Human rights

I like this analogy: "But to understand public health only in these terms is similar to understanding marine biology in terms of shells on the shore."

They've named a lot of things that public health is responsible for, yet those things they have listed seem as different from one another as the different shells you can find on the beach.

Can you see what all of these activities have in common, to make up a cohesive discipline called "public health"?

Let's see how they develop this point.

Shifting Priorities, Multiple Disciplines, Various Roles

Apart from limited exposure to the public health system, the discipline of public health can be difficult to grasp, in part because the focus of public health action has evolved over the past two centuries. This is because the activities of public health are primarily driven by its goal—to improve health and prevent disease, injury, and disability. Thus, as threats to human health vary with time and geography, so too do specific public health projects and efforts. For example, during the 18th and 19th centuries, yellow fever was a great scourge in America. In Philadelphia in 1793, for example, yellow fever killed 5,000 people in only three months—roughly 10 percent of the population.⁵ Today, this disease is essentially unknown in the United States, and it is not a current focus of public health action.

This clarifies the point to a degree: "[Public health's goal is] to improve health and prevent disease, injury, and disability. Thus, as threats to human health vary with time and geography, so too do specific public health projects and efforts."

That's what all these things have in common, and how they fit into the vision of healthy people in healthy communities. We specialize in musculoskeletal issues, for example, and infectious-disease specialists concentrate on communicable diseases, oncologists specialize in cancer, and so forth.

Public health's priorities, on the other hand, are driven by the needs of the particular community in question.

Occupational public health might have repetitive musculoskeletal injuries in assembly-line workers as a focus in one community.

In a different place, the spread of an infectious disease like whooping cough or hantavirus might be that community's highest health threat at a particular time, much as yellow fever used to be in 18th-century Philadelphia.

Yet another community may have much higher-than-expected cancer rates, and that might be the public health workers' focus as they try to figure out why that is, and what can be done to address the risk there.

So while we and other individual practitioners have particular specialties that we focus on, public health's priorities for focus is driven by the immediate needs of the community in question.

As progress was made against infectious diseases in the 20th century, the public health community expanded its focus to include other threats to human health (e.g., occupational illnesses, motor vehicle injuries, chronic diseases, exposures to toxic waste and other environmental hazards, interpersonal violence, and suicide).^3,4 Of course, new or reemerging infectious disease threats (e.g., AIDS, hantavirus, and drug-resistant tuberculosis) continue to command the attention of public health officials.

Another aspect of public health that makes the concept hard to grasp derives from its varying interventions, which have involved diverse professional disciplines. Many activities—like road and building design, toxic waste disposal, water treatment, school safety, immigrant health, protection of the food supply, even municipal design to promote healthy lifestyles—have been key to promoting health and preventing disease and injury. In addition to nurses, physicians, epidemiologists, and statisticians, the public health system also relies on engineers, social workers, outreach workers, laboratory workers, health communication specialists, sanitarians, environmental specialists, nutritionists, lawyers, legislators, and others to apply efforts that promote health and prevent disease. The public health system comprises allied government, community, professional, voluntary, and academic institutions and organizations that might not be officially termed (or consider themselves) public health agencies. In this paper, we focus on governmental public health agencies.

Finally, public health as a discipline encompasses an amalgam of science, action, research, policy, advocacy, and government. Public health practitioners play each of these roles at different times, but as a professional discipline, public health is not adequately described by any one of them. If public health were simply a scientific enterprise, government function, or any one of the elements listed previously, the concept would be easier to grasp. But public health professionals do wear distinct hats according to the nature of the various threats to community health, the political and social context of the community, and the often incomplete scientific knowledge regarding available preventive interventions. This also makes understanding the extent and nature of public health as a discipline difficult.

The take-home point from this section is that when a focus is driven by a goal such as immediate health needs of a community, that goal is so open-ended and flexible that a variety of approaches and specialties are needed to address that goal.

