Question
State the specific type of epidemiologic study described by each of the following paragraphs and, in NO MORE THAN ONE OR TWO SENTENCES, give a reason for your answer:
a. To find out if incentives would increase the use of insecticide-treated bed nets to prevent malaria, 22 villages in Madagascar were randomized following a bed net distribution campaign to receive either a household-level coupon for one bed net plus an additional cash incentive or to receive only the coupon. After six months, there was no difference in the frequency of bed net use between the groups of villages.
b. Mothers of children aged 24-60 months evaluated for autism in northern California in 2005 were interviewed at the same time as the evaluation to collect data on maternal vitamin intake before and during pregnancy. The findings revealed an association between autism and mothers not taking prenatal vitamins during the three months before pregnancy or during the first month of pregnancy.
c. A group of investigators are interested in examining the relationship between diet and risk of multiple sclerosis (MS). A study was initiated at a Veterans Administration Medical Center by identifying cases of MS diagnosed within the last 5 years using the electronic medical record system. The system was also used to identify non-MS individuals, matched to cases with respect to age, sex, and race. All individuals, with and without MS, were contacted and asked about their fruit and vegetable consumption in adolescence, in their 20’s, in their 30’s, and current consumption.
d. Four hundred babies were followed from birth to age seven to determine if those whose mothers exclusively breastfed them had better cognitive achievements. Children breastfed exclusively for at least six months scored significantly higher on intelligence quotient (IQ) tests at age seven than those who were breastfed for less than six months. The findings supported the investigators’ hypothesis that benefits of breastfeeding remain apparent later in childhood.
e. In Australia, to explore an association between parental occupational exposure to pesticides and increased risk of acute lymphoblastic leukemia (ALL) in the offspring, information about the occupational pesticide exposures of mothers and fathers of 416 ALL patients aged 15 years or younger was collected. Data from the ALL patients were compared to the same data collected from 2071 eligible families recruited through random digit dialing. Paternal occupational exposure to pesticides before or around conception was not related to increased risk of childhood ALL.
f. To explore the impact of ectopic pregnancy (EP) on subsequent pregnancies, researchers collected data from a Scottish national dataset on all women whose first pregnancy occurred between 1981 and 2000. These records were then linked to records of subsequent pregnancies. Women who had experienced an EP during their first pregnancy were compared to women whose first pregnancy resulted in a (non-EP) live birth, miscarriage, or termination. Women with an initial EP suffered an increased risk of another EP in a subsequent pregnancy compared to women with a live birth, miscarriage, or termination in their first pregnancy.
g. To explore a hypothesis that herbal dietary supplements promote excretion of lead (absorbed from food, water, or air), investigators collected data on a representative sample of the US population. Participants were interviewed about their use of herbal supplements and blood samples were collected for measurement of lead levels. The study found that use of herbal supplements was associated with significantly higher blood lead levels among women, but not in men.
h. In a study of nuclear power workers, a significantly greater proportion of workers exposed to ionizing radiation than unexposed workers developed reticuloendothelial system (RES) cancers over a 20-year follow-up period. This led to a second study, in which more detailed information on exposures was collected from the RES cancer cases and from a group of their coworkers who did not have RES cancers. What was the second study?
i. To determine whether meditative exercise has benefits for patients with chronic heart failure, investigators assigned 100 patients with systolic heart failure to either a 12-week yoga program or to standard education. Each person had an equal chance of being assigned to either intervention. The study found no significant differences in exercise capacity improvements between the groups, but patients in the yoga exercise group had greater improvements in quality of life than patients in the education group.
j. A study was conducted to identify risk factors for hospitalized seasonal influenza in rural western Kenya. A questionnaire was administered to 217 people hospitalized with influenza and to a group of people without influenza who lived in the same neighborhoods. The study found that individuals with HIV infection and chronic lung disease were at increased risk of being hospitalized for influenza.
Source: 2016 250W Problem Set #3 (Michael Bates)
