Geographical-level contributions of risk factors for HIV infections using generalized additive models: results from a cohort of South African women

Wand, Handan; Dassaye, Reshmi; Reddy, Tarylee; Yssel, Justin; Ramjee, Gita

doi:10.1080/09540121.2018.1556382

Cited by 9 publications

(10 citation statements)

References 23 publications

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“…Previous methods used to define ferritin thresholds to identify iron deficiency include receiver operating characteristic curves (versus absent bone marrow iron) and the evaluation of population reference ranges [3] . In this study, we used the non-parametric regression method of generalized additive modeling to fit the relationship between variables [19] . This approach is increasingly applied in biology and medicine[ 18 , 19 ], and we feel it has several advantages.…”

Section: Discussionmentioning

confidence: 99%

“…In this study, we used the non-parametric regression method of generalized additive modeling to fit the relationship between variables [19] . This approach is increasingly applied in biology and medicine[ 18 , 19 ], and we feel it has several advantages. First, it can be used when other predefined parametric forms do not perform well or cannot be effectively applied.…”

Section: Discussionmentioning

confidence: 99%

“…To identify thresholds, we then used the method of finite differences to estimate the first derivatives (the instantaneous rate of change) of the fitted trend spline from the generalized additive modeling smoother. A similar mathematical approach has been recently applied in environmental and clinical research [ 18 , 19 ].…”

Section: Participants and Methodsmentioning

confidence: 99%

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Threshold ferritin and hepcidin concentrations indicating early iron deficiency in young women based on upregulation of iron absorption

et al. 2021

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Background: Plasma ferritin is a widely used indicator to detect iron deficiency, but the threshold ferritin that defines iron deficiency remains uncertain. Our aim was to define the ferritin concentration at which the body begins to upregulate iron absorption from the diet; this could provide a functionally-defined threshold of incipient iron deficiency. We hypothesized this threshold ferritin concentration would correspond to the threshold hepcidin concentration at which iron absorption begins to increase. Methods: We performed a pooled analysis of our stable iron isotope studies (n = 1058) conducted from 2006 to 2019 in healthy women (age 18À50 years; mean §SD ferritin 33.7 § 27.1 mg/L) that measured iron absorption from labeled test meals providing physiological amounts of iron. To fit relationships between iron absorption, ferritin and hepcidin, we used generalized additive modeling, and to identify thresholds, we estimated the first derivatives of the fitted trend to assess inflection points in these relationships. Findings: Hepcidin increased linearly with increasing ferritin over the entire range of ferritin values. Iron absorption began to increase below a threshold hepcidin value of 3.09 (95%CI: 2.80, 3.38) nmol/l, above which iron absorption remained stable. Iron absorption began to increase below a threshold ferritin value of 51.1 (95%CI: 49.1, 53.1) mg/l, above which iron absorption remained stable. The latter two findings were internally consistent in that, in the relationship between hepcidin and ferritin, a hepcidin of~3 nmol/l corresponded to a ferritin of~51 mg/l. Interpretation: Based on physiological upregulation of iron absorption, a threshold ferritin of <50 mg/L, corresponding to a threshold hepcidin of <3 nmol/l, indicates incipient iron deficiency in young women.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Threshold ferritin and hepcidin concentrations indicating early iron deficiency in young women based on upregulation of iron absorption

et al. 2021

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“…We screened 769 abstracts and 17 full-text reports (online supplementary figure 1). We excluded 13 full-text reports – four reported on data already included in the 2016 review, six were letters or conference abstracts, and three had an irrelevant exposure, outcome or comparison group 12–24. From a conference abstract,13 we identified an additional 'in press' study, which has now been published 25.…”

Section: Resultsmentioning

confidence: 99%

Hormonal contraception and HIV acquisition among women: an updated systematic review

