Methods for the New Science of CVD Epidemiology and Prevention
The need for valid, reliable, standard, and practical methods for field work in chronic disease epidemiology is obvious to investigators today, who apply them without imagining a time when every new study required reinvention of the wheel. But part of the uniqueness of CVD epidemiology lies in the situation confronting researchers who initiated studies in mid-20th century. Mainly clinical and laboratory experts without experience in epidemiological methods, they were for the first time addressing questions among populations and departing from familiar clinical environs and practices.
Background on development and details of specific CVD epidemiological methods is found in Essays. Tests of observer variation in diagnosis, for example, were unknown to clinicians of the time, and, when first attempted by the novice epidemiologues, caused great wonder and chagrin. Repeat observations became an essential ceremony of the medical researcher’s baptism in, and conversion to epidemiology.
Some younger recruits in those early days made career marks with their assignments to translate clinical impressionism into repeatable, more objective recording of symptoms, signs, and diagnostic labels. They set out to devise improved ways to measure and classify the health history, symptoms, blood pressure, electrocardiograms, and laboratory tests.
Here we offer a PDF summarizing some of the early developments converting clinical observations, measurements, and diagnoses to quantities applicable in field conditions, along with stories about those where we had direct experience.
- Clinical Methods Converted to Field Use
- Specific Field Methods
- Rose and Blackburn: The Making of WHO Technical Manual No. 56
- The Electrocardiogram in Population Studies: The Minnesota Code
- Indirect Blood-Pressure Measurement
- Anthropometry: Measures of Body Mass and Body Build
- Blood Lipids and Lipoproteins: A Call for Standards
- Dietary Assessment and Food Analysis
- Tobacco Exposure and Smoking Habit
- Physical Activity and Fitness Measures
Concepts and Design
The evolution of causal concepts and study design lagged behind study initiatives in the new science, CVD epidemiology. Early studies were fraught with errors of method, design, analysis, and interpretation. Agencies quickly focused on strengthening their sponsored researches. Guidelines to causal inference arrived in the mid-60s along with analytical methods and computing power to tighten design for the new generation of cohort studies and trials of the 1970s-80s.
- Introduction: Evolution of Concepts and Design
- Evolution in CVD Epidemiological Concept, Method, and Mission
- Guidelines to Causal Inference
Data Handling and Analysis
At the moment in the 1960s that vast quantities of data began to arrive from the first generation of prospective CVD population studies, and just as the investigators were becoming frustrated with handling, storing and analyzing data with multiple variables on many subjects, made over the years, relief arrived. Complex cross-tabulations of intercorrelated variables were rapidly facilitated and research strengthened by new multivariable analyses made possible with accelerated computing power. Here are mainly stories about the transition to modern computing, mentioning a few of the giants who resolved the issues with their wits and famed machines.
- Introduction: CVD Epidemiology Leads the Way
- Data Processing at One Center
- Sir Ronald Fisher and his “Millionaire” Calculator
- Risk Assessment Tools
- AHA Pooling Project
Dietary Assessment and Food Analysis
This report supplements earlier descriptions of the dietary survey methods for the baseline data collection among the 16 cohorts of the Seven Countries Study. Diets of cohorts across a wide range of eating patterns were analysed for relationships of average nutrients consumed at entry versus average serum cholesterol levels and subsequent cohort rates of death from coronary heart disease and all-causes. All analyses in these publications are confined to ecologic correlations of disease outcomes with dietary nutrients and other traits among the cohorts rather than among individuals within the cohorts.
- Fatty acids
- Survey cohorts
- Dietary data collection in the field
- Tables for converting SCS baseline survey food records to macronutrient intake
- Food table and cohort references
- Chemical analysis for macronutrients
- The special case of the Greek Islands baseline dietary surveys and chemical analysis
- Average cohort nutrient values. Food table conversions versus chemical analysis
- Cohort differences in foods rather than nutrients consumed
A complete list of sources for the Methods section.