Portosystemic shunts versus endoscopic intervention with or without medical treatment for prevention of rebleeding in people with cirrhosis.

BACKGROUND: People with liver cirrhosis who have had one episode of variceal bleeding are at risk for repeated episodes of bleeding. Endoscopic intervention and portosystemic shunts are used to prevent further bleeding, but there is no consensus as to which approach is preferable. OBJECTIVES: To compare the benefits and harms of shunts (surgical shunts (total shunt (TS), distal splenorenal shunt (DSRS), or transjugular intrahepatic portosystemic shunt (TIPS)) versus endoscopic intervention (endoscopic sclerotherapy or banding, or both) with or without medical treatment (non-selective beta blockers or nitrates, or both) for prevention of variceal rebleeding in people with liver cirrhosis. SEARCH METHODS: We searched the CHBG Controlled Trials Register; CENTRAL, in the Cochrane Library; MEDLINE Ovid; Embase Ovid; LILACS (Bireme); Science Citation Index - Expanded (Web of Science); and Conference Proceedings Citation Index - Science (Web of Science); as well as conference proceedings and the references of trials identified until 22 June 2020. We contacted study investigators and industry researchers. SELECTION CRITERIA: Randomised clinical trials comparing shunts versus endoscopic interventions with or without medical treatment in people with cirrhosis who had recovered from a variceal haemorrhage. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. When possible, we collected data to allow intention-to-treat analysis. For each outcome, we estimated a meta-analysed estimate of treatment effect across trials (risk ratio for binary outcomes). We used random-effects model meta-analysis as our main analysis and as a means of presenting results. We reported differences in means for continuous outcomes without a meta-analytic estimate due to high variability in their assessment among all trials. We assessed the certainty of evidence using GRADE. MAIN RESULTS: We identified 27 randomised trials with 1828 participants. Three trials assessed TSs, five assessed DSRSs, and 19 trials assessed TIPSs. The endoscopic intervention was sclerotherapy in 16 trials, band ligation in eight trials, and a combination of band ligation and either sclerotherapy or glue injection in three trials. In eight trials, endoscopy was combined with beta blockers (in one trial plus isosorbide mononitrate). We judged all trials to be at high risk of bias. We assessed the certainty of evidence for all the outcome review results as very low (i.e. the true effects of the results are likely to be substantially different from the results of estimated effects). The very low evidence grading is due to the overall high risk of bias for all trials, and to imprecision and publication bias for some outcomes. Therefore, we are very uncertain whether portosystemic shunts versus endoscopy interventions with or without medical treatment have effects on all-cause mortality (RR 0.99, 95% CI 0.86 to 1.13; 1828 participants; 27 trials), on rebleeding (RR 0.40, 95% CI 0.33 to 0.50; 1769 participants; 26 trials), on mortality due to rebleeding (RR 0.51, 95% CI 0.34 to 0.76; 1779 participants; 26 trials), and on occurrence of hepatic encephalopathy, both acute (RR 1.60, 95% CI 1.33 to 1.92; 1649 participants; 24 trials) and chronic (RR 2.51, 95% CI 1.38 to 4.55; 956 participants; 13 trials). No data were available regarding health-related quality of life. Analysing each modality of portosystemic shunts individually (i.e. TS, DSRS, and TIPS) versus endoscopic interventions with or without medical treatment, we are very uncertain if each type of shunt has effect on all-cause mortality: TS, RR 0.46, 95% CI 0.19 to 1.13; 164 participants; 3 trials; DSRS, RR 0.93, 95% CI 0.65 to 1.33; 352 participants; 4 trials; and TIPS, RR 1.10, 95% CI 0.92 to 1.31; 1312 participants; 19 trial; on rebleeding: TS, RR 0.28, 95% CI 0.14 to 0.56; 127 participants; 2 trials; DSRS, RR 0.26, 95% CI 0.11 to 0.65; 330 participants; 5 trials; and TIPS, RR 0.44, 95% CI 0.36 to 0.55; 1312 participants; 19 trials; on mortality due to rebleeding: TS, RR 0.25, 95% CI 0.06 to 0.96; 164 participants; 3 trials; DSRS, RR 0.31, 95% CI 0.13 to 0.74; 352 participants; 5 trials; and TIPS, RR 0.65, 95% CI 0.40 to 1.04; 1263 participants; 18 trials; on acute hepatic encephalopathy: TS, RR 1.66, 95% CI 0.70 to 3.92; 115 participants; 2 trials; DSRS, RR 1.70, 95% CI 0.94 to 3.08; 287 participants; 4 trials, TIPS, RR 1.61, 95% CI 1.29 to 1.99; 1247 participants; 18 trials; and chronic hepatic encephalopathy: TS, Fisher's exact test P = 0.11; 69 participants; 1 trial; DSRS, RR 4.87, 95% CI 1.46 to 16.23; 170 participants; 2 trials; and TIPS, RR 1.88, 95% CI 0.93 to 3.80; 717 participants; 10 trials. The proportion of participants with shunt occlusion or dysfunction was overall 37% (95% CI 33% to 40%). It was 3% (95% CI 0.8% to 10%) following TS, 7% (95% CI 3% to 13%) following DSRS, and 47.1% (95% CI 43% to 51%) following TIPS. Shunt dysfunction in trials utilising polytetrafluoroethylene-covered stents was 17% (95% CI 11% to 24%). Length of inpatient hospital stay and cost were not comparable across trials. Funding was unclear in 16 trials; 11 trials were funded by government, local hospitals, or universities. AUTHORS' CONCLUSIONS: Evidence on whether portosystemic shunts versus endoscopy interventions with or without medical treatment in people with cirrhosis and previous hypertensive portal bleeding have little or no effect on all-cause mortality is very uncertain. Evidence on whether portosystemic shunts may reduce bleeding and mortality due to bleeding while increasing hepatic encephalopathy is also very uncertain. We need properly conducted trials to assess effects of these interventions not only on assessed outcomes, but also on quality of life, costs, and length of hospital stay.