So what role(s) might massage play in promoting healthy communities and healthy people? That's something to give serious consideration to, but not because it's so hard to fit massage in--it's not at all hard to envision multiple ways that massage could work with public health realize our commitment to wellness.

The real question is, with so many possibilities that can be imagined, where to start?

Coming up with specifics and prioritizing them would be a good next step. At the  May 2010 Seattle conference on Massage Therapy in Complementary and Integrative Medicine, there was a panel discussion: "The Role of Massage Therapy in Public Health". William Meeker, DC, MPH served as moderator, and the panel included Marissa Brooks, MPH, LMP; Cynthia Price, PhD, LMP; Deborah Senn, former Washington state Insurance Commissioner; and John Weeks, executive director of the Academic Consortium for Complementary and Alternative Health Care.

I've written to the Massage Therapy Foundation, who organized and put on the conference, to ask whether the video or proceedings from the panel are available. If they are, I will pass along the links so that you can see what points were raised in the discussion.

In addition, the problem of having to work in the here and now with incomplete scientific knowledge--of not being able to afford to wait until all the evidence is in, because people need relief right now--is certainly a familiar one to us, as well.

Defining Principles and Core Functions of Public Health

Although the focus of public health action and the nature of public health interventions continue to evolve, the fundamental principles of public health remain clear and stable. We previously stated four principles that define, guide, and provide the context for the types of activities and challenges that are undertaken in furtherance of public health.¹ These principles derive from the scope and nature of public health itself and tend to distinguish public health from medicine and health care. These four principles can be useful as a guide to those attempting to understand public health.

• The primary focus of public health is to promote the health of populations and not the health of specific individuals.

With these four principles as guides, public health can be further defined and understood in terms of its core functions. In 1988, the Institute of Medicine (IOM) published The Future of Public Health,⁶ in which it articulated three activities that ideally comprise the core functions of an effective public health system—assessment, policy development, and assurance. The first core function refers to the assessment and monitoring of the health of communities and populations at risk, to identify health problems and priorities. Policy development involves formulating public policies, in collaboration with community and government leaders, that are designed to solve identified health problems. Assurance refers to the responsibility of the public health system to ensure that all populations have access to appropriate and cost-effective care, including health promotion and disease prevention services, and evaluation of the effectiveness of that care.

These points could be relevant to MT in the following ways, among other possibilities:

• assessment: looking out for, and being able to recognize, problems in a community or a population. This point needs further exploration on how assessment systems in an MT's community can be relevant to the MT, and how the MT can support the system in promoting community health.
• policy development: What are the identified health problems in our communities, and how can MTs participate in plans to address them?
• assurance: What is MT doing to ensure that all populations have access to the care we offer? How do we evaluate the effectiveness of what we do, and how do we work to increase that effectiveness?

Information is central to each of these core functions. For example, the essence of community health assessment is the collection, analysis, interpretation, and communication of data and information. Timely and authoritative information is also central to the informed development of public health policy. Finally, the assurance function described in the IOM report moves public health away from “clinical care provider of last resort” toward the role of monitor and communicator of information about community access to critical health services. Thus, each of these core functions accentuates the importance of public health as information broker, directly underscoring the need for public health officials to be effective planners, developers, and users of health information systems.

Another way of describing epidemiology is the study of health-related patterns in populations. Epidemiologists study what diseases occur in particular populations, and they look for cause-and-effect explanations why this particular condition is an issue for this particular population at this particular time and place.

For example, in the early 1980s, it was observed that numerous young gay men of all ethicities were showing up in physicians' offices with symptoms of Kaposi's sarcoma, a particular kind of tumor of connective tissue that previously had primarily been observed only occasionally, and typically in middle-aged men of Mediterranean, Southern European, and Jewish ancestry.

Source: http://upload.wikimedia.org/wikipedia/commons/3/3c/Kaposi%27s_Sarcoma.jpg accessed 2 July 2012

In trying to understand why the patterns of this disease had changed so dramatically, epidemiologists were a major part of the team that eventually discovered how the previously-unknown HIV/AIDS virus was causing such devastation in the community.

