Evidence-based Public Health . . .and some reasons why we need it

Russell S. Kirby, PhD, MS, FACEProfessor and Vice Chair

Department of Maternal and Child HealthSchool of Public Health

University of Alabama at Birmingham

Objectives

Describe the evidence-based practice (EBP) paradigm

Identify key characteristics of evidence-based public health (EBPH)

Differentiate between EBP and EBPH Review several recent controversies and

their impact Speculate on the future uses of evidence

Brief Summary for Those Who Are Knitting, Doing Crossword Puzzles, or Discerning the Geometric

Pattern in the Carpeting Evidence-based public health is the leading edge of

modern public health practice. It requires the same level of diligence with understanding

principles of study design, sources of bias, internal and external generalizability, and research synthesis as is necessary in evidence-based practice.

Many of the necessary materials are ephemeral, but this is also true of clinical research due to the publication bias.

Several examples serve to show how this can work well, and . . . perhaps, not so well.

The Practice of Evidence-based Practice

“integrating individual clinical expertise with the best available external clinical evidence from systematic research”

individual clinical expertise: the proficiency and judgment acquired through experience and practice in clinical settings

external clinical evidence: clinically relevant research, from basic medical science and patient-centered clinical research

How Do We Practice EBP? EBP is a life-long process of self-directed learning, in which

caring for patients creates for the clinician a need for clinically important information about diagnosis, therapy, prognosis, and other clinical and health services issues. In this process, we:– Convert information needs into answerable questions

(testable hypotheses)– Track down the best evidence with which to answer them– Critically appraise the evidence for validity and usefulness– Apply the results of this appraisal in clinical practice– Evaluate performance

Why EBP? New types of evidence are being generated which, when

known and understood, have the potential to create frequent and major changes in the way we care for our patients

Although we need this evidence daily, we usually fail to get it Because of this, both our up-to-date knowledge and clinical

performance deteriorate over time Trying to remedy this personally through traditional CME/CEU

programs generally doesn’t improve clinical performance A different approach to clinical learning has been shown to

keep its practitioners up-to-date. EBP is that different approach.

Quality of EvidenceI: Evidence obtained from at least one properly randomized

controlled trial.

II-1: Evidence obtained from well-designed controlled trials without randomization.

II-2: Evidence obtained from well-designed cohort or case-control analytic studies, preferably from more than one center or research group.

II-3: Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled experiments (i.e. results of introduction of penicillin treatment in 1940s) could also be regarded as this type of evidence.

III: Opinions of well-respected authorities, based on clinical experience; descriptive studies and case reports; or reports of expert committees.

What is Evidence-based Public Health?

Develop an initialstatement of the issue

Quantify the issue

Search the scientific literature

and organize information Develop and

prioritize programoptions

Evaluate the program

or policy

Develop an action

plan and implement

interventions

ImplementRe-tool

Refine theissue

Tools: rates and risks,surveillance data

Tools: systematic reviews,risk assessment, economicdata

Sequential Framework for Enhancing Evidence-based Public Health

(Brownson, et al.)

Key Differences Between EBP and EBPH

Characteristic EBP EBPH

Quality of evidence Experimental Studies Observational and quasi- experimental studies

Volume of evidence Larger Smaller

Time from intervention Shorter Longer to outcome

Professional training More formal, with Less formal,certification/licensing no standard certification

Decision making Individual Team

Comparison of the Types of Scientific Evidence

Characteristic Type I Type II

Typical data/ Strength of preventable Relative effectiveness of

relationship risk-disease relationship public health intervention

Common setting Clinic or controlled Socially intact groups or

community setting community-wide

Quantity of evidence More Less

Action “Something should be done” “This should be done”

Types of evidence

Type I: ‘something should be done’– Analytic data on specific health condition

and its link to preventable risk factor(s)

Type II: ‘specifically, this should be done’– Focus on relative effectiveness of

specific interventions to address a particular health condition

The Realistic Evidence-Based Rating Scale

Class 0: Things I believe Class 0a:Things I believe despite the available data Class 1: Randomized controlled clinical trials that

agree with what I believe Class 2: Other prospectively collected data Class 3: Expert opinion Class 4: Randomized controlled clinical trials that

don’t agree with what I believe Class 5: What you believe that I don’t

Some examples

VBAC and Cesarean section Folic Acid and prevention of neural

tube defects Back to Sleep HRTs: the mystery continues

Trends in Cesarean Deliveries and VBACs, United States 1990-2002

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5.0

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25.0

30.0

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

Year

Per

cen

t o

f L

ive

Bir

ths

Total C- Section RatePrimary C-Section RateVBAC Rate

Trends

The velocity of the increase in the primary Cesarean section rate and the decline in VBAC rates in the recent past in the US is unprecedented.

