[Comparative analysis of the groin and SCIP flap in reconstructive microsurgery of soft tissues of the maxillofacial area and oral cavity]. / Sravnitel'nyi analiz pakhovogo i SCIP-loskuta v rekonstruktivnoi mikrokhirurgii myagkikh tkanei chelyustno-litsevoi oblasti i polosti rta.

Most of the articles on the groin flap were published in the period from 1975 to 2010, from 2015 to 2022, the SCIP flap surpassed the groin flap in the number of publications. According to the results of a literature search in PubMed and RINC, 30 articles were found and selected, including 288 flaps from the iliac region. The length of the vascular pedicle, the diameter of the vessels, the complications, the prevalence of the flap in the reconstruction of the head and neck, the thickness and the size of the flap were evaluated. Both of these flaps have the same nutrition, but different levels of dissection. In comparison with the groin flap, the SCIP flap has a longer vascular pedicle, which can be enlarged due to new techniques, which also allows it to be used as an ultra-thin flap, and it reduces the need for secondary procedures for defatting and reduces the risks of the complications in the donor area. The thickness of the SCIP flap is less than the groin one, which, according to the author, increases the aesthetic level of operations in the facial area in the case of the texture and color of the flap. Vascular anatomy of the SCIP flap is variable, therefore, the use of preoperative planning is necessary. Despite this, complications in the donor or recipient area during reconstruction with a SCIP flap are minimal. It has been proved that the SCIP flap is versatile and safe in all aspects of reconstruction. It can be concluded that the SCIP flap should be considered as a «workhorse¼ in reconstructive microsurgery of soft tissues of the throat and oral cavity.

On semiparametric estimation of a path-specific effect in the presence of mediator-outcome confounding.

Path-specific effects constitute a broad class of mediated effects from an exposure to an outcome via one or more causal pathways along a set of intermediate variables. Most of the literature concerning estimation of mediated effects has focused on parametric models, with stringent assumptions regarding unmeasured confounding. We consider semiparametric inference of a path-specific effect when these assumptions are relaxed. In particular, we develop a suite of semiparametric estimators for the effect along a pathway through a mediator, but not through an exposure-induced confounder of that mediator. These estimators have different robustness properties, as each depends on different parts of the likelihood of the observed data. One estimator is locally semiparametric efficient and multiply robust. The latter property implies that machine learning can be used to estimate nuisance functions. We demonstrate these properties, as well as finite-sample properties of all the estimators, in a simulation study. We apply our method to an HIV study, in which we estimate the effect comparing two drug treatments on a patient's average log CD4 count mediated by the patient's level of adherence, but not by previous experience of toxicity, which is clearly affected by which treatment the patient is assigned to and may confound the effect of the patient's level of adherence on their virologic outcome.

Cardiovascular risk prevention and all-cause mortality in primary care patients with an abdominal aortic aneurysm.

BACKGROUND: Perioperative mortality is low for patients undergoing abdominal aortic aneurysm (AAA) repair, but long-term survival remains poor. Although patients diagnosed with AAA have a significant burden of cardiovascular disease and associated risk factors, there is limited understanding of the contribution of cardiovascular risk management to long-term survival. METHODS: General practice records within The Health Improvement Network (THIN) were examined. Patients with a diagnosis of AAA and at least 1 year of registered medical history were identified from 2000 to 2012. Medical therapies for cardiovascular risk were classified as antiplatelet, statin or antihypertensive agents. Progression to death was investigated using the G-computation formula with time-dependent co-variables to account for differences in exposure to cardiovascular risk-modifying treatments and the confounding between exposure, co-morbidities and death. RESULTS: Some 12 485 patients had a recorded diagnosis of AAA. From 2000 to 2012, prescription of medications that modify cardiovascular risk increased: from 26·6 to 76·7 per cent for statins, from 56·5 to 73·9 per cent for antiplatelet agents and from 75·3 to 84·0 per cent for antihypertensive drugs. Adjusted Kaplan-Meier curves demonstrated a better 5-year survival rate in patients receiving statins (68·4 versus 42·2 per cent), antiplatelet agents (63·6 versus 39·7 per cent) or antihypertensive agents (61·5 versus 39·1 per cent), compared with rates in patients not receiving each therapy. CONCLUSION: Appropriate risk factor modification could significantly reduce long-term mortality in patients with AAA. In the UK, up to 30 per cent of patients are not currently receiving these medications.

Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.

BACKGROUND: Concern has been raised regarding international discrepancies in perioperative mortality after repair of ruptured abdominal aortic aneurysm (rAAA). The variation in in-hospital mortality is difficult to interpret, owing to international differences in discharge strategies. This study compared 90-day and 5-year mortality in patients who had a rAAA in England and Sweden. METHODS: Patients undergoing rAAA repair were identified from English Hospital Episode Statistics and the Swedish Vascular Registry (Swedvasc) between 2003 and 2012. Ninety-day and 5-year mortality were compared after matching for age and sex. Within-country analyses examined the impact of co-morbidity, teaching hospital status or hospital annual caseload, adjusted with causal inference techniques. RESULTS: Some 12 467 patients underwent rAAA repair in England, of whom 83.2 per cent were men; the median (i.q.r.) age was 75 (70-80) years. A total of 2829 Swedish patients underwent rAAA repair, of whom 81.3 per cent were men; their median (i.q.r.) age was 75 (69-80) years. The 90-day mortality rate was worse in England (44.0 per cent versus 33.4 per cent in Sweden; P < 0.001), as was 5-year mortality (freedom from mortality 38.6 versus 46.3 per cent respectively; P < 0.001). In England, lower mortality was seen in teaching hospitals with larger bed capacity, higher annual caseloads and greater use of endovascular aneurysm repair (EVAR). In Sweden, lower mortality was associated with EVAR, high annual caseload, or surgery on weekdays compared with weekends. CONCLUSION: Short- and long-term mortality after rAAA repair was higher in England. In both countries, mortality was lowest in centres performing greater numbers of AAA repairs per annum, and more EVAR procedures.

Estimation of a Semiparametric Natural Direct Effect Model Incorporating Baseline Covariates.

Establishing cause-effect relationships is a standard goal of empirical science. Once the presence of a causal relationship is established, the precise causal mechanism involved becomes a topic of interest. A particularly popular type of mechanism analysis concerns questions of mediation, that is to what extent an effect is direct, and to what extent it is mediated by a third variable. A semiparametric theory has recently been proposed which allows multiply robust estimation of direct and mediated marginal effect functionals in observational studies (Tchetgen Tchetgen & Shpitser, 2012). In this paper we extend the new theory to handle parametric models of natural direct and indirect effects within levels of pre-exposure variables with an identity or log link function, where the model for the observed data likelihood is otherwise unrestricted. We show that estimation is generally not feasible in this model because of the curse of dimensionality associated with the required estimation of auxiliary conditional densities or expectations, given high-dimensional covariates. Thus, we consider multiply robust estimation and propose a more general model which assumes that a subset but not all of several working models holds.