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Workshop Overview. Role of local health departmentsImportance of local dataEvidence-based public healthIntroduction to basic epidemiologic conceptsIntroduction to local data sources and overview of the reference guidesWhat's availableHow to use itAdvantages and limitations of these data sourc
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1. Data Tools for MCH Professionals:Introduction to Local Data Sources and Analytic Considerations Michael D. Kogan, PhD
Director, Office of Data and Program Development
US Dept of Health and Human Services
Health Resources and Services Administration
Maternal and Child Health Bureau
Laurin Kasehagen Robinson, PhD
Senior MCH Epidemiologist
CDC Assignee to CityMatCH
Adjunct Assistant Professor in Pediatrics
University of Nebraska Medical Center
2. Workshop Overview Role of local health departments
Importance of local data
Evidence-based public health
Introduction to basic epidemiologic concepts
Introduction to local data sources and overview of the reference guides
What’s available
How to use it
Advantages and limitations of these data sources
Hands-on case studies I and presentations
Break
Hands-on case studies II and presentations
Discussion
What was most useful?
What was missing?
3. Role of Local Health Departments Local health departments
play a key role in the provision of public health services to both rural and urban communities
are the closest source for information on and assistance with public health issues and concerns in a community
Serve 3 core functions
4. Core Function #1 Assess community problems, needs, and resources, through
Health needs assessments
Data
Surveillance
5. Core Function #2 Provide leadership in organizing strategies to address health problems, through
Programs designed to meet community needs
6. Core Function #3 Assure that direct services necessary for meeting local public health goals are available to all community residents, through
Community health services, including
Screenings
Education
Prevention
Outreach
7. Why is local data important? Essence of the importance of local level data summarized by Shah, Whitman & Silva in “Variations in the Health Conditions of 6 Chicago Community Areas: A Case for Local-Level Data”
“Variations in health measures identified at the local level shed light on the limitations of the existing city data often used in establishing public health policies and monitoring population health. . . . [Such] data are essential in identifying communities most at risk of poor health outcomes, exploring the determinants of such variations in health, and ultimately guiding community health programs and policies.”
8. Potential Limitations of / for Local Data Often limited to jurisdictions with populations of at least 100,000
Why? Issues of small numbers, accuracy and confidentiality
Sometimes limited because of relatively rare events
E.g., maternal mortality, autism, teen pregnancies, unintentional injuries
The data may not be current
Denominators may be based on the 2000 Census
City / County / MSA population may be based on 2000 Census
Data may not be collected at the household or city or county level Utility of instruments that gather data at micropolitan / local levels – generalizability, small numbers / few events, ability to analyze data for subsets of population (e.g., by age group, race / ethnicity, or some other characteristic)
Nevertheless, it is the local level data that is needed to further reduce / have an impact on disparities in health, wellnessUtility of instruments that gather data at micropolitan / local levels – generalizability, small numbers / few events, ability to analyze data for subsets of population (e.g., by age group, race / ethnicity, or some other characteristic)
Nevertheless, it is the local level data that is needed to further reduce / have an impact on disparities in health, wellness
9. Evidence-Based Public Health: Gathering and Using the Best Evidence for Local Data
10. Evidence-Based Medicine Health care practices based on review of current best evidence on the effectiveness of a test, drug, surgery or other medical practice
Collect and analyze all of the research studies conducted on a particular intervention
Evidence is then graded
Best evidence based on findings from clinical trials and meta-analysis
Weakest evidence based on case reports
11. Definition of Evidence-Based Public Health “EBPH is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of communities and populations in the domain of health protection, disease prevention, health maintenance and improvement.” Jenicek (1997) Key terms in this definition of EBPH are…
EXPLICIT: Use defined methods
JUDICIOUS: Use judgment
BEST EVIDENCE: Sort through the literature and identify what is useful
Key terms in this definition of EBPH are…
EXPLICIT: Use defined methods
JUDICIOUS: Use judgment
BEST EVIDENCE: Sort through the literature and identify what is useful
12. Differences between Public Health and Medicine
13. So what is “best evidence”?
14. Best Evidence Makes sense (it’s relevant)
Unbiased
Available
Statistically significant
Significant to public health
Leads to correct decisions
15. Evidence
16. Steps of Evidence-Based Public Health Develop an initial statement of the issue
Search the scientific literature and organize information
Quantify the issue using sources of existing data
Develop and prioritize program options; implement interventions
Evaluate the program or policy These are the steps of Evidence-Based Public Health (EBPH) as described by Brownson et al.
These are the steps of Evidence-Based Public Health (EBPH) as described by Brownson et al.
