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Study flow diagram
Figures and Tables -
Figure 1

Study flow diagram

Table 1. Research recommendation

What are the effects of nutritional supplements in patients being treated for active visceral leishmaniasis (VL)?

Evidence: we found no eligible studies for this systematic review.

Elements

Proposal

Comments

Population

People being treated for VL

  • Include all relevant participant groups, such as people with HIV.

  • Large, adequately powered trial.

  • Preferably multi‐centre trial, in order to achieve adequate sample size (Laville 2017).

  • Stratify allocation according to age and basic nutritional status, to enable robust a priori subgroup analyses.

Intervention

Oral nutritional supplement

  • If only a nutrient is tested, a placebo can be easily used, and a blinded RCT can be conducted (Laville 2017).

  • The study should be planned with few interventions, to allow the effect of the micronutrient to be evaluated.

  • Provide details of all the interventions and co‐interventions undertaken, of their compliance and their acceptability (Hoffmann 2014; MRC 2008).

  • In order to disentangle the effects of the nutrient on the outcome measure, the co‐interventions must be similar in all study groups.

  • Compliance can be checked by counting pills, and possibly by assessing the nutrient concentration or related functions (Laville 2017).

Comparison

Placebo

Outcomes

Relevant outcomes for key stakeholders defined, measured, collected, and reported in an objective, reliable, accurate, and actionable way

  • To our knowledge, there is no 'core outcome set' (COS)a developed with a rigorous methodology for RCTs of nutritional supplements.

  • COS for RCTs of nutritional supplements should be developed with the method proposed in the COMET Handbook (Williamson 2017).

  • Blinding of patients, care givers and outcome assessment should be ensured with the use of placebo as a control group. The use of objective outcomes that are less susceptible to bias can also minimize the risk of detection bias (Lin 2012).

  • Relevant harms related to the use of nutrients should be specified beforehand, and should be assessed (Ioannidis 2004).

Study type

RCT

Cluster‐RCTs (RCTs that randomize groups (clusters) rather than individuals) have several advantages compared to individual‐RCTs (López‐Alcalde 2015). For example, they may be less costly and time‐consuming, as they simplify the logistics of implementation (Smith 2008); they control for confounding (Safdar 2008), and minimize treatment contaminationb between intervention and control participants (Hayes 2000); they are better for measuring the overall group effect of an intervention, and for judging effectiveness (Hayes 2000), that is, the extent to which a specific intervention, when used under ordinary circumstances, does what it is intended to do (Cochrane 2017). Moreover, they have broader generalizability. For example, cluster‐RCTs minimize the Hawthorne effect, which is the effect on the people being studied (usually positive or beneficial), of being under study (Porta 2008).

Abbreviations: COS: core outcome set; HIV: human immunodeficiency virus; RCT: randomized controlled trial; VL: visceral leishmaniasis.
aCore outcome set: agreed standardized set of outcomes that should be measured and reported in all trials for a specific clinical area (Williamson 2012).
bContamination: in a controlled trial, contamination is the inadvertent application of the intervention being evaluated to people in the control group, or the inadvertent failure to apply the intervention to people assigned to the intervention group (Cochrane 2017).

Figures and Tables -
Table 1. Research recommendation
Summary of findings for the main comparison. Nutritional supplements versus no nutritional supplements for people who are being treated for active visceral leishmaniasis (VL)

Nutritional supplements versus no nutritional supplements for people who are being treated for active VL

Patient or population: people who are being treated for active VL
Setting: any
Intervention: nutritional supplements
Comparison: no nutritional supplements

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

Number of participants
(studies)

Certainty of the evidence
(GRADE)

Comments

Risk with no nutritional supplements

Risk with nutritional supplements

Primary cure

No trials met the inclusion criteria. Thus, there is no data for this outcome.

(0 RCTs)

Definitive cure

No trials met the inclusion criteria. Thus, there is no data for this outcome.

(0 RCTs)

Treatment completion

No trials met the inclusion criteria. Thus, there is no data for this outcome.

(0 RCTs)

Self‐reported recovery from illness or resolution of symptoms

No trials met the inclusion criteria. Thus, there is no data for this outcome.

(0 RCTs)

Weight gain, increased skinfold thickness, or other measures of lean or total mass, or growth in children

No trials met the inclusion criteria. Thus, there is no data for this outcome.

(0 RCTs)

Adverse outcomes

No trials met the inclusion criteria. Thus, there is no data for this outcome.

(0 RCTs)

*The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

GRADE Working Group grades of evidence
High certainty: we are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Abbreviations: CI: confidence interval; VL: visceral leishmaniasis; RCT: randomized controlled trial; RR: risk ratio; OR: odds ratio.

Figures and Tables -
Summary of findings for the main comparison. Nutritional supplements versus no nutritional supplements for people who are being treated for active visceral leishmaniasis (VL)