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Meta-Analysis
. 2017 Nov 3;11(11):CD011564.
doi: 10.1002/14651858.CD011564.pub2.

Vitamin D supplementation for chronic liver diseases in adults

Goran Bjelakovic  1 , Dimitrinka Nikolova, Marko Bjelakovic, Christian Gluud
Affiliations
Meta-Analysis

Vitamin D supplementation for chronic liver diseases in adults

Goran Bjelakovic et al. Cochrane Database Syst Rev. .

Update in

Abstract

Background: Vitamin D deficiency is often reported in people with chronic liver diseases. Therefore, improving vitamin D status could have a beneficial effect on people with chronic liver diseases.

Objectives: To assess the beneficial and harmful effects of vitamin D supplementation in people with chronic liver diseases.

Search methods: We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, and Conference Proceedings Citation Index - Science. We also searched databases of ongoing trials and the World Health Organization International Clinical Trials Registry Platform. We scanned bibliographies of relevant publications and asked experts and pharmaceutical companies for additional trials. All searches were up to January 2017.

Selection criteria: Randomised clinical trials that compared vitamin D at any dose, duration, and route of administration versus placebo or no intervention in adults with chronic liver diseases. Vitamin D could have been administered as supplemental vitamin D (vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol)), or an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol), 25-hydroxyvitamin D (calcidiol), or 1,25-dihydroxyvitamin D (calcitriol)).

Data collection and analysis: We used standard methodological procedures expected by The Cochrane Collaboration. We contacted authors of the trials to ask for missing information. We conducted random-effects and fixed-effect meta-analyses. For dichotomous outcomes, we calculated risk ratios (RRs), and for continuous outcomes, we calculated mean differences (MD), both with 95% confidence intervals (CI) and Trial Sequential Analyses-adjusted CIs. We calculated Peto odds ratio (OR) for rare events. We considered risk of bias in domains to assess the risk of systematic errors. We conducted Trial Sequential Analyses to control the risk of random errors. We assessed the quality of the evidence with GRADE.

Main results: We included 15 randomised clinical trials with 1034 participants randomised. All trials had a parallel group design. Nine trials were conducted in high-income countries and six trials in middle-income countries. All trials were at high risk of bias. Six trials included participants with chronic hepatitis C, four trials included participants with liver cirrhosis, four trials included participants with non-alcoholic fatty liver disease, and one trial included liver transplant recipients. All included trials reported the baseline vitamin D status of participants. Participants in six trials had baseline 25-hydroxyvitamin D levels at or above vitamin D adequacy (20 ng/mL), while participants in the remaining nine trials were vitamin D insufficient (less than 20 ng/mL). All trials administered vitamin D orally. Mean duration of vitamin D supplementation was 0.5 years and follow-up was 0.6 years. Eleven trials (831 participants; 40% women; mean age 52 years) tested vitamin D3, one trial (18 men; mean age 61 years) with three intervention groups tested vitamin D2 and 25-dihydroxyvitamin D in separate groups, and three trials (185 participants; 55% women; mean age 55 years) tested 1,25-dihydroxyvitamin D. Seven trials used placebo, and eight trials used no intervention in the control group.The effect of vitamin D on all-cause mortality at the end of follow-up is uncertain because the results were imprecise (Peto OR 0.70, 95% CI 0.09 to 5.38; I2 = 32%; 15 trials; 1034 participants; very low quality evidence). Trial Sequential Analysis on all-cause mortality was performed based on a mortality rate in the control group of 10%, a relative risk reduction of 28% in the experimental intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 6396 participants. The cumulative Z-curve did not cross the trial sequential monitoring boundary for benefit or harm after the 15th trial, and the Trial Sequential Analyses-adjusted CI was 0.00 to 2534.The effect of vitamin D on liver-related mortality (RR 1.62, 95% CI 0.08 to 34.66; 1 trial; 18 participants) and on serious adverse events such as hypercalcaemia (RR 5.00, 95% CI 0.25 to 100.8; 1 trial; 76 participants), myocardial infarction (RR 0.75, 95% CI 0.08 to 6.81; 2 trials; 86 participants), and thyroiditis (RR 0.33 95% CI 0.01 to 7.91; 1 trial; 68 participants) is uncertain because the results were imprecise. The evidence on all these outcomes is of very low quality. The effect of vitamin D3 on non-serious adverse events such as glossitis (RR 3.70, 95% CI 0.16 to 87.6; 1 trial; 65 participants; very low quality of evidence) is uncertain because the result was imprecise.Due to few data, we did not conduct Trial Sequential Analysis on liver-related mortality, and serious and non-serious adverse events.We found no data on liver-related morbidity and health-related quality of life in the randomised trials included in this review.

Authors' conclusions: We are uncertain as to whether vitamin D supplements in the form of vitamin D3, vitamin D2, 1,25-dihydroxyvitamin D, or 25-dihydroxyvitamin D have important effect on all-cause mortality, liver-related mortality, or on serious or non-serious adverse events because the results were imprecise. There is no evidence on the effect of vitamin D supplementation on liver-related morbidity and health-related quality of life. Our conclusions are based on few trials with an insufficient number of participants and on lack of data on clinically important outcomes. In addition, the analysed trials are at high risk of bias with significant intertrial heterogeneity. The overall quality of evidence is very low.

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Conflict of interest statement

None known.

Figures

1
1
Study flow diagram
2
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Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
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3
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
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4
Funnel plot of comparison: 1 Vitamin D versus placebo or no intervention, outcome: 1.1 All‐cause mortality.
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5
Trial Sequential Analysis on all‐cause mortality up to 1.4‐year follow‐up in 15 vitamin D trials, based on mortality rate in the control group of 10%, a relative risk reduction of 28% in the intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 6396 participants. The cumulative Z‐curve (blue line) did not cross the trial sequential monitoring boundary for benefit or harm (red inward sloping lines) and did not enter the trial sequential monitoring area for futility (inner‐wedge with red outward sloping lines).
6
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Trial Sequential Analysis on rapid virological response in the two vitamin D trials was performed based on a mortality rate in the control group of 5%, a relative risk reduction (RRR) of 30% in the intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 11958 participants. The cumulative Z‐curve crossed the conventional monitoring boundary for benefit. The trial sequential monitoring boundary is ignored due to little information use (1.56%).
7
7
Trial Sequential Analysis on early virological response in the two vitamin D trials was performed based on a mortality rate in the control group of 5%, a relative risk reduction (RRR) of 30% in the intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 11958 participants. The cumulative Z‐curve crossed the conventional monitoring boundary for benefit. The trial sequential monitoring boundary is ignored due to little information use (1.17%).
8
8
Trial Sequential Analysis on sustained virological response in the five vitamin D trials was performed based on a mortality rate in the control group of 5%, a relative risk reduction (RRR) of 30% in the intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 69798 participants. The trial sequential monitoring boundary is ignored due to little information use (0.45%).
9
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Trial Sequential Analysis on acute cellular rejection in the one vitamin D trial was performed based on a mortality rate in the control group of 5%, a relative risk reduction (RRR) of 30% in the intervention group, a type I error of 2.5%, and type II error of 10% (90% power). There was no diversity. The required information size was 11958 participants. The cumulative Z‐curve did not cross the conventional monitoring boundary. The trial sequential monitoring boundary is ignored due to little information use (0.84%).
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