17. Different Sources of Evidence in Public Health: The Information Continuum
18. So why isn’t evidence-based decision-making used more often?
19. How are Decisions Often Made? Decisions on policies and programs are often made based on:
Personal experience
What we learned in formal training
What we heard at a conference
What a funding agency required / suggested
What others are doing
20. Evidence and Public Health Decision Making Good news
Strong evidence on the effect of many policies / programs aimed to improve public health, like immunizations or smoking cessation
Major efforts underway to assess the body of evidence for wide range of public health interventions, like the Cochrane Collaborative or the AMCHP Best Practices program
23. What Works to Improve the Public’s Health? Bad news
Many public health professionals are unaware of this evidence
Some who are aware don’t use it
Many existing disease control programs have interventions with insufficient evidence –while others use interventions with strong evidence of effectiveness
Lack of use of effective interventions can adversely affect fulfilling mission and getting public support
24. Evidence-Based Maternal and Child Health True or false?
For women who are experiencing problems with their pregnancy, bed rest is effective in preventing preterm labor.
25. Evidence-Based Maternal and Child Health FALSE!
Obstetric practices for which there is little evidence of effectiveness in preventing or treating preterm labor include bed rest. (Goldenberg, Obstetrics and Gynecology, 2002)
26. The True Story of the 3 Local MCH Departments and Governor Wolf’s Office
27. Once… …the office of Governor Wolf called up the first local MCH department and wanted to know the preterm birth rate for 2006 and 2007.
The local data staff ran to the computer and quickly calculated the number of preterm births divided by the number of normal gestational age births.
And proudly showed it to the Governor. And it was also the wrong denominator to begin with!And it was also the wrong denominator to begin with!
28. “That’s not a rate, that’s a ratio!!!” thundered Governor Wolf (who had a doctorate in epidemiology).
And he huffed and he puffed and he blew away 25% of their funding.
29. So, the office of Governor Wolf called up the second local MCH department and wanted to know the preterm birth rate for 2006 and 2007.
The local data staff ran to the computer and quickly calculated the number of preterm births divided by the total number of births.
And proudly showed it to the Governor.
30. “Great,” said the Gov, “is it the same in 2006 and 2007?”
“Oh, we’re not sure of the year” said the second local MCH staff.
“Then it’s not a rate, it’s a proportion!!!” thundered Governor Wolf.
And he huffed and he puffed and he blew away 35.8% of their funding.
31. And then, Governor Wolf called up the third local MCH department and wanted to know the preterm birth rate for 2006 and 2007.
The local data staff ran to the computer and quickly calculated the number of preterm births divided by the total number of births for each year.
And proudly showed them to the Governor.
32. “Great,” said the Gov, “is it the same in 2006 and 2007?”
“No, it was 12.8 per 100 live births in 2006, and 10.2 per 100 live births in 2007; a significant decline” said the third local MCH department staff.
“Excellent!!!” cried Governor Wolf.
33.
And he wiped out their funding altogether because of an immediate state budget crisis.
34. Was Governor Wolf correct? Or, would any of the local health department responses suffice? (or, was the Governor just throwing around his epidemiologic weight)
36. Measures of Disease Frequency
37. Counts Simplest, most frequently performed quantitative measure in epidemiology
Refer to the number of cases of disease, injury, events, or other health phenomenon being studied
Examples
No. of pregnant women who were screened for Hepatitis B during a prenatal care visit
No. of women who initiated breastfeeding in the U.S. in 2007
No. of newborns screened for genetic, metabolic, hormonal and/or functional conditions within 24-48 hours of birth
38. Why isn’t enumeration sufficient? Can’t / Don’t always detect ALL events
Census
Sample
How would you know whether the counts
Represent events that are big, small, a problem, important?
Represent phenomena common or unique to a population?
Change over time?
Are similar or different between 2 different populations?
39. Frequency Measures – Ratio, Proportion, Rate Characterize part of a distribution
Can be used to compare one part of a distribution to another part of a distribution
Contrast to measures of central tendency that provide single values that summarize entire distributions of data (e.g., mean, median, mode) Fractions are made up of two parts: Numerator is the upper portion of the fraction; Denominator is the lower portion of the fraction.
Fractions are made up of two parts: Numerator is the upper portion of the fraction; Denominator is the lower portion of the fraction.
