Dtsch Arztebl Int
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The findings of observational studies can be distorted by a number of factors. So-called confounders are well known, but distortion by collider bias (CB) has received little attention in medical research to date. The goal of this article is to present the principle of CB, and measures that can be taken to avoid it, by way of a few illustrative examples. ⋯ CB is a distortion that arises through restriction on or stratification by a collider variable, or through statistical adjustment for a collider variable in a regression model. CB can arise in many ways. The graphic representation of causal structures helps to identify potential sources of CB. It is important to distinguish confounders from colliders, as methods that serve to correct for confounding can themselves cause bias when applied to colliders. There is no generally applicable method for correcting CB.
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In 2017, the prevalence of obesity (BMI ≥= 30 kg/m2) in Germany was approximately 16%. Obesity increases an individual's risk of developing type 2 diabetes (T2DM) and arterial hypertension; it also increases overall mortality. Consequently, effective treatment is a necessity. Approximately 20 000 bariatric operations are performed in Germany each year. ⋯ In view of an increasing number of patients undergoing bariatric surgery, it will probably not be feasible in the future for lifelong follow-up to be provided exclusively in specialized centers.
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Involvement of the temporomandibular joint can be shown in 40-90% of patients with rheumatoid arthritis and juvenile idiopathic arthritis (JIA), although it is often asymptomatic. Restricted jaw mobility and jaw pain can be found in approximately 20% of patients with JIA (prevalence: 70 per 100 000 persons). Early diagnosis and treatment of the underlying disease are essential for a good outcome, but uniform, consensus-based management is still lacking. ⋯ Oligosymptomatic and asymptomatic cases are common even with radiologic evidence of marked joint damage. The possibility of rheumatic involvement of the temporomandibular joint must be kept in mind so that serious complications can be avoided. Regular clinical evaluation of the temporomandibular joint is recommended, particularly for patients with juvenile idiopathic arthritis.
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The term "orbital complication" does not designate an independent nosological entity, but is rather a collective designation for diseases or disease effects that involve the orbit and its internal structures by extension from outside. In general, their most prominent manifestation is swelling of the orbital soft tissues, usually unilaterally. The incidence of sinogenic orbital complications is approximately 1.6 per 100 000 children and 0.1 per 100 000 adults per year. ⋯ In 95-98% of cases in stages I-IV, healing is complete and without further sequelae. Even if vision is affected preoperatively, it usually recovers fully when therapy is appropriate. Approximately 15% of the patients who undergo surgery need more than one operative procedure.
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In the western world, 10-15% of women of child-bearing age suffer from iron-deficiency anemia. Iron overload due to chronic treatment with blood transfusions or hereditary hemochromatosis is much rarer. ⋯ Our improving understanding of the molecular pathophysiology of iron metabolism aids in the evaluation of iron deficiency and iron overload and may in future enable treatment not just with iron supplementation or iron chelation, but also with targeted pharmacological modulation of the hepcidin regulatory system.