Pharmacoepidemiology

In the first nine months of 2019, a total of 1249 cases of measles were reported in the United States—the highest number on record since 1992 and nearly double the number of cases seen in any year in the past decade.1,2 In the Democratic Republic of the Congo, a striking 4000 deaths were attributed to measles in 2019, and more than 200,000 measles cases have been reported year to date.3 Efforts to vaccinate Congolese children and supply medicines are ongoing as health authorities attempt to gain control of the epidemic.4 In the United States, the resurgence of measles has been attributed to reduced vaccination rates driven by vaccine hesitancy and misinformation.5,6 Fear of vaccines rose in 1998 in response to the now widely discredited claim that the MMR vaccine causes autism.7 Readers are referred to my June Note,8 within which I described ways to engage with those who remain opposed to vaccination to help mitigate their concerns. Similar real-world observational studies confirmed the role of nicotine in addiction to cigarettes, smoking as a risk factor for lung cancer,12 and folic acid in preventing spina bifida and other neural tube defects.13 Other potential uses are population-based comparative effectiveness studies. In other words, to find an event that occurs in 1 in 1000 persons, one would need a population of 3000. [...]to conduct a split-half reliability assessment, one would need a minimum of 6000 persons.