40. What is a ratio? A fraction in which the numerator is NOT part of the denominator
Numerator and denominator need not be related
Limits -- 8 to 8
Result is often expressed as the “x”:1
E.g.,
male-to-female ratio
no. of controls to no. of cases
no. of LBW births to no. of violent crimes in a neighborhood
41. How to Calculate a Ratio Ratio = Number or rate of events, items, persons, etc. in one group
Number or rate of events, items, persons, etc. in another group Example:
Sex ratio – male live births to female live births
= 2,118,982 / 2,019,367
= 1.049:1 (or 1,049 male live births per 1,000 female live births)
42. What is a proportion? Compares a part to the whole
The numerator is ALWAYS part of the denominator
Type of ratio, “x/y”
May be expressed as a decimal, a fraction, or a percentage
Limits – 0 to 1
In epidemiology, tells us the fraction of the population that’s affected
E.g.,
proportion of children in a school vaccinated against measles
proportion of women in PRAMS who initiated breastfeeding
% of women who initiated PNC in the 1st trimester
43. How to Calculate a Proportion Proportion = Number of persons or events with a particular characteristic
Total number of persons or events of which the numerator
is a subset
44. What is a rate? A ratio that consists of a numerator and a denominator in which TIME forms a part of the denominator
Measures the frequency with which an event occurs in a defined population over a specified period of time
45. Properties and Uses of Rates Useful for putting disease frequency in the perspective of the size of the population
Can be used to compare among different groups of persons with potentially different sized populations (i.e., rate is a measure of risk)
Limits – 0 to 8
Can be expressed in any form that is convenient (e.g., per 1000, per 100,000, etc.)
46. How to Calculate a Rate Rate = No. of persons or events in a given time period
No. of persons or events in a reference population
(at mid-point of year or time period)
47. Are percentages ratios? Proportions? And/or Rates? Yes, Ratio – e.g., number of mothers in one group (e.g., 1st trimester) over the number of mothers in another group (e.g., all who had late or no PNC)
Yes, Proportion – e.g., the ratio of mothers in one group who are a subset of the other group
Perhaps, Rate – when percentages are a ratio that consists of a numerator and a denominator in which TIME forms a part of the denominator
48. Incidence Refers to the occurrence of new cases of disease, injury, attribute or events in a population over a specified period of time
Is a proportion, rate
Fundamental tool for exploring the etiology and causality of disease because new events provide estimates of risk of developing disease
Several types of incidence measures
Incidence proportion
Attack rates
Incidence rate
49. How to Calculate Incidence Proportion (Risk)
Incidence Number of NEW cases of disease, injury, events, or deaths
Proportion = during a specified period of time
_______________________________________________
Population at start of the specified period of time
50. Uses of Incidence Data Determining the extent of a disease or health problem in a community
Helping to determine etiology of disease because an estimate of risk of developing disease can be calculated
Identifying changes in disease over time
Comparing incidence rates in populations that differ in exposure – permits estimation of effects of exposure to a hypothesized factor of interest
51. Prevalence Refers to the number of persons in a population with a specified disease, injury or attribute or event at a specified point in time or over a specified period of time
Is a proportion, rate
Point prevalence
Measured at a particular point in time
Period prevalence
Measured over an interval of time
52. How to Calculate Prevalence Total number of persons with [NEW + PREEXISTING cases of
Prevalence disease] OR [attribute of interest] during a specified period of time
of Disease / = _________________________________________________________
an Attribute Population during the same specified period of time
53. Properties of Prevalence Data Prevalence and incidence are frequently confused . . .
Prevalence refers to the proportion of persons who have a condition at or during a specific period of time
Incidence refers to the proportion or rate of persons who develop a condition during a particular period of time
54. Uses of Prevalence Data Provides an indication of the extent of a health problem and may have implications for the scope of health services needed
Useful for
Describing the health burden of a population
Estimating frequency of an exposure
Allocating health resources
BUT, NOT for determining etiology
55. Measures of Association Quantify the relationship between exposure and disease among two groups of people within the same population or two different populations of people
Exposure is used loosely to mean inherent characteristics, biologic characteristics, acquired characteristics, activities, social or environmental conditions, etc.
