Chapter 4: descriptive epidemiology: person, place, time – Flashcards

1. descriptive (studies used to identify a health problem that may exist. characterize the amount and distribution of the disease) 2. analytic (studies are done after descriptive studies, used to identify the CAUSE of the health problem)

1, evaluate and compare trends in health/disease among populations 2. give bases for planning/provision/ evaluation of health services 3. identify problems that should be studied by analytic methods. (create hypotheses)

-hypotheses = theories tested by gathering facts. either accept or reject -3 ways to state hypotheses: 1. positive declaration (research hypothesis. ie) infant mortality IS higher in one region than another) 2. negative declaration (null hypothesis). (ie there is no difference). **this is actually what is tested. can prove absolute truth in science 3. implicit question (study the association between infant mortality rates and regions)

use Mill's Canons of Inductive Reasoning: ways to see if our observations can be 'causations' 1. method of difference (all of the factors in 2 or more domains are the same except for a single factor. so imply disease from one thing. ie two students go to nurse office, one had coleslaw and got sick other didnt have coleslaw didnt get sick. so coleslaw caused sickness) 2. method of agreement (single factor is common in many settings. hypothesize that the common factor is cause of the disease. ie students all had coleslaw, so coleslaw caused the food poisoning), 3. the method of concomitant variation (frewquecy of disease depends on potency of a factor. suggests the facotr causes the disease. ie one student had no coleslaw, not sick. one student had one bite, sick. one student had half a plate, violently ill ) 4. method of residues (subtract potential factors to determine which one has most impact (regression analysis). ie) student comes in and has a headache, rash, and also sick. nurse already knows that pizza causes a rash and pop causes a headache. so subtract these from the lunch, must be coleslaw)

The method of analogy (from MacMahon and Pugh) -the mode of transmission and symptoms of a diseases of unknown etiology have a pattern similar to that of a known disease -so suggests that both diseases have similar etiologies

1. case reports (counts), simplest category. from one single situation, individual. 2. case series (summarize characteristics of patients from major clinical settings. ie look at 5 different cases of someone with the same disease) 3. cross-sectional studies (survey population to estimate prevalence of a disease or exposure)

1. age 2. sex 3. marital status 4. race/ethnicity 5. nativity/migration 6. religion 7. SES

-one of most important factors when describing occurrence of disease/illness because DISEASE CHANGES OVER TIME -childhood: developmetnal problems, birth defects -teen: unplanned pregnancy, substance abuse -adults: accidental injury, homicide, suicide. -older adults: chronic diseases

1. validity of diagnosis: ie older people may die of a number of things but only diagnose one 2. multimodality of trends: several peaks and declines in frequency of diseases at different ages 3. latency effects (between environmental exposure and disease development. ie exposed to toxins, get cancer later) 4. human biological clock (get more vulnerable, immune system worsens) 5. life cycle and behaviour (ie younger people more risk taking, obesity is behaviour)

-all-case age specific mortality rates usually higher for men than women -maybe due to social factors -maybe due to biological differences (ie hormone levels) -generally, death rates for both sexes declining

-single, nonmarries, commonlaw, divorced etc -married people have lower rates of morbidity/mortality -divorce and seperation leads to adverse health outcomes among older women

-canada is getting more diverse -need to be aware of OCAP for conducting research with first nations people (FN have ownership over research that has to do with them) -race is ambiguous; overlaps with many other factors -some scientists say race is a social construct

-people are screened before they come to Canada (for nutrition, tuberculosis, etc) -also need to make physicians familiar with uncommon diseases (like tropical diseases) -healthy migrant effect: healthier, younger people usually are the majority of migrants.

-certain religions have certain lifetsyles that influence rates of morbidity/mortality ie)Seventh Day Adventists: follow vegetarian diet, no alcohol or tobacco. have lower rates of CHD, reduced cancer risk, lower blood pressure. -similar with mormons

social class is very important; low social class related to more mortality/morbidity/disability factors include: -poor housing -crowded conditions -racial disadvantage -low income -poor education -unemployment

1. international 2. geographical (within country) 3. urban/rural 4. localized occurence of disease

1. gene/environment interactions: more people with sickle-cell gene in Africa in high malaria areas; protective gene. 2. climate: mild climate allows more pathogenic organisms to live, ie Yaw's disease in tropics. 3. environmental factors (ie nuclear testing in US and cancer development)

1. cyclic fluctuations 2. point epidemics 3. secular time trends 4. clustering

-periodic changes in frequency of diseases over time. -related to change in lifestle/ climate/ cirulence of an infectious agent -ie) more acidents in the summer, from traveling/alcohol/longer days -ie) flu begins in cold winter months, not in summer

-response of a group of people in a plcae and time to be a common source of infection/ other exposure that they got at the same time -for example, at a bbq, potato salad caused sickness

-gradual changes in frewuency of disease over long periods of time. -ie) decrease in heart disease. from public health programs, awareness, food choices/ health care access

-unusual aggregation of health events grouped together in space and time 1. temporal clustering: time clustering. such as postpartum depression happens a few days after childbirth. 2. spatial clustering: concentration of disease in certain geographical area. people living close together all get same disease.