” The paper compares the classification of NI based the CDC definition of the infection and carrier state criterion. The article is highly important in showing the two definitions of NIs. However, the use of each of the definitions in surveillance programs can cause

confusion. Lacking a widely-accepted standard definition for infections, such as nosocomial infections, can lead physicians to incorrect diagnosis and treatment of infections. The first study about hospital infection in ICUs in Iran showed that for correct comparison and control of hospital infections, we need to use international standards in population of study,8 to be able to have correct comparisons and plans to control infections. In addition, it is better Inhibitors,research,lifescience,medical that the cut-off time and carrier status of admitted patients are compared in several aspects including diagnosis, burdens of diseases in the community, health care workers’ concern about the origin of infection, various precautions and use of various diagnostic techniques. Inhibitors,research,lifescience,medical Nosocomial

infections is over estimated in the cut-off time definition and underestimated in carrier state definition protocol. If comparison of different classification methods could be accompanied with a strong research design and analysis, additional financial and psychological Inhibitors,research,lifescience,medical costs could be reduced.
Background: The traditional methods of PLX4032 ic50 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 with breast cancer. Methods: The interaction of genetic and environmental factor Inhibitors,research,lifescience,medical as well as the ratio of control to population Inhibitors,research,lifescience,medical odds ratio was calculated for case-only (300 patients with breast cancer) and case-control (300 cases of breast cancer and 300 matched controls) designs.

Results: The confidence intervals and -2log likelihood in all variables in case-only design was smaller than those in the Metalloexopeptidase matched case-control design. In case-only design, the standard errors of some variables such as age at menarche, the first delivery at the age of 35 yrs and more or no delivery, the history of having live birth, use of oral contraception pills, breastfeeding history were less than those in the matched case-control design. Conclusion: The findings indicate that the case-only design is an efficient method to investigate the interaction of genetic and environmental factors. Key Words: Case-control, breast cancer, gene-environment interaction Introduction Many common diseases are caused by the interaction of genetic and environmental factors.1 Interaction is used in epidemiology to describe a situation in which two or more risk factors adjust the effects of each other with respect to the level of a certain outcome.