Background: The traditional methods of studying the gene-environment interactions need a control group. However, the selection of an appropriate control group has been associated with problems. Therefore, new methods, such as case-only design, have been created to study such interactions. The objective of this study was to compare the case-only and case-control designs using data from patients ...

background: a crucial part of a case-control study is the selection of a sample of controls that represent the base-popula­tion from which cases were drawn. controls may be matched to cases by one or more potentially important confounding vari­ables, such as socioeconomic status. in the united kingdom, one method for control selection has been based on the pa­tient list of the general practice ...

Matched case-control study designs are commonly implemented in the field of public health. While matching is intended to eliminate confounding, the main potential benefit of matching in case-control studies is a gain in efficiency. Methods for analyzing matched case-control studies have focused on utilizing conditional logistic regression models that provide conditional and not causal estimates...

background febrile seizures (fs) are the most common type of convulsion in young children. the predisposing factors are still under investigation; however, iron insufficiency might play a role in this regard. objectives our objective was to determine the association between iron status and febrile seizure. patients and methods this prospective case-control study was conducted among 109 children...

Introduction:Orthodontic treatment is associted with a risk of root resorption.The aim of this study was to determine the risk of moderate and sever root resorption in orthodontic patients treated with fixed orthodontic appliance.   Method:A case-control study was performed on 70 orthodontic treated patients with moderate and sever root resorption and 70 controls matched for age,sex,duration ...

Background. Mechanical relation between the foot and pelvic alignment had been studied in healthy subjects and individuals with other musculoskeletal disorders; however, in chronic ankle instability (CAI), it has not yet been determined. Objectives. To investigate the difference in pelvic torsion (PT) among individuals with CAI and uninjured subjects and correlate PT with perceived ankle insta...