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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Vitamin supplementation for prevention of mother-to-child transmission of HIV and pre-term delivery: a systematic review of randomized trial including more than 2800 women

EJ Mills, P Wu, D Seely, and GH Guyatt.

Review published: 2005.

CRD summary

This well-conducted review assessed the effectiveness of vitamin A and multivitamin supplementation in preventing mother-to-child transmission of the human immunodeficiency virus and pre-term delivery. The authors concluded that the evidence was conflicting, without strong evidence of benefit and with a possibility of harm. This conclusion appears overly cautious as the results suggest no effect of vitamin supplementation on these outcomes.

Authors' objectives

To assess the effectiveness of vitamin A and multivitamin supplementation in preventing mother-to-child transmission (MTCT) of the human immunodeficiency virus (HIV) and pre-term delivery.

Searching

MEDLINE, AMED, AltHealthWatch, CINAHL, EMBASE, the Cochrane Library, National Research Register (UK) and ClinicalTrials.gov were searched from inception to January 2005 without any language restrictions. The reference lists of relevant articles were screened for further studies.

Study selection

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) were eligible for inclusion.

Specific interventions included in the review

Studies of vitamin A or multivitamin treatment were eligible for inclusion. In the included studies, vitamin A was given alone or in combination with B-carotene, and control groups received placebo. In some studies an additional high dose of vitamin A was given at delivery. The components of the multivitamin supplements varied between studies, but these were again compared with placebo. The gestational week at which treatment began varied within and between studies.

Participants included in the review

Studies of pregnant women with HIV were eligible for inclusion. All of the included studies were set in African countries.

Outcomes assessed in the review

Studies reporting MTCT or pre-term delivery were eligible for inclusion. The review also included the outcome of childhood mortality at 1 year.

How were decisions on the relevance of primary studies made?

Two reviewers independently assessed primary studies for inclusion.

Assessment of study quality

The following methodological quality criteria were assessed: methods of randomisation, allocation concealment, blinding of patients and assessors, use of placebo, informed consent, a priori sample size estimation, use of intention-to-treat analysis, and sources of funding. Study authors were contacted for clarification of study methods. Two reviewers working independently performed the quality assessment.

Data extraction

Two reviewers independently extracted the data. The reproducibility of the data extraction form was tested amongst three reviewers. For the outcome of MTCT, the reviewers extracted children's infection status at the latest time point reported. Pre-term delivery was defined as delivery before 37 weeks' gestation. Childhood mortality was extracted where reported. Analyses were based on numbers of births rather than numbers of pregnant women. Relative risks (RRs) for each of the three outcomes and 95% confidence intervals (CIs) were calculated from raw data, where provided.

Methods of synthesis

How were the studies combined?

RRs with 95% CIs were pooled using a random-effects model.

How were differences between studies investigated?

Statistical heterogeneity was assessed using the Zalen test and the I-squared test. The authors intended to assess quality assessment items, study design and length of follow-up as potential sources of heterogeneity. Further differences between the studies were discussed in the text.

Results of the review

Five publications reporting data on 4 RCTs involving 2,863 pregnant women and 2,620 births were included.

Three studies described how the randomisation sequence was generated, two reported concealment of treatment allocation, one study reported on blinding, four reported that informed consent was obtained, four reported an a priori sample size estimation, and three used an intention-to-treat analysis. All studies disclosed sources of funding.

Vitamin A (3 RCTs, 2,503 women and 2,268 births).

One study suggested that vitamin A supplementation increased MTCT; the other two reported no effect of treatment. Overall, there was no significant difference in MTCT with vitamin A supplementation compared with placebo (RR 1.05, 95% CI: 0.78, 1.41, p=0.2), but there was significant heterogeneity in this analysis (p=0.01; I-squared 75%).

One study suggested that vitamin A supplementation decreased pre-term delivery, while another reported no effect of treatment. Overall, there was no effect on pre-term delivery (RR 0.85, 95% CI: 0.53, 1.37, p=0.5), but again there was significant heterogeneity (p=0.03; I-squared 77%).

Three studies reported no difference in child mortality at 1 year between vitamin A and placebo (RR 1.05, 95% CI: 0.88, 1.27, p=0.5). There was no evidence of heterogeneity (p=0.8; I-squared 0%).

Multivitamins (2 RCTs, 1,438 participants).

Both studies suggested that multivitamins may reduce pre-term delivery but the results were not statistically significant. Overall, multivitamin supplementation had no significant effect on pre-term delivery compared with placebo (RR 0.88, 95% CI: 0.73, 1.06, p=0.1; 2 studies). A single study also reported no significant effects on MTCT or child mortality at 1 year.

Authors' conclusions

The evidence on the use of vitamin A or multivitamins to prevent MTCT of HIV and pre-term delivery is conflicting, without strong evidence of benefit and with a possibility of harm.

CRD commentary

This review question and inclusion criteria were clearly defined. A range of sources were searched for primary studies. There were no language restrictions and unpublished studies were actively sought, which reduces the risk of publication and language bias. The study selection, data extraction and quality assessment processes were all performed by two independent reviewers, thereby minimising the introduction of error and bias at these stages. The quality of the included studies was assessed and the results of this assessment described.

The studies were combined using appropriate techniques, statistical heterogeneity was assessed, and clinical differences between the studies were also discussed. The authors highlighted the limitations of the review, most notably the small number of studies available and their unexplained heterogeneity in results. The review was well conducted and its results are likely to be reliable. Although the authors concluded that the evidence is conflicting, the results presented suggest that vitamin supplementation does not prevent MTCT or pre-term delivery, therefore this conclusion appears overly cautious.

Implications of the review for practice and research

Practice: The authors stated that the use of vitamins to prevent MTCT is inadvisable, although nutritional programmes may play a role in preventing other harmful pregnancy outcomes.

Research: The authors stated that trials are needed to assess the impact of effective nutrition on pregnant women with HIV, particularly those of low nutritional status.

Funding

Not stated.

Bibliographic details

Mills E J, Wu P, Seely D, Guyatt G H. Vitamin supplementation for prevention of mother-to-child transmission of HIV and pre-term delivery: a systematic review of randomized trial including more than 2800 women. AIDS Research and Therapy 2005; 2:4. [PMC free article: PMC1131887] [PubMed: 15877818]

Indexing Status

Subject indexing assigned by CRD

MeSH

Adult; Anti-HIV Agents /therapeutic use; Delivery, Obstetric /methods; Dietary Supplements; Female; HIV Infections /congenital /drug therapy /prevention & control /transmission; Infant; Infant Mortality; Infant, Newborn; Infectious Disease Transmission, Vertical /prevention & control; Obstetric Labor, Premature /prevention & control; Pregnancy; Pregnancy Complications, Infectious /virology; Puerperal Disorders /drug therapy; Risk Factors; Viral Load; Vitamin A /administration & dosage /adverse effects; Vitamin A Deficiency /prevention & control; Vitamins /administration & dosage

AccessionNumber

12007000039

Database entry date

09/08/2008

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 15877818

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