RESULTS
An initial key word search yielded 2184 titles. Of these, 2090 were removed due to duplicate data and or irrelevant references. Ninety-four abstracts were deemed to be relevant and were reviewed in full. Of these, a further 68 studies were removed as they failed to meet the inclusion criteria. Seventeen studies with 2049 subjects in total met the inclusion criteria and were included in this literature review. This process is shown in Figure 1.