ObjectiveTo systematically review the dose-response relationship between body mass index (BMI) and the risk of stroke. MethodsPubMed, EMbase, Web of Science, The Cochrane Library, CBM, VIP, WanFang Data and CNKI databases were electronically searched to collect studies on BMI and the risk of stroke from inception to December 2021. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies; then, meta-analysis was performed by using Stata 16.0 software, and the dose-response relationship between BMI and risk of stroke was analyzed by using restricted cubic spline function and generalized least squares estimation (GLST). ResultsA total of 19 studies involving 3 689 589 patients were included. The results of meta-analysis showed that compared with normal BMI, overweight (RR=1.28, 95%CI 1.19 to 1.39, P<0.01) and obesity (RR=1.41, 95%CI 1.15 to 1.72, P<0.01) had a higher risk of stroke. Dose-response meta-analysis suggested that there was no significant non-linear relationship between BMI and stroke risk (nonlinear test P=0.318), and linear trend showed that the risk of stroke increased by 4% for each unit increase in BMI (RR=1.04, 95%CI 1.03 to 1.05, P<0.01). ConclusionCurrent evidence suggests that increased BMI is associated with an increased risk of stroke. Due to limited quality and quantity of the included studies, more high-quality studies are needed to verify the above conclusion.
Dose-response meta-analysis, an important tool in investigating the relationship between a certain exposure and risk of disease, has been increasingly applied. Traditionally, the dose-response meta-analysis was only modelled as linearity. However, since the proposal of more powerful function models, which contains both linear, quadratic, cubic or more higher order term within the regression model, the non-linearity model of dose-response relationship is also available. The packages suit for R are available now. In this article, we introduced how to conduct a dose-response meta-analysis using dosresmeta and mvmeta packages in R.
ObjectivesTo compare different formula calculated dosages with the actual doses of warfarin from patients in Beijing Hospital so as to investigate suitable warfarin dosing models for Chinese patients.MethodsOne hundred and three Chinese patients with long-term prescription of warfarin were randomly selected from Beijing Hospital from July 2012 to May 2013. The CYP2C9 and VKROC1 genotypes and basic statistical information were collected. SPSS 18.0 software was used to compare the differences between different formula calculated dosages and the actual dosages of warfarin.ResultsFive genotypes were found in 103 patients, including: CYP2C9 AA genotype + VKORC1 AA genotype (n=72, 69.9%), CYP2C9 AA genotype + VKORC1 AG genotype (n=17, 16.5%), CYP2C9 AC genotype + VKORC1 AA genotype (n=10, 9.7%), CYP2C9 AC genotype + VKORC1 AG genotype (n=3, 2.9%) and CYP2C9 AA genotype + VKORC1 GG genotype (n=1, 1%). Compared with the actual dosages of warfarin, the degree of coincidence was highest for dosages calculated by Jeffrey’s formula.Conclusions Using Jeffrey’s formula to calculate warfarin dosages may be more suitable for Chinese patients with using long-term warfarin. Due to limited sample size, prospective and large sample size studies are required to verify the above conclusion.
ObjectiveTo systematically evaluate the dose-response relationship between coffee consumption and liver cancer risk. MethodsThe PubMed, Web of Science, Cochrane Library, EMbase, CNKI, VIP, WanFang Data, and CBM databases were searched from inception to December 2022. Two reviewers independently screened literature, extracted data and assessed the risk of bias of the included studies. Meta-analysis was then performed by using Stata 17.0 software. ResultsFifteen studies (11 cohort studies and 4 case-control studies) involving 557 259 participants were included. The results of meta-analysis showed that coffee consumption was significantly negatively associated with the risk of liver cancer (RR=0.39, 95%CI 0.27 to 0.57, P<0.01). The dose-response meta-analysis showed a non-linear dose-response relationship between coffee consumption and the risk of liver cancer (P<0.01). Compared with people who did not drink coffee, people who drank 1 cup of coffee a day had a 25% lower risk of liver cancer (RR=0.75, 95%CI 0.67 to 0.83), and people who drank 2 cups of coffee a day had a 38% lower risk of liver cancer (RR=0.62, 95%CI 0.56 to 0.70). The risk of liver cancer decreased by 45% (RR=0.55, 95%CI 0.48 to 0.62) for 3 cups of coffee and by 51% (RR=0.49, 95%CI 0.43 to 0.56) for 4 cups of coffee. ConclusionCurrent evidence suggests that there is a nonlinear dose-response relationship between coffee consumption and the risk of liver cancer. These results indicate that habitual coffee consumption is a protective factor for liver cancer. Due to the limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusion.
