Systematic reviews (SRs) have a number of important functions, but are essential for supporting Health Technology Assessments. SR questions are based on PICO elements which specify types of participants (P), interventions (I) comparators (C), and outcomes (O) of interest. Evidence reviews (ERs) can act as stand-alone documents and allow the researcher to acquire a detailed understanding of a disease area and literature base, in order to develop robust PICO elements. These PICO elements are then used to develop focused SR questions. ERs are also useful for determining if the proposed SR question has been previously answered within the literature. ERs typically take between 6 and 12 weeks to complete and, if being used to develop PICO, initially involve understanding the end-purpose of the SR (e.g. to support a network meta-analysis, or economic model). Once this is understood, researchers can agree contents of the ER. For example if the ER will be used to develop PICO for a safety and efficacy SR, it would need to include sections outlining current treatments, clinical guidelines and treatment pathways, key clinical trials, and previously published systematic reviews. Targeted searches, covering both published and grey literature, and the write-up of results are then conducted for each agreed ER section. Findings from the ER are used to develop a rationale for each of the PICO elements, including considerations such as geographical and timeframe limitations. Understanding the disease classification, subtypes, and line of treatment justifies the selection of participants. Knowing which treatments are available, whether they are recommended in clinical guidelines, and relevant treatment stratification factors for the target participants justifies interventions and comparators. The methods used for reporting efficacy in clinical trials informs outcomes. In conclusion, ERs are a useful way of informing the framing of PICO elements and refining search questions for SRs.