Grading the evidence of systematic reviews on animal studies will contribute to the improvement in the feasibility of transforming the results of animal studies into clinical trials or clinical practice. High quality evidence from animal studies is more likely to be successfully applied into clinical practice (i.e. more confident). Therefore, the present study will introduce the principles, methods and challenges of the application of GRADE in systematic reviews on animal studies.
At present, systematic reviews of animal experimental studies has become a new trend and an important way to synthesize the results of animal experimental studies, improve the conducting and reporting quality of animal experimental studies and provide references for the furture clinical research. However, there are many problems in the design and implementation process of published systematic reviews of animal experimental studies. Therefore, it is important to design a scientific and standard practical process to improve the quality of systematic reviews of animal experimental studies. In this paper, we developed a standard process for systematic reviews of animal experimental studies, in order to improve the quality of systematic reviews of animal experimental studies.
ObjectiveTo systematically review the dose-response relationship between body mass index (BMI) and all-cause mortality in the elderly with frailty.MethodsPubMed, EMbase, Web of Science, CNKI, VIP, WanFang Data, and CBM databases were electronically searched to collect cohort studies on the association of BMI and mortality in frail adults from inception to November 2019. Two reviewers independently screened literature, extracted data and assessed risk bias of included studies; Stata 15.0 software was then used to analyze the dose-response analysis of BMI and mortality by restricted cubic spline function and generalized least squares method.ResultsA total of 4 cohort studies involving 12 861 frail adults were included. Meta-analysis results showed that compared with normal BMI, the frail elderly who were overweight (HR=0.80, 95%CI 0.74 to 0.88, P<0.001) and obese (HR=0.89, 95%CI 0.79 to 1.00, P=0.047) had lower all-cause mortality. The results of dose-response meta-analysis showed that there was a non-linear relationship between BMI and all-cause mortality in the elderly with frailty (P value for nonlinearity was 0.035), for which the elderly with frailty had a BMI nadir of 27.5-31.9 kg/m2. For linear trends, and when BMI was less than 27.5 kg/m2, the risk of all-cause death was reduced by 4% for every 1 kg/m2 increase in BMI (RR=0.96, 95%CI 0.90 to 1.03, P=0.320), when BMI was greater than 27.5 kg/m2, the risk of all-cause death increased by 4% for every 1 kg/m2 increase in BMI (RR=1.04, 95%CI 1.03 to 1.05, P<0.001).ConclusionsThere is a paradox of obesity and a significant nonlinear relationship between BMI and all-cause mortality in the frailty elderly, with the lowest all-cause mortality in the frailty elderly at BMI 27.5-31.9 kg/m2. Due to limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusions.