Descriptive Epidemiology PDF

DESCRIPTIVE EPIDEMIOLOGY: PATTERNS OF DISEASE—PERSON, PLACE, TIME  LEARNING OBJECTIVES Define the term descriptive epidemiology one of two main branches of epidemiology Compare and Contrast the types of descriptive epidemiologic studies and their uses Describe the process of ep...

DESCRIPTIVE EPIDEMIOLOGY: PATTERNS OF DISEASE—PERSON, PLACE, TIME  LEARNING OBJECTIVES Define the term descriptive epidemiology one of two main branches of epidemiology Compare and Contrast the types of descriptive epidemiologic studies and their uses Describe the process of epidemiologic inference in the context of descriptive epidemiology Give examples each of person, place, and time variables and describe how they relate to the distribution of health outcomes  DEFINITION: DESCRIPTIVE EPIDEMIOLOGY The field of descriptive epidemiology classifies the occurrence of disease according to the following variables: ─ person (who is affected) ─ place (where the condition occurs) ─ time (when and over what time period the condition has occurred) DESCRIPTIVE EPIDEMIOLOGIC STUDY A descriptive epidemiologic study is one that is...concerned with characterizing the amount and distribution of health and disease within a population.  DESCRIPTIVE EPIDEMIOLOGY Provides valuable information for the following activities: 1. Prevention of disease 2. Design of interventions 3. Conduct of additional research (Analytic studies: case control, cohort)  APPLY IT! EXCLUSIVE BREASTFEEDING  American Academy of Pediatrics and the WHO policy to support continued breastfeeding, along with appropriate complementary foods introduced at about 6 months, as long as mutually desired for 2 years or beyond. American Academy of Pediatrics, 2022 2 year old Under 6mo breastfeeding breastfeeding  CHILD HEALTH BENEFITS OF BREASTFEEDING  Infectious Disease  Decreases the incidence and/or severity of: bacterial meningitis, bacteremia, diarrhea, respiratory tract infection necrotizing enterocolitis, otitis media, urinary tract infection, and late-onset sepsis in preterm infants. And post-neonatal infant mortality rates in the United States are reduced by 21%  Decreased rates of sudden infant death syndrome in the first year of life and reduction in incidence of insulin-dependent (type 1) and non–insulin-dependent (type 2) diabetes mellitus, lymphoma, leukemia, and Hodgkin overweight and obesity, hypercholesterolemia, and asthma in older children and adults who were breastfed, compared with individuals who were not breastfed. American Academy of Pediatrics, 2012  MATERNAL HEALTH BENEFITS OF BREASTFEEDING  The benefits include decreased postpartum bleeding and more rapid uterine involution attributable to increased concentrations of oxytocin, decreased menstrual blood loss and increased child spacing attributable to lactational amenorrhea, earlier return to pre-pregnancy weight, decreased risk of breast cancer, decreased risk of ovarian cancer, decreased type 2 diabetes, hypertension, and possibly decreased risk of hip fractures and osteoporosis in the postmenopausal period. American Academy of Pediatrics, 2012 EXAMPLE OF A DESCRIPTIVE EPIDEMIOLOGIC STUDY U.S. infants born in 2018 who were breastfed: ─ Although 83.9% of children were exclusively breastfed at 2 days, this figure dropped to 46.3% at 3 months and 25.8% at 6 months ─ About 56.7% were breastfed through the age of six months and 35.0% at 12 months. ─ From descriptive information, hypotheses for interventions to increase breastfeeding can be derived.  Breastfeeding rates by race and ethnicity 2018. Centers for Disease Control and Prevention, Department of Health and Human Services, National Immunization Survey (2021). THINGS WE KNOW ABOUT BREASTFEEDING  Low-income women breastfed less often than women from higher income levels.  Breastfeeding study showed the race, age and marital status all impacted if they breastfeed  Other factors that influenced breastfeeding early on: delivery mode (c-section vs natural), duration of labor, labor medications, use of non-breast milk fluids and/or pacifiers, maternal overweight all decreased successful breastfeeding. USES OF DESCRIPTIVE EPIDEMIOLOGIC Permit evaluation ofSTUDIES trends in health and disease Provide a basis for planning, provision, and evaluation of health services Identify problems to be studied by analytic methods and suggest areas that may be fruitful for investigation TYPES OF DESCRIPTIVE EPIDEMIOLOGIC STUDIES Case reports Case series Cross-sectional studies  CASE REPORTS (CASE STUDIES)  Accounts of a single occurrence of a noteworthy health-related incident or of a small collection of such events  Tracks people with a known exposure or looks back via medical records for a common exposure and health outcome.  Can be prospective or retrospective studies  Retrospective- Looking back at events that have already taken place. Criteria are established for selecting cases from historical records for inclusion in the study.  Prospective- Looking forward at events that are likely to occur in the future. Criteria are established and cases EXAMPLE CASE REPORTS  Example: Adverse reactions due to cosmetic surgery in the United States  Case 1. On 12-8-20, a 42 yr woman received soft tissue filler in her buttocks at facility A. Within 30 mins, she noted her urine looked like purple blood. Acute renal failure and 10 days in the hospital.  Case 2. One 12-8-20, a 26 yr woman received soft tissue filler in her buttocks at Facility A. She had acute renal failure and required at 13 day hospital stay and 5 wks of hemodialysis.  Case 3. On 12-8-20, 26 yr woman received soft tissue filler injection in her buttocks…..became ill… 2 weeks in hospital and hemodialysis.  CASE SERIES  In comparison with a case report, a case series is a larger collection of cases of disease, often grouped consecutively and listing common features, e.g. characteristics of affected patients.  Example: reported cases of primary amebic meningoencephalitis (154 cases reported between 1962 and 2021). Common features include: 76.6% male, median age 11, common recent exposure to fresh warm untreated water. Naegleria floleri N=157; Year of exposure unknown for one case  CROSS-SECTIONAL STUDIES  A type of investigation …that examines the relationship between diseases (or other health-related characteristics) and other variables of interest as they exist in a defined population at one particular time.  A type of prevalence study  Example: the Behavioral Risk Factor Surveillance System (BRFSS)  State survey, collects data on related risk behaviors and chronic disease risk factors collected by a phone survey  EPIDEMIOLOGIC INFERENCES FROM DESCRIPTIVE DATA Descriptive epidemiology and descriptive studies provide a basis for generating hypotheses. Descriptive epidemiologic studies connect intimately with the process of epidemiologic inference. Epidemiologic inference is initiated with descriptive observations.  PERSON VARIABLES: EXAMPLES Age Marital Status Sex Nativity (place of Race/Ethnicity origin) Socioeconomic Migration Status Religion AGE  Perhaps the most important factor to consider when describing occurrence of disease or illness  Age-specific disease rates usually show greater variation than rates defined by almost any other personal attribute.  EXAMPLES OF AGE ASSOCIATIONS  The incidence of and mortality from chronic diseases increase with age.  Some infections, e.g., mumps and chickenpox occur more commonly during childhood.  The leading cause of death among young adults is unintentional injuries.  Maternal age is associated with rates of diabetes and related complications.  SEX  Epidemiologic studies have shown sex differences in a wide scope of health phenomena including morbidity and mortality.  Examples:  All cause age-specific mortality rates higher among males  Differences in cancer rates, e.g., cancers of the genital system RACE/ETHNICITY  Five major race categories in Census 2020:  White  Black or African American  American Indian and Alaska Native  Asian  Native Hawaiian and other Pacific Islander  Ethnicity- Non-Hispanic or Hispanic  Since the 2000 census respondents could check a multiracial category 1. White alone non-Hispanic population at 57.8% 2. Hispanic or Latino population at 18.7% 3. Black or African American alone non-Hispanic population at 12.1%  RACE/ETHNICITY: OTHER CONSIDERATIONS  Somewhat ambiguous classification  Tends to overlap with nativity and religion  Some scientists propose that it is a social construct rather than a biological construct  Used to track various health outcomes  NATIVITY  Place of origin of the individual or his or her relatives  Subdivisions include:  Foreign-born  Native-born RACE/ETHNICITY (CONT.)  Examples of racial/ethnic differences in health characteristics include the following:  Lower frequency of asthma reported among Hispanics.  