Plasma expanders for people with cirrhosis and large ascites treated with abdominal paracentesis.

BACKGROUND: Plasma volume expanders are used in connection to paracentesis in people with cirrhosis to prevent reduction of effective plasma volume, which may trigger deleterious effect on haemodynamic balance, and increase morbidity and mortality. Albumin is considered the standard product against which no plasma expansion or other plasma expanders, e.g. other colloids (polygeline , dextrans, hydroxyethyl starch solutions, fresh frozen plasma), intravenous infusion of ascitic fluid, crystalloids, or mannitol have been compared. However, the benefits and harms of these plasma expanders are not fully clear. OBJECTIVES: To assess the benefits and harms of any plasma volume expanders such as albumin, other colloids (polygeline, dextrans, hydroxyethyl starch solutions, fresh frozen plasma), intravenous infusion of ascitic fluid, crystalloids, or mannitol versus no plasma volume expander or versus another plasma volume expander for paracentesis in people with cirrhosis and large ascites. SEARCH METHODS: We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS, CNKI, VIP, Wanfang, Science Citation Index Expanded, and Conference Proceedings Citation Index until January 2019. Furthermore, we searched FDA, EMA, WHO (last search January 2019), www.clinicaltrials.gov/, and www.controlled-trials.com/ for ongoing trials. SELECTION CRITERIA: Randomised clinical trials, no matter their design or year of publication, publication status, and language, assessing the use of any type of plasma expander versus placebo, no intervention, or a different plasma expander in connection with paracentesis for ascites in people with cirrhosis. We considered quasi-randomised, retrieved with the searches for randomised clinical trials only, for reports on harms. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. We calculated the risk ratio (RR) or mean difference (MD) using the fixed-effect model and the random-effects model meta-analyses, based on the intention-to-treat principle, whenever possible. If the fixed-effect and random-effects models showed different results, then we made our conclusions based on the analysis with the highest P value (the more conservative result). We assessed risks of bias of the individual trials using predefined bias risk domains. We assessed the certainty of the evidence at an outcome level, using GRADE, and constructed 'Summary of Findings' tables for seven of our review outcomes. MAIN RESULTS: We identified 27 randomised clinical trials for inclusion in this review (24 published as full-text articles and 3 as abstracts). Five of the trials, with 271 participants, assessed plasma expanders (albumin in four trials and ascitic fluid in one trial) versus no plasma expander. The remaining 22 trials, with 1321 participants, assessed one type of plasma expander, i.e. dextran, hydroxyethyl starch, polygeline, intravenous infusion of ascitic fluid, crystalloids, or mannitol versus another type of plasma expander, i.e. albumin in 20 of these trials and polygeline in one trial. Twenty-five trials provided data for quantitative meta-analysis. According to the Child-Pugh classification, most participants were at an intermediate to advanced stage of liver disease in the absence of hepatocellular carcinoma, recent gastrointestinal bleeding, infections, and hepatic encephalopathy. All trials were assessed as at overall high risk of bias. Ten trials seemed not to have been funded by industry; twelve trials were considered unclear about funding; and five trials were considered funded by industry or a for-profit institution.We found no evidence of a difference in effect between plasma expansion versus no plasma expansion on mortality (RR 0.52, 95% CI 0.06 to 4.83; 248 participants; 4 trials; very low certainty); renal impairment (RR 0.32, 95% CI 0.02 to 5.88; 181 participants; 4 trials; very low certainty); other liver-related complications (RR 1.61, 95% CI 0.79 to 3.27; 248 participants; 4 trials; very low certainty); and non-serious adverse events (RR 1.04, 95% CI 0.32 to 3.40; 158 participants; 3 trials; very low certainty). Two of the trials stated that no serious adverse events occurred while the remaining trials did not report on this outcome. No trial reported data on health-related quality of life.We found no evidence of a difference in effect between experimental plasma expanders versus albumin on mortality (RR 1.03, 95% CI 0.82 to 1.30; 1014 participants; 14 trials; very low certainty); serious adverse events (RR 0.89, 95% CI 0.10 to 8.30; 118 participants; 2 trials; very low certainty); renal impairment (RR 1.17, 95% CI 0.71 to 1.91; 1107 participants; 17 trials; very low certainty); other liver-related complications (RR 1.10, 95% CI 0.82 to 1.48; 1083 participants; 16 trials; very low certainty); and non-serious adverse events (RR 1.37, 95% CI 0.66 to 2.85; 977 participants; 14 trials; very low certainty). We found no data on heath-related quality of life and refractory ascites. AUTHORS' CONCLUSIONS: Our systematic review and meta-analysis did not find any benefits or harms of plasma expanders versus no plasma expander or of one plasma expander such as polygeline, dextrans, hydroxyethyl starch, intravenous infusion of ascitic fluid, crystalloids, or mannitol versus albumin on primary or secondary outcomes. The data originated from few, small, mostly short-term trials at high risks of systematic errors (bias) and high risks of random errors (play of chance). GRADE assessments concluded that the evidence was of very low certainty. Therefore, we can neither demonstrate or discard any benefit of plasma expansion versus no plasma expansion, and differences between one plasma expander versus another plasma expander.Larger trials at low risks of bias are needed to assess the role of plasma expanders in connection with paracentesis. Such trials should be conducted according to the SPIRIT guidelines and reported according to the CONSORT guidelines.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND: Our previous systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review. OBJECTIVES: To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults. METHODS: Search methods: We searched The Cochrane Library, Medline, Embase, Lilacs, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials. Selection criteria: We included all primary and secondary prevention randomized clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Data collection and analysis: Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimize the risk of systematic errors. Trial sequential analyses were conducted to minimize the risk of random errors. Random effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity. MAIN RESULTS: Seventy-eight randomized trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant ...

