2. Methods
cancer, HIV, or the chronic, sore throat, allergic, mood disorders, fever, malignancy, URTIs, cognitive damage, cough, scratchy
SORE THROAT, NEUROLOGICAL DISORDERS, ADVERSE EVENTS, CHRONIC ASTHMA, EVENT, RECRUITMENT, MULTIPLE SCLEROSIS, EVENTS, INFLAMMATORY RESPONSE
This was a double-blind, randomised, placebo-controlled trial conducted over 12 weeks that utilised an active group (Levagen+) and a placebo group (maltodextrin). Potential participants were provided with the participant information sheet, and following initial screening via a telehealth consultation, acceptable participants gave their written consent to participate in the study and completed baseline measures. This trial was registered with ANZTCR: number ACTRN12620000846921.Four hundred and twenty-six participants aged between 18 and 65 years old were recruited from databases and public media outlets. Participants were included in the study if they were able to provide informed consent and agreed not to take other supplements or medications aimed at preventing URTIs for the duration of the trial (e.g., Echinacea, Vitamin C, zinc, Tamiflu, or Relenza). Exclusion criteria included those with cognitive damage; serious mood disorders or neurological disorders, such as multiple sclerosis; or those with an unstable or serious illness (e.g., renal, hepatic, gastrointestinal, cardiovascular, diabetes, thyroid gland function, malignancy, lung conditions, chronic asthma). Participants were also excluded if they had experienced acute sickness in the previous 2 months; were active smokers or abused nicotine or drugs; had chronic alcohol use (>14 alcoholic drinks per week); were allergic to any of the ingredients in the active or placebo formula; were pregnant or lactating women; were medically prescribed medications that could affect the immune and/or inflammatory response; had participated in a related clinical trial in the 1 month prior; or had treatment for cancer, HIV, or the chronic use of steroids in the past year.Once enrolled, participants were randomly allocated to one of two groups: either the active (PEA) or placebo group. Randomisation was performed using random allocation site (Sealedenvelope.com, accessed on 10 July 2020) by an individual who was not involved in the trial to ensure both participants and investigators were blinded to the allocation. Those in the PEA (Levagen+During the study period, participants were asked to complete the SF-8 questionnaire as a measure of health-related quality of life every 4 weeks (baseline, week 4, week 8, and week 12). SF-8 was scored according to If participants experienced the onset of URTI symptoms (e.g., cough, sneezing, stuffy or runny nose, fever, scratchy or sore throat, or nasal breathing), they were required to record their daily symptoms online, including severity, using the WURSS-24 questionnaire for the duration of the event or up to 2 weeks (whichever occurred first). If the participant’s symptoms continued for more than 2 weeks, they were asked to stop recording the event and seek medical advice. Once symptoms of an event subsided, participants were asked to continue taking the trial product for the remaining duration of the trial period and record any subsequent URTI events.The primary outcome measure for this study was a change in URTI incidence between groups. Secondary outcome measures included changes in URTI duration, severity (as measured by WURSS-24), general health (as measured by SF-8 questionnaire), number of days off work, and any product tolerance or adverse events.The sample’s size was calculated using G*power (v3.0.10), accounting for an α probability of 0.05 and powered to 0.95 for a 20% difference in URTI incidence (i.e., 30% vs. 24%); the resulting effect size was 0.74. Group sizes of at least 41 URTI incidents were required; therefore, up to 500 participants were to be recruited with the aim of achieving a minimum of 82 URTI events. Once 82 URTIs were recorded, recruitment into the study was closed, and those enrolled completed the study. Analysis was performed using IBM Statistics (version 25.0 for Windows, IBM, Chicago, IL, USA). Differences between the number of URTIs and symptoms reported per group were assessed using chi-square tests. Changes in URTI symptom severity and duration were analysed using Wilcoxon rank sum (Mann–Whitney U) tests. Statistical significance was set at 