Preventive Medicine and Public Health Handout (April 2024) PDF

TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch sin...

TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. 3. Popularity bias – Occurs when its experts may preferentially admit and keep track of these cases over other less challenging or less interesting ones 4. Referral filter bias – The selection that occurs at each stage of the referral process can generate patient samples at tertiary care centers that are much different from those found in the general population 5. Diagnostic access bias – Patients differ in financial and geographic access to the clinical technology that identifies them as eligible for studies of the course and prognosis of disease 6. Berkson Bias – study population selected from hospital is less healthy than the general population BIAS IN PREFORMING THE STUDY 1. Recall bias – relates to differences in the ways exposure information is remembered or reported by cases who have experienced an adverse health outcome and by controls who have not. 2. Measurement bias – Occurs when the methods of measurement are dissimilar among groups of patients 3. Diagnostic suspicion bias - The clinician knows that a patient possesses a prognostic factor of presumed importance may carry out more frequent or more detailed searches for the relevant prognostic outcomes 4. Procedure bias – subjects in different groups are not treated the same 5. Observer-Expectancy bias – Pathologist who interpret diagnostic specimen can have their judgments dramatically influenced by prior knowledge of the clinical features of the case BIAS IN INTERPRETING THE STUDY 1. CONFOUNDING BIAS – Factor related to both exposure and outcome (but not on causal path) distorts effect of exposure on outcome (vs effect modification, in which the exposure leads to different outcomes in subgroups stratified by the factor) To determine if confounder or effect modifier, stratify according to the suspected confounder. Confounding is a third variable that entirely or partially explains the apparent association between exposure (alcohol use) and outcome (lung cancer). If you stratify across smoking status (potential confounder), the association vanishes à true confounder. Effect modifier is a third variable that has a real effect in the association between exposure (OCP use) and outcome (breast cancer). If you stratify across family hx of breast cancer (potential confounder), there is a difference in associations à effect modification. Dr. Vidal 2. Lead-time bias – Early detection interpreted as ↑survival, but the disease course has not changed o refers to the phenomenon where early diagnosis of a disease falsely makes it look like people are surviving longer. This occurs most frequently in the context of screening. o survival may appear to be increased among screen-detected cases simply because the diagnosis was made earlier in the course and yet the outcome of the disease remains unchanged. https://first10em.com/ebm/lead-time-bias/ For example, a man with metastatic lung cancer dies at age 70. His cancer was discovered 1 year ago, when he was 69. Therefore, it appears as if he lived for 1 year with the cancer. However, imagine that instead his cancer was discovered on a screening CT scan when he was 65 years old. If he still dies at the age of 70, it now looks like he survived for 5 years with the diagnosis of cancer (the 5-year survival rate is much better), but in fact there was no real change in his survival https://first10em.com/ebm/lead-time-bias/ Dr. Mann 3. Length-time bias - Screening test detects diseases with long latency period, while those with shorter latency period become symptomatic earlier o refers to the fact that screening is more likely to pick up slowergrowing, less aggressive cancers, which can exist in the body longer than fast-growing cancers before symptoms develop o the length of detectable preclinical phase can vary substantially from person to person; more slowly progressive disease, with less capacity to prove