In less than five years, more than ten years of increasing VBAC rates has disappeared.

Is this a good thing, or even a matter of concern?

Trends in Induction of Labor, United States, 1980-2002

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5.0

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20.0

25.0

1980 1985 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

Year

Pe

rce

nt

of

Liv

e B

irth

s/D

eli

ve

rie

s

Induction NHDSMedical Induction NHDS

Surgical Induction NHDSInduction-Birth Certificates

Trends

Rates of induction have increased dramatically across the nation.

There are differences based on data source, but no one can dispute the direction of the trend.

Let’s look at some specifics for Alabama:

Trends in Induction, C-Section, and VBAC, Alabama 1998-2002

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5

10

15

20

25

30

35

1998 1999 2000 2001 2002

Year

Per

cen

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C-Section RateVBAC Rate

Primary C-S RateRepeat C-S RateInduction %

Is this a public health concern? Con: public health does not focus on clinical

management of patients. That is in the responsibility of the health care system, peer review, quality compliance, and provider organizations.

Pro: Cesarean section is among the most common surgical procedures. It is more expensive per total hospital stay than vaginal delivery, and leads to more complications and re-hospitalizations.

Is this a public health concern?(continued)

The Public Health Service has established goals for the year 2010 promoting continued reduction in overall Cesarean section rates and increases in VBAC rates for the United States.– Objective 16-9a: Reduce C-S among low-risk

nulliparous women– Objective 16-9b: Reduce C-S among women with

prior Cesarean birth

Where do Alabama and Wisconsin fit in?

Historically, Wisconsin has had one of the lowest C-section rates in the US. Alabama, on the other hand, generally has one of the highest.

In 1960, the national rate was 4%, and from the 1970s on the C-section rate has tended to be 25-33% lower than the national rate.

Wisconsin has also been a leader in the use of vaginal birth after Cesarean section, while Alabama has been comparatively slow to adopt.

Total Cesarean Section Rate and VBAC Rateby Race of Mother, 2001

United States Compared to Wisconsin and Alabama

US

Rate Rate State Rank Rate State Rank

Total C-Section Rate 24.4 19.1 45th highest 27.6 4th highest

White Non-Hispanic 24.5 19.7 28.5 Black Non-Hispanic 25.9 16.9 26.8 Hispanic 23.6 18.4 21.5

VBAC Rate 16.4 23.0 43rd lowest 11.8 6th lowest White Non-Hispanic 16.8 22.3 11.0 Black Non-Hispanic 16.7 28.8 13.5 Hispanic 14.7 22.9 12.3

Wisconsin Alabama

Risk Factors Associated with Cesarean Delivery

Many patient, health care system, and physician characteristics are associated with higher or lower rates of Cesarean section.

A partial list includes maternal age (increased risk), parity (decreased risk), obesity and short stature (increased risk), estimated fetal weight > 4000g (increased risk), breech presentation (increased risk), delivery in teaching hospital (decreased risk), private insurance (increased risk), fear of malpractice suits (greatly increased risk).

Method of Delivery by Body Mass Index (BMI)Sinai Samaritan CNM Patients, 1994-1998

BMI Cesarean Vaginal Total

No. % No. % No. %

< 20 9 3.2 271 97.1 279 15

20 - 24.9 31 3.9 759 96.1 790 42

25 - 25.9 28 6.5 407 93.8 434 23

30 + 28 7.4 348 92.6 376 20

Total 96 5.1 1785 94.9 1881

Chi-Square (3 df) = 10.19, p<0.018

Adjusted Odds of Cesarean Delivery, SSMC CNM Patients, 1994-1998

Characteristic Odds Ratio 95 % C.I. p-valueObesity (BMI 30 +) 3.26 (1.60, 6.67) 0.0012Weight Gain > Recommended 2.09 (1.06, 4.11) 0.0326Short Stature (< 155 cm) 2.52 (1.12, 5.64) 0.0252No Previous Live Births 4.30 (1.78, 10.37) 0.0012Age 35 + 4.93 (1.08, 22.61) 0.0399Failure to Progress 60.42 (29.86, 122.24) 0.0001Breech Presentation 458.34 (133.74, 999) 0.0001

Placental Abruption 82.56 (19.00, 358.67) 0.0001

Fetal Distress 5.71 (2.58, 12.64) 0.0001

Severe Pre-eclampsia 8.68 (1.09, 69.20) 0.0412

Adjusted for race of mother (black), marital status, primigravidity and very low birth weight.

Clinical Documentation of Previous Cesarean Section

Most clinicians practice in settings that do not have comprehensive, unified clinical informatics applications.

In a patient who’s previous delivery was with another provider, how likely is it that the patient’s history will document the type of incision, the position of the uterine scar, whether single- or double-suturing was used, etc?