to generate clusters by placing subjects into groups not defined a priori but according to the similarity of clinical characteristics. Results: Patients admitted to the Acute care Unit were found malnourished in 16.2% of cases. Dysphagia was detected in 24.2% of patients while dehydration was found in 49.7% of cases. As far as it is concerned the Sub-acute care Unit, dysphagia was reported in 22.2% of cases, malnutrition in 22.2% of cases and dehydration in 45.8% of cases. A total of 114 patients died during the follow-up period. One-hundred-two were admitted to the Acute care Unit, while 12 were admitted to the Sub-acute care Unit. In both group no significant association between malnutrition and dehydration and mortality or pulmonary complications was found. On the other hand, dysphagia significantly affected survival. In the Acute care Unit 33 out of the 117 patients with dysphagia died during the 6 months follow-up; while in the Sub-acute care Unit 8 out of the 45 patients with dysphagia died during the 6 months follow-up. In addition, the presence of dysphagia significantly increased the risk of developing pulmonary complications (Odds Ratio = 5.493; p = 0.007 in Acute care settings and Odds Ratio = 2.809; p = 0.029 in Sub-acute care settings). Also critical weight loss significantly affected survival and increased the risk of develop pulmonary complications both in Acute and in Sub-acute care settings. Patients with both critical weight loss and dysphagia had a higher mortality risk than patients with critical weight loss but without dysphagia or patients with dysphagia but without critical weight loss (Odds Ratio = 4.943; p = 0.019 in Acute care settings and Odds Ratio = 2.732; p = 0.032 in Subacute care settings). Using the clustering approach, a dendrogram was generated and a 4-cluster reduction was chosen to describe the results. Patients in different clusters demonstrated significant differences both in the results of continuous and categorical data. In addition, significant differences among clusters were also found in survival and in the risk to develop pulmonary complications. In particular, patients of cluster 2 died more frequently than patients in the other clusters (p = 0.019), while pulmonary complications were more frequently in patients of cluster 1 and 2 (p = 0.021). Discussion: the prevalence of malnutrition, dehydration and dysphagia was high, both in Acute and Subacute care settings. Interestingly, malnutrition and dehydration did not influence the occurrence of negative clinical outcomes. On the other hand, dysphagia and critical weight loss significantly affected survival and occurrence of pulmonary complications. In particular, dysphagic patients who experienced a critical weight loss had the poorest prognosis. The unsupervised statistical methods based upon hierarchical clustering was able to classify patients into 4 clusters which described patients who shared common clinical features. Even if it is unlikely that these clusters represent distinct pathophysiologies, patients in different clusters have significantly different prognoses. It is possible that the application of unsupervised clustering method in the classification of hospitalized patients could provide interesting prognostic information.