Motherisk Int J 2020;1:4
Shimon Barak MD
President, Israeli Society of Ambulatory and Community Pediatrics
Vice President, European Confederation of Primary Care Pediatricians
In many cases we define agents as causing developmental delay based on a difference in a few IQ points. That must depend on who is our “normal”?
We invited a leading pediatrician to overview the issue of Normalcy from its clinical, statistical and philosophical aspects.
When estimating early childhood neuro-psychological development and pending final diagnosis, children are labeled by their performance in diagnostic tests either as “Normal” or “Suspected delayed”. With proper screening, 70-80% of those with developmental disabilities (1) and 80-90% of those with mental health problems (2) should be correctly diagnosed. Unfortunately in real life these numbers are not achieved, as inadequate evaluation by primary health caretakers (3; 4) causes as many as one-half of affected children not to be identified by the time they enter kindergarten (5; 6), in spite that the majority of them, at least in the USA (7) and in Israel (8), are cared by certified pediatricians supposedly trained to and recognize “Normal” from “Presumed non normal”.
Why do primary caretakers – especially pediatricians – fail the mission?
While in the dictionary its definition is exact and absolute, in “real” life Normality is in the eyes of the discipline defining it, ranging from the philosophical idea implying it’s the most usual manifestation of a phenomenon (9) to the scientific view that refers it to the middle of a distribution (10). Determining “Normality, Wellness and Wholeness" is essential for the understanding of the sick (11), but the definition is not an easy task, as divergence is wide, and telling the normal from the pathological is often challenging (12). This is especially true in pediatrics, where variation in growth, physical appearance, behavior, and emotional development can be enormous without reaching the pathological.
In its colloquial use by doctors, parents and members of the educational team, a “Normal Child” is usually interchangeable with “an Healthy Child” (13) and is used to describe those who seem likely to eventually grow up into becoming satisfactory members of society, even if some of them may at some time show symptoms and signs inconsistent with the expected course of development. This definition is basically similar to the way Chief Justice Potter Stewart defined obscenity (Jacobellis V. Ohio 1964) (14). In Judge Stewart’s words: “I shall not attempt to further define the kinds of material I understand to be embraced within that shorthand description, and perhaps I could never succeed in intelligibly doing so, but I know it when I see it”.
But this intuitive “knowledge” of Normality is problematic. In spite of the 30 plus years that have elapsed since the Alma Ata declaration (15), training of Medical professionals is still focused on teaching the Science of Disease as reflected in hospital based medicine instead of training for the recognition of health, that “state of complete physical, mental and social wellbeing, and not merely the absence of disease or infirmity”, as present in primary care settings. This was not the settings in which the author of this article received his training. First of all, our teachers were first and foremost pediatricians, unlike today’s chiefs of pediatrics who are almost with no exceptions subspecialists in the intricacies of the profession. Secondly, most of our generation was familiar and exposed early in its training with the works of Ronald Stanley Illingworth, as the basic layer for the science and practice of pediatrics in the UK and author of more than 600 articles and 21 books. Prof. Illingworth saved countless doctors from the perils of misdiagnosing normality in children, his thesis being that a thorough knowledge of the normal is an essential basis for knowledge of the abnormal. In his words: “Lack of knowledge of the normal is harmful to the child, parents and family” (16) (Not to mention the doctor!!).
Thirdly, modern 21st century pediatricians are trained almost exclusively in hospitals where most children have either rare or grave diseases and only few are “lightly ill” or healthy. Therefore trainees seldom see “normal healthy children” during their internship in pediatrics. On top of it even updated textbooks have reduced the information regarding “normality” and no better example than the “Bible of Pediatrics”, the Nelson’s textbook, that has limited its data on Normal development saying “information about “normal development” during this period should be directed to reliable sources including the AAP website” (17).
Last but not least, while once we could rely on the wisdom of the crowd to make the differences, gone are the days when extended kin and large numbers of siblings shared in the tasks of childrearing made the knowledge of Normal childhood habitual and common. Modern life often finds parents in relative isolation, without the accumulated wisdom and helpful hands of grandmothers, aunts or cousins. Faced with the endless supply of scientific (or pseudo-scientific) information about children’s health and development available in the Internet, parents, instead of easing their anxieties, often just attune to a broad array of potential problems. We, pediatricians, encounter their worries on a daily basis and rarely meet parents who do not ask, at one time or another, if some aspect of their child’s anatomy, growth or development might be "not normal” (at their minds “not normal” being a synonym of “pathological”).
The importance of recognizing Normality
The three main fields of child upbringing that raise most concerns on “normality” are
· Phenotyping: the recognition between allomorphism, dysmorphism, anatomic variations and anomalies.
· Differentiation between variations in size, height and stature within normal limits versus those requiring medical intervention
· The diagnosis of abnormal cognitive development.
The definition of a specific phenotype as normal is today a relatively easy task as the huge leap genetics has done since the decoding of the human genome allows scientific answers acceptable to both families and the Medical community.
