User:AddisonBlacksmith/sandbox

The Nurses' Health Study (NHS) is a series of prospective studies that examine epidemiology and the long-term effects of nutrition, hormones, environment, and nurses' work-life on health and disease development. The studies have been among the largest investigations into risk factors for major chronic diseases ever conducted. The studies have led to many insights on health and well-being, including cancer prevention, cardiovascular disease, and type 2 diabetes. They have include clinicians, epidemiologists, and statisticians at the Channing Laboratory (of Brigham and Women's Hospital), Harvard Medical School, Harvard School of Public Health, and several Harvard-affiliated hospitals, including Brigham and Women's Hospital, Dana–Farber Cancer Institute, Children's Hospital Boston, and Beth Israel Deaconess Medical Center.

Cohorts
The Nurses' Health Study (NHS) (original cohort) was established in 1976 by Dr. Frank Speizer. Initially, the study investigated contraceptive use, smoking, cancer, and cardiovascular disease. The1976 baseline group included married female registered nurses between the ages of 30 and 55. Approximately 121,700 participants in 11 of the most populous U.S. states (California, Connecticut, Florida, Maryland, Massachusetts, Michigan, New Jersey, New York, Ohio, Pennsylvania, and Texas) responded to the study's survey, which was then distributed biennially thereafter. Over the years, the principle investigator (PI) of the NHS has included Frank Speizer, Graham Colditz, Sue Hankinson, and Meir Stampfer.

Over time, the study expanded. Most notably, a dietary questionnaire was added in 1980 due to investigators recognizing the impact of diet and nutrition on the development of Chronic disease. Blood, urine, saliva, and other physical samples were received and tested beginning in 1982. Experimenters followed up reports of morbidity using the National Death Index. Where possible and permitted, cancer diagnoses were reviewed. Although reports of other diseases were not followed up, self-reporting has been confirmed by medical records and doctors unaware of the answers to the study's questions.

The Nurses' Health Study II (NHS II) was established in 1989 by Dr. Walter Willett, who has been the NHS II PI since inception. The focus of the study was women's health, especially the long term adverse effects of oral contraceptives. The sample population contained females within the age range of 25-42, employed as nurses, from 14 U.S. States. Data collected included the brand of pill and length of use. Over time, the study expanded to include information on basic practices and measurements of health, such as exercise practices and food intake.

Between the years of 1996 and 1999, approximately 30,000 nurses volunteered to provide blood and urine samples to the study. Of these women, 18,500 were pre-menopausal, providing samples at specific points in the menstrual cycle. These data allowed researchers to study how hormone levels influence the risk of disease. A second set of samples was collected from 16,500 of the same group of women in 2010-2012, by which time most of the women were postmenopausal. Over 25,000 children of women in the Nurses' Health Study II cohort were enrolled in their own follow-up study called the Growing Up Today Study, or GUTS, which has followed the subjects through their early life so as to obtain a second generation of data.

The Nurses' Health Study 3 (NHS3) was developed in 2010 by Drs. Jorge Chavarro, Walter Willett, Janet Rich-Edwards, and Stacey Missmer. The study includes investigators from the Channing Division of Network Medicine at Brigham and Women's Hospital, Harvard Medical School, and Harvard T.H. Chan School of Public Health. The original population contained females 19-49 in age and expanded to include Canadian subjects. Unlike the predecessor studies, the NH3 includes participants of both male and female genders in 2015. Jorge Chavarro has been the PI of NHS3 since its 2010 inception.

Findings
The studies revealed many correlations between environmental factors and risk for health conditions.

Smoking: Related to a higher likelihood of Type 2 Diabetes, Cardiovascular Disease (CVD), Colorectal and Pancreatic Cancer, Psoriasis, Multiple Sclerosis, and Eye Disease

Exercise Lack of physical activity correlated to an increased the likelihood of subjects developing Type 2 Diabetes. Exercise related directly to Breast Cancer survival. Physical activity was related to a decreased risk of the development of CVD.

Obesity Obesity correlated with higher likelihood of developing Type 2 Diabetes, CVD, Breast Cancer, Pancreatic Cancer, Psoriasis, Multiple Sclerosis, Gallstones , and Eye Disease

Oral Contraceptives Present use decreased likelihood of Ovarian Cancer. No statistically significant effects of oral contraceptives were observed in regard to risk of Breast Cancer. Present or past use did not correlate significantly with CVD.