Incidence of gonorrhea is higher among non-Hispanic blacks than other groups. Humanterific  SOCIOECONOMIC STATUS (SES)  Defined as a “Descriptive term for a person’s position in society,…”  Often formulated as a composite measure of the following dimensions:  A person’s income level  Education level  Type of occupation  A single dimension of SES (e.g., poverty level) may be used SOCIOECONOMIC STATUS (SES) (CONT.) The social class gradient  Strong, inverse association of SES with levels of morbidity and mortality  Those in lowest SES positions are confronted with excesses of morbidity and mortality from numerous causes. PERCENTAGE OF ADULTS AGED 18−64 WITH A DENTAL VISIT IN THE PAST 12 MONTHS, BY URBANICITY AND FAMILY INCOME AS A PERCENTAGE OF THE FEDERAL POVERTY LEVEL: UNITED STATES, 2019  DEFINITION: HEALTH DISPARITIES Differences in the occurrence of diseases and adverse health conditions in the population ─ Example: cancer health disparities— “…adverse differences in cancer incidence (new cases), cancer prevalence (all existing cases), cancer death (mortality), cancer survivorship, and burden of cancer or related health conditions that exist among specific population groups in the United States.” ─ African Americans (in comparison with other groups) have the highest age-adjusted overall cancer incidence and death rates.  PLACE VARIABLES Morbidity and mortality vary greatly with respect to place. International National (within- country) Urban-rural differences Localized patterns of disease Map of the world by population density  INTERNATIONAL VARIABLES  World Health Organization (WHO) studies:  Both infectious and chronic diseases show great variation from one country to another.  Climate, cultural factors, national dietary habits, and access to health care affect disease occurrence.  Variations in life expectancy (U.S. ranked number 40 in 2021).  NATIONAL (WITHIN-COUNTRY)  Regional differences may affect the prevalence and incidence of disease.  Factors include:  Climate  Latitude  Environmental pollution  Example: Regional variations by state LIFE EXPECTANCY FROM BIRTH BY STATE IN YEARS, 2019 Seattle Times https://www.seattletimes.com/seattle-news/health/one-of-the-best-place-to-grow-old-washington-has-8th-highest-life-expectancy-in-u-s-study-finds/  URBAN-RURAL DIFFERENCES  Urban and rural sections of the United States show variations in morbidity and mortality related to environmental and lifestyle issues.  Urban example: elevated occurrence of lead poisoning among children who live in older buildings.  Rural example: pesticide exposure and farming injuries among agricultural workers. LOCALIZED PATTERNS OF DISEASE  Associated with specific environmental conditions that may exist in a particular geographic area. Examples:  Cancer and radon gas  Naturally occurring arsenic in water supply  Presence of disease vectors Radon is a naturally occurring radioactive gas and comes from the natural breakdown (radioactive decay) of uranium TIME VARIABLES Secular trends Cyclic (seasonal) trends Point epidemics Clustering SECULAR TRENDS Refer to gradual changes in the frequency of disease over long time periods. Examples: ─Yearly suicide rates of U.S. females— firearm-associated suicides decreased, but those by hanging increased. ─Age-adjusted prevalence of hypertension (no secular trend shown). TREND OF SUICIDE MORTALITY AMONG US WHITES BY GENDER AND METHODS, 15-84 YEARS OF AGE, 1999-2017 By Bin Yu, MD  CYCLIC (SEASONAL) TRENDS Cyclic trends are increases and decreases in the frequency of a disease or other phenomenon over a period of several years or within a year.  POINT SOURCE EPIDEMICS A point epidemic may indicate the response of a group of people circumscribed in place to a common source of infection, contamination, or other etiologic factor to which they were exposed almost simultaneously. ─ Example:outbreak of Vibrio infections following Hurricane Katrina in 2005 CLUSTERING A closely grouped series of events or cases of a disease or other health-related phenomena with well-defined distribution patterns in relation to time or place or both. They are suspected to be greater than the number expected but may not be known.  CLUSTERING (CONT.) Often used to describe aggregation of uncommon conditions such as leukemia or cancer. Clustering may reflect: ─ Common exposure to an etiologic agent ─ Chance occurrences Spatial clustering—refers to aggregation of events in a geographic region. Temporal clustering—denotes the occurrence of events related to time. NUMBER OF POSTVACCINATION SYNCOPE EPISODES REPORTED TO THE VACCINE ADVERSE EVENT REPORTING SYSTEM, BY MONTH AND YEAR OF REPORT - UNITED STATES, JANUARY 1, 2004-JULY 31, 2007. DESCRIPTIVE EPIDEMIOLOGY  Descriptive epidemiology is one of the two areas of epidemiological studies. It determinates the patterns of disease occurrence, focusing on clinical information, person, place, and time.  Uses demographic information, including age, sex, material status, personal habits. Uses socioeconomic information such as education, occupation, income, residence, and place of work. Also, uses cultural information, including ethnicity, dietary habits, and religious preferences to determine to demonstrate what has an effect on disease.  Descriptive epidemiologists collect relatively accessible data used for program planning, generating hypotheses, and suggesting ideas for further studies QUESTIONS?