Includes
Relative risk (risk ratio)
Rate ratio
Odds ratio
Proportionate mortality ratio
56. Relative Risk / Risk Ratio (RR) Compares the risk of a health event among one group with the risk among another group
The two groups are typically differentiated by demographic features or exposure to a suspected risk factor
Measure of association for cohort studies
When
RR = 1, same risk among the two groups
RR > 1, increased risk for the group in the numerator (usually the exposed group)
RR < 1, decreased risk for the group in the numerator (in some instances the exposure might be a protective factor)
57. Relative Risk of Hashimoto’s Thyroiditis
58. Rate Ratio Compares the incidence rates, person-time rates, or mortality rates of two groups
The two groups are typically differentiated by demographic features or exposure to a suspected risk factor
When
Rate ratio = 1, equal rates in the two groups
Rate ratio > 1, increased risk for the group in the numerator (usually the exposed group)
Rate ratio < 1, decreased risk for the group in the numerator (could indicate that the exposure is a protective factor)
59. Male:Female Rate Ratio of Syphillis
60. Odds Ratio (OR) Quantifies the relationship between an exposure with two categories and health outcome
Sometimes called the cross-product ratio
Measure of choice in case-control studies
Often, the size of the population from which the cases are identified is not known; thus, risks, rates, risk ratios, and rate ratios cannot be calculated
Odds ratios approximate risk ratios (relative risks), particularly when the disease or outcome is rare
When
Odds ratio = 1, equal rates in the two groups
Odds ratio > 1, increased risk for the exposed group
Odds ratio < 1, decreased risk for the unexposed group
61. Odds Ratios of Self-Reported Severity of Asthma Symptoms
62. Measures of Natality
63. Measures of Morbidity
64. Measures of Mortality A pregnancy-associated death is the death of any woman, from any cause, while pregnant or within 1 calendar year of termination of pregnancy, regardless of the duration
and the site of pregnancy.
A pregnancy-related death is a pregnancy-associated death resulting from 1) complications of the pregnancy itself, 2) the chain of events initiated by the pregnancy that led to death, or 3) aggravation of an unrelated condition by the physiologic or pharmacologic effects of the pregnancy that subsequently caused death.
See CDC’s “Structure of Pregnancy-Related Mortality”A pregnancy-associated death is the death of any woman, from any cause, while pregnant or within 1 calendar year of termination of pregnancy, regardless of the duration
and the site of pregnancy.
A pregnancy-related death is a pregnancy-associated death resulting from 1) complications of the pregnancy itself, 2) the chain of events initiated by the pregnancy that led to death, or 3) aggravation of an unrelated condition by the physiologic or pharmacologic effects of the pregnancy that subsequently caused death.
See CDC’s “Structure of Pregnancy-Related Mortality”
65. Measures of Public Health Impact Used to place the association between an exposure and an outcome into a meaningful public health context
Reflect the burden that an exposure contributes to the frequency of disease in a population
Contrasts with measures of association, which quantify the relationships between exposures and diseases and provide insight to causal relationships
Includes
Attributable proportion
Efficacy
Effectiveness Efficacy NE Effectiveness
Efficacy = indicates that the therapeutic effect of a given intervention (e.g. intake of a medicine, an operation, or a public health measure) is acceptable. 'Acceptable' in that context refers to a consensus that it is at least as good as other available interventions to which it will have ideally been compared to in a clinical trial. In strict epidemiological language, 'efficacy' refers to the impact of an intervention in a clinical trial, differing from 'effectiveness' which refers to the impact in real world situations.
Effectiveness = ability to cause the expected or intended effect or result. The word effective is sometimes used in a quantitative way, "being very or not much effective". However it does not inform on the direction (positive or negative) and the comparison to a standard of the given effect. Efficacy, on the other hand, is the ability to produce a desired amount of the desired effect, or success in achieving a given goal. Contrary to efficiency, the focus of efficacy is the achievement as such, not the resources spent in achieving the desired effect. Therefore, what is effective is not necessarily efficacious, and what is efficacious is not necessarily efficient.
Efficacy NE Effectiveness
Efficacy = indicates that the therapeutic effect of a given intervention (e.g. intake of a medicine, an operation, or a public health measure) is acceptable. 'Acceptable' in that context refers to a consensus that it is at least as good as other available interventions to which it will have ideally been compared to in a clinical trial. In strict epidemiological language, 'efficacy' refers to the impact of an intervention in a clinical trial, differing from 'effectiveness' which refers to the impact in real world situations.
Effectiveness = ability to cause the expected or intended effect or result. The word effective is sometimes used in a quantitative way, "being very or not much effective". However it does not inform on the direction (positive or negative) and the comparison to a standard of the given effect. Efficacy, on the other hand, is the ability to produce a desired amount of the desired effect, or success in achieving a given goal. Contrary to efficiency, the focus of efficacy is the achievement as such, not the resources spent in achieving the desired effect. Therefore, what is effective is not necessarily efficacious, and what is efficacious is not necessarily efficient.
