The primary outcome is the improvement of the nutritional status in a probiotic-receiving group in comparison to a placebo-receiving group. The nutritional status will be evaluated by means of anthropometric parameters (body mass index, fat mass, muscle mass, total body water), laboratory tests (the level of albumin, total protein, transferrin, total lymphocyte count) and Nutritional Risk Screening 2002 (NRS 2002 tool).
First secondary outcome is to estimate the differences of enteral nutrition tolerance in patients receiving placebo or probiotic supplements. Second secondary outcome is to evaluate the difference of QOL of patients receiving placebo or probiotic supplements.
The timetable of follow-up visits and measurements is presented using The Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) diagram in the Figure 2. Each of the participants will visit the study centre three times (at baseline, after 4 weeks, and after 12 weeks). During follow-up visits, patients will receive study products depending on allocation. At baseline – 60 capsules for 30 days; after 4 weeks – 120 capsules for next 60 days. If during this trial, any participant fails to continue the study protocol, the data will be collected and this information will be further noted in the publication.
Table 1. Schedule of enrollment, interventions, and assessments. (see Table 1 in the Supplementary Files)
Blood sampling and preparation
The level of albumin, total protein, transferrin, and total lymphocyte count will be measured. The blood samples will be taken from a forearm vein by a nurse at the baseline, after 4 weeks, and next after 12 weeks. All blood samples will be taken in Counselling Nutritional Centre Copernicus in Gdansk and the same day they will be given to the laboratory to conduct the analysis.
The analysis of the body mass composition (fat mass, muscle mass, total body water) will be conducted using a BIA analyser – Medical Jawon. It will be performed by a nutritionist in the Department of Clinical Nutrition and Dietetics (at baseline, after 4 weeks, and after 12 weeks). The body mass index will be also calculated by the nutritionist.
NRS 2002 tool
This is a validated screening tool divided into two parts. The first one assesses the nutritional status based on unintentional weight loss during last 1 to 3 months and food intake during last 1 to 3 weeks. The second part regards the occurrence of diseases or types of treatment which are related to increased daily calories intake (e.g. bone marrow transplant, radio- or chemotherapy). Patients aged 70 and above receive additional score. Nutritional support should be provided if the NRS score is 3 and more. Assessment of nutritional status will be conducted by a nutritionist in the Department of Clinical Nutrition and Dietetics using NRS 2002 tool at baseline, after 4 weeks, and after 12 weeks.
The EN tolerance will be evaluated by the nutritionist in the Department of Clinical Nutrition and Dietetics using own questionnaire including information, such as number of stools, occurrence of nausea, vomiting, abdominal pain, and flatulence. The questionnaire will be filled every day for 12 weeks by patients or their caregivers and evaluated during follow-up visits after 4 and 12 weeks of the study.
Quality of life
Patients’ QOL will be assessed by the nutritionist in the Department of Clinical Nutrition and Dietetics. To assess the patients’ QOL the World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire will be used. It contains questions divided into 4 domains (environmental, psychological, somatic, and social factors). The QOL will be evaluated at baseline, after 4 and 12 weeks.
Patients are instructed to inform the researchers about any changing conditions during the trial. Furthermore, during follow-up visits the researchers will ask about adverse events which may be related to the intervention. If any adverse events occur it will be noted in report form and reported in publication. However, according to the best of our knowledge, adverse events after administration of L. plantarum 299v were not noted.
The study protocol has been approved by the Independent Bioethics Committee for Scientific Research at Medical University of Gdansk (the project indentification code: 422/2016). All participants will give informed consent before randomization and the information about the trial will be explained to them. They will be informed about potential benefits and adverse events that may occur during this trial.
Clinical trial registration
The study has been registered in ClinicalTrials.gov which is a database of privately and publicly funded clinical studies conducted around the world (ClinicalTrials.gov Identifier: NCT03940768).
When computing a priori sample size, we assummed that of all existing approaches used in screening and assessment of malnutrition and cachexia, weight loss – among others - is a phenotype always evaluated by international organizations and commonly used tools/surveys , that this parameters will serve as pivotal to calculate required sample size. Calculating the mean weight loss (major component of nutritional status) in a 70kg men and assuming 1:1 allocation ratio and 80% statistical power we evaluated that the number of participants will be 36. Allowing for a withdrawal rate of 20% for the primary outcome we aim to randomly allocate 40 participants to receive either active product or placebo. The required sample size were evaluated using G-power analysis software. Significance level will be 0.05.
The calculations will be carried out with the use of Statistica package by Dell Inc. The descriptive statistics will include averages, medians, standard deviations, maximum and minimum values. In order to check the normality of distribution of populations subject to research, the W Shapiro-Wilk test will be applied. To check the homogeneity of variations of the groups compared, the Brown-Forsythe test will be applied. Then, depending on the type of data and shape of distributions compared, the U Mann-Whitney test, Student's t-test or a version of Student's t-test with independent variance estimation will be applied.