Vitamin D supplementation for prevention of mortality in adults.

BACKGROUND: Available evidence on the effects of vitamin D on mortality has been inconclusive. In a recent systematic review, we found evidence that vitamin D3 may decrease mortality in mostly elderly women. The present systematic review updates and reassesses the benefits and harms of vitamin D supplementation used in primary and secondary prophylaxis of mortality. OBJECTIVES: To assess the beneficial and harmful effects of vitamin D supplementation for prevention of mortality in healthy adults and adults in a stable phase of disease. SEARCH METHODS: We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index-Expanded and Conference Proceedings Citation Index-Science (all up to February 2012). We checked references of included trials and pharmaceutical companies for unidentified relevant trials. SELECTION CRITERIA: Randomised trials that compared any type of vitamin D in any dose with any duration and route of administration versus placebo or no intervention in adult participants. Participants could have been recruited from the general population or from patients diagnosed with a disease in a stable phase. Vitamin D could have been administered as supplemental vitamin D (vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol)) or as an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol) or 1,25-dihydroxyvitamin D (calcitriol)). DATA COLLECTION AND ANALYSIS: Six review authors extracted data independently. Random-effects and fixed-effect meta-analyses were conducted. For dichotomous outcomes, we calculated the risk ratios (RRs). To account for trials with zero events, we performed meta-analyses of dichotomous data using risk differences (RDs) and empirical continuity corrections. We used published data and data obtained by contacting trial authors.To minimise the risk of systematic error, we assessed the risk of bias of the included trials. Trial sequential analyses controlled the risk of random errors possibly caused by cumulative meta-analyses. MAIN RESULTS: We identified 159 randomised clinical trials. Ninety-four trials reported no mortality, and nine trials reported mortality but did not report in which intervention group the mortality occurred. Accordingly, 56 randomised trials with 95,286 participants provided usable data on mortality. The age of participants ranged from 18 to 107 years. Most trials included women older than 70 years. The mean proportion of women was 77%. Forty-eight of the trials randomly assigned 94,491 healthy participants. Of these, four trials included healthy volunteers, nine trials included postmenopausal women and 35 trials included older people living on their own or in institutional care. The remaining eight trials randomly assigned 795 participants with neurological, cardiovascular, respiratory or rheumatoid diseases. Vitamin D was administered for a weighted mean of 4.4 years. More than half of the trials had a low risk of bias. All trials were conducted in high-income countries. Forty-five trials (80%) reported the baseline vitamin D status of participants based on serum 25-hydroxyvitamin D levels. Participants in 19 trials had vitamin D adequacy (at or above 20 ng/mL). Participants in the remaining 26 trials had vitamin D insufficiency (less than 20 ng/mL).Vitamin D decreased mortality in all 56 trials analysed together (5,920/47,472 (12.5%) vs 6,077/47,814 (12.7%); RR 0.97 (95% confidence interval (CI) 0.94 to 0.99); P = 0.02; I(2) = 0%). More than 8% of participants dropped out. 