https://www.selleckchem.com/products/salvianolic-acid-b.html Involvement of vulnerable populations in research is critical to inform the generalisability of evidence-based medicine to all groups of the population. In this communication, we reflect on our previous research, and that of other authors, to identify and explore key ethical and methodological considerations. Focus groups are a widely implemented qualitative methodology, but their use, particularly in vulnerable neurodegenerative disease populations, is not straightforward. Although the risk of harm is generally low in focus group research, neurodegenerative disease populations are particularly vulnerable to issues relating to comprehension and their capacity to consent. Physical and cognitive impairments may also affect social interactions among participants and therefore impact data collection and analyses. We offer a number of ethical and methodological recommendations to facilitate the processes of recruitment and data collection when conducting focus groups with neurodegenerative disease populations. We offer a number of ethical and methodological recommendations to facilitate the processes of recruitment and data collection when conducting focus groups with neurodegenerative disease populations. Vitamin D insufficiency is much more common among patients with cancer than the general population. Previous meta-analyses of controlled trials showed an approximately 15% reduction of cancer mortality by vitamin D supplementation compared with placebo or no treatment in the general population.On top of updating the latest systematic review on vitamin D supplementation and cancer mortality in the general population, we aim to conduct the first meta-analyses of trials on vitamin D supplementation and cancer-specific and overall survival of patients with cancer. Besides, we will conduct for the first time subgroup analyses based on individual patient data collected from randomised controlled trials. A systemati