ORCID Profile
0000-0003-1593-3770
Current Organisation
ACT Health
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Publisher: Wiley
Date: 14-06-2021
DOI: 10.1002/PRP2.810
Abstract: In this in idual patient data meta‐analysis we examined datasets of two randomized placebo‐controlled trials which investigated the effect of nasal carrageenan separately on children and adults. In both trials, iota‐carrageenan was administered nasally three times per day for 7 days for patients with the common cold and follow‐up lasted for 21 days. We used Cox regression to estimate the effect of carrageenan on recovery rate. We also used quantile regression to calculate the effect of carrageenan on colds of differing lengths. Nasal carrageenan increased the recovery rate from all colds by 54% (95% CI 15%–105% p = .003). The increase in recovery rate was 139% for coronavirus infections, 119% for influenza A infections, and 70% for rhinovirus infections. The mean duration of all colds in the placebo groups of the first four quintiles were 4.0, 6.8, 8.8, and 13.7 days, respectively. The fifth quintile contained patients with censored data. The 13.7‐day colds were shortened by 3.8 days (28% reduction), and 8.8‐day colds by 1.3 days (15% reduction). Carrageenan had no meaningful effect on shorter colds. In the placebo group, 21 patients had colds lasting over 20 days, compared with six patients in the carrageenan group, which corresponds to a 71% ( p = .003) reduction in the risk of longer colds. Given that carrageenan has an effect on erse virus groups, and effects at the clinical level on two old coronaviruses, it seems plausible that carrageenan may have an effect on COVID‐19. Further research on nasal iota‐carrageenan is warranted.
Publisher: Wiley
Date: 23-09-2022
DOI: 10.1002/JRSM.1601
Publisher: Research Square Platform LLC
Date: 16-11-2020
DOI: 10.21203/RS.3.RS-108775/V1
Abstract: Carrageenan is a sulfated polysaccharide that has been extensively used in food products. Since the 1980s, carrageenan has been shown to prevent infections due to several viruses in cell cultures, including rhinoviruses which cause the common cold. In animal studies it prevented mortality caused by influenza A. Carrageenan is generally regarded as safe by the FDA. This in idual patient data meta-analysis examined the datasets of two randomized placebo-controlled trials which investigated the effect of carrageenan separately on children and adults. In both trials, iota-carrageenan was administered nasally 3 times per day for 7 days for patients with the common cold and follow-up lasted for 21 days. Nasal carrageenan increased the recovery rate from all colds by 54% (95% CI 15% to 105% P = 0.003). The increase in recovery rate was 140% in coronavirus infections, 119% in influenza A infections, and 70% in rhinovirus infections. We used quantile regression to calculate the effect of carrageenan on colds of differing lengths, by iding the distribution into 5 quintiles. The mean duration of colds in the placebo groups of the first four quintiles were 4.0, 6.8, 8.8 and 13.7 days, respectively. The fifth quintile contained patients with censored data. The 13.7-day colds were shortened by 3.8 days (28% reduction), and 8.8-day colds by 1.3 days (15% reduction). Carrageenan had no meaningful effect on shorter colds. In the placebo group, 21 patients had colds that lasted over 20 days, compared with 6 patients in the carrageenan group. This corresponds to a 71% (P = 0.003) reduction in the risk of longer colds. Finally, in the placebo group, 37 patients had recurring cold symptoms after first being cured, compared with 16 in the carrageenan group. This corresponds to a 56% (P = 0.002) reduction in the risk of recurring symptoms. Given that carrageenan has an effect on erse virus groups, and its demonstrated effects on two old coronaviruses, it seems plausible that nasal carrageenan may also have an effect on the new coronavirus SARS-CoV-2. Further research on nasal iota-carrageenan is warranted.
