The study, “Impact of nutritional status on pulmonary function after lung transplantation for cystic fibrosis,” was published in the United European Gastroenterology Journal.
CF is the third most common cause for lung transplants worldwide (16.8 percent of all cases). Although the disease is mostly associated with respiratory symptoms, gastrointestinal complications are also known to afflict patients, such as diarrhea, constipation, malnutrition, and inflammation in the pancreas, liver and intestines.
Previous studies suggest that malnutrition is linked to a poor prognosis in those needing a lung transplant. However, data on the impact of nutritional status on pulmonary function in those who have received a transplant is still quite limited.
In a retrospective study, a team of researchers at the Medical University of Vienna set out to evaluate the impact of nutritional status on pulmonary function of CF patients who underwent a double lung transplant within a median of 2.3 years.
Patients’ nutritional status was assessed using two different criteria: body mass index (BMI; kg/m2), and body composition measured by bioelectrical impedance analysis (BIA) — a technique that allows researchers to estimate body composition, especially fat content, by calculating the resistance posed by body tissues to the passage of an electrical current.
Lung health was analyzed by spirometry, a common test based on the amount of air a person can inhale and quickly exhale.
Investigators analyzed a total of 147 spirometries and BIAs performed on 58 CF patients (median age, 30.1), who were divided into four groups depending on their BMI scores. These groups were set according to BMI the guidelines defined by the World Health Organization (WHO), were: malnutrition (less than 18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), or obese (more than 30 kg/m2).
Data showed that malnourished patients (27.6%) had a significantly poorer in lung function than those of normal weight (63.8%) or overweight (8.6%), as measured by the percentage of forced expiratory volume in one second (FEV1% predicted, 57% vs 77%), and the percentage of maximum vital capacity (percent predicted, 62% vs 75%).
Investigators also found that lung function measured by FEV1% worsened over time in malnourished patients (decreasing by up to 15%), unlike normal weight and overweight individuals. In these patients, FEV1% remained stable throughout the observation period (median of 10.3 months).
Further analysis also showed that the ratio of extracellular mass (ECM) over body cell mass (BCM), as measured by BIA, accurately predicted lung function over time in CF transplant recipients, suggesting that BIA is superior to BMI in predicting patients’ pulmonary function.
The team concluded “nutritional status assessed by BIA predicted lung function in CF transplant recipients,” and suggested that “BIA represents a non-invasive, safe, fast, mobile, and easy-to-use procedure to evaluate body composition. Thus, it may be used in everyday clinical practice and bears the advantage of repeatability at every patient follow-up.”
The researchers also emphasized the importance of multidisciplinary patient care provided by dietitians and gastroenterologists to try and prevent or diminish malnourishment in CF patients, and so help preserve lung function after a transplant.