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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].

Efficacy and clinical effectiveness of influenza vaccines in HIV-infected individuals: a meta-analysis

J Atashili, L Kalilani, and AA Adimora.

Review published: 2006.

CRD summary

The authors concluded that influenza vaccines are moderately effective in reducing the incidence of influenza in individuals infected with the human immunodeficiency virus. However, given the unknown quality of the included studies, the reliability of the evidence is uncertain.

Authors' objectives

To assess the efficacy and effectiveness of influenza vaccines to prevent influenza in individuals infected with the human immunodeficiency virus (HIV).

Searching

MEDLINE (1966 to 2005), EMBASE (1974 to 2005), the World Health Organization website, the Cochrane CENTRAL Register (including the trials register of the Cochrane Acute Respiratory Infections Group) and ClinicalTrials.gov were searched; the search terms were reported. The reference lists of relevant publications were also checked. Studies in any language were eligible for inclusion.

Study selection

Studies that compared any influenza vaccine with placebo or no treatment were eligible for inclusion. Any vaccine dose, preparation or time schedule were eligible. Most of the included studies used a dose of 15 μg of vaccine. All of the vaccines evaluated in the review included more than one viral strain.

Studies of HIV-infected individuals of all ages and from any geographical location were eligible for inclusion. The participants included were aged from 20 to 78 years and the majority were male. In all but one study the participants were not severely immunocompromised (median CD4 count above 400 cells/μL). The proportion of participants receiving highly active antiretroviral therapy ranged from 56 to 96% across the included studies. All of the included studies were conducted in 'developed' countries.

The primary outcomes were the occurrence of culture- or seriologically-confirmed influenza or clinical influenza-like illness during the influenza season.

Randomised controlled trials (RCTs), cohort and case-control studies were eligible for inclusion. To be eligible, studies had to report sufficient data to calculate effectiveness. The follow-up period of the included studies ranged from 3 months to 2 years.

Two authors independently selected the studies, with any disagreements resolved by consensus.

Assessment of study quality

The authors did not state that they assessed validity.

Data extraction

Data were extracted from each study to calculate the risk difference (RD), number-needed-to-vaccinate, and vaccine efficacy or effectiveness. Trial authors were contacted for missing information on study characteristics.

Two authors independently extracted the data, with any disagreements resolved by consensus.

Methods of synthesis

A meta-analysis examining the pooled RD and 95% confidence intervals (CIs) was performed using both fixed-effect and random-effects (DerSimonian and Laird) models, although only the results of the random-effects model were reported. Heterogeneity was assessed using the χ2 test. Publication bias was assessed using funnel plots, Begg's rank correlation test and Egger's regression method.

Results of the review

Four studies (n=646) were included in the review: one RCT and three observational studies. The sample sizes ranged from 71 to 328 participants.

Influenza vaccination resulted in a significant reduction of influenza in HIV-infected participants (4 trials; RD -0.27, 95% CI: -0.42, -0.11). There was, however, statistical heterogeneity between the studies (I2=77%).

There was no evidence of publication bias.

Authors' conclusions

The current limited evidence suggests that influenza vaccines are moderately effective in reducing the incidence of influenza in HIV-infected individuals.

CRD commentary

The review addressed a clear question and was supported by appropriate inclusion criteria. Several relevant databases were searched, although unpublished studies were not sought, thus potentially introducing publication bias. The authors did, however, assess publication bias using funnel plots and statistical tests. Two reviewers were involved in the selection and abstraction of studies, which reduces some risk of reviewer bias. In addition, while details of the primary studies were presented, information on study quality was lacking. The authors were appropriately cautious of their summary statistic given the statistical heterogeneity between the studies. However, in view of the unknown quality of the included studies, the reliability of the evidence is uncertain.

Implications of the review for practice and research

Practice: The authors stated that influenza vaccination should be considered for HIV-infected individuals.

Research: The authors stated that further large trials are needed to assess the effectiveness of influenza vaccines in HIV-infected individuals, particularly in populations most affected by HIV.

Funding

NIH Fogarty grants (DHHS/NIH/FIC 5 D43: TW01039-08 and TW006568-04) to the University of North Carolina, Chapel Hill.

Bibliographic details

Atashili J, Kalilani L, Adimora A A. Efficacy and clinical effectiveness of influenza vaccines in HIV-infected individuals: a meta-analysis. BMC Infectious Diseases 2006; 6:138. [PMC free article: PMC1574329] [PubMed: 16965629]

Indexing Status

Subject indexing assigned by NLM

MeSH

Adult; Aged; Antiretroviral Therapy, Highly Active; HIV Infections /drug therapy /immunology /virology; Influenza Vaccines /immunology /therapeutic use; Middle Aged; Orthomyxoviridae Infections /immunology /prevention & control /virology

AccessionNumber

12006007597

Database entry date

01/12/2008

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: 16965629

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