ObjectivesTo estimate the proportion of children who die with chronic conditions and examine time trends in childhood deaths involving chronic conditions.DesignRetrospective population-based death cohort study using linked death certificates and hospital discharge records.SettingEngland, Scotland and Wales.ParticipantsAll resident children who died aged 1–18 years between 2001 and 2010.Primary and secondary outcome measuresThe primary outcome was the proportion of children who died with chronic conditions according to age group and type of chronic condition. The secondary outcome was trends over time in mortality rates involving chronic conditions per 100 000 children and trends in the proportion of children who died with chronic conditions.Results65.4% of 23 438 children (95% CI 64.8%, 66.0%) died with chronic conditions, using information from death certificates. This increased to 70.7% (95% CI 70.1% to 71.3%) if hospital records up to 1 year before death were also included and was highest (74.8–79.9% depending on age group) among children aged less than 15 years. Using data from death certificates only led to underascertainment of all types of chronic conditions apart from cancer/blood conditions. Neurological/sensory conditions were most common (present in 38.5%). The rate of children dying with a chronic condition has declined since 2001, whereas the proportion of deaths affected by chronic conditions remained stable.ConclusionsThe majority of children who died had a chronic condition. Neurological/sensory conditions were the most prevalent. Linkage between death certificate and hospital discharge data avoids some of the under-recording of non-cancer conditions on death certificates, and provides a low-cost, population-based method for monitoring chronic conditions in children who die.

Background: The Buffalo Concussion Treadmill Test (BCTT) is a graded exertion test for assessing exercise tolerance after concussion, but its utility is limited for certain populations. Hypothesis: We developed the Buffalo Concussion Bike Test (BCBT) and tested its comparability with the BCTT. We hypothesize that heart rate (HR) at symptom exacerbation on the BCBT will be equivalent to the BCTT. Study Design: Case-control study. Level of Evidence: Level 3. Methods: Adolescents with acute concussion (AC) (n = 20; mean age, 15.9 ± 1.1 years; 60% male) presenting to a concussion clinic within 10 days of injury and age- and sex-matched healthy controls (n = 20; mean age, 15.9 ± 1.1 years; 60% male) performed the BCTT at first visit and returned within 3 days to perform the BCBT. Test duration, HR, symptom severity (measured using a visual analog scale), and exertion (measured using the Borg Rating of Perceived Exertion) were collected during each test. Results: Adolescents with AC who were exercise intolerant on the BCTT were also intolerant on the BCBT, with symptom exacerbation occurring at a mean 8.1 ± 2.8 minutes on the BCTT versus 14.6 ± 6.0 minutes on the BCBT ( P < 0.01). Two 1-sided t tests showed that the HR at symptom exacerbation in AC patients (137 ± 28 bpm on BCTT vs 135 ± 25 bpm on BCBT; 95% CI, <0.01-0.03) and at voluntary exhaustion for controls (175 ± 13 bpm on BCTT vs 175 ± 13 bpm on BCBT; 95% CI, 0.03-0.03) on each test were statistically equivalent. Conclusion: The HR at symptom exacerbation on BCBT is equivalent to the BCTT for the assessment of exercise tolerance after concussion in adolescents. Clinical Relevance: The BCBT can be used in patients with limited mobility or for research interventions that require limited participant motion.

It is well known that quaternions are intimately connected with spherical trigonometry, and in fact they reduce that subject to a branch of algebra. The question is suggested whether there is not a system of quaternions complementary to that of Hamilton, which is capable of expressing trigonometry on the surface of the equilateral hyperboloids. The rules of vector-analysts are approximately complementary to those of quaternions. In this paper I propose to show how they can be made completely complementary, and that, when so rectified, they yield the hyperbolic counterpart of the spherical quaternions.

This article presents a brief, focused physical examination [PE, the Buffalo Concussion Physical Examination (BCPE)] for sport-related concussion (SRC) to be considered for use in the outpatient setting by sports medicine physicians, pediatricians, and primary-care physicians. This companion paper describes how to perform the PE, which was derived in a separate study presented in this journal. It is envisioned for use at the initial and follow-up outpatient visits both for acute concussions and in patients with prolonged symptoms. A pertinent PE, combined with other assessments, can help identify specific treatment targets in those with persistent symptoms after SRC. The BCPE includes orthostatic vital signs and examinations of the cranial nerves, oculomotor/ophthalmologic, cervical, and vestibular systems. Supplementary tests, including testing for exercise tolerance and neurocognitive function, may be performed if indicated. It is recommended that a PE be performed at the initial visit and every 1 to 2 weeks after SRC. On return of symptoms, cognition, and the PE to baseline, as well as normalization of any supplementary tests, patients can begin a return to play program.

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