Other epidemiologists work on issues such as figuring out whether cancer clusters are occurring in particular neighborhoods (and--if-so--then why), or what it causing increases in infectious-disease incidence in certain regions, and similar pattern observation and figuring out the problem behind the pattern.

In the 1990s, as this newspaper article from the Spokane (Washington) Spokesman-Review describes, national attention was focused on why the small Western Washington Shoalwater Bay Tribe was suffering such a disproportionately high rate of miscarriage. The paper reports that "Out of 13 pregnancies in 1997 and 1998, only one Shoalwater baby is alive today [Jun 15, 1999].".

Source: Google news search, http://news.google.com/newspapers?nid=1314&dat=19990615&id=Io9XAAAAIBAJ&sjid=GvIDAAAAIBAJ&pg=5918,5084426 accessed 2 July 2012

The individual anguish to families that each of these miscarriages caused, and which is part of the issues that an individual clinician would work with those families about, is compounded by fears of the tribe going extinct, of environmental pesticides or other toxins that may be silently poisoning the community, of the effects that poverty, isolation, and health sequelae caused by socioeconomic status, as well as by many other issues.

That's what I was referring to earlier when I mentioned that the whole is often more than the sum of its parts. Certainly, 12 miscarriages out of 13 pregnancies are 12 family tragedies--there is no doubt about that. But, even more than that foundation, the community issues surrounding the complex causes and meaning of the deaths are what make it a community public health issue.

And trying--not always succeeding--to figure out what's going on, what pattern we are seeing, what meaning the pattern has, and what is causing the pattern is a job that falls, in large part, to epidemiologists.

In the case study in this article, the epidemiologists are trying to figure out a pattern of neural tube defects, another kind of tragedy that strikes developing fetuses, their mothers and fathers, and their entire families.

Before we continue, though, so that I don't leave you wondering what ultimately happened in the Shoalwater Bay Tribe, I found this update in the obituary of Herbert Whitish, the chairman of the tribe, who died in 2005.

Herbert "Ike" Whitish, 1955-2005: Native leader led Shoalwater Bay Tribe through crisis

By Paul Shukovsky, Seattle Post-Intelligencer Reporter

Published 10:00 p.m., Thursday, September 8, 2005

A Native American leader who played a central role in saving a tiny southwest Washington tribe from extinction has died after a lengthy illness. He was 50.

Herbert "Ike" Whitish grew up in Seattle before returning home and ultimately becoming chairman of his beloved Shoalwater Bay Tribe when it needed him the most. In the 1990s, the tribe's babies began dying, and no one knew why.

Always outspoken, Whitish used blunt language and media savvy to bring his tribe's troubles to the attention of the nation. Stories about the mysterious scourge of miscarriages, stillbirths and infant deaths ran in newspapers and on television stations across the country in the 1990s.

Whitish gave access to reporters who were specific in describing the tragedy engulfing the tiny tribe, which had about 200 members in the late 1990s. Whitish parlayed the attention into mobilizing politicians and government health officials, who sent in elite epidemiological teams from the U.S. Centers for Disease Control and Prevention to investigate.

No cause was ever uncovered, but Whitish prevailed on Congress to pay for a health care clinic and comprehensive program for pregnant women at the tribe's isolated reservation on the north end of Willapa Bay.

"He led his tribe through the crisis," said Kathy Spoor, Pacific County's public health director. "Through his efforts to assure better health care access and support services for his people, the situation has improved."

Spoor said the outcomes of pregnancies at the Shoalwater Bay reservation have been running at normal levels for at least the past two years.

...

So now that we have a clearer idea of what epidemiologists do, lets get back to the case report in this article.

The article assumes that we're all on the same page regarding our understanding of neural tube defects; let's briefly sum it up to make sure that that assumption will carry us through the rest of the article.

