Abstract
INTRODUCTION: Sexually transmitted infections (STIs) are a major global health concern, with millions of new cases occurring annually, particularly among young adults. These infections can lead to serious health complications, including infertility and increased risk of HIV, and are compounded by social stigma and mental health challenges. There have been significant global increases in STI diagnoses in recent years. The objective of this systematic review is to synthesise evidence on the predictors of trends in gonorrhoea, chlamydia, syphilis, and HIV over the last ten years. We aim to provide insight into the multifaceted drivers of the recent increasing STI diagnosis rates. METHODS: We have developed a comprehensive search strategy that includes searching for relevant published literature and grey literature. We will include studies that contain evidence of longitudinal associations between changes in the incidence of diagnoses of four targeted STIs (i.e., gonorrhoea, chlamydia, syphilis, and HIV) during the last ten years. In addition, we will explore changes in sociodemographic and behavioural variables during the same time among representative samples of national populations. We will conduct a narrative analysis of the included studies. DISCUSSION: The proposed synthesis plan is part of a larger research project that has been designed in response to the priorities of sexual health policymakers in Ireland. It will provide useful information regarding recent international trends in diagnoses of gonorrhoea, chlamydia, syphilis, and HIV, which will inform further efforts to understand the recent increases in STI diagnoses in Ireland. We acknowledge that it will be limited by publication bias, the biases affecting the included studies, a potential lack of data on important sub-populations, and restrictions related to testing availability across countries. Ultimately, trends in STI diagnoses are best understood through the design of comprehensive behavioural surveillance systems, which this review may usefully inform.