Postmenopausal Hormone Therapy Present use related to a lower likelihood of CVD. Combination hormones (progesteron and estrogen) were associated with higher risk of Breast Cancer.

Many relationships and factors were examined over the course of the study, including diet, coffee consumption, and sleep. Many publications were produced as a result.

History
Beginning in the 1960s, oral contraceptives were used by the public in the U.S. and U.K. As soon as 1966, however, there were reports of women falling ill with cardiovascular disease in association with these contraceptives. Doctors Frank Speizer and Martin Vessey hoped to better understand the effects of long-term use of oral contraceptives on the health of women. After receiving funding from the National Cancer Institute in 1974, the study was directed towards the wives of doctors. When it was discovered that such responses were not ideal due to lack of medical knowledge of the participants, the study shifted its focus to nurses. The studies did not remain focused on oral contraceptives, but expanded to investigate factors such as smoking, diet, and exercise. These conditions demonstrated relationships with states of health, such as risk of developing chronic disease. Because the women continued submitting their responses as time passed, the Nurses' Health Study was the first cohort study of such magnitude to follow a population over time. The study has continued into 2018, and as of 2016 were funded almost entirely (90%) by the federal government.

Impact
Data received from the study expanded the understanding of women's health. Public messages from the United States Surgeon General, World Health Organization, and World Cancer Research Fund have resulted from the findings of the Nurses' Health Study. Policies such as the '2008 Physical Activity Guidelines for Americans' and the Dietary Guidelines of the Food and Drug Administration regarding trans-fat related to the findings of these studies. To date, the Horses Health Study has led to the publication of hundreds of peer-reviewed papers.

Public Reaction
This study was referenced in popular news by many sources. The term "Nurses' Health Study" has been stated in over three hundred articles of the New York Times and The Washington Post alone. These articles discussed the findings of the study, such as one titled Women, Alcohol and the Search for Certainty. Published as early as 1988, this Washington Post article discussed the effect of the NHS on the relationship between women and alcohol, citing the former as a factor which effects a woman's risk for CVD and strokes. News outlets have also described the more general implications of the study, such as a piece titled It's Never Too Late to Be Healthy, Studies Show. The 2004 article discusses the research of the study and resulting understanding of general health in older populations. The impact of the study itself was also in the public eye. In the New York Times article In Nurses' Lives, a Treasure Trove of Health Data, nurses themselves were cited as changing daily habits and considering their choices as a result of their participation. In this way, the findings and magnitude of the Nurses Health Study reached the public over its history.

Limitations and Controversy
The NHS 1 contained populations representing nurses of the time, but did not reflect great diversity. The participants had a slightly higher income than the average of the time and a majority were white (97%). In 2012, however, minority participants were increasingly sought after. Leaders of the experiment made this a priority by sending extra information on the study to possible subjects living in areas of high diversity. In 2015 males were accepted into the study, which was caused by an increase in the number of males in the nursing profession.

The Nurses' Health Study faced controversy based on its recommendations. The study published in 1985 that taking estrogen as a part of Hormone Replacement Therapy would lead to large decreases in risk of heart disease (a third of the risk of those who did not take supplements). However, the Framingham Heart Study found the opposite result. This controversy caused a 10 year follow up by the Nurses' Health Study which again concluded that risks of CVD were lower in populations currently taking hormones. Further studies such as the Heart and Estrogen-progestin Replacement Study found that estrogen tablets actually increase risk for heart disease. This was a double-blind trial following an experimental group of women who were given replacement therapy pills and a control group following the same procedure with placebos. Findings from the study displayed a direct relationship between therapy and risk for heart disease, as opposed to the previously stated benefits. This finding largely opposed the published NHS conclusion.

Other Mass Health Studies
British Doctors Study

Framingham Heart Study

External links and PUBMED ID
PUBMED ID of summaries of the Nurses' Health Studies: 27459450

External Links:
 * Channing.harvard.edu - 'The Nurses' Health Study', Channing Laboratory, Harvard University


 * Video
 * Video series on history of Nurses' Health Studies


 * Audio
 * PBS Frontline interview with Walter Willett (April 8, 2004)