HIV is a major public health issue affecting millions globally. Women and girls account for 46% of new HIV infections in 2022 and approximately 1.3 million females become pregnant every year. Vertical transmission of HIV from persons living with HIV (PLHIV) to infants may occur through different modalities, such as through breast/chest feeding. Notably, 82% of PLHIV who chose to breast/chest feed are on antiretroviral therapy (ART) when feeding their infants. Precise estimates of the risk of postpartum transmission to infants during breast/chest feeding at varying viral load levels remain a significant gap in the literature.

A rapid systematic search of electronic databases will be conducted from January 2005 to the present, including Medline, Embase and Global Health. The objective of this rapid review is to explore and assess the available evidence on the effect of varying viral load levels on the risk of HIV transmission to infants during breast/chest feeding when the birthing or gestational parent living with HIV is on ART. Study characteristics will be summarised and reported to support the narrative summary of the findings. The focus will be on the absolute risk of HIV transmission from birthing parent to infant during chest/breast feeding. The findings will also be stratified by month, including the risk of HIV transmission for 6 months and greater than 6 months postpartum. We will ascertain the risk of bias using A Measurement Tool to Assess Systematic Reviews 2, Quality of Prognosis Studies and Downs and Black checklist for the appropriate study type. A summary score will not be calculated, rather the strengths and limitations of the studies will be narratively described.

No human subjects will be involved in the research. The findings of this rapid review will inform a future systematic review and will be disseminated through peer-reviewed publications, presentations and conferences.

CRD42024499393.

To externally validate a recently developed cardiovascular disease (CVD) risk model for Omanis with type 2 diabetes mellitus (T2DM).

Retrospective cohort study.

Nine primary care centres in Muscat Governorate, Oman.

A total of 809 male and female adult Omani patients with T2DM free of CVD at baseline were selected using a systematic random sampling strategy.

Data regarding CVD risk factors and outcomes were collected from the patients’ electronic medical records between 29 August 2020 and 2 May 2021. The ability of the model to discriminate CVD risk was assessed by calculating the area under the curve (AUC) of the receiver-operating characteristic curve. Calibration of the model was evaluated using a Hosmer-Lemeshow ² test and the Brier score.

The incidence of CVD events over the 5-year follow-up period was 4.6%, with myocardial infarction being most frequent (48.6%), followed by peripheral arterial disease (27%) and non-fatal stroke (21.6%). A cut-off risk value of 11.8% demonstrated good sensitivity (67.6%) and specificity (66.5%). The area under the curve (AUC) was 0.7 (95% CI 0.60 to 0.78) and the Brier score was 0.01. However, the overall mean predicted risk was greater than the overall observed risk (11.8% vs 4.6%) and the calibration graph showed a relatively significant difference between predicted and observed risk levels in different subgroups.

Although the model slightly overestimated the CVD risk, it demonstrated good discrimination. Recalibration of the model is required, after which it has the potential to be applied to patients presenting to diabetic care centres elsewhere in Oman.