Which of the following observational types of studies is usually used to estimate prevalence of a health condition or prevalence of a behavior, risk factor, or potential for disease?
Correct Answer B:
Cross-sectional study: A study done at one time, not over the course of time. A cross-sectional study might be of a disease such as AIDS at one point in time to learn its prevalence and distribution within the population. Also known as a synchronic study.
First, distinguish between observational (cross-sectional, cohort, case-control) and experimental (Randomized Controlled Trial, Quasi-Experimental) studies. In observational studies, the researcher observes and systematically collects information, but does not try to change the people being observed. In an experiment, by contrast, the researcher intervenes to change something and then observes what happens. In an observational study there is no intervention.
You care for a family that consists of a husband, a wife, a daughter, and a son. Each family member is healthy. The 71-year-old maternal grandmother lived with the family until 4 weeks ago when she died suddenly after a prolonged respiratory illness. Autopsy revealed that she had active pulmonary tuberculosis at the time of her death. The organism tested sensitive to all commonly used anti-tuberculosis drugs.
In following up on the grandmother's illness, the most appropriate first step in managing this family is to:
Correct Answer C:
The entire family has been exposed to the grandmother, who has had active tuberculosis. As close contacts, they are at risk for transmission of TB. The appropriate screening test at this time would be PPD testing. The family members should be considered at intermediate risk for TB, and therefore, a 5 mm area of induration would be considered a positive test.
A PPD Test is considered positive when the induration is:
Which one of the following is true regarding PPD testing for tuberculosis?
Correct Answer A:
Because the risk of developing active disease is highest in patients within 2 years after conversion, recent converters should generally be treated regardless of age. BCG vaccination has a limited effect on PPD reactivity; tests should not be interpreted any differently in patients who have previously received BCG. The use of a two-step approach (i.e. retesting 1-4 weeks later in patients who initially test negative) is designed to decrease the false-negative rate of PPD testing. The significance of a positive result on either phase of the test is the same. Patients who are HIV positive are at a higher risk for false-negative PPDs and active disease, but PPD testing is not contraindicated.
Which one of the following is true regarding direct observational therapy (DOT) in the treatment of active tuberculosis?
Correct Answer D:
In the treatment of active tuberculosis, direct observational therapy (DOT) involves providing the antituberculosis drugs directly to patients and watching them swallow the medications. It is the preferred care management strategy for all patients with tuberculosis. The use of DOT does no guarantee the ingestion of all doses of every medication, as patients may miss appointments, may not actually swallow the pills, or may (deliberately or otherwise) regurgitate the medication.
Research has shown that DOT cannot be limited merely to passive observation of medication ingestion. There must be aggressive interventions when patients miss doses. DOT should be used for all patients residing in institutional settings, such as hospitals, nursing homes, or correctional facilities, or other settings, such as methadone treatment sites, that are conducive to observational therapy. Because DOT does not guarantee complete compliance with an antituberculosis regimen, all patients should continue to be monitored for signs of treatment failure. Enhanced DOT (DOT along with incentives and enablers) produces the highest treatment completions rates (in excess of 90% across a range of geographic and socioeconomic settings), and reinforces the importance of patient-related factors in designing and implementing case management. Examples of enablers are reminder systems and follow-up for missed appointments, as well as personnel who speak the languages of the populations served. Incentives include such things as clothing or personal products, as well as use of a patient contract.
A 51-year-old immigrant from Laos presents with a 3-week history of nocturnal fever, sweats, cough, and weight loss. A chest radiograph reveals a right upper lobe cavitary infiltrate. A PPD produces 17 mm of induration, and acid-fast bacilli are present on a smear of induced sputum.
While awaiting formal laboratory identification of the bacterium, which one of the following would be most appropriate?
Correct Answer E:
Leading authorities, mandate aggressive initial four-drug treatment when tuberculosis is suspected. Delays in diagnosis and treatment not only increase the possibility of disease transmission, but also lead to higher morbidity and mortality. Standard regimens including INH, ethambutol, rifampin, and pyrazinamide are recommended, although one regimen does not include pyrazinamide but extends coverage with the other antibiotics. Treatment regimens can be modified once culture results are available.
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