fatal, may have a longer pre-symptomatic screen-detectable period and will therefore be more likely to be screen-detected = artificial survival advantage to screen-detected cases. • EFFECT MODIFIER – in contrast to a confounder, this does not obscure the nature of a relationship between two other variables; rather it changes the relationship MNEMONIC • Length-time bias is due to slow cases being detected more often simply because they are slowly progressing. Remember the "g" in length is for slowly progressing. • Lead-time bias is due to early detection. Remember the "d" in lead is for early detection. Dr. Mann • OVER-DIAGNOSIS BIAS o An extreme example of length bias o aggressive search for abnormalities might actually lead to harm and great cost without reaping any benefits o tendency to discover cancer that will not affect the life expectancy of the patient • SELF-SELECTION BIAS o people presenting for screening tend to be healthier leading to false sense of better outcomes ✔GUIDE QUESTIONS Which bias is being described in these situations? A. Lead time bias B. Length-time bias C. Surveillance bias D. Recall bias TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 26 of 79 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. ✔GUIDE QUESTIONS 1. Women who take postmenopausal estrogens are more likely to have breast cancers detected than those who do not take postmenopausal estrogens. 2. Medical students who fail a physiology examination are more likely to report missing two or more physiology lectures than those who fail a neuroanatomy examination. What type of bias is demonstrated? 3. A man with metastatic lung cancer dies at age 70. His cancer was discovered 1 year ago, when he was 69. Therefore, it appears as if he lived for 1 year with the cancer. However, imagine that instead his cancer was discovered on a screening CT scan when he was 65 years old. If he still dies at the age of 70, it now looks like he survived for 5 years with the diagnosis of cancer (the 5year survival rate is much better), but in fact there was no real change in his survival. What is this type of bias? 4. The mortality rate for patients of breast cancer is the same for screening and non-screening groups. Those who were diagnosed during screening had more benign or slowly progressing forms of the disease. The study concludes that screening increases survival rates. What is this type of bias? Answers discussed in lecture video EXAMPLES OF SCREENING AND DIAGNOSTIC TESTS AND POSSIBLE GOLD STANDARDS DISEASE SCREENING GOLD STANDARD • Mantoux Tuberculosis tuberculin skin • Culture test, QuantiFERON Breast • Mammography • Biopsy result cancer • fecal occult blood • Colonoscopy ± Colon cancer test (FOBT) biopsy • Colposcopy with Cervical appropriate biopsy • Pap smear cancer or sentinel lymph node biopsy • IgG and IgM Rapid • Real-time reverse Antibody Test transcriptionCOVID-19 (RAT) (Serum) polymerase chain • Antigen Test reaction (rRT(Swab) PCR) assay Monkeypox • None yet Modified from Maxim, L Daniel et al. “Screening tests: a review with examples.” Inhalation toxicology vol. 26,13 (2014): 811-28. doi:10.3109/08958378.2014.955932 SCREENING • Screening is defined as the presumptive identification of unrecognized disease in an apparently healthy, asymptomatic population by means of tests, examinations or other procedures that can be applied rapidly and easily to the target population (WHO) • Sometimes termed medical surveillance • Ideal test: high sensitivity, high specificity Screening tests do not diagnose the illness Dr. Mann TYPES OF SCREENING • There are different types of screening, each with specific aims: o mass screening aims to screen the whole population (or subset); o multiple or multiphasic screening uses several screening tests at the same time; o targeted screening of groups with specific exposures, e.g. workers in lead battery factories, is often used in environmental and occupational health o case-finding or opportunistic screening is aimed at patients who consult a health practitioner