HB A1c - Chaos to Harmony!

Haemoglobin A1c (HbA1c) is due to celebrate its 40th birthday. Many people would argue that the clinical studies relating the test to diabetes complications while in its late 20s are likely to be its finest ever achievement. However, this article looks at how HbA1c has matured since then and discusses in detail how its many strengths and idiosyncrasies as a marker of glycaemic risk have, as a 30-something, become more clearly understood.

As HbA1c approaches middle age, this paper also describes how the test appears to be developing a mid-life crisis, as debate over how its results should be expressed seems likely to divide opinion among clinicians for some time to come.

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Sleep Apnea and Stroke in CAD

Sleep disorders are more common in CAD patients and this not frequently recognised. This is associated with increased cardiovascular accidents Patients with CAD should therefore be considered for sleep apnea investigations and subsequent treatment. Read this paper in Circulation..

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Clinician's Long Tails

DB has written a series of posts on this concept (here, here, here, here, here and here). There’s little I can add but I wanted to get them into my own links, and going through the exercise below has helped my understanding of the concept.

The long tail refers to the horizontal tail of a power law graph. This is a polynomial function which has garnered great interest because of its applicability to a large number of phenomena in commerce and nature. When applied to differential diagnosis the horizontal axis can be visualized as an array of diseases of increasing rarity the farther away from the origin. The vertical axis represents the probability of the given disease explaining the patient’s presentation. A small number of common diseases are clustered toward the origin (to the left). Toward the right (in the long tail) are uncommon diseases, becoming increasingly rare as the graph approaches the horizontal axis as an asymptote.

Individual diseases in the long tail are uncommon. But, because the tail is long (there are many rare diseases), in the aggregate a significant number of patients is represented. That principle, a challenge for the clinician, is explained here.

DB uses the sore throat as an illustration. Pneumonia is another example. Pneumococcal pneumonia would be near the origin. Blastomycosis, ANCA associated pulmonary capillaritis and bronchoalveolar carcinoma, diseases which can present as “pneumonia”, are in the long tail. For recurrent abdominal pain irritable bowel syndrome would belong on the left, with celiac disease and acute intermittent porphyria occupying positions progressively to the right. And so on.

The challenge of the long tail is knowing when to enter it and, once you do, to generate a wide enough differential diagnosis to encompass the disease the patient has, and finally to select appropriate tests to pinpoint the diagnosis. That’s why the long tail separates clinicians from automatons. Algorithms and guidelines won’t help. Up to Date may not even help! What’s needed is judgment along with a vast fund of knowledge about diseases. Key to knowing when and when not to enter the long tail, as DB explains, is knowledge of natural history. How long, for example, should it take your patient with pneumonia to get better? At what point, as a corollary, should you start searching for another diagnosis?

The description of this cognitive process and the contrast between clinician and automaton makes a compelling case for the revival of the original concept of the internist.
Syndicated from RW.

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Does patient have osteomyelitis ? Bone of Contention

Diabetic foot ulcers are common reason for diabetic patients get admitted to medical wards. 20% of foot ulcers are complicated with osteomyelitis. Diagnosis of ostetomyelitis is always challenging. we always find ourselves discussing what is the best way to confirm osteomyelitis. Clinical examination is good enough or what would be the best diagnostic modality. This is a meta analysis that looked at accuracy of tests used to diagnose osetomyelitis. Read more ....

Click on osteomyelitis...

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Biomarkers and Etiology of stroke subtypes

Diagnosis of etiology of stroke sub types is not always possible in some patients and this prevents these patients from receiving definitive treatment. In this interesting study authors looked at the diagnostic value of a panel of biochemical markers to differentiate stroke sub types. Is it not wonderful if there is a blood test that will clinch the etiology. Read this article published in Stroke recent issue.


Read Here.

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Diastolic Heart Failure and Symptoms

Image details: Patient with an Oxygen Mask served by picapp.com

Diastolic heart failure patients' perceptions of symptoms are out of proportion to evidence of their cardiac abnormalities, say UK researchers. (Source: MedWire News - Heart Failure)

If you want to read abstract of original article click here.

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Clinical review of viral meningitis

BMJ 2008;336:36-40 (5 January). Clinical review
by: Sarah A E Logan, specialist registrar, Eithne MacMahon, consultant Infection and Immunology:

* Bacterial and viral meningitis cannot reliably be differentiated clinically, and all suspected cases should be referred to hospital
* Viral meningitis is most common in young children; the incidence decreases with age
* Enteroviruses are the most common cause at all ages
* Although most cases are self limiting, morbidity may be considerable
* Herpes simplex virus causes viral meningitis, which may recur
* Genital herpes infection may be acquired from a partner after many years within a monogamous relationship
* Meningitis is a feature of HIV seroconversion
* In the absence of associated encephalitis, the prognosis is usually good

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