'Worst-best case' and 'best-worst case' scenario analyses demonstrated that vitamin D could be associated with a dramatic increase or decrease in mortality. When different forms of vitamin D were assessed in separate analyses, only vitamin D3 decreased mortality (4,153/37,817 (11.0%) vs 4,340/38,110 (11.4%); RR 0.94 (95% CI 0.91 to 0.98); P = 0.002; I(2) = 0%; 75,927 participants; 38 trials). Vitamin D2, alfacalcidol and calcitriol did not significantly affect mortality. A subgroup analysis of trials at high risk of bias suggested that vitamin D2 may even increase mortality, but this finding could be due to random errors. Trial sequential analysis supported our finding regarding vitamin D3, with the cumulative Z-score breaking the trial sequential monitoring boundary for benefit, corresponding to 150 people treated over five years to prevent one additional death. We did not observe any statistically significant differences in the effect of vitamin D on mortality in subgroup analyses of trials at low risk of bias compared with trials at high risk of bias; of trials using placebo compared with trials using no intervention in the control group; of trials with no risk of industry bias compared with trials with risk of industry bias; of trials assessing primary prevention compared with trials assessing secondary prevention; of trials including participants with vitamin D level below 20 ng/mL at entry compared with trials including participants with vitamin D levels equal to or greater than 20 ng/mL at entry; of trials including ambulatory participants compared with trials including institutionalised participants; of trials using concomitant calcium supplementation compared with trials without calcium; of trials using a dose below 800 IU per day compared with trials using doses above 800 IU per day; and of trials including only women compared with trials including both sexes or only men. Vitamin D3 statistically significantly decreased cancer mortality (RR 0.88 (95% CI 0.78 to 0.98); P = 0.02; I(2) = 0%; 44,492 participants; 4 trials). Vitamin D3 combined with calcium increased the risk of nephrolithiasis (RR 1.17 (95% CI 1.02 to 1.34); P = 0.02; I(2) = 0%; 42,876 participants; 4 trials). Alfacalcidol and calcitriol increased the risk of hypercalcaemia (RR 3.18 (95% CI 1.17 to 8.68); P = 0.02; I(2) = 17%; 710 participants; 3 trials). AUTHORS' CONCLUSIONS: Vitamin D3 seemed to decrease mortality in elderly people living independently or in institutional care. Vitamin D2, alfacalcidol and calcitriol had no statistically significant beneficial effects on mortality. Vitamin D3 combined with calcium increased nephrolithiasis. Both alfacalcidol and calcitriol increased hypercalcaemia. Because of risks of attrition bias originating from substantial dropout of participants and of outcome reporting bias due to a number of trials not reporting on mortality, as well as a number of other weaknesses in our evidence, further placebo-controlled randomised trials seem warranted.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases.

BACKGROUND: Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review. OBJECTIVES: To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults. SEARCH METHODS: We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials. SELECTION CRITERIA: We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. DATA COLLECTION AND ANALYSIS: Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity. MAIN RESULTS: Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002). AUTHORS' CONCLUSIONS: We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Vitamin D supplementation for prevention of mortality in adults.