for some other purpose. CONDITIONS/SITUATIONS FOR A SCREENING PROGRAM TO BE ACCEPTABLE AND EFFECTIVE • Condition screened must be a vital or important health condition that affects majority of the population • The disease must have a well-developed natural history • There are means to detect the early stages of the disease • There must be a difference between treatment during the early stage to that of the late stage • The screening test should be acceptable, inexpensive, easy to administer, would cause minimal discomfort, reliable, and valid • The cost of the test should be outweighed by its benefits • Adequate health service provision should be made • Interval for repeating testing is determined SUPPLEMENT: GOLD STANDARD TEST • Screening tests need to be benchmarked against an agreed “Gold Standard” test • A gold standard test is the best available diagnostic test for determining whether a patient does or does not have a disease or condition • a diagnostic test that is usually regarded as definitive (e.g. by biopsy or autopsy). The actual gold standard test may be invasive (e.g. biopsy), unpleasant, too late (e.g. autopsy) to be relevant, too expensive or otherwise impractical to be used widely as a screening test EXAMPLES OF SCREENING AND DIAGNOSTIC TESTS AND POSSIBLE GOLD STANDARDS DISEASE SCREENING GOLD STANDARD Urinary tract • Urinalysis • Urine culture infection • Viral isolation, Dengue • NS1 antigen serological conversion QUICK GUIDE: TEST STATISTICS NOMENCLATURE • It is important for us to define the component of our contingency table or 2x2 table, this is a different approach of definition which I think you need to be familiar too, iba iba lang chika pero iisa lang naman point, BTW these exact definitions were asked, TIP memorize formula using the TP-FP-FN-TN nomenclature. Dr. Mann • A true positive test result is one that detects the condition when the condition is present. • A true negative test result is one that does not detect the condition when the condition is absent. • A false positive test result is one that detects the condition when the condition is absent. • A false negative test result is one that does not detect the condition when the condition is present. • Sensitivity measures the ability of a test to detect the condition when the condition is present. Thus, Sensitivity = TP/(TP+FN). • Specificity measures the ability of a test to correctly exclude the condition (not detect the condition) when the condition is absent. Thus, Specificity = TN/(TN+FP). • Predictive value positive is the proportion of positives that correspond to the presence of the condition. Thus, Predictive value positive = TP/(TP+FP). • Predictive value negative is the proportion of negatives that correspond to the absence of the condition. Thus, Predictive value negative = TN/(TN+FN). https://groups.bme.gatech.edu/groups/biml/resources/useful_documents/Test_Statistics.pdf EVALUATION OF A SCREENING TEST SCREENING TEST VALIDITY • ability of a screening test to accurately identify diseased and non-disease individuals. An ideal screening test is exquisitely sensitive (high probability of detecting disease) and extremely specific (high probability that those without the disease will screen negative) • A 2 x 2 table, or contingency table, is used when testing the validity of a screening test CONTINGENCY TABLE Test DISEASED/(+) NON-DISEASED/(-) Total (+) TP (A) FP (B) A+B (-) FN (C) TN (D) C+D Total A+C B+D A+B+C+ D TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 27 of 79 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ I. SENSITIVITY This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. SUMMARY OF THE 2x2 TABLE PLUS THE FORMULA o Ability of the test to label positive those who really have the disease o Number of true positives (TP) divided by number of all people with the disease o High sensitivity is desirable for a SCREENING TEST! 