Journal Club: TV, TB, and how to say hello

Are new assays useful for detecting TB?

The test was positive in 17% of the study group, negative in 48%, and indeterminate in 35%. Analysis showed that age younger than 5 years and being immunocompromised were both independently associated with a higher probability of an indeterminate result. In children who were not immunocompromised, the likelihood of an indeterminate test result was inversely correlated with age, decreasing by 13% for each additional year of age (Haustein T et al: Pediatr Infect Dis J 2009;28:669).

These tests are based on detection of interferon gamma production by mononuclear cells after exposure to antigens produced by M tuberculosis. They offer a potentially useful tool for making the often confusing diagnosis of both tuberculosis infection and disease.

One advantage of these tests over the traditional tuberculin skin test is that bacille Calmette-Guérin and most nontuberculous mycobacteria do not generate the antigens necessary to cause a positive test. The tests now available include a positive control: In other words, if the control is not positive, the tested sample may be inadequate, or the patient may not be able to mount the appropriate response even in the presence of these TB antigens. These authors show that indeterminant tests such as these are more common in the youngest patients and in those with immune deficiency, the very patients who are most likely to develop TB disease after infection.

The 2009 Red Book offers a clear explanation of the current role of these assays in detection of TB. As more information is obtained, that role will likely increase. -MB

PARENTS EXPECT TO BE GREETED BY NAME

Overall, 83% of the adults wanted the doctor to shake hands, and most did (70% of residents, 66% of attendings). Even more parents, 87%, wanted their physicians to address them by name, but only 14% of residents and 24% of attendings did so. Physicians did best in meeting expectations by introducing themselves at encounters, with 84% of residents and 93% of attendings extending this courtesy (Amer A et al Clin Pediatr 2009;48:720).

COMMENTARY

Name tags for everyone. In 9% of encounters, physicians incorrectly addressed the parent by using the child's last name. I wonder how often physicians fail to call the parent by name so as to avoid this error. If that's the case, we need to display parents' names prominently on patient charts, on appointment lists, and in the hospitalized child's room. -MB