On the size of children we accept without a wink that a “normal” child can be born weighing anything between 2500 to 3800 grams and size and height are eventually a synthesis of geography, genetics, social status, economic background, and interpersonal dominance in dyadic interactions. On top of it, pharmacological treatment with somatropin, the man-made copy of natural growth hormone, has been available for the more than 30 years, making possible the treatment of short statured children, mainly those with growth hormone deficiency (GHD), having being born small for gestational age (SGA), having Idiopathic short stature and even suffering from certain pathologies such as Prader-Willi and Turner syndromes.
On the subject of development we are in big trouble. Development is a continuous “flowing” process, from conception to maturity, incorporating biological, psychological & emotional changes occurring as children progress from dependency to autonomy. Although having a predictable sequence, its course is unique for every individual, as it progresses at different rhythms and paces and each stage is affected by the preceding steps and experiences. It entails interaction between genetics and environment and is the result of the individual personal ability to learn from the circumstances of life.
Optimal development is vital to society. The quest to better understanding of the social, cognitive, emotional and educational development of children has produced high quality research and a variety of theories seeking to explain and describe the expected sequence of states, thus helping to develop strategies to promote optimal results. But while behaviorists and Child developmental experts might quote Piaget, Vygotsky, Bandura and Erikson, most “plain” pediatricians base their diagnoses of “abnormal” development on the work of an 18th century German mathematician, Johann Carl Friedrich Gauss and the specific spot where the index child stands in comparison to the Gaussian bell curve of his/her peers.
“There are three kinds of lies’ – said Mark Twain (18) - lies, damned lies, and statistics. In medicine it is also a controversial issue. Normal range, AKA "normal distribution”, is an arbitrary number in the bell curve shape you would expect to find within a group of data. Depending on the limits we choose (whether we take the 3rd and 97th or the 10th and 90th percentiles) six to 20% of humanity is defined as “Not Normal”. And actually “Normality" has emerged in Western cultures hand in hand with statistics, as prior to this there were literary and artistic representations of the ideal (19). Only with the emergence of statistics and the bell-shaped curve, the idea of “normalcy” took root in the collective imagination, many times accompanied by the stench of eugenicists hoping to eliminate “undesirable” deviation from normal and improve the human race.
Normal statistical distribution is a much misunderstood term. Most people assume that data must somehow scatter to fit approximately the “normal distribution” when in fact non-normality is much more common. For example if length is normally distributed, and weight is related to it by an allometric equation, then weight cannot be normally distributed. Many distributions of real data are heterogeneous and are comprised of various discrete groups - with different means and standard deviations. Sometimes it can be more instructive to separate distributions into their component parts, than to argue for their normality. Evelback et al (20) suggested, for example, that the basic premise that routine laboratory values give a mixture of two identifiable Gaussian (or "normal") distributions (one for the sick and one for the healthy) is untrue, and proposed that the misleading phrase "normal limits" should be dropped and changed by "clinical limits" to refer to the limit 2.5 and 97.5 percentage points of the distribution in healthy persons.
Taking the Gaussian bell curve as a key to define normality we accept that 68% of the population falls within one standard deviation from the 50th percentile, leaving at the most 16% of the population on either sides of the line. And indeed recent estimates in the United States show that about one in six (about 17%) of children aged 3 through 17 years have one or more developmental disabilities (21; 22). Actually, based on epidemiologic studies, the prevalence of intellectual disabilities (ID) among children in the United States range widely from 8.7 to 36.8 per 1,000 (23; 24) when a major source of this wide range is the variation in the inclusion of mild ID. While the prevalence of serious ID (IQ <50 with deficits in adaptive behavior) in the United States and other developed countries is consistently found to be in the range of 2.5 to 5 per 1,000 children, that of mild ID ranges from as low as 2 to more than 30 per 1,000, being highest among children of low socioeconomic status (25; 26). Evidence gathered by Data Resource Center for Child and Adolescent Health (27), imply that disparities in the rates of ID and confounders for these disparities are race and ethnicity, gender, socioeconomic status and parental education, not to mention test and diagnostic bias(28).
Since for the vast majority of children with a mild delay in development, the cause is not medical but rather social/natural (gender, ethnicity, family structure, socioeconomic status, poverty level, parental education and more), a question arises: should we drop the ways we measure normality in child development and adopt a more personalized system?
Arkun et al (29) postulated, for example, that definition of “normal” values for common laboratory tests may depend on demographic traits of the tested population including age, race, and sex and ideally, laboratory test results should be interpreted in reference to a population of “similar” “healthy” individuals. “With the evolution of medicine into fully personalized or “precision” medicine there may be interest in trying to match each person to an increasingly granular normal reference population” (30).
