Respiratory Function Correlates with Fat Mass Index and Blood Triglycerides in Institutionalized Older Individuals

Abstract

Background: We investigated the relationship between respiratory function measured by spirometry analysis and anthropometric variables (skeletal and fat mass) and nutritional status in the institutionalized elderly, particularly at high-risk for adverse outcomes after respiratory infections and malnutrition. Design: This is a multicenter cross-sectional study with a quantitative approach conducted among older people institutionalized living in nursing homes. Methods: Respiratory function was assessed by measuring the forced vital capacity, forced expiratory volume in the first second, the ratio between FEV1 and FVC (FEV1/FVC), and peak expiratory flow in percentage by means of spirometric analysis (values of the forced expiratory volume measured during the first second of the forced breath (FEV1) and forced vital capacity (FVC)). Nutritional assessment and anthropometry analyses were performed to evaluate under or over nutrition/weight. Results: There was a significant (p<0.05) and positive correlation between FEV1 and skeletal muscle mass index, whereas fat mass index correlated significantly (p<0.01) with the FEV1/FVC index. FEV1/FVC values were both significantly (p<0.05) associated with high body mass index and triglyceride levels in the blood. The prevalence of individuals with ventilator restrictive pattern (FEV1/FVC>70% with FEV1 and FVC<80%) was 27.6% and 12 individuals (21.1%) received daily bronchodilators as part of the pharmacological treatment for respiratory disorders. Logistic regression was performed to identify predictors of restrictive respiratory patterns. The following variables were included in the model: age group, female gender, Charlson comorbidity index, body-mass index (BMI), fat mass index, skeletal muscle mass index, total cholesterol, and triglycerides concentration. The model was statistically significant (p < 0.05; R2 = 0.39), correctly classifying 70.0% of cases, with a sensitivity of 89.3% and a specificity of 50.0%. Area under curve was 0.71 (IC95% 0.54-0.88; p=0.023).The highest OR for the restrictive respiratory pattern was for BMI (OR=5.09) and triglycerides concentration in blood (>150 mg/dl) (OR=5.59). Conclusion: The relationship between a restrictive pattern of respiratory function and fat mass deserves future investigation to manage these parameters as a possible modifiable factor of altered respiratory function in overweight institutionalized older individuals.