Browsing by Subject "Respiratory tract infections"

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  • Hemilä, Harri (2017)
    Background: The relative scale has been used for decades in analysing binary data in epidemiology. In contrast, there has been a long tradition of carrying out meta-analyses of continuous outcomes on the absolute, original measurement, scale. The biological rationale for using the relative scale in the analysis of binary outcomes is that it adjusts for baseline variations; however, similar baseline variations can occur in continuous outcomes and relative effect scale may therefore be often useful also for continuous outcomes. The aim of this study was to determine whether the relative scale is more consistent with empirical data on treating the common cold than the absolute scale. Methods: Individual patient data was available for 2 randomized trials on zinc lozenges for the treatment of the common cold. Mossad (Ann Intern Med 125:81-8, 1996) found 4.0 days and 43% reduction, and Petrus (Curr Ther Res 59:595-607, 1998) found 1.77 days and 25% reduction, in the duration of colds. In both trials, variance in the placebo group was significantly greater than in the zinc lozenge group. The effect estimates were applied to the common cold distributions of the placebo groups, and the resulting distributions were compared with the actual zinc lozenge group distributions. Results: When the absolute effect estimates, 4.0 and 1.77 days, were applied to the placebo group common cold distributions, negative and zero (i.e., impossible) cold durations were predicted, and the high level variance remained. In contrast, when the relative effect estimates, 43 and 25%, were applied, impossible common cold durations were not predicted in the placebo groups, and the cold distributions became similar to those of the zinc lozenge groups. Conclusions: For some continuous outcomes, such as the duration of illness and the duration of hospital stay, the relative scale leads to a more informative statistical analysis and more effective communication of the study findings. The transformation of continuous data to the relative scale is simple with a spreadsheet program, after which the relative scale data can be analysed using standard meta-analysis software. The option for the analysis of relative effects of continuous outcomes directly from the original data should be implemented in standard meta-analysis programs.
  • Hemilä, Harri (BioMed Central, 2017)
    Abstract Background The relative scale has been used for decades in analysing binary data in epidemiology. In contrast, there has been a long tradition of carrying out meta-analyses of continuous outcomes on the absolute, original measurement, scale. The biological rationale for using the relative scale in the analysis of binary outcomes is that it adjusts for baseline variations; however, similar baseline variations can occur in continuous outcomes and relative effect scale may therefore be often useful also for continuous outcomes. The aim of this study was to determine whether the relative scale is more consistent with empirical data on treating the common cold than the absolute scale. Methods Individual patient data was available for 2 randomized trials on zinc lozenges for the treatment of the common cold. Mossad (Ann Intern Med 125:81–8, 1996) found 4.0 days and 43% reduction, and Petrus (Curr Ther Res 59:595–607, 1998) found 1.77 days and 25% reduction, in the duration of colds. In both trials, variance in the placebo group was significantly greater than in the zinc lozenge group. The effect estimates were applied to the common cold distributions of the placebo groups, and the resulting distributions were compared with the actual zinc lozenge group distributions. Results When the absolute effect estimates, 4.0 and 1.77 days, were applied to the placebo group common cold distributions, negative and zero (i.e., impossible) cold durations were predicted, and the high level variance remained. In contrast, when the relative effect estimates, 43 and 25%, were applied, impossible common cold durations were not predicted in the placebo groups, and the cold distributions became similar to those of the zinc lozenge groups. Conclusions For some continuous outcomes, such as the duration of illness and the duration of hospital stay, the relative scale leads to a more informative statistical analysis and more effective communication of the study findings. The transformation of continuous data to the relative scale is simple with a spreadsheet program, after which the relative scale data can be analysed using standard meta-analysis software. The option for the analysis of relative effects of continuous outcomes directly from the original data should be implemented in standard meta-analysis programs.
  • Lahtiharju, Tapio (Helsingfors universitet, 2015)
    Tavoite. Selvittää, aiheuttavatko toistuvat hengitystieinfektiot vauvalle unihäiriöitä 8 kuukauden ikäisenä. Aineisto. Tutkimusaineisto oli Terveyden ja hyvinvoinnin laitoksen (THL) projektista Lapsen uni ja terveys ja käytettävissä oli vanhempien täyttämiä kyselylomakkeita sekä synnytyssairaalan tiedot. Alussa mukaan tulleista 1667 vauvasta tähän tutkimukseen osallistui 1125 vauvaa (67,5 %). Aineistossa korkeasti koulutettujen äitien määrä oli huomattavasti suurempi kuin väestössä keskimäärin. Metodit. Hengitystieinfektioiden vaikutusta unihäiriöihin tutkittiin logistisella regressiolla kolmella eri selitettävällä muuttujalla: ensisijaisesti ISQ-pisteillä (Infant Sleep Questionnaire), toissijaisisesti Richmanin kriteereillä ja vanhempien kokemuksella vauvan unihäiriöistä. Kovariaatit valittiin kirjallisuuden ja varianssianalyysien perusteella. Tulokset. Ryhmässä, jotka sairastivat enemmän hengitystieinfektioita, olivat suuremmat ISQ-pisteet (p ,050; OR 1,46), täyttyi useammin Richmanin kriteerit (p ,027; OR 1,59), ja vanhemmat useammin kokivat vauvalla olevan uniongelmia (p ,044; OR 1,46). Päätelmät. Tulokset viittaavat siihen, että runsaat hengitystieinfektiot lisäävät unihäiriöiden riskiä 8 kuukauden iässä. Tulokset eivät kuitenkaan ole yleistettävissä, koska aineisto oli vääristynyt ja sosioekonominen asema oli selvitetty epätäydellisesti.