Publisher: Springer Science and Business Media LLC
Date: 14-02-2022
Publisher: Elsevier BV
Date: 06-2004
Publisher: Korean Society of Infectious Diseases and Korean Society for Chemotherapy
Date: 2020
Publisher: Elsevier BV
Date: 06-2022
Publisher: Informa UK Limited
Date: 03-06-2023
Publisher: Elsevier BV
Date: 02-2021
Publisher: Oxford University Press (OUP)
Date: 14-02-2023
DOI: 10.1093/CID/CIAD078
Publisher: Oxford University Press (OUP)
Date: 04-05-2022
Publisher: University of Helsinki
Date: 2021
Publisher: Informa UK Limited
Date: 23-03-2023
Publisher: Research Square Platform LLC
Date: 03-2021
DOI: 10.21203/RS.3.RS-289381/V1
Abstract: The COVID A to Z trial (JAMA Netw Open. 2021 :e210369) is important as it focused specifically on SARS-CoV-2 coronavirus patients and examined a high dose of vitamin C which was previously predicted to reduce the duration of respiratory virus infections by about 20%. Unfortunately, there are several limitations in the trial methods. The COVID A to Z trial was “stopped early for futility”. In the s le size calculation, the authors assumed a 1.0 day shorter symptoms by intervention. Duration of symptoms was reduced by 1.2 days in the vitamin C arm compared with the usual care arm. Given that the observed vitamin C effect was 20% greater than the expected effect (1.2 vs. 1.0), it is illogical to have stopped the trial early because of “futility”. In this reanalysis we calculated the rate ratio of recovery between the vitamin C and usual care arms and found that vitamin C increased the rate of recovery by 70% (95% CI 6.8% to 170%, P = 0.025). Furthermore, we calculated quantile treatment effect of vitamin C. At the 60th percentile level of symptom distribution, duration was 9 days in the usual care arm, and 6 days in the vitamin C arm, which corresponds to reduction in symptom duration by 3 days (95% CI 3 to 4.6 days P 0.001). The analysis of the quantile treatment effect indicates that there may be around 30% reduction in symptom duration in patients with the longest symptoms. Our reanalysis indicates a need for methodologically sound trials with larger numbers of patients to investigate the treatment effects of vitamin C against SARS-CoV-2.
Publisher: Wiley
Date: 31-01-2013
Publisher: MDPI AG
Date: 24-02-2020
DOI: 10.3390/NU12020586
Abstract: We recently published a meta-analysis on vitamin C and the length of intensive care unit [ICU] stay [...]
Publisher: Springer Science and Business Media LLC
Date: 07-02-2020
DOI: 10.1186/S40560-020-0432-Y
Abstract: Our recent meta-analysis indicated that vitamin C may shorten the length of ICU stay and the duration of mechanical ventilation. Here we analyze modification of the vitamin C effect on ventilation time, by the control group ventilation time (which we used as a proxy for severity of disease in the patients of each trial). We searched MEDLINE, Scopus, and the Cochrane Central Register of Controlled Trials and reference lists of relevant publications. We included controlled trials in which the administration of vitamin C was the only difference between the study groups. We did not limit our search to randomized trials and did not require placebo control. We included all doses and all durations of vitamin C administration. One author extracted study characteristics and outcomes from the trial reports and entered the data in a spreadsheet. Both authors checked the data entered against the original reports. We used meta-regression to examine whether the vitamin C effect on ventilation time depends on the duration of ventilation in the control group. We identified nine potentially eligible trials, eight of which were included in the meta-analysis. We pooled the results of the eight trials, including 685 patients in total, and found that vitamin C shortened the length of mechanical ventilation on average by 14% ( P = 0.00001). However, there was significant heterogeneity in the effect of vitamin C between the trials. Heterogeneity was fully explained by the ventilation time in the untreated control group. Vitamin C was most beneficial for patients with the longest ventilation, corresponding to the most severely ill patients. In five trials including 471 patients requiring ventilation for over 10 h, a dosage of 1–6 g/day of vitamin C shortened ventilation time on average by 25% ( P 0.0001). We found strong evidence that vitamin C shortens the duration of mechanical ventilation, but the magnitude of the effect seems to depend on the duration of ventilation in the untreated control group. The level of baseline illness severity should be considered in further research. Different doses should be compared directly in future trials.
