Factors associated with advanced tricuspid regurgitation after left-side double valve replacement in propensity-score-matched analysis: Propensity score matching in observational studies

In recent years, research has focused on the causality relationship between variables. It is possible to divide the variables in a causal relationship into two as “independent” variable(s) which is in the “cause” state and “dependent” variable(s) which is in the “result” state. The investigation of the effect of the change in the independent variable(s) on the dependent variable forms the basis of the causality structure. Researches on causality can be examined under two main headings as experimental and observational studies. Experimental studies, known as studies investigating the effectiveness of diagnosis and treatment methods, are studies conducted under conditions determined by the experimenter and in which the intervention to subjects/individuals is possible. For instance, in an experimental study in which the effect of the drug is investigated, the drug is given to the individuals and what type of changes it causes in the outcome variable (such as increased blood sugar due to the drug effect) are evaluated. Experimental studies, in which it is possible to partially control the factors affecting the outcome variable, can also be divided into studies with a control group and studies without a control group. It is not possible to make comparisons between methods in experimental studies that do not include a control group. On the other hand, in experimental studies involving a control group, it is determined whether the effect of the applied method or treatment method on the outcome variable is caused by the method or other factors. Studies involving a control group are preferred to studies without a control group, as such studies can provide better control over the independent variable(s), are used more frequently, particularly in regression analysis, and contain more information about cause-effect relationships than observational studies. However, observational studies are preferred instead of experimental studies in some special cases that may arise, such as the failure to provide the desired laboratory conditions for the experiment, the possibility of harming the health of the subject. In observational studies, data are obtained from records or patient files. In such studies, observation is made without interfering with the natural course of the event. In other words, no additional monitoring, testing or treatment is used, while the data are being observed. Since the factors examined in observational studies cannot be controlled, they cannot be changed at any time. In addition, it is not possible to repeat the observations under the same conditions. It is possible to classify observational studies that examine the incidence, distribution or causes of diseases in the population as descriptive, case-control, cross-sectional and cohort studies. In addition, it is not under the control of the researcher as to which group the observed units would be assigned to. As a result, there may be large differences in the observed cofounder of groups and patients with unrepaired mild-to-moderate TR. A total of 157 patients, 52% of whom were women, participated in the study and the data were evaluated using propensity score analysis. A comparison of baseline clinical and echocardiographic parameters between TV repair and no-TV repair groups was made, and it was observed that AF was significantly lower in the no-TV repair group, while the TV repair group had a significantly longer cardiopulmonary bypass duration. In addition, there was no statistically significant difference between the groups in valvular etiology. On the other hand, the no-TV repair group had significantly decreased pulmonary artery pressure and decreased TR degree. The no-TV repair group had a significantly smaller tricuspid annulus diameter, and a smaller left atrial diameter. It was also observed that neurological complications did not make a significant difference between the groups. However, the TV repair group had a lesser degree of TR and the mechanical ventilation and intensive care unit (ICU) stay were significantly shorter in the no-TV repair group. While group comparisons of continuous variables were made using the Mann-Whitney U test, categorical variables were compared using the chi-square test. © 2022. All right reserved by the Turkish Society of Cardiovascular Surgery. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes (http://creativecommons.org/licenses/by-nc/4.0/).