Evidence before this study: Acute appendicitis is the most common general surgical emergency in children. Its diagnosis remains challenging and children presenting with acute right iliac fossa (RIF) pain may be admitted for clinical observation or undergo normal appendicectomy (removal of a histologically normal appendix). A search for external validation studies of risk prediction models for acute appendicitis in children was performed on MEDLINE and Web of Science on 12 January 2017 using the search terms ["appendicitis" OR "appendectomy" OR "appendicectomy"] AND ["score" OR "model" OR "nomogram" OR "scoring"]. Studies validating prediction models aimed at differentiating acute appendicitis from all other causes of RIF pain were included. No date restrictions were applied. Validation studies were most commonly performed for the Alvarado, Appendicitis Inflammatory Response Score (AIRS), and Paediatric Appendicitis Score (PAS) models. Most validation studies were based on retrospective, single centre, or small cohorts, and findings regarding model performance were inconsistent. There was no high quality evidence to guide selection of the optimum model and threshold cutoff for identification of low-risk children in the UK and Ireland. Added value of this study: Most children admitted to hospital with RIF pain do not undergo surgery. When children do undergo appendicectomy, removal of a normal appendix (normal appendicectomy) is common, occurring in around 1 in 6 children. The Shera score is able to identify a large low-risk group of children who present with acute RIF pain but do not have acute appendicitis (specificity 44%). This low-risk group has an overall 1 in 30 risk of acute appendicitis and a 1 in 270 risk of perforated appendicitis. The Shera score is unable to achieve a sufficiently high positive predictive value to select a high-risk group who should proceed directly to surgery. Current diagnostic performance of ultrasound is also too poor to select children for surgery. Implications of all the available evidence: Routine pre-operative risk scoring could inform shared decision making by doctors, children, and parents by supporting safe selection of lowrisk patients for ambulatory management, reducing unnecessary admissions and normal appendicectomy. Hospitals should ensure seven-day-a-week availability of ultrasound for medium and high-risk patients. Ultrasound should be performed by operators trained to assess for acute appendicitis in children. For children in whom diagnostic uncertainty remains following ultrasound, magnetic resonance imaging (MRI) or low-dose computed tomography (CT) are second-line investigations.

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Human immunodeficiency virus (HIV) is a retrovirus that is associated with mortality in the final stage. The advancement of antiretroviral therapy (ART) improved the life expectancy of patients with HIV. However, the long age of such patients is associated with different comorbidities such as cardiovascular diseases. Also, HIV therapy increased the concern about cardiovascular diseases. This systematic review aims to assess the risk of myocardial infarction (MI) among patients with HIV by reviewing the previous studies conducted on this subject. Research gate, Google Scholar, and PubMed databases were explored starting from 2012 till 2022. The keywords used for the searching process included "HIV, MI, AMI, Association, Correlation, and Risk." The inclusion criteria were original articles conducted on HIV patients and reported MI, written in English language, and available in full text. A total of 1,570 articles were obtained, but only seven articles met the inclusion criteria. The included studies were published between 2012 and 2019 and involved a total number of 496,600 participants; there were 266,274 who had HIV infection, with a sample size ranging from 1,147 to 252,150. The incidence of MI is higher among HIV compared to the general population. The risk factors associated with MI among HIV patients, as found in our analysis, included male gender, viral load of HIV, low CD4 count, higher CD8 count, and types of ART.