A 40-year-old male who recently immigrated from central Africa presents to a public health clinic where you are working. He was referred by a physician in the local emergency department, who made a diagnosis of type 2 diabetes mellitus. The patient has no history of fever or night sweats, weight loss, or cough. He does have a history of receiving bacille Calmette-Guérin (BCG) vaccine in the past. Screening tests for HIV and hepatitis performed in the emergency department were negative.
Which one of the following is true regarding screening for latent tuberculosis infection by in vitro interferon-gamma release assay (IGRA) compared to screening by the traditional targeted tuberculin skin test (TST) in this patient?
Correct Answer C:
In vitro interferon-gamma release assays (IGRAs) are a new way of screening for latent tuberculosis infection. One of the advantages of IGRA is that it targets antigens specific to Mycobacterium tuberculosis. These proteins are absent from the BCG vaccine strains and from commonly encountered nontuberculous mycobacteria. Unlike skin testing, the results of IGRA are objective. It is unnecessary for IGRA to be done in tandem with skin testing, and it eliminates the need for two-step testing in high-risk patients. IGRAs are labor intensive, however, and the blood sample must be received by a qualified laboratory and incubated with the test antigens within 12 hours of the time it was drawn.
IGRAs do not help differentiate latent tuberculosis infection (LTBI) from tuberculosis disease. A diagnosis of LTBI requires that TB disease be excluded by medical evaluation. This should include checking for signs and symptoms suggestive of TB disease, a chest radiograph, and, when indicated, examination of sputum or other clinical samples for the presence of M. tuberculosis.
During a routine visit you find that your 45-year-old patient has tendinous xanthomas over his right Achilles tendon and left patella. Your patient tells you that a few months ago he started smoking and that his older brother was diagnosed with familial hypercholesterolemia a few years ago.
Physical examination: heart rate 79 bpm, respiratory rate 18 bpm, blood pressure 134/87 mmHg and body temperature 36.9°C. Other than the xanthomas you noted earlier, physical examination is normal. You screen your patient by measuring serum total cholesterol and low density lipoprotein and you find that both are high.
Which of the following should you obtain in order to calculate Framingham Risk Score of coronary artery disease for your patient?
Correct Answer E:
Level of high density lipoprotein cholesterol (choice E) is required for calculation of the 10 years risk of coronary artery disease in this patient. Calculation of Framingham Risk Score uses five items:
The first four factors are provided in the case scenario and thus you need to obtain the fifth one, high density lipoprotein cholesterol (HDL-C). It is noteworthy that high levels of serum HDL-C decrease the risk of coronary artery disease.
→ Level of physical activity (choice A) is not required for calculation of Framingham Risk Score. The level of physical activity, however, influences the risk of coronary artery disease irrespective of the Framingham Risk Score. It is not known how physical activity influences the risk of coronary heart disease but physical activity influences other risk factors of coronary artery disease like, body mass index, waist circumference and blood lipid profile. Thus, although the level of physical activity is not incorporated in the equation used to calculate Framingham Risk Score, it remains an important tool for modifying the risk of coronary artery disease.
→ Number of cigarettes smoked per day (choice B) is not required for calculation of Framingham Risk Score. Calculation is based on whether or not the subject smokes irrespective of number of cigarettes smoked. However, the risk of coronary heart disease increases as the number of cigarettes smoked.
→ Family history of coronary artery disease (choice C) is not required for calculation of Framingham Risk Score. But, coronary heart disease in a male first degree relative at < 55 years of age or a female first degree relative at < 65 years of age is considered a major risk factor for coronary artery disease.
→ Waist circumference or body mass index (BMI) (choice D) is not required for calculation of Framingham Risk Score. Obesity as indicated by BMI is a minor risk factor for coronary heart disease. The effect of obesity on the risk of coronary artery disease is potentiated by waist circumference of > 102 cm in men and > 88 in women.
Key point:
Framingham Risk Score is calculated on the basis of age; smoking; systolic blood pressure; total serum cholesterol and serum level of high density lipoprotein cholesterol. Not all known risk factors are used for calculation of Framingham Risk Score of coronary artery disease.
Which one of the following would be most appropriate for stroke prevention in a patient with hypertension, diabetes mellitus, and atrial fibrillation?
Correct Answer D:
The CHADS2 score is a validated clinical prediction rule for determining the risk of stroke and who should be anticoagulated. Points are assigned based on the patient’s comorbidities. One point is given for each of the following: history of congestive heart failure (C), hypertension (H), age 75 (A), and diabetes mellitus (D). Two points are assigned for a previous stroke or TIA (S2).
For patients with a score of 0 or 1, the risk of stroke is low and warfarin would not be recommended. Warfarin is the agent of choice for the prevention of stroke in patients with atrial fibrillation and a score >2. In these patients, the risk of stroke is higher than the risks associated with taking warfarin.
Enoxaparin is an expensive injectable anticoagulant and is not indicated for the long-term prevention of stroke.
The Canadian Hypertension Education Panel (CHEP), in collaboration with the Canadian Diabetes Association, have recommended that patients with diabetes mellitus should be treated to attain BP of:
Persons with diabetes mellitus should be treated to attain SBP <130 mm Hg and DBP <80 mm Hg. These target BP levels are the same as the BP treatment thresholds. Combination therapy using 2 first-line agents may also be considered as initial treatment of hypertension if SBP is 20 mm Hg above target or if DBP is 10 mm Hg above target. However, caution should be exercised in patients in whom a substantial fall in BP is more likely or poorly tolerated (e.g. elderly patients, patients with autonomic neuropathy).
{Treatment of Hypertension Canadian Diabetes Association Clinical Practice Guidelines Expert Committee, 2013}
The best available evidence supports which one of the following statements regarding the cardiovascular effects of hypoglycemic agents?
Correct Answer B:
Metformin is the only hypoglycemic agent shown to reduce mortality rates in patients with type 2 diabetes mellitus. A recent systematic review concluded that cardiovascular events are neither increased nor decreased with the use of sulfonylureas. The effect of incretin mimetics and incretin enhancers on cardiovascular events has not been determined. The STOP-NIDDM study suggests that "-glucosidase inhibitors reduce the risk of cardiovascular events in patients with impaired glucose tolerance.
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