BACKGROUND: The available evidence on vitamin D and mortality is inconclusive. OBJECTIVES: To assess the beneficial and harmful effects of vitamin D for prevention of mortality in adults. SEARCH STRATEGY: We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science (to January 2011). We scanned bibliographies of relevant publications and asked experts and pharmaceutical companies for additional trials. SELECTION CRITERIA: We included randomised trials that compared vitamin D at any dose, duration, and route of administration versus placebo or no intervention. Vitamin D could have been administered as supplemental vitamin D (vitamin D(3) (cholecalciferol) or vitamin D(2) (ergocalciferol)) or an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol) or 1,25-dihydroxyvitamin D (calcitriol)). DATA COLLECTION AND ANALYSIS: Six authors extracted data independently. Random-effects and fixed-effect model meta-analyses were conducted. For dichotomous outcomes, we calculated the risk ratios (RR). To account for trials with zero events, meta-analyses of dichotomous data were repeated using risk differences (RD) and empirical continuity corrections. Risk of bias was considered in order to minimise risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. MAIN RESULTS: Fifty randomised trials with 94,148 participants provided data for the mortality analyses. Most trials included elderly women (older than 70 years). Vitamin D was administered for a median of two years. More than one half of the trials had a low risk of bias. Overall, vitamin D decreased mortality (RR 0.97, 95% confidence interval (CI) 0.94 to 1.00, I(2) = 0%). When the different forms of vitamin D were assessed separately, only vitamin D(3) decreased mortality significantly (RR 0.94, 95% CI 0.91 to 0.98, I(2) = 0%; 74,789 participants, 32 trials) whereas vitamin D(2), alfacalcidol, or calcitriol did not. Trial sequential analysis supported our finding regarding vitamin D(3), corresponding to 161 individuals treated to prevent one additional death. Vitamin D(3) combined with calcium increased the risk of nephrolithiasis (RR 1.17, 95% CI 1.02 to 1.34, I(2) = 0%). Alfacalcidol and calcitriol increased the risk of hypercalcaemia (RR 3.18, 95% CI 1.17 to 8.68, I(2) = 17%). Data on health-related quality of life and health economics were inconclusive. AUTHORS' CONCLUSIONS: Vitamin D in the form of vitamin D(3) seems to decrease mortality in predominantly elderly women who are mainly in institutions and dependent care. Vitamin D(2), alfacalcidol, and calcitriol had no statistically significant effect on mortality. Vitamin D(3) combined with calcium significantly increased nephrolithiasis. Both alfacalcidol and calcitriol significantly increased hypercalcaemia.

Antioxidant supplements for preventing gastrointestinal cancers.

BACKGROUND: Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory. OBJECTIVES: To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers. SEARCH STRATEGY: We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials in The Cochrane Library (Issue 2, 2007), MEDLINE, EMBASE, LILACS, SCI-EXPANDED, and The Chinese Biomedical Database from inception to October 2007. We scanned reference lists and contacted pharmaceutical companies. SELECTION CRITERIA: Randomised trials comparing antioxidant supplements to placebo/no intervention examining occurrence of gastrointestinal cancers. DATA COLLECTION AND ANALYSIS: Two authors (GB and DN) independently selected trials for inclusion and extracted data. Outcome measures were gastrointestinal cancers, overall mortality, and adverse effects. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on random-effects and fixed-effect model meta-analysis. Meta-regression assessed the effect of covariates across the trials. MAIN RESULTS: We identified 20 randomised trials (211,818 participants), assessing beta-carotene (12 trials), vitamin A (4 trials), vitamin C (8 trials), vitamin E (10 trials), and selenium (9 trials). Trials quality was generally high. Heterogeneity was low to moderate. Antioxidant supplements were without significant effects on gastrointestinal cancers (RR 0.94, 95% CI 0.83 to 1.06). However, there was significant heterogeneity (I(2) = 54.0%, P = 0.003). The heterogeneity may have been explained by bias risk (low-bias risk trials RR 1.04, 95% CI 0.96 to 1.13 compared to high-bias risk trials RR 0.59, 95% CI 0.43 to 0.80; test of interaction P < 0.0005), and type of antioxidant supplement (beta-carotene potentially increasing and selenium potentially decreasing cancer risk). The antioxidant supplements had no significant effects on mortality in a random-effects model meta-analysis (RR 1.02, 95% CI 0.97 to 1.07, I(2) = 53.5%), but significantly increased mortality in a fixed-effect model meta-analysis (RR 1.04, 95% CI 1.02 to 1.07). Beta-carotene in combination with vitamin A (RR 1.16, 95% CI 1.09 to 1.23) and vitamin E (RR 1.06, 95% CI 1.02 to 1.11) significantly increased mortality. Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In five trials (four with high risk of bias), selenium seemed to show significant beneficial effect on gastrointestinal cancer occurrence (RR 0.59, 95% CI 0.46 to 0.75, I(2) = 0%). AUTHORS' CONCLUSIONS: We could not find convincing evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, antioxidant supplements seem to increase overall mortality. The potential cancer preventive effect of selenium should be tested in adequately conducted randomised trials.

Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis.

CONTEXT: Antioxidant supplements are used for prevention of several diseases. OBJECTIVE: To assess the effect of antioxidant supplements on mortality in randomized primary and secondary prevention trials. DATA SOURCES AND TRIAL SELECTION: We searched electronic databases and bibliographies published by October 2005. All randomized trials involving adults comparing beta carotene, vitamin A, vitamin C (ascorbic acid), vitamin E, and selenium either singly or combined vs placebo or vs no intervention were included in our analysis. Randomization, blinding, and follow-up were considered markers of bias in the included trials. The effect of antioxidant supplements on all-cause mortality was analyzed with random-effects meta-analyses and reported as relative risk (RR) with 95% confidence intervals (CIs). Meta-regression was used to assess the effect of covariates across the trials. DATA EXTRACTION: We included 68 randomized trials with 232 606 participants (385 publications). DATA SYNTHESIS: When all low- and high-bias risk trials of antioxidant supplements were pooled together there was no significant effect on mortality (RR, 1.02; 95% CI, 0.98-1.06). Multivariate meta-regression analyses showed that low-bias risk trials (RR, 1.16; 95% CI, 1.04[corrected]-1.29) and selenium (RR, 0.998; 95% CI, 0.997-0.9995) were significantly associated with mortality. In 47 low-bias trials with 180 938 participants, the antioxidant supplements significantly increased mortality (RR, 1.05; 95% CI, 1.02-1.08). In low-bias risk trials, after exclusion of selenium trials, beta carotene (RR, 1.07; 95% CI, 1.02-1.11), vitamin A (RR, 1.16; 95% CI, 1.10-1.24), and vitamin E (RR, 1.04; 95% CI, 1.01-1.07), singly or combined, significantly increased mortality. Vitamin C and selenium had no significant effect on mortality. CONCLUSIONS: Treatment with beta carotene, vitamin A, and vitamin E may increase mortality. The potential roles of vitamin C and selenium on mortality need further study.

Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis.

BACKGROUND: Oxidative stress can cause cancer. Our aim was to establish whether antioxidant supplements reduce the incidence of gastrointestinal cancer and mortality. METHODS: With the Cochrane Collaboration methodology, we reviewed all randomised trials comparing antioxidant supplements with placebo for prevention of gastrointestinal cancers. We searched electronic databases and reference lists (February, 2003). Outcome measures were incidence of gastrointestinal cancers, overall mortality, and adverse effects. Outcomes were analysed with fixed-effect and random-effects model meta-analyses and were reported as relative risk with 95% CIs. FINDINGS: We identified 14 randomised trials (n=170,525). Trial quality was generally high. Heterogeneity of results was low to moderate. Neither the fixed-effect (relative risk 0.96, 95% CI 0.88-1.04) nor random-effects meta-analyses (0.90, 0.77-1.05) showed significant effects of supplementation with beta-carotene, vitamins A, C, E, and selenium (alone or in combination) versus placebo on oesophageal, gastric, colorectal, pancreatic, and liver cancer incidences. In seven high-quality trials (n=131727), the fixed-effect model showed that antioxidant significantly increased mortality (1.06, 1.02-1.10), unlike the random-effects meta-analysis (1.06, 0.98-1.15). Low-quality trials showed no significant effect of antioxidant supplementation on mortality. The difference between the mortality estimates in high-quality and low-quality trials was significant (Z=2.10, p=0.04 by test of interaction). beta-carotene and vitamin A (1.29, 1.14-1.45) and beta-carotene and vitamin E (1.10, 1.01-1.20) significantly increased mortality, whereas beta-carotene alone only tended to increase mortality (1.05, 0.99-1.11). In four trials (three with unclear or inadequate methodology), selenium showed significant beneficial effect on the incidence of gastrointestinal cancer. INTERPRETATION: We could not find evidence that antioxidant supplements can prevent gastrointestinal cancers; on the contrary, they seem to increase overall mortality. The potential preventive effect of selenium should be studied in adequate randomised trials.