China
Africa
Explore chapters and articles related to this topic
Answers
Published in Ken Addley, MCQs, MEQs and OSPEs in Occupational Medicine, 2023
The cohort study is the appropriate design to study incidence of a disease. Randomised controlled trials are interventional studies. Cross-sectional studies give an indication of prevalence. A case-control study cannot measure incidence because you start with cases and non-cases, so you cannot calculate relative risk.
Designing and Running a Clinical Trial
Published in Trevor F. Cox, Medical Statistics for Cancer Studies, 2022
A cohort study is a prospective study, where subjects are selected according to some criteria, and then followed for a period of time to establish who succumbs to the disease in question. For example, a group of people are selected, some of whom smoke and others do not, and during the next twenty years records are kept of who develop lung cancer and who do not. One problem with this is that you have to wait twenty years! A retrospective study can use data that was collected in the past and this will give a much speedier result. For example, patients needing frequent repeat interventions for chronic lymphocytic leukaemia (CLL) are selected from hospital records. Then their medical notes are scrutinised from the start of their treatment until ten years later, in order to map the progress of the disease. Other examples are given in Figure 4.1.
Study Limitations to Consider
Published in Lisa Chasan-Taber, Writing Grant Proposals in Epidemiology, Preventive Medicine, and Biostatistics, 2022
Selection bias is generally more of a concern for a case-control study or a cross-sectional study than for a prospective cohort study. Why? Because in a case-control and cross-sectional study, both the outcome and exposure have already occurred at the time the investigator initiates the study. Because of this timing, it is possible that having both the exposure and the disease can influence a person's decision to participate in the study. In other words, selection bias becomes more likely when being exposed differentially influences the participation of diseased and nondiseased people into the study.
The association of plasma NT-proBNP level and progression of diabetic kidney disease
Published in Renal Failure, 2023
Yuancheng Zhao, Lijun Zhao, Yiting Wang, Junlin Zhang, Honghong Ren, Rui Zhang, Yucheng Wu, Yutong Zou, Nanwei Tong, Fang Liu
This study, for the first time, revealed that the plasma NT-proBNP level was significantly associated with the progression of DKD. Of course, a few limitations in this study should be noted. First, it was a retrospective cohort study; therefore, selection bias was inevitable. Kidney biopsy is an invasive procedure, resulting in a proportion of patients being reluctant to undergo kidney biopsy, which contributes to the limited sample size and mismatched baseline data between groups in this study. However, the HRs were still significant after important confounding factors were adjusted in multivariable Cox analysis, which shows that the results in this study are still reliable. Second, the sample size was limited. Third, the severity of the patient’s condition varies when performing a kidney pathology biopsy. Fourth, the measurement of plasma NT-proBNP level was only measured once at baseline, and sequential measurements during the follow-up may help to further investigate its association with diabetic ESKD. Fifth, during follow-up, NT-pro-BNP levels did not correlate with HbA1c levels, insulin usage, or the fasting glucose levels of the patients with T2DM or DKD. Finally, we did not control therapeutic interventions (especially antidiabetic drugs with nephroprotective effects) during follow-up, which may be confounders to the results. In summary, our findings provide evidence that NT-proBNP levels can predict kidney prognosis in patients with T2DM and biopsy-proven DKD.
Psychological factors increase the risk of ovarian cancer
Published in Journal of Obstetrics and Gynaecology, 2023
Shuo Geng, Xu Zhang, Xiaoyu Zhu, Yadi Wang, Yingchen Wang, Yewu Sun
This review assessed recent studies of psychological factors and ovarian cancer risk, including a total of 10 sets of data from four articles. We determined that overall, psychological factors increase the risk of ovarian cancer, with the exception of in case-control studies. Stress may promote high-risk behaviours, such as smoking, poor diet, lack of exercise, obesity, excessive alcohol consumption, poor sleep and lower treatment adherence (van Tuijl et al.2021). Additionally, psychological factors may impact biological mechanisms, which in turn promote malignant growth. Psycho-social processes initiate a cascade of information-processing pathways in the central nervous system and periphery, thereby impacting hormonal secretion (, Glaser and Kiecolt-Glaser, 2005, Charmandari et al.2005, Antoni et al. 2006). These changing hormones could modulate the activity of multiple components of the tumour microenvironment (Antoni et al.2006, Chida et al.2008). According to the enrolled cohort study data, the researchers attempted to avoid the influence of confounding factors such as behavioural factors other than psychology and adjusted for smoking, physical activity, nutrition, and other potential confounders. The results nonetheless suggest a higher risk of ovarian cancer in people with psychological distress, which we cautiously interpret as evidence that psychological stress increases the risk of ovarian cancer.
Risk factors for hypocalcemia in dialysis patients with refractory secondary hyperparathyroidism after parathyroidectomy: a meta-analysis
Published in Renal Failure, 2022
Dan Gao, Yan Lou, Yingchun Cui, Shengmao Liu, Wenpeng Cui, Guangdong Sun
The inclusion criteria for the study are as follows: (a) the study was a case-control or cohort study; (b) the study focused on the risk factors for hypocalcemia in patients with SHPT after PTX; (c) patients at the CKD-5D stage who met the diagnostic criteria for refractory SHPT and underwent PTX were also considered; (d) the surgical methods included total PTX, subtotal PTX, with or without parathyroid autotransplantation, or ultrasound-guided microwave ablation (MWA); and (e) the outcomes reported were adjusted or non-adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) on multiple logistic regression analysis. Hypocalcemia after surgery was defined as the minimum serum calcium level lower than 2.1 mmol/L (8.4 mg/dL) within three days postoperatively. The search was limited to English language manuscripts.