𝑇𝑃 𝐴 𝑆𝑒𝑛𝑠𝑖𝑡𝑖𝑣𝑖𝑡𝑦 (𝑆𝑛) = 𝑥100 = 𝑥100 𝑇𝑃 + 𝐹𝑁 𝐴+𝐶 • A highly sensitive test means that there are few false negative results; few actual cases are missed. • A false negative means that a subject with the disease is misclassified as not having the disease on the basis of the screening test. The subject is given a misleading impression that he/she is free of the disease and thus does not undergo more suitable diagnostic tests Dr. Mann II. SPECIFICITY o Ability of the test to label negative those who do not have the disease o Number of true negatives (TN) divided by number of all people without the disease o High specificity is desirable for a CONFIRMATORY TEST! 𝑇𝑁 𝐷 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐𝑖𝑡𝑦 (𝑆𝑝) = 𝑥100 = 𝑥100 𝑇𝑁 + 𝐹𝑃 𝐷+𝐵 • A highly specific test means that there are few false positive results • A false positive means that a subject without the disease is misclassified as having the disease on the basis of the screening test. The subject is given the misleading impression that he/she has the disease and thus endures the unnecessary psychological consequences as well has having to undergo possibly invasive diagnostic or treatment procedures MNEMONIC SnOUT SpIN SN-N-OUT = highly SeNsitive SP-P-IN = highly SPecific test, test, when Negative, rules OUT when Positive, rules IN disease disease Value approaching 100% is Value approaching 100% is desirable for ruling out disease desirable for ruling in disease and indicates a low false- and indicates a low falsenegative rate. positive rate • It is important to remember that the PPV or NPV are dependent on both the population under study and the technical characteristics of the screening test • A screening test with relatively high sensitivity and specificity may still have a low PPV if the population prevalence is sufficiently low • Predictive values are dependent on the prevalence of the disease. • The higher the prevalence of a disease, the higher the PPV of a test Dr. Mann PLEASE PLEASE PLEASE kung may tatandaan kayong computation mula sa biostatistics, it will be the ones in this section of evaluation of a screening test. Favorite nila to! Dr. Vidal Dr. Mann • To understand the concept of Sensitivity and Specificity you MUST always remember that you are in the CONTEXT of screening • A screening tool has a result of being “positive” and “negative” • Suppose urinalysis has a 100% sensitivity and specificity meaning kung ano result ng test we are 100% sure na tama ang result. • Example: nag request ka ng urinalysis for one patient and the result is POSITIVE so you can say that your patient has UTI and kung negative naman wala siyang UTI. • So with the working definitions: Sensitivity – is the test's ability to correctly designate a subject with the disease as positive SN-N-OUT = highly SeNsitive test, when Negative, rules OUT disease • If urinalysis is 100% sensitive at lumabas sa resulta ng patient mo ay NEGATIVE for UTI then you can RULE OUT the possibility that your patient has UTI. Because you know that your test is highly sensitive meaning Kaya niya ma identify 100% kung sino lang ang may UTI talaga. So kung negative ka sa test you can confidently RULE out that disease that is why we use the mnemonic SN-N-OUT • What if urinalysis naman ay 100% specific? Again, remember our working definitions: Specificity – is the test's ability to correctly designate a subject without the disease as negative SP-P-IN = highly SPecific test, when Positive, rules IN disease • So nag request ka ng Urinalysis lumabas na result ay POSITIVE so you can say that your patient has UTI so you RULE IN the possibility of your patient having UTI. Kaya we use the mnemonic SP-P-IN Dr. Mann III. POSITIVE PREDICTIVE VALUE (PPV) o The probability of having the condition, given a positive test o Number of true positives divided by number of people who tested positive for the disease 𝑇𝑷 𝐴 𝑷𝑃𝑉 = = 𝑇𝑷 + 𝐹𝑷 𝐴 + 𝐵 IV. NEGATIVE PREDICTIVE VALUE (NPV) o The probability of not having the condition, given a negative test o Number of true negatives divided by number of people who tested negative for the disease. 