Publisher: Springer Science and Business Media LLC
Date: 03-08-2019
Publisher: Springer Science and Business Media LLC
Date: 25-02-2015
Publisher: MDPI AG
Date: 27-03-2019
DOI: 10.3390/NU11040708
Abstract: A number of controlled trials have previously found that in some contexts, vitamin C can have beneficial effects on blood pressure, infections, bronchoconstriction, atrial fibrillation, and acute kidney injury. However, the practical significance of these effects is not clear. The purpose of this meta-analysis was to evaluate whether vitamin C has an effect on the practical outcomes: length of stay in the intensive care unit (ICU) and duration of mechanical ventilation. We identified 18 relevant controlled trials with a total of 2004 patients, 13 of which investigated patients undergoing elective cardiac surgery. We carried out the meta-analysis using the inverse variance, fixed effect options, using the ratio of means scale. In 12 trials with 1766 patients, vitamin C reduced the length of ICU stay on average by 7.8% (95% CI: 4.2% to 11.2% p = 0.00003). In six trials, orally administered vitamin C in doses of 1–3 g/day (weighted mean 2.0 g/day) reduced the length of ICU stay by 8.6% (p = 0.003). In three trials in which patients needed mechanical ventilation for over 24 hours, vitamin C shortened the duration of mechanical ventilation by 18.2% (95% CI 7.7% to 27% p = 0.001). Given the insignificant cost of vitamin C, even an 8% reduction in ICU stay is worth exploring. The effects of vitamin C on ICU patients should be investigated in more detail.
Publisher: Wiley
Date: 26-09-2017
Publisher: The Sax Institute
Date: 09-2016
DOI: 10.17061/PHRP2641646
Abstract: Inhalation of asbestos fibres is the predominant cause of malignant mesothelioma. Domestic exposure to asbestos is a major community concern in the Australian Capital Territory (ACT) because of loose-fill asbestos home insulation. Little is known about how trends in mesothelioma rates in the ACT compare with those elsewhere. The objective of this study was to describe trends in mesothelioma rates in the ACT and compare them with those for the rest of Australia. We used de-identified data from the ACT Cancer Registry (1982- 2014), and the Western Australia (WA) Cancer Registry and the Australian Cancer Database (1982-2011). We calculated crude mesothelioma rates, by 3-year periods, for the ACT and for the rest of Australia (excluding WA). We used Poisson regression to analyse mesothelioma trends from 1994 to 2011 (complete reporting period) using an indirect standardisation approach to adjust for age and sex. There were 140 mesothelioma cases reported to the ACT Cancer Registry between 1982 and 2014 - 81% male and 19% female. Between 1994 and 2011, age- and sex-adjusted mesothelioma rates in the ACT increased over time, on average by 12% per 3-year period (relative risk [RR] 1.12 95% confidence interval [CI] 0.99, 1.26). Compared with the rest of Australia (excluding WA), ACT rates were, on average, lower (RR 0.84 95% CI 0.69, 1.02), but they increased at a higher rate (RR 1.12 per 3-year period 95% CI 0.99, 1.27). These results are strongly influenced by the higher rate of mesothelioma observed in the ACT in 2009-2011, when ACT rates became similar to those for the rest of Australia (excluding WA). Although mesothelioma rates may have increased more in the ACT than the rest of Australia (excluding WA) during the past two decades, there is considerable uncertainty in the trends. More information is needed regarding the health risks associated with living in a house with loose-fill asbestos insulation. This is the subject of further studies within the ACT Asbestos Health Study.
No related grants have been discovered for Elizabeth Chalker.