Neural tube defects (NTDs) are one of the most common birth defects, occurring in approximately one in 1,000 live births in the United States. An NTD is an opening in the spinal cord or brain that occurs very early in human development. In the 3rd week of pregnancy called gastrulation, specialized cells on the dorsal side of the fetus begin to fuse and form the neural tube. When the neural tube does not close completely, an NTD develops.

--Wikipedia: "Neural tube defect" accessed 2 July 2010

Take-home points:

• a neural-tube defect (NTD) is a birth defect;
• in the US, approximately one in every 1000 babies born alive will have some form of NTD;
• NTDs occur when parts of the brain or spinal cord do not completely close as part of normal development, so that part of the baby's central nervous system is left open and exposed to the environment.

A severe NTD can be a life-threatening event, but mild or moderate NTDs can be repaired or managed.

Wikipedia lists a number of famous people who were born with spina bifida (one of the kinds of NTD that we will discuss in a bit); the ones I had heard of include musicians John Mellencamp, Lucinda Williams, and Hank Williams. They also list Karin Muraszko as the chair of the Department of Neurosurgery at University of Michigan, first female appointed to such a position in the US--evidence that being born with spina bifida is not necessarily an obstacle to succeeding at a demanding medical career.

That level of knowledge is enough for us to pick up reading the article and its discussion of the public health approach to NTDs.

Public Health Approach to a Problem

The public health approach to a problem is illustrated in Figure 1. Public health surveillance is defined generally as the ongoing systematic collection, analysis, and interpretation of health-related data for use in planning, implementing, and evaluating public health practice.^13,14 Surveillance is a key data-driven activity of public health and is crucial for the detection and description of problems. After a potential problem is recognized through surveillance, we identify risk factors to determine the cause of the problem. After risk factors have been characterized, we evaluate interventions to decide which ones work most effectively to prevent disease or illness. Subsequently, we implement programs that include such interventions. We then loop back to the beginning, to ongoing surveillance, to determine whether our programs have affected disease incidence.

Figure 1

Public health approach. Reproduced from materials used by the National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia.

You can see how this approach is very similar to the scientific method of observation, forming and testing a hypothesis, and evaluating results.

It's also very similar to what we do with individual clients in practice--we observe, develop a treatment plan, and--based on how well that plan works--either keep going with it as it succeeds, or change it in response to feedback.

Not all conditions of interest are under public health surveillance, partly because no single source of data or system contains information for all diseases or conditions of interest. Public health surveillance information systems, like other distributed information systems, are resource-intensive. They use data from various sources, some of which are collected from health care providers, laboratories, or individuals or directly from medical records and birth and death certificates explicitly for surveillance purposes. Decisions about what conditions to monitor are made not by CDC but rather by the state health departments or state legislatures, who might also manage or appropriate specified funds for conducting surveillance activities. Thus, the conditions that are under public health surveillance vary by state.^15,16

Take-home point--public health approaches and decisions are often made, necessarily on constrained or incomplete or politically-managed information.

In a perfect world, we'd have all the information we need to make out decisions; in the world we actually operate in, however, we recognize the limitations of the information available to us to rely upon.

Factors that influence what conditions are under surveillance in each state include the frequency of disease (i.e., incidence, prevalence, and mortality), the severity (i.e., hospitalization rate, case-fatality rate, years of potential life lost, and disability- and quality-adjusted life-years), the cost of caring for those with the condition, its preventability, its communicability, and the public interest in the condition.¹⁴ These criteria for surveillance show why public health officials monitor the occurrence of neural tube defects (NTDs). Neural tube defects affect 1 in every 1,000 pregnancies in the United States, or approximately 4,000 fetuses annually.¹⁷ Anencephalic infants are stillborn or die shortly after birth, and although many infants with spina bifida survive, they often suffer from severe lifelong disabilities. The total monetary cost of spina bifida over a lifetime has been calculated as $294,000 per infant (in 1992 dollars).¹⁷ It is now known that approximately 50 percent of NTDs can be prevented.^18–23

Anencephalic (Ancient Greek ἀν- (an-) + ἐγκέφαλος (egkephalos, “within the head”) + -ia, from ἐν (en, “in”) + κεφαλή (kephalē, “head”)), meaning "without a brain", is a severe and fatal birth defect in which the brain simply fails to develop at the appropriate stage in the fetus. Infants born without a brain typically live a few hours--sometimes a few days--before dying; it's an extremely traumatic experience for a family to go through.