The equivalent to laboratory tests, when diagnosing development, would be the use of proper screening tools adjusted to gender, ethnicity, family structure, socioeconomic status, poverty level, parental education of the child tested. Unfortunately no universally accepted screening tool is recommended as appropriate for all populations/ages (31) and although medical literature does not identify a standard criterion in developmental assessment, other than the lengthier screening test performed after a referral has been made (32), no ideal test that covers all areas of development, equally applicable to all ages, with construct validity and a sensitivity/specificity close to 100%(33) has been recognized.
Furthermore, there are no randomized studies of contemporary tools that compare children who have been screened with those who have not (34). Sensitivity and specificity of most tests is below 80 % (35) and the original sources for milestone data cited in most texts have been drawn from small size populations with no diversity. Arnold Gesell’s classic studies were conducted in the late 1920s and early 1930s on a population of 107 all white infants and children from families from a single city in Connecticut, chosen to be “most representative of the average” and the Child Development Inventories by Harold Ireton were developed in the 90s based on a population of 568 children from a single community in Minnesota, “without extremes of wealth or poverty” and 95% white.
What can be done to improve the recognition of Normal Children?
The task of improving the recognition of normal children in the daily practice of pediatrics must focus on avoiding the seven pitfalls in daily practice.
1. INADEQUATE TRAINING: as most of the children a pediatrician will see in her/his career will be “normal”, emphasis on the “properties” of normality and the use of accurate and effective diagnostic tools.
2. AWARENESS OF THE PREVALENCE: a pediatrician that does not diagnose 10-15% of her/his patients as having a “suspected delay” is failing in his job.
3. INCONSISTENT FOLLOW-UP: Development emerges and so do developmental problems. Consistent and repeated measurement will ensure that a normal babbling infant has begun using words at the appropriate age and combines words into a sentence by 24 months. This is a mixture of problems: doctor shopping, locum tenens, failing to check-in consecutive visits, etc.
4. OVER-RELIANCE ON CLINICAL OBSERVATION (instead of measurement): Developmental problems are usually far too subtle to simply observe. Clinical judgment may identify pallor, fussiness and other symptoms of illness, but in the same way that heart rate is measured with the help of a clock and fever with a thermometer and not by putting a hand to the forehead) development and behavior require quality instruments to detect delays and disabilities. On the other hand we should “Rethink the meaning of the mean” (36). Development cannot be thought in terms of mere milestones and we should see milestones as achievements in specific mental/physical abilities marking the transition between two developmental stages, understanding them in this way. Delays should be diagnosed by comparison with the characteristic variability of a milestone, not with respect to average age at achievement. Before any milestone is reached a child has to go through many preceding stages and for a precise diagnosis one has to be conversant with all these stages. Diagnosis does not consist so much of observing what a child does but how he does it - not whether a 7-month old child can sit but how he sits and with what degree of maturity he does it. Studies almost invariably ignore this aspect. They record the fact that a child can sit but fail to record the maturity which he has reached. The sequence of development is the same for all children, the rate varies from child to child. The age at which children learn to sit and walk varies considerably. A child has to learn to sit before he can walk, but he will not walk until he stops using his hands for locomotion. “Extreme outliers" are not abnormal. They are simply outside the “normal” expected distribution. A baby who crawls at four months is outside the norm and should be referred as an early crawler. A baby who does crawl until 14 months would be a late crawler. A baby who started walking without crawling at all would be a non-crawler! All these babies might still be perfectly healthy, but this by itself does not categorized them as being “normal” or “abnormal”.
5. HAVING DIFFICULTIES IN COMMUNICATING WITH FAMILIES: Parents may fail to raise concerns about their children due to ignorance, modesty, lack of awareness or lack of knowledge what the primary care provider is interested to know about their child’s development and behavior. Informal questions to parents do not work well. E.g.: “Do you have worries about your child’ development?” The word “worries” may sound sometimes too strong and many do not know what “development” means. The CDC in the USA found that only 2% of families will answer to the question while the prevalence of problems is 16% - 18%.
6. USE OF “IRREPRODUCIBLE” MILESTONES: Some “gold standards” of developmental milestones are neither good predictors of developmental delays nor standardized to developmental age. E.g. color recognition. The literature is full with research on the subject (37). But stating that a child “knows colors” might mean he knows the names of the colors (If so, how many?) or that he can point to colors when named or maybe simply match them. The difference in skill levels required for these tasks ranges from 2½ to 4½ years.
7. FAILURE TO REFER TO THE PROPER RESOURCES: Many children, even if found to have problems, are not referred to the proper facility or even not referred at all. Many primary care providers are unaware of the referral resources in their communities or there might be a lack of cross information between the referent and the interventionists.
Most children will be found at a certain moment in their lives as being ahead or behind their age-compatible counterparts yet eventually will develop and prove to be as “normal” as the others. Judging a child development at a certain arbitrary point in the race is like judging a marathon runner in the 10th Km mark. Close follow up “per se” dose not discover abnormal development in children unless the examiner knows his job and avoids pitfalls.
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