Dose-response meta-analysis, as a subset of meta-analysis, plays an important role in dealing with the relationship between exposure level and risk of diseases. Traditional models limited in linear regression between the independent variables and the dependent variable. With the development of methodology and functional model, Nonlinear regression method was applied to dose-response meta-analysis, such as restricted cubic spline regression, quadratic B-spline regression. However, in these methods, the term and order of the independent variables have been assigned that may not suit for any trend distribution and it may lead to over fitting. Flexible fraction polynomial regression is a good method to solve this problem, which modelling a flexible fraction polynomial and choosing the best fitting model by using the likelihood-ratio test for a more accurate evaluation. In this article, we will discuss how to conduct a dose-response meta-analysis by flexible fraction polynomial.
Objective To investigate the effect of the synthetic bone morphogenetic protein 2 (BMP-2)derived peptide on the osteogenic induction in the marrow mesenchymal stem cells (MSCs）and to evaluate the osteoinductivity and dosedependence of the BMP-2 derived peptide in vitro. Methods MSCs of 4-week old Wistar rats were separated and cultured. In the 3rd passage, the conditional culture medium was changed, in which the BMP-2-derived peptide in the following doses was added: 300,200, 100, 50, and 0 μg/ml, respectively (Groups A-E). The activity of alkaline phosphatase (ALP）and the amount of calciumdeposition were meassured at 5，10，15 and 20 days during the culture with the conditional culture medium. The real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) was performed to measure the mRNA expressions of collagen type Ⅰ, osteopontin (OPN), and osteocalcin（OCN）and to measure the osteoinductivity of the BMP-2-derived peptide in the different concentrations.Results Under the inverted phase contrast microscope, MSCs cultured in the conditional culture medium for 3-4 days were changed in shape, from long fusiform to short fusiform or polygon. As the concentration of the BMP-2-derived peptide increased, the time for MSCs to change into the osteoblasts decreased. There was a significantly greater level of the ALP activity and amount of the calcium deposition in Groups A and B than in the other groups（Plt;0.05）. However,there was no significant difference between Group A and Group B （Pgt;0.05）. Theresult of FQPCR showed that after MSCs were cultured in the different doses of theconditional culture medium for 14 days, the mRNA expressions of collagen type Ⅰ, OPN andOCN were at higher levels. An increasing order in the level of the cycle threshold (Ct) was found in the following groups: Agt;Bgt;Cgt;D. Almost no expression was found in Group E. The Ct levels were significantly greater in Groups A and B thanin Groups C and D（Plt;0.05）. However, there was no significant difference between Group A and Group B （Pgt;0.05）.ConclusionThe BMP-2-derived peptide can greatly promote differentiation of MSCs into the osteoblasts, the promotion of osteogenesis has a dosedependent pattern, and the best inducing dosage is 200 μg/ml.