If it is any small consolation at all in a very painful situation to watch helplessly, the infants are typically not in pain from their condition. The damage, however, is often so severe that basic reflexes such as breathing and sucking/nursing are damaged or absent.

At the Wikipedia article on anencephaly, if you want to, you can see what anencephalic fetuses and newborns look like, but I'm not including those pictures here, because many people find them so distressing.

Spina bifida is--like anencephaly--an NTD, but a much less severe one, and one that occurs much more commonly than anencephaly does as well. Usually occurring in the lumbar or thoracic regions, spina bifida ("split", "divided into 2 branches, forked") is a condition where part of the spinal cord protrudes out through an opening where the neural tube failed to fully close.

Source: Centers for Disease Control http://www.cdc.gov/ncbddd/spinabifida/images/spina_bifida-web.jpg accessed 2 July 2012

Spina bifida can cause serious effects in severe cases--paralysis, other orthopedic issues, bowel and bladder control problems, just to name a few.

But it doesn't have to be that severe; it is possible to have a case of spina bifida so mild that the affected person doesn't even realize they have a condition. As I previously mentioned, Wikipedia has a list of notable people who were born with the condition, and for whom it did not prevent them from having successful careers, often grueling ones. Unlike anencephaly, which is not survivable, there is an entire spectrum of people's experience in living with spina bifida

That's the condition(s) that the case report here is about. Now, the authors explain how the incidence of NTDs get the epidemiologists' awareness in the first place.

Surveillance: What is the Problem?

A universally available source of data regarding the incidence of NTDs is the birth certificate, which is completed for all live births in the United States. A standardized format is used for birth certificates, the U.S. Standard Certificate of Birth (Figure 2), which includes information about the parents, the month prenatal care began, the gestational age and Apgar scores of the infant, the mother's relevant medical and reproductive history, details about the labor and delivery, and check-boxes to indicate whether the newborn has certain congenital anomalies. This latter revision, introduced in 1989,^24,25 lists anencephaly and spina bifida first and second, respectively.

 

Figure 2

U.S. Standard Certificate of Birth.

Since this article is written primarily for informaticians, an interesting side point here is that so much information is contained, not in modern computerized information systems (although, no doubt, later birth certificates are online), but for so many Americans, on paper birth certificates stored in the records area of public-health departments. It's an important point about our current dependence on computers to get information, yet so much vital information is not available on computers yet.

As with any other information system, however, birth certificate data have certain limitations. First, timeliness is an issue. A birth certificate generally must be completed, usually by a clerk at the hospital, and filed within five to ten days of birth. The local registrar forwards the information to the state department of health within one to four weeks and states send birth certificate data to the National Center for Health Statistics (NCHS) of CDC anytime, from daily to weekly to monthly. Most states send the data to NCHS within 60 days of birth. Finally, nationwide data are not usually available until a year after the calendar year in which birth occurred.

So if the epidemiologists want to know how many births in a certain area are recorded with the NTDs that they are tracking, there is a certain time lag that they have to take into account in their work--if they want nationwide data, for example, they have to work at least a year behind the year we are currently in.

It's an important point about the availability and accessibility of information that serves as the basis for public-health decisions--the information isn't, and can never be, perfect, and we have to make our decisions with that fact in mind.

