BackgroundStudies of the associations between soft drinks and the risk of cancer showed inconsistent results. No previous published systematic reviews and meta-analysis has investigated a dose-response association between exposure dose and cancer risk or assessed the certainty of currently available evidence. Therefore, we aim to demonstrate the associations and assessed the certainty of the evidence to show our confidence in the associations.MethodsWe searched Embase, PubMed, Web of Science, and the Cochrane Library from inception to Jun 2022, to include relevant prospective cohort studies. We used a restricted cubic spline model to conduct a dose-response meta-analysis and calculated the absolute effect estimates to present the results. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the certainty of the evidence.ResultsForty-two articles including on 37 cohorts enrolled 4,518,547 participants were included. With low certainty evidence, increased consumption of sugar-sweetened beverages (SSBs) per 250 mL/day was significantly associated with a 17% greater risk of breast cancer, a 10% greater risk of colorectal cancer, a 30% greater risk of biliary tract cancer, and a 10% greater risk of prostate cancer; increased consumption of artificially sweetened beverages (ASBs)re per 250 mL/day was significantly associated with a 16% greater risk of leukemia; increased consumption of 100% fruit juice per 250 mL/day was significantly associated with a 31% greater risk of overall cancer, 22% greater risk of melanoma, 2% greater risk of squamous cell carcinoma, and 29% greater risk of thyroid cancer. The associations with other specific cancer were no significant. We found linear dose-response associations between consumption of SSBs and the risk of breast and kidney cancer, and between consumption of ASBs and 100% fruit juices and the risk of pancreatic cancer.ConclusionsAn increment in consumption of SSBs of 250 mL/day was positively associated with increased risk of breast, colorectal, and biliary tract cancer. Fruit juices consumption was also positively associated with the risk of overall cancer, thyroid cancer, and melanoma. The magnitude of absolute effects, however, was small and mainly based on low or very low certainty of evidence. The association of ASBs consumption with specific cancer risk was uncertain.

Background Mild cognitive impairment (MCI) is a cognitive state falling between normal aging and dementia. The relation between alcohol intake and risk of MCI as well as progression to dementia in people with MCI (PDM) remained unclear. Objective To synthesize available evidence and clarify the relation between alcohol intake and risk of MCI as well as PDM. Method We searched electronic databases consisting of PubMed, EMBASE, Cochrane Library, and China Biology Medicine disc (CBM) from inception to October 1, 2019. Prospective studies reporting at least three levels of alcohol exposure were included. Categorical meta-analysis was used for quantitative synthesis of the relation between light, moderate and heavy alcohol intake with risk of MCI and PDM. Restricted cubic spline and fixed-effects dose-response models were used for dose-response analysis. Result Six cohort studies including 4244 individuals were finally included. We observed an unstable linear relation between alcohol intake (drinks/week) and risk of MCI (P linear = 0.0396). It suggested that a one-drink increment per week of alcohol intake was associated with an increased risk of 3.8% for MCI (RR, 1.038; 95% CI 1.002-1.075). Heavy alcohol intake (> 14 drinks/week) was associated with higher risk of PDM (RR = 1.76; 95% CI 1.10-2.82). And we found a nonlinear relation between alcohol intake and risk of PDM. Drinking more than 16 drinks/week (P nonlinear = 0.0038, HR = 1.42; 95% CI 1.00-2.02), or 27.5 g/day (P nonlinear = 0.0047, HR = 1.46; 95% CI 1.00-2.11) would elevate the risk of PDM. Conclusion There was a nonlinear dose-response relation between alcohol intake and risk of PDM. Excessive alcohol intake would elevate the risk of PDM.

Background Supplier-induced demand (SID) for health care could be a crucial factor of rising health expenditures. However, there is thus far no consensus on the topic. Objective To assess how physician density (physician-to-population ratio) and health care consumption correlate. Methods A systematic review of studies retrieved through electronic databases: Medline, Econlit, PsychINFO and Embase. Search, inclusion and quality appraisal were based on standard procedures and applied independently by two researchers. Results Twenty-five studies, generally of moderate quality, were included. Despite a substantial heterogeneity in study design and data modelling, a significant association between physician density and health care consumption was consistently observed. However, estimates varied according to a number of method parameters such as the definition of the dependent variable (physician volume or care intensity), the geographical entity or the medical specialty under consideration, and the adjustment for confounding factors. Conclusions The exact importance of SID and the underlying motivations remain poorly understood. We discuss technical issues for better SID assessment. In the absence of more accurate information, limiting physician supply as a measure of cost containment should also be considered cautiously.