Why sophistication If our motive is to manipulate

Why sophistication? If our motive is to manipulate, our communication and our leadership in general will prove to be ineffective over time. -- Stephen R. Covey 10/23/2021 Why sophisticated biostat? 1

What is Epi? Epidemiology “study of distribution and determinants of health and disease…, and application…” Epi = “methodological backbone” of public health 10/23/2021 Why sophisticated biostat? 2

Does Scientific Public Health Work? Life Expectancy Objective interpretation 10/23/2021 Why sophisticated biostat? 3

Epidemiologic Transition Leading Causes of Death 1900 1990 1 Pneumonia / influenza Heart disease 2 Tuberculosis 3 Diarrhea Neoplasms Cerbrovascular 20 th century shift from acute, contagious diseases to chronic lifestyle diseases Why have the causes of morbidity and mortality shifted? (That’s a different question…) 10/23/2021 Why sophisticated biostat? 4

Reasons for Epi. Transition • First half of twentieth century (advances in childhood) – – Industrialization → standard of living Birth control & maternal education (first half of 20 th century) Improved nutrition Sanitation and vector control • Second half of 20 th century (advances in middle age) – Improvements in lifestyle – Improved medical education – Specific medical treatment (e. g, antibiotics, anti-hypertensives, improved surgical safety…) Doll, R. (1992). Health and the environment in the 1990 s. Am J Public Health, 82(7), 933 -941. Surtout, Messieurs, point de zele. – Talleyrand 10/23/2021 Why sophisticated biostat? 5

Age-Adjusted Death Rates, US objectivity … please 10/23/2021 Why sophisticated biostat? 6

Demographic Transition (a) ↓ mortality at early and middle age (b) ↓ fertility (c) ↑ longevity 10/23/2021 Why sophisticated biostat? 7

Modern Epidemiology • Shift in morbidity and mortality (“epi. transition”) mandate shift in epi methods • Advent of “modern epidemiology” • Focus on multiple factors acting together (confounding and interaction) 10/23/2021 Why sophisticated biostat? 8

Rothman on Cause Disease from the Definitionresults of “cause” cumulative effects of condition multiple • Any event, act, or causes actingdisease togetheror illness • preceding ( • causal interaction ) without which disease would not have occurred • or would have occurred at a later time Ken Rothman (contemporary epidemiologist) Gerstman 10/23/2021 Why sophisticated biostat? 9

Types of Causes • Necessary cause ≡ found in all cases • Contributing cause ≡ needed in some cases • Sufficient cause ≡ the constellation of necessary & contributing causes that make disease inevitable in an individual Gerstman 10/23/2021 A given disease can have multiple sufficient mechanisms Why sophisticated biostat? 10

Causal Complement (Causal Pie) • Causal complement ≡ the set of factors that completes a sufficient causal mechanism • Example: tuberculosis – Necessary agent Mycobacterium tuberculosis – Causal complement “Susceptibility” Gerstman 10/23/2021 Why sophisticated biostat? 11

Yellow Shank Illustration • Yellow shank disease occurs only in susceptible chicken strains fed yellow corn • What would a farmer think if he started feeding yellow corn to a susceptible flock? yellow corn genetic trait • What would a farmer think if he added susceptible chickens to a flock being fed yellow corn? • Is yellow shank disease environmental or genetic? Is cancer genetic or environmental? Gerstman 10/23/2021 Why sophisticated biostat? 12

A lesson from the past Contagion Theory vs. Miasma Theory Competing 19 th Century Theories of Cause & Prevention [and a lesson in confounding] 10/23/2021 Why sophisticated biostat? 13

Competing 19 th Century Theories 10/23/2021 Why sophisticated biostat? 14

Miasma Theory • Miasma ≡ “bad air” • Noxious vapors & atmospheric conditions spontaneously propagate the non-living cholera poison from ordinary organic decay and decomposition • Cholera poison inhaled • Dominant theory of Sanitation (19 th Public Health) Movement 10/23/2021 Why sophisticated biostat? 15

Contagion Theory • • • Cholera agent is free-living Multiplies within the host Water-borne transmission Spread via fecal contamination Patho-physiology oral ingestion diarrhea fluid loss smudging of blood asphyxiation John Snow (1813– 1858) 10/23/2021 Why sophisticated biostat? 16

Water-borne cholera transmission 10/23/2021 Why sophisticated biostat? 17

Snow Died in Obscurity • Initially known as a great surgeon • BUT died in obscurity • WHY? his views on the etiology of cholera were in opposition to the prevailing public health mood at the time (Lilienfeld 2000, Winkelstein 1995) 10/23/2021 Why sophisticated biostat? 18

William Farr (Founding Sanitarian) • First registrar of a national morbidity and mortality reporting system • “Father of public health statistics” • Subscribed to a “part miasma / part contagion” theory” 1807 - 1883 10/23/2021 Why sophisticated biostat? 19

Farr’s View of Cholera 10/23/2021 Why sophisticated biostat? 20

Farr's graph of cholera and elevation Farr’s theory atmospheric condition prevalent in lowlying areas allowed nonliving decomposing organic matter to become poisonous and enter the lungs. Farr figure showing Y = elevation (0 to 350 feet) and X = Cholera mortality per 10000 10/23/2021 Why sophisticated biostat? 21

Modern analysis of Farr’s data r = −. 99 Regression of cholera incidence on mean elevation above sea level log-log scales 10/23/2021 Why sophisticated biostat? 22

What was wrong with Farr’s analysis? The relationship between elevation (exposure) and cholera (disease) was confounded by proximity to contaminated water sources (extraneous “confounder”) Correlation ≠ causation 10/23/2021 Why sophisticated biostat? 23

What was wrong with Farr’s analysis? Miasma theory (and the Sanitation Movement) was ultimately discredited My “bad”! In 1885 (about 40 years later), Farr adopted the contagion theory. 10/23/2021 Why sophisticated biostat? 24

Lesson’s Learned • Simplistic interpretations of data are detrimental to the public’s health • We MUST consider multiple variables acting together (confounding and interaction) • John Snow brilliance = his understanding of inter-relations between social and environmental factors with sound pathological principals • Farr was ultimately willing to change his mind when confronted with overwhelming evidence Many items in this piece were derived from Farr was a good scientist The John Snow Archive & Research Companion 10/23/2021 Why sophisticated biostat? 25