Second, although the checkboxes for anencephaly and spina bifida appear on the birth certificate, a few states have not consistently required that congenital anomalies be reported.²⁶ Third, even if congenital anomalies are supposed to be reported, they might not be recorded on the birth certificate. The sensitivity of the birth certificate for anencephaly has been documented at approximately 60 percent and for spina bifida at only 40 percent.^27,28 Fortunately, given the relative clarity and ease of the diagnosis at birth, the positive predictive value or accuracy of the birth certificate for NTDs approaches 100 percent.^27,28

The quality of the information on which public-health decisions are made is also an issue.

"Sensitivity" is the name that epidemiologists tend to use for the statistical measure that information scientists tend to refer to as "recall", but whichever name they use, they are both measuring the same thing: how good a job does their measuring instrument do of finding all of the relevant cases that are really there?

Or, how sure are they that they are not missing real cases, because whoever was responsible for entering the information on the birth certificate failed to do so for infants born alive with cases of anencephaly or spina bifida?

If the sensitivity of the birth certificate for anencephaly is about 60 percent, and for spina bifida is about 40 percent, that means that:

• For every 100 babies born alive with anencephaly, about 60 of them will have a birth certificate that correctly records their condition, and
• For every 100 babies born alive with spina bifida, about 40 of them will have a birth certificate that correctly records their condition.

If those numbers are making you wonder just how good the information that makes its way to you for you to make clinical decisions about may actually be--well, that is a very good question for all of us to be asking ourselves from time to time.

Fortunately, although a lot of relevant cases are missed when it comes to entering them on the birth certificate, the relevant cases that are not missed--the ones where they did correctly record the condition--are almost perfectly right. That's what it means to say that the positive predictive value approaches 100 percent.

It means that you can have almost absolute trust that, if these conditions are recorded on the birth certificate, that the infants really did have those conditions. There are almost no times when a normal healthy infant was mistakenly recorded as having one of these conditions, and there are also almost no instances where someone mistook some other condition for anencephaly or spina bifida.

A lot of real cases of NTDs at birth were missed when it came to recording them on the birth certificate (the 60% and 40% sensitivity rates).

But, if whoever was responsible for recording that information on the birth certificate did put one of those conditions, you can trust with almost perfect certainty that the baby actually does have that condition, and that the birth certificate does not mistakenly put anencephaly or spina bifida for infants who are normal, or who have different conditions present at birth.

Finally, however, a key limitation of using birth certificates for complete ascertainment or determination of NTDs is that they do not include fetuses that have been miscarried or terminated. Approximately 50 percent of fetuses with NTDs are diagnosed prenatally and aborted.^29,30 Thus, in states where detection of all birth defects is a priority, additional resources are invested in gathering data from other sources in addition to the birth certificate.

Approximately 21 states or localities conduct active surveillance for birth defects.³¹ Active surveillance refers to the increased effort and resources invested by the health department to seek information on a regular basis from sources. Active surveillance, which is initiated primarily by a health department, differs from passive surveillance, which relies on providers to report to the health department.

These birth defects monitoring programs cover various fractions of their population and use various combinations of data sources, which include obstetric offices, prenatal diagnostic centers and laboratories, fetal and neonatal autopsy programs, outpatient perinatal centers, genetic service and other specialty clinics, hospital discharge data and medical records, vital records, ultrasonography records, and neonatal intensive care units; certain ones include passive reports from schools and community agencies. Data from each of these systems are useful for decision making and planning within a jurisdiction, providing information that facilitates understanding the incidence of a problem, the population affected, their rates of prenatal diagnosis and termination and, thus, the most useful points for and types of public health interventions.

An excellent point about the limitations of data from birth certificates--they only record the incidence of NTDs in babies who were born alive.

If the NTD is serious enough to kill the baby before it's born, or if parents decide to terminate the pregnancy because of the effects of the NTD, the cases where those happen are invisible if you rely only on birth certificates to understand what is really going on.

You need multiple sources of data to get closer to the entire picture.

Active surveillance is when the public-health agency reaches out and asks sources in the community for information about cases they are seeing.

Passive surveillance is when the public-health agency does not do its own outreach, but works on the data that providers and other community sources deliver to them.

You can see how those different methods of information collection might have an effect on how representative and thorough the collected data could turn out to be.

Risk Factor Identification: What is the Cause?

Diverse scientific investigations might prove useful to public health officials attempting to identify the etiology or cause of a problem or, at minimum, risk factors that influence the occurrence of a condition. For NTDs, such studies include basic or molecular research into the genetic and biochemical bases of NTDs. They also include clinical research such as that conducted among family planning clinic or prenatal care patients (e.g., case-control or cohort studies to evaluate risk factors and clinical trials to study patient interventions). Naturally, population-based research regarding diet or risk behaviors (e.g., ecologic studies of cultures or nations, state- or communitywide surveys, or case-control studies using cases identified through surveillance) also play a role in the public health understanding of the problem.

The best outcome is when public-health workers can determine exactly what causes a problem, and address it head on--such as in 1854 when the British physician John Snow demonstrated that cases in a London cholera outbreak were coming from a public drinking-water pump in Broad Street contaminated with human sewage, or when the human immunodeficiency virus was demonstrated to be the cause of AIDS.

However, we don't always get that best possible outcome. Sometimes, we have to settle only for correlations, or associations, rather than understanding cause and effect.

The best we get, in some cases, may be to recognize that certain populations are at higher risk for a particular condition than other populations are, without ever being able to exactly pin down the causality.

Wikipedia has an illustration that shows some of the different ways that epidemiologists can study these questions.

There are, essentially, 3 factors involved in these types of studies:

• the exposure (or non-exposure) to the causative agent behind the condition;
• whether or not members of that population actually get the condition; and
• at what point the researcher gets involved in the investigation.

This diagram shows the interactions among those factors in different types of epidemiological studies:

Source: http://upload.wikimedia.org/wikipedia/en/b/b5/ExplainingCaseControlSJW.jpg accessed 3 July 2012

First of all, we are going to ignore the ORs and RRs in the captions, because the explanations of those statistics will get us rather far away from the topic of the article we are reading here. If you want to know more about them, you can look up "odds ratio" (OR) and "relative risk" (RR), and we'll also discuss them in other places here at POEM. But since the original article didn't bring them up, and since you've slogged through a lot of material already, we won't add a new pair of statistics on right here.

The key at the bottom of the diagram tells you how to read each part of the diagram. The green question mark is what we are trying to find out; the black dot is members of the population in which the condition is present; the white dot is members of the population in which the condition is absent, and the stick figure comes into the diagram at the point in which the researcher gets involved with the study.

So in the first one, the case-control study, the researcher enters the scene after the exposure, and after it is clear who has the condition (the "cases" of disease) and who doesn't have the condition (the "controls", no disease), and tries to investigate something about the exposure itself (the green question marks).

The next two are cohort studies over a long time period, where the condition--whether or not the different members of the population were exposed to the risk factor for the disease--is known, and the question the researcher is investigating is whether or not those different members of the population go on to develop the disease.

If the researcher gets involved before the diseases develop and studies them as they occur, then that is a prospective ("forward-looking") cohort study.

Working backwards (such as investigating birth certificates or other historical records) means that the researcher is conducting a retrospective ("backward-looking") cohort study.

These different kinds of studies shed different kinds of light on associations between exposure to some kind of disease-causing factor, and what really happens in terms of people going on to actually develop those conditions.

Public health officials might also learn more about the cause of a problem during the course of outbreak or cluster investigations. When a cluster of anencephaly occurred along the Texas–Mexico border several years ago,³² public health officials conducted an investigation because of concerns that the outbreak was related to environmental contamination either from the industrial plants along the Mexican border or from pesticide use and that the number of cases was not a statistical anomaly. However, they were unable to identify an etiologic association for this cluster.