Curtis

Hannaford

Rodríguez

et al. 2020

BMJ Sex Reprod Health

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ObjectiveTo update a 2016 systematic review on hormonal contraception use and HIV acquisition.MethodsWe searched Pubmed and Embase between 15 January 2016 and 26 June 2019 for longitudinal studies comparing incident HIV infection among women using a hormonal contraceptive method and either non-users or users of another specific hormonal contraceptive method. We extracted information from newly identified studies, assessed study quality, and updated forest plots and meta-analyses.ResultsIn addition to 31 previously included studies, five more were identified; three provided higher quality evidence. A randomised clinical trial (RCT) found no statistically significant differences in HIV risk among users of intramuscular depot medroxyprogesterone acetate (DMPA-IM), levonorgestrel implant (LNG implant) or the copper intrauterine device (Cu-IUD). An observational study found no statistically significant differences in HIV risk among women using DMPA, norethisterone enanthate (NET-EN), implants (type not specified) or Cu-IUD. Updated results from a previously included observational study continued to find a statistically significant increased HIV risk with oral contraceptives and DMPA compared with no contraceptive use, and found no association between LNG implant and HIV risk.ConclusionsHigh-quality RCT data comparing use of DMPA, LNG implant and Cu-IUD does not support previous concerns from observational studies that DMPA-IM use increases the risk of HIV acquisition. Use of other hormonal contraceptive methods (oral contraceptives, NET-EN and implants) is not associated with an increased risk of HIV acquisition.

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“…The review of incidence and prevalence data on HIV infection shows that South Africa, particularly KZN, contributes significantly to the global burden of the pandemic (Wand et al, 2019). Moreover, the highest number of infection-related mortality and morbidity is found in this region.…”

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confidence: 99%

Zulu Men’s Conceptions, Understanding, and Experiences of Voluntary Medical Male Circumcision in KwaZulu-Natal, South Africa

Nxumalo

Mchunu

2020

Am J Mens Health

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Voluntary Medical Male Circumcision (VMMC) is proven to reduce transmission of HIV/AIDS. Despite concerted efforts to scale up VMMC in men aged 18–49, the number of medically circumcised men in this age group remains suboptimal. Research has shown that several individual factors hinder and promote uptake of VMMC. The nature of these factors is not clearly understood within the dimensions of religion, culture and tradition, particularly in a low-income rural setting. This study aimed to analyze Zulu men’s conceptions, understanding and experiences regarding VMMC in KwaZulu-Natal (KZN), South Africa. A qualitative phenomenographic study approach was used to collect data from 20 uncircumcised males at six different clinics that provide VMMC services. Ethical approval to collect data was obtained from the Biomedical Research Ethics Committee of the University of KZN (BREC – BE627/18). Individual in-depth face to face interviews were conducted using a semistructured interview guide. Audiotapes were used to record interviews which were transcribed verbatim and then analyzed manually. The conceptions regarding medical circumcision appeared to be related to religious and cultural beliefs surrounding circumcision and the historical traditional practice thereof. The understanding of males regarding VMMC was mainly attributed to HIV prevention; however, knowledge on the degree of partial protection appeared to be limited. An array of negative accounted in the form of complications such as poor wound healing and postoperative pain undergone by peers and other close influencers’ accounted for participants’ experiences of VMMC. Poor knowledge and negative experiences relating to VMMC could account for reasons why men choose not to undergo VMMC.

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Geographical-level contributions of risk factors for HIV infections using generalized additive models: results from a cohort of South African women

Cited by 9 publications

References 23 publications

Threshold ferritin and hepcidin concentrations indicating early iron deficiency in young women based on upregulation of iron absorption

Threshold ferritin and hepcidin concentrations indicating early iron deficiency in young women based on upregulation of iron absorption

Hormonal contraception and HIV acquisition among women: an updated systematic review

Zulu Men’s Conceptions, Understanding, and Experiences of Voluntary Medical Male Circumcision in KwaZulu-Natal, South Africa

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