𝑇𝑵 𝐷 𝑵𝑃𝑉 = = 𝐹𝑵 + 𝑇𝑵 𝐶 + 𝐷 • The figure below depicts the relationship between disease prevalence and predictive value in a test with 95% sensitivity and 95% specificity. • Using the same screening test in a population with a higher prevalence increases positive predictive value. • Conversely, increased prevalence results in decreased negative predictive value. WHEN TO MINIMIZE FALSE POSITIVES Reducing incorrect positive results holds significance when the expenses or dangers associated with subsequent treatment are significant, especially in cases where the ailment isn't life-threatening. For instance, in elderly men with prostate cancer or when obstetricians evaluate the risks posed by a false positive maternal serum AFP test. This test might lead to further procedures like amniocentesis, ultrasonography, heightened fetal monitoring, causing anxiety for the parents and potentially labeling the unborn child, all of which must be weighed against the potential advantages. WHEN TO MINIMIZE FALSE NEGATIVES We aim to avoid any incorrect negatives in cases where the illness commonly shows no symptoms and is either • severe, advances rapidly, and responds better to early treatment OR • easily transmits from person to person. Dr. Vidal ✔GUIDE QUESTIONS The Philippines, in 2025, recovers from the COVID-19 pandemic, and now the disease is well-managed in the public health level. Epidemiologists have estimated the nationwide baseline prevalence of the disease to be at 5%. You have a highly sensitive (90%) and specific (90%) test that you want to develop for use in the entire country as a point-of-care test, and you are piloting it in the Philippine General Hospital, where the prevalence of COVID-19 is around 20%. What will happen to the positive predictive value if you utilize it among communities nationwide? A. Positive predictive value will increase. B. Positive predictive value will decrease. C. Positive predictive value will remain unchanged. D. Any prediction with the positive predictive value cannot be made at this point. Answer: B TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 28 of 79 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. ✔GUIDE QUESTIONS What happens to the negative predictive value as prevalence falls? A. Negative predictive value will increase. B. Negative predictive value will decrease. C. Negative predictive value will remain unchanged. D. Any prediction with the negative predictive value cannot be made at this point. LRs can be used to project the change in the odds of having a particular condition from what we first thought (i.e., the pretest odds) to the odds after the test results are interpreted (i.e., the posttest odds). Answer: A What happens to the sensitivity and specificity of the test as prevalence falls? A. Sensitivity and specificity will increase B. Sensitivity and specificity will decrease C. Sensitivity and specificity will remain unchanged D. Any prediction with the sensitivity and specificity cannot be made at this point Odds are harder to interpret probabilities are easier. But to do this a “translation” step must be taken. Answer: C V. LIKELIHOOD RATIOS • likelihood ratios are used for assessing the value of performing a diagnostic test. • Although well established, sensitivity and specificity have some deficiencies in clinical use. o These are population measures, not individual measures. • What clinicians need is a measure that combines the true and false positives (or negatives) into one. The predictive values were such an attempt. o However, this measure is critically dependent on the population chosen and the prevalence of disease. Likelihood Ratio of a POSITIVE TEST 𝑃𝑟𝑜𝑏𝑎𝑏𝑖𝑙𝑖𝑡𝑦 𝑡ℎ𝑎𝑡 𝑡𝑒𝑠𝑡 𝑖𝑠 (+) 𝑎𝑚𝑜𝑛𝑔 𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 𝐿𝑅8 = 𝑃𝑟𝑜𝑏𝑎𝑏𝑖𝑙𝑖𝑡𝑦 𝑡ℎ𝑎𝑡 𝑡𝑒𝑠𝑡 𝑖𝑠 (+)𝑎𝑚𝑜𝑛𝑔 𝑁𝑂𝑁 − 𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 𝑆𝑛 = 1 − 𝑆𝑝 Likelihood Ratio of a NEGATIVE TEST 𝑃𝑟𝑜𝑏𝑎𝑏𝑖𝑙𝑖𝑡𝑦 𝑡ℎ𝑎𝑡 𝑡𝑒𝑠𝑡 𝑖𝑠 (−) 𝑎𝑚𝑜𝑛𝑔 𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 𝐿𝑅9 = 𝑃𝑟𝑜𝑏𝑎𝑏𝑖𝑙𝑖𝑡𝑦 𝑡ℎ𝑎𝑡 𝑡𝑒𝑠𝑡 𝑖𝑠 (−)𝑎𝑚𝑜𝑛𝑔 𝑁𝑂𝑁 − 𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 