In this case, like in the Shoalwater Bay case, they were able to figure out that this was a real pattern of more disease than you would expect in a population this size, rather than just a chance result that looked like a pattern.

But, also like in the Shoalwater Bay case, they did not succeed in finding out what the cause (or causes) of that increased disease rate was.

Sometimes, disappointingly, that's the best we're able to do.

However, the NTD case study in this report has a better outcome than those more intractable cases.

Two of the three potential approaches require the pregnant women to take active steps to change food habits, or to start taking vitamins. The third one is passive on the part of the woman, since it involves putting extra micronutrients in the food supply (fortification).

Part of the problem is that--even if you can reach the women, and if they are motivated to begin changing habits--the necessary process of development takes place so early that it is often finished--correctly or imperfectly--before the woman even realizes she is pregnant. So it's too late to change the outcome at that point.

Fortifying the common food supply that everyone--not only the pregnant women--eats from raises safety concerns, among others. These are some of the trade-offs involved in making that decision.

Evaluate Intervention: What Works?

Although science indicated that folic acid was effective in preventing certain NTDs, the question of how to implement effective programs to produce this outcome remained. First was the issue of ensuring that health care providers and consumers were aware of the recommendation, especially the need of women to take folic acid before becoming pregnant. Second, dietary changes are widely acknowledged as difficult to implement, even for a motivated, knowledgeable persons. And above all, the fact that half of pregnancies in this country are unplanned augmented the public health challenge. Clearly, the approach to this problem would have to be multi-pronged.

This is often what the findings of public-health studies reveal--very, very rarely is it a simple, 1-1 cause and effect, where one solution fits all.

Rather, as you might expect in a diverse population, a variety of different approaches is often more effective in promoting community health.

Another important point alluded to in this paragraph is that it's not just about what the science shows. Translating scientific findings into effective practices, and educating and encouraging practitioners and clients to make use of those effective practices, is a much bigger, and different, problem.

Implement Program: How Do You Do It?

As in the 1992 recommendation, FDA pursued the option of fortification of the food supply. They published a proposed rule in the Federal Register in 1993 and a final rule in March 1996.³⁶ At that time, fortification was optional; however, the rule required fortification of enriched grain products (e.g., flours and pastas) with 140μg folic acid/100g grain beginning Jan 1, 1998. This action was expected to add 0.1mg of folate to the average person's daily diet and was intended to result in 50 percent of women of reproductive age receiving 0.4mg folate from all sources.^37,38 Questions regarding whether more birth defects could be prevented with a larger dose of folic acid remain,³⁹ but FDA wanted to balance this theoretic benefit with concerns about safety and masking vitamin B12 deficiency.

What does this mean for products that you purchase where you do your food shopping in the US?

What were the trade-offs involved in deciding on the final dose?

What is the effect of this intervention on the population?

Public health partners working together to disseminate information about folic acid included CDC, FDA, HRSA, and state health agencies, along with obstetric associations and other provider groups, health plans, maternal and child health advocacy groups, public school educators, and community organizations. A CDC publication, “Preventing Neural Tube Birth Defects: A Prevention Model and Resource Guide,” outlines ways to design, develop, deliver, and evaluate an NTD prevention program in a community by using folic acid promotion as a model.⁴⁰ It includes informational materials targeted at the media, physician's offices, clinics, schools, and even health clubs. In addition, in 1999, CDC, the March of Dimes Birth Defects Foundation, and the National Council on Folic Acid began a national education campaign with materials targeted to women who are thinking about pregnancy, the contemplators, and women who are able to get pregnant even if not planning to in the near future, the non-contemplators. The “Before You Know It” and “Ready, Not” brochures produced for these two groups, respectively, along with other materials, were developed after focus groups were conducted with women who were contemplators and non-contemplators, including Spanish-speaking women from various countries of origin. These materials are readily available in English and Spanish from the CDC Web site and the CDC facsimile information service.