Objective To investigate the effects of QUE on proliferation and DNA synthesis of cultured retinal pigment epithelium(RPE) cells with or without EGF. Methods With or without EGF, cultured RPE cells were treated with QUE by various concentrations(200,100,50,1mu;mol/L) and with QUE 200mu;mol/L at different times(24-168 hr), cells proliferation and DNA synthesis were evaluated by cell count method and the uptake of thymidine. The viability of cells was determined by trypanblue exclusion. Results The best concentration of QUE which inhibits proliferation and DNA synthesis of PRE cells was 200mu;mol/L. The significant inhibition effect of QUE occurred at 48hr, and the best inhibition of QUE occurred at 96hr. QUE had more powerful effect of antiproliferation on RPE cells, and the viability of RPE cells was over85%. Conclusion The results suggested that QUE could inhibit the proliferation of RPE cells in a dose-dependent and time-dependent manner, especially inhibit the proliferation induced by EGF stimulating. QUE had no cyto-toxic effect on RPE cells cultured in vitro. (Chin J Ocul Fundus Dis,1999,15:27-29)
Dose-response meta-analysis is being increasingly applied in evidence production and clinical decision. The research method, synthesizing certain dose-specific effects across studies with the same target question by a certain types of weighting schedule to get a mean dose-response effect, is to reflect the dose-response relationship between certain exposure and outcome. Currently, the most popular method for dose-response meta-analysis is based on the classical "two-stage approach", with the advantage that it allows fixed- or random-effect model, according to the amount of heterogeneity in the model. There are two types of random-effect model available for dose-response meta-analysis, that is, the generally model and the coefficient-correlation-adjusted model. In this article, we briefly introduce two models and illustrate how they are applied in Stata software, which is expected to provide theoretical foundation for evidence-based practice.
ObjectiveTo systematically review the dose-effect relationship between resistance exercise intervention and lower extremity muscle strength and function enhancement in the aging. MethodsEBSCO, PubMed, Web of Science, CNKI, VIP, and WanFang Data databases were electronically searched to collect randomized controlled trials (RCTs) on the effects of resistance exercise on muscle strength and function of the lower extremities in older adults from inception to July 2022. Two reviewers independently screened literature, extracted data and assessed the risk of bias of the included studies. A network meta-analysis was then performed by using RevMan 5.4 and Stata 15.0 software. ResultsA total of 32 RCTs with a total sample size of 1 594 individuals were included. The results of network meta-analysis showed that the elements of resistance exercise prescription: intensity 50%-70% 1RM, period 8-12 weeks, frequency 3-4 times/week, duration 30-45 min, and intervals 1.1-2 min were superior to other doses. ConclusionThe optimal dose of resistance exercise for improving lower extremity muscle strength and function in older adults is moderate exercise intensity (50%-70% 1RM) for 8-12 weeks, 3-4 times per week, 30-45 min per exercise, and 1.1-2 min interval between sets.
Objective To assess the radiation dose and image quality with low-dose multi-detector row CT urography （CTU） for the evaluation of children patients with ureteropelvic junction stenosis （UJS）. Methods In this prospective study， 30 children patients with UJS underwent CTU were classified half-randomly through exam numbers into 3 groups （115 mA， 100 mA， and 75 mA）. Consecutive acquisitions including CT dose index weighted （CTDIw） and dose long product （DLP） were obtained in each patient and compared for each group. Three experienced chest radio-logists were unaware of the CT technique reviewed CT images for overall image quality using a 3-grade scale （excellent， good， and worst）. The data were analyzed using a parametric analysis of variance test and Wilcoxon’s signed rank test. Results The CTDIws of 115 mA group， 100 mA group， and 75 mA group were （7.63±0.83） mGy， （6.29±0.51） mGy， and （4.72±0.18） mGy， respectively， the difference was significant among three groups （F=36.445， P=0.000）. The mean CTDIw reduction was 38.2% in the 75 mA group as compared with 115 mA group （P＜0.001）. The DLPs of 115 mA group， 100 mA group， and 75 mA group were （173.89±29.88） mGy?cm， （145.96±26.21） mGy?cm， and （102.78±12.72） mGy?cm， respectively， the difference was significant among three groups （F=13.955， P=0.000）. The mean radiation dose reduction was 40.9% （75 mA group versus 115 mA group， P＜0.001）. The assessment of image quality was no significant difference with the same protocol and post-processing technique （Wilcoxon’s signed rank test， P＞0.05）. There was a good agreement for image quality scoring among the three reviewers （Kappa=0.736）. Conclusion Low-dose multi-detector row CTU should be considered as a promising technique for the evaluation of children patients with UJS because it could decrease radiation dose and obtain acceptable image quality.