Question

View the scenario presented:M12 Activity – Public Health Screening Program

Suppose that you are part of a team that serves as a body of experts to provide recommendations to state legislators and local public health officials. Your team analyzes and interprets information in order to guide best-practice decisions for state-wide public health policy and program planning. Recent research has surfaced regarding the potential of a new screening test for lead poisoning among children. While the current gold standard screening test is extremely good at producing correct results, it is expensive and involves the collection of arterial blood, which is highly invasive and not well-tolerated among children. The new screening test, on the other hand, is much cheaper to administer and only requires simple finger pricks for the collection of venous blood, which is much preferred among children. However, as shown in the following study results, the venous blood test is not as good at producing correct results with regard to lead poisoning among children as compared to the arterial blood test. Lead Poisoning (Positive Arterial Blood Test) No Lead Poisoning (Negative Arterial Blood Test) Total Positive Venous Blood Test 445 244 689 Negative Venous Blood Test 55 256 311 Total 500 500 1,000 Given the development of a new, cheaper, less invasive screening test for lead poisoning, the state is considering public policy that would mandate universal screening with the venous blood test among the general population of children as a requirement for kindergarten entry. Work with your team to analyze and interpret the information provided in order to make a recommendation regarding this policy.

 It may help to consider the following questions: 

1) What is the validity (sensitivity and specificity) of the venous blood test and what do these measures mean? 

2) What is the predictive value (positive and negative) of the venous blood test and what do these measures mean? 

3) What are the benefits of true test results (true positives and true negatives)? 

4) What are the implications of false test results (false positives and false negatives)? 

5) What are the implications of making/not making screening for lead poisoning a requirement? 

6) Does screening for lead poisoning among the general population of children with the new venous blood test meet the World Health Organization’s (WHO) guidelines for planning and implementing screening programs (available on page 299 of your textbook)? 

7) Are there alternative ways to screen specific populations of children that may be more acceptable? 

8) Are there alternative ways to use the venous blood test, possibly in combination with the arterial blood test or other measures to identify children at high-risk for lead poisoning?

Answer 1

1) The advantages of the use of sensitivity and specificity in the assessment of diagnostic tests. Statistically, the advantages of the usage of sensitivity and specificity are: They do now not alter if the incidence adjustments between populations (see predictive values) They can be utilized in extraordinary populations.

In medical diagnosis, test sensitivity is the capability of a take a look at to effectively pick out these with the ailment (true tremendous rate), whereas check specificity is the ability of the test to effectively become aware of those except the disease (true negative rate).

2) Positive predictive value is the chance that subjects with a high-quality screening check virtually have the disease.

If a take a look at challenge has an bizarre screening check (i.e., it's positive), what is the chance that the difficulty in reality has the disease? In the example we have been using there were 1,115 topics whose screening test was positive, but only 132 of these sincerely had the disease, in accordance to the gold popular diagnosis. Therefore, if a subject's screening test used to be positive, the chance of disease was 132/1,115 = 11.8%

Negative predictive value is the likelihood that topics with a negative screening check simply do not have the sickness .

Negative predictive value: If a take a look at situation has a poor screening test, what is the probability that the problem certainly does now not have the disease? In the same example, there were 63,895 subjects whose screening take a look at used to be negative, and 63,650 of these were, in fact, free of disease. Consequently, the negative predictive value of the take a look at used to be 63,650/63,695 = 99.9%

3) A true positive is an outcome where the model efficiently predicts the tremendous class. Similarly, a actual bad is an effect the place the model correctly predicts the poor class.

4) Since medical tests cannot be truely true, false fantastic and false bad are two issues we have to deal with. A false superb can lead to pointless treatment and a false poor can lead to a false diagnostic, which is very serious considering a ailment has been ignored.

5) Lead poisoning symptoms in children

Signs and signs of lead poisoning in young people include:

•Developmental delay

•Learning difficulties

•Irritability

•Loss of appetite

•Weight loss

•Sluggishness and fatigue

•Abdominal pain

•Vomiting

•Constipation

•Hearing loss

•Seizures

•Eating things, such as paint chips, that are not food (pica)

•Lead poisoning signs and symptoms in newborns

Babies exposed to lead before delivery might:

•Be born prematurely

•Have lower beginning weight

•Have slowed growth

•Lead poisoning signs in adults

Although adolescents are principally at risk, lead poisoning is additionally dangerous for adults. Signs and signs in adults might include:

•High blood pressure

•Joint and muscle pain

•Difficulties with memory or concentration

•Headache

•Abdominal pain

•Mood disorders

•Reduced sperm be counted and extraordinary sperm

•Miscarriage, stillbirth or premature delivery in pregnant ladies.

6) Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP) ACCLPP Recommendations for Health-Care Providers: All adolescents enrolled in Medicaid should be screened with a blood lead take a look at at ages 12 and 24 months or at ages 36--72 months if they have not previously been screened.

7) In 1975, genetic screening had been described as the search in a populace for persons possessing sure genotypes that

(1) are already related with disorder or predispose to disease,

(2) may additionally lead to disease in their descendants, or

(3) produce other variations now not recognised to be related with disease. Today, genetic screening might also be described as any type of check carried out for the systematic early detection or exclusion of a hereditary disease, the predisposition to such a sickness or to determine whether or not a individual contains a predisposition that may produce a hereditary disease in offspring. With higher expertise of the genetics of a number of illnesses and a larger capability of genetic technology, genetic screening at an early stage for an increasing wide variety of medical problems is possible. Justifications provided in support of genetic screening include early diagnosis and treatment and reproductive decisions.

Genetic screening refers to express and systematic programmes directed both at whole populations of asymptomatic people or at subpopulations in which risk is recognised to be increased. Genetic screening has to be special from genetic checking out due to the fact the implications are different. Genetic checking out is carried out on sufferers who for some thing purpose have taken the initiative and are trying to find professional advice. In genetic screening, checks can also be seen to be imposed on individuals. The moral dilemmas are magnified and the obligations for the health practitioner correspondingly greater.2 The genetic nature of a ailment effects in hazard implications to family individuals of the individual screened, even although they might also no longer be, nor possibly wish to be, included in the screening programme. Genetic screening is also distinct from other varieties of screening because it does not necessarily lead to the prevention or cure of diseases.

8) The first step in treating lead poisoning is to do away with the source of the contamination. If you cannot get rid of lead from your environment, you would possibly be capable to limit the probability that it will reason problems.

For instance, occasionally it is better to seal in rather than take away historical lead paint. Your local health branch can suggest methods to identify and limit lead in your domestic and community.

For children and adults with highly low lead levels, honestly warding off exposure to lead would possibly be adequate to limit blood lead levels.

Treating greater levels

For more-severe cases, your doctor may recommend:

Chelation therapy. In this treatment, a medicine given by way of mouth binds with the lead so that it is excreted in urine. Chelation therapy may be endorsed for youth with a blood degree of forty five mcg/dL or larger and adults with excessive blood tiers of lead or symptoms of lead poisoning.

EDTA chelation therapy. Doctors treat adults with lead ranges larger than forty five mcg/dL of blood and kids who can not tolerate the drug used in conventional chelation therapy most usually with a chemical called calcium disodium ethylenediaminetetraacetic acid (EDTA). EDTA is given by injection.