66. Measures of Spread Standard deviation
Conveys how widely or tightly the observations are distributed from the center point or values
Measure of spread used most commonly with the mean
Usually calculated only when the data are more or less normally distributed Dark blue is less than one standard deviation from the mean. For the normal distribution, this accounts for about 68% of the set (dark blue) while two standard deviations from the mean (medium and dark blue) account for about 95% and three standard deviations (light, medium, and dark blue) account for about 99.7%. Dark blue is less than one standard deviation from the mean. For the normal distribution, this accounts for about 68% of the set (dark blue) while two standard deviations from the mean (medium and dark blue) account for about 95% and three standard deviations (light, medium, and dark blue) account for about 99.7%.
67. Standard Error of the Mean Refers to the variability that could be expected in the means of repeated samples taken from the same population
Assumes sample comes from a large population
Sample of interest is just one of an infinite number of possible samples
The mean is just one of an infinite number of sample means
Standard error quantifies the variation observed in the sample means
Primary use of standard error is in calculating confidence intervals around the mean
SE = std dev
vn
68. Confidence Intervals Common method for indicating a measurement’s precision
Narrow interval = high precision
Wide interval = low precision
Represents the range of values consistent with the data from a study . . . Simply a guide to the variability in a study
Confidence intervals can be calculated for some, but not all, epidemiologic measures . . . Regardless of measure, the interpretation is the same
Means
Geometric means
Proportions
Risk ratios
Odds ratios
69. Some Methods to Compare Differences between Groups Rate ratios
Used to compare rates for 2 populations
Simply the ratio of 2 rates
Note: the multiplier must be the same for both rates
Relative percent difference (RPD)
Another method for comparing differences between 2 groups using prevalence
70. Prevalence of Diabetes and Relative Percent Difference RPD between the rate of diabetes in Hispanics and non-Hispanic white women Mention confidence intervalsMention confidence intervals
71. Assessing Trends Trend = long-term movement in an ordered series
Can be used to assess the overall pattern of change of an indicator, geographic areas, time periods, populations
Can be influenced by small numbers, changes in how data collected / defined
Can minimize effect by “smoothing” data via 3-year moving averages or data transformation (natural log scale)
Also can be used loosely to refer to an association which is consistent between 2 sets of data or strata, but not necessarily statistically significant Can test for difference between trends using a chi-square test for trend or regression analysesCan test for difference between trends using a chi-square test for trend or regression analyses
72. How to Judge / Evaluate Data Sources Timeliness
Geographic specificity
Specificity of demographic data
Data consistency and standardization
Availability over time
Ability to identify individuals / events
Adequate sample size
Sample validity
Primary data collection potential
73. Caveats Caveat . . . unique data sources
Not necessarily an abundance for local data, but may be packaged or presented in different ways
Some states try to ensure that data are available at county level
A number of websites that catalog or compile links to data sources, e.g.,
California – UCSF Family Health Outcomes Project -- http://familymedicine.medschool.ucsf.edu/fhop/htm/ca_mcah/index.htm
Texas – UT School of Public Health -- http://www.sph.uth.tmc.edu/charting/
74. Next Steps in this Workshop What you have in hard copy and on disk
Source descriptions
Source quick reference guide
Case studies
Case studies “cheat sheet”
Copy of this presentation
Let’s take a look and GET STARTED!
75. Acknowledgments Belovich-Faust and Ligi. Role of the Local Health Dept., Bethlehem, PA Health Dept.
Shah, Whitman & Silva. Variations in the Health Conditions of 6 Chicago Community Areas: A Case for Local-Level Data. Am J Public Health 96(8): 1485-91 (2006).
Jenicek. Epidemiology, Evidence-Based Medicine, and Evidence-Based Public Health. J Epidemiol 7:187-97 (1997).
Brownson, et al. Evidence-Based Decision-Making in Public Health. J Public Health Manag Prac 5:86-87 (1999).
Goldenberg. The Management of Preterm Labor. Obstetrics and Gynecology 100(5 Pt 1):1020-37 (2002).
Lewis. Moneyball, 2003.
76. Contact Information & Copies of Workshop Training Materials Laurin Kasehagen Robinson, PhD, MA
CityMatCH
Senior MCH Epidemiologist / CDC Assignee to CityMatCH
Adjunct Asst Professor in Pediatrics
University of Nebraska Medical Center, Department of Pediatrics
982170 Nebraska Medical Center
Omaha, NE 68198-2170
402-561-7523
lkasehagen@unmc.edu Michael D. Kogan, PhD
HRSA/MCHB
Director, Office of Data and Program Development
5600 Fishers Lane, Room 18-41
Rockville, MD 20857
301-443-3145
mkogan@hrsa.gov