  • Hemila, Harri; Chalker, Elizabeth (2015)
    BACKGROUND: A previous meta-analysis found that high dose zinc acetate lozenges reduced the duration of common colds by 42%, whereas low zinc doses had no effect. Lozenges are dissolved in the pharyngeal region, thus there might be some difference in the effect of zinc lozenges on the duration of respiratory symptoms in the pharyngeal region compared with the nasal region. The objective of this study was to determine whether zinc acetate lozenges have different effects on the duration of common cold symptoms originating from different anatomical regions. METHODS: We analyzed three randomized trials on zinc acetate lozenges for the common cold administering zinc in doses of 80-92 mg/day. All three trials reported the effect of zinc on seven respiratory symptoms, and three systemic symptoms. We pooled the effects of zinc lozenges for each symptom and calculated point estimates and 95% confidence intervals (95% CI). RESULTS: Zinc acetate lozenges shortened the duration of nasal discharge by 34% (95% CI: 17% to 51%), nasal congestion by 37% (15% to 58%), sneezing by 22% (-1% to 45%), scratchy throat by 33% (8% to 59%), sore throat by 18% (-10% to 46%), hoarseness by 43% (3% to 83%), and cough by 46% (28% to 64%). Zinc lozenges shortened the duration of muscle ache by 54% (18% to 89%), but there was no difference in the duration of headache and fever. CONCLUSIONS: The effect of zinc acetate lozenges on cold symptoms may be associated with the local availability of zinc from the lozenges, with the levels being highest in the pharyngeal region. However our findings indicate that the effects of zinc ions are not limited to the pharyngeal region. There is no indication that the effect of zinc lozenges on nasal symptoms is less than the effect on the symptoms of the pharyngeal region, which is more exposed to released zinc ions. Given that the adverse effects of zinc in the three trials were minor, zinc acetate lozenges releasing zinc ions at doses of about 80 mg/day may be a useful treatment for the common cold, started within 24 hours, for a time period of less than two weeks.
  • Hemilä, Harri (2017)
    In the early literature, vitamin C deficiency was associated with pneumonia. After its identification, a number of studies investigated the effects of vitamin C on diverse infections. A total of 148 animal studies indicated that vitamin C may alleviate or prevent infections caused by bacteria, viruses, and protozoa. The most extensively studied human infection is the common cold. Vitamin C administration does not decrease the average incidence of colds in the general population, yet it halved the number of colds in physically active people. Regularly administered vitamin C has shortened the duration of colds, indicating a biological effect. However, the role of vitamin C in common cold treatment is unclear. Two controlled trials found a statistically significant dose-response, for the duration of common cold symptoms, with up to 6-8 g/day of vitamin C. Thus, the negative findings of some therapeutic common cold studies might be explained by the low doses of 3-4 g/day of vitamin C. Three controlled trials found that vitamin C prevented pneumonia. Two controlled trials found a treatment benefit of vitamin C for pneumonia patients. One controlled trial reported treatment benefits for tetanus patients. The effects of vitamin C against infections should be investigated further.
  • Hemila, Harri (2016)
    Analyses in nutritional epidemiology usually assume a uniform effect of a nutrient. Previously, four subgroups of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of Finnish male smokers aged 50-69 years were identified in which vitamin E supplementation either significantly increased or decreased the risk of pneumonia. The purpose of this present study was to quantify the level of true heterogeneity in the effect of vitamin E on pneumonia incidence using the I-2 statistic. The I-2 value estimates the percentage of total variation across studies that is explained by true differences in the treatment effect rather than by chance, with a range from 0 to 100 %. The I-2 statistic for the effect of vitamin E supplementation on pneumonia risk for five subgroups of the ATBC population was 89% (95% CI 78, 95 %), indicating that essentially all heterogeneity was true variation in vitamin E effect instead of chance variation. The I-2 statistic for heterogeneity in vitamin E effects on pneumonia risk was 92% (95% CI 80, 97 %) for three other ATBC subgroups defined by smoking level and leisure-time exercise level. Vitamin E decreased pneumonia risk by 69% among participants who had the least exposure to smoking and exercised during leisure time (7.6% of the ATBC participants), and vitamin E increased pneumonia risk by 68% among those who had the highest exposure to smoking and did not exercise (22% of the ATBC participants). These findings refute there being a uniform effect of vitamin E supplementation on the risk of pneumonia.