Annals of Internal Medicine tip sheet for Dec. 6, 2011

Rates of total knee replacement surgery doubled in the United Kingdom between 1991 and 2006 and increased 8-fold in the United States between 1979 and 2002. Researchers hypothesized that aging and increased obesity could be to blame. Using survey data from six NHANES (National Health and Nutrition Examination Survey) surveys between 1971 and 2004 and three examination periods in the FOA (Framingham Osteoarthritis) Study between 1983 through 2005, researchers studied the trend in prevalence of knee pain and symptomatic knee osteoarthritis. The goal was to assess whether age, obesity, and knee osteoarthritis (detected by radiography) explain the trend. A U.S. population representative sample of study participants reported knee pain more frequently in recent years. This knee pain was unexplained by changes in age and body mass index, and radiography in the Framingham study did not find more reports of knee osteoarthritis. The researchers conclude that increasing knee pain or an increased awareness of knee pain, but not increased radiographic osteoarthritis, seem to accompany the rising frequency of total knee replacements.

Pregnant women have increased morbidity and mortality from flu, especially during pandemic years. In 2009, the influenza strain A(H1N1), or swine flu, reached pandemic levels, putting pregnant women and their babies at substantial risk. Researchers studied 107 pregnant women between 22 and 32 weeks of gestation to determine if vaccine for the 2009 strain of H1N1 administered during pregnancy could protect mother and child from infection. Nearly all women who received a single dose of a nonadjuvant 2009 H1N1 vaccine in their second and third trimesters of pregnancy tested positive for protective antibodies. Antibody measures found in cord blood samples from 95 percent of the infants were also at a level considered protective. The researchers conclude that a single dose of influenza vaccine administered to women during pregnancy should protect both mothers and their newborns from this common and potentially dangerous strain of swine flu.

Treatment decisions may depend on patient preference for dosing, side effects, and cost

Major depressive disorder, or MDD, will affect more than 16 percent of adults during their lifetime. Typically, drugs are prescribed to treat symptoms of MDD. The majority of antidepressants prescribed are second-generation drugs, which differ from each other in pharmacologic action. Researchers reviewed 234 published studies to compare the benefits and harms of second-generation antidepressants used to treat MMD in adults. The research showed no clinically important differences in efficacy among the medications. However, differences did exist in onset of action, dosing regimens, and adverse effects. Physicians should base prescribing decisions on patient preferences regarding possible side effects, convenience of dosing regimens, and cost.