Annals of Internal Medicine tip sheet for June 21, 2011

For patients with hypertension, physicians typically use a single in-office blood pressure (BP) reading to assess how well medical interventions are working and then adjust hypertension medications accordingly. However, some patients may experience a phenomenon known as "white coat" hypertension, meaning they have a higher than normal BP due to the anxiety associated with the office visit. Researchers sought to determine how many readings would be needed to accurately determine whether a patient's BP was under control. They followed 444 veterans with hypertension for 18 months to compare three different strategies for BP measurement: standardized research BP measurement every six months; in-office BP measurements taken during outpatient visits; and home BP measurements using a monitor that transmitted results electronically. The researchers found that taking an average BP reading from several measurements resulted in substantially greater accuracy in diagnosis. The authors recommend that home monitoring could improve the quality of blood pressure care.

Acute appendicitis can be difficult to diagnose, as the symptoms of appendicitis mirror those of other illnesses. Accurate diagnosis is important because patients with appendicitis go to surgery, while those that do not have appendicitis do not. Computed tomography is often used to help diagnose appendicitis, but high quality studies of its effectiveness in this situation have been lacking. Researchers reviewed hospital records for 2,871 adult patients with suspected appendicitis between 2000 and 2009 to determine if multidetector computed tomography (MDCT) could accurately rule in or rule out appendicitis. The researchers found that MDCT was sensitive and specific enough to identify the approximately one quarter of patients with actual appendicitis who needed urgent surgery, and it identified a probable alternative cause of symptoms in those who did not have appendicitis. In addition, preoperative MDCT can reduce rates of perforation and negative findings at appendectomy. The researchers recommend MDCT as the standard of care for suspected appendicitis in adults.

Thiopurine-based drugs are sometimes used to treat patients with chronic inflammatory autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease. Because thiopurine-based drugs can lead to severe lowering of blood counts in patients with reduced or absent thioputine S-methyltransferase (TPMT) enzyme, some experts recommend routine measurement of TPMT activity before prescribing these drugs. Another approach is to start the drugs, monitor blood counts, and stopping the drug if blood counts fall. Researchers reviewed 55 published studies to examine the sensitivity and specificity of TPMT genotyping for several purposes: measuring TPMT enzymatic activity; reducing harm from thiopurine; and to determine the association of thiopurine toxicity with TPMT status in adults and children with chronic inflammatory diseases. The researchers found insufficient evidence that TPMT pretesting guides appropriate prescribing or improves patient outcomes (such as by limiting toxicity) compared with routine blood count monitoring in patients receiving thiopurine therapy. The authors of this study and the author of an accompanying editorial call for more research about biological testing to preempt prescribing mediations with potentially harsh side-effects in particular patients.