1 − 𝑆𝑛 = 𝑆𝑝 • Likelihood ratios (LR) in medical testing are used to interpret diagnostic tests. Basically, the LR tells you how likely a patient has a disease or condition. The higher the ratio, the more likely they have the disease or condition. Conversely, a low ratio means that they very likely do not. Therefore, these ratios can help a physician rule in or rule out a disease. • Pre-test probability o is simply the prevalence of disease in a population. o Is the proportion of people in the population at risk who have the disease at a specific time or time interval, i.e. the point prevalence or the period prevalence of the disease. In other words, it is the probability − before the diagnostic test is performed • Post-test probability o This is the proportion of patients testing positive who truly have the disease. It is similar to the positive predictive value but apart from the test performance also includes a patientbased probability of having disease o pre-test probability refers to the chance that an individual has a disorder or condition prior to the use of a diagnostic test • NOMOGRAM o a diagram representing the relations between three or more variable quantities by means of a number of scales, so arranged that the value of one variable can be found by a simple geometric construction, for example, by drawing a straight line intersecting the other scales at the appropriate values By comparing the pre- and post-test probabilities, it is possible to determine whether the probability of diagnosis has risen (i.e., the posttest probability has increased) or fallen (i.e., post-test probability has decreased). In this way, it is possible to provide comprehensive information about a screening test in order to enable informed choice. Rather than looking at diagnostic tests as a yes or no answer to the question of whether a patient has disease, it makes us realize that positive or negative results simply increase or decrease the likelihood of disease, judged on the basis of our history and physical examination. NOMOGRAM FOR LR Bayes Nomogram: Draw a line connecting the baseline probability (pretest probability) with the value for the likelihood ratio for the test used. Extend this line to the right to find the posttest probability. (Adapted from Fagan TJ. Nomogram for Bayes Theorem. N Engl J Med. 1975;293(5):257.) https://www.healthknowledge.org.uk/content/pre-and-post-test-probability PRACTICE SAMPLE COMPUTATION Question: A researcher develops a new tumor marker for pancreatic cancer, he then compares it to tissue histology. There was a total of 300 patients, 100 patients were found to have pancreatic cancer, of these, 70 tested positives for the tumor marker, the tumor marker was also positive in 15 patients without pancreatic cancer. Tumor TISSUE HISTOLOGY Marker W/DISEASE W/O DISEASE + 70 15 85 30 185 215 100 200 300 When presented with this kind of question, first thing you need to do is to draw a 2x2 table and supply appropriate data in the cell/box Dr. Mann 𝑇𝑃 70 𝑺𝒆𝒏𝒔𝒊𝒕𝒊𝒗𝒊𝒕𝒚 = = = 𝟕𝟎% 𝑇𝑃 + 𝐹𝑁 70 + 30 𝑇𝑁 185 𝑺𝒑𝒆𝒄𝒊𝒇𝒊𝒄𝒊𝒕𝒚 = = = 𝟗𝟐. 𝟓% 𝑇𝑁 + 𝐹𝑃 185 + 15 𝑇𝑃 70 𝑷𝑷𝑽 = = = 𝟖𝟐. 𝟑𝟓% 𝑇𝑃 + 𝐹𝑃 70 + 15 𝑇𝑁 185 𝑵𝑷𝑽 = = = 𝟖𝟔. 𝟎𝟓% 𝑇𝑁 + 𝐹𝑁 185 + 30 70Z 𝑃𝑟𝑜𝑏 𝑜𝑓 + 𝑇𝑒𝑠𝑡 𝑎𝑚𝑜𝑛𝑔 𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 100 = 𝟗. 𝟑𝟑 𝑳𝑹(+) = = 𝑃𝑟𝑜𝑏 𝑜𝑓 + 𝑇𝑒𝑠𝑡 𝑎𝑚𝑜𝑛𝑔 𝑁𝑂𝑁𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 15Z 200 𝑳𝑹(−) = 30< 𝑃𝑟𝑜𝑏 𝑜𝑓 − 𝑇𝑒𝑠𝑡 𝑎𝑚𝑜𝑛𝑔 𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 100 = 𝟎. 𝟑𝟐 = 𝑃𝑟𝑜𝑏 𝑜𝑓 − 𝑇𝑒𝑠𝑡 𝑎𝑚𝑜𝑛𝑔 𝑁𝑂𝑁𝑑𝑖𝑠𝑒𝑎𝑠𝑒𝑑 185< 200 alternative formula: 𝐿𝑅(+) = 0.32 !" #$!% = &.( #$&.)*+ = 9.33 𝐿𝑅(−) = #$ !" !% = #$&.( &.)*+ = Magkapit-kapit tayo ng kamay at magdasal sana po walang computation sa exam, sana po maging display lang calculator ko sa exam, YES! kailangan ng calculator sa boards. At dahil mahal kita oo, mahal kita! ito yung link ng PRC for allowable calculators, baka kasi dalhin mo pa yung calculator ng nanay mong na napakalaki at pag pinipindot eh tumutunog-tunog pa! TINDERA KA GHORL? https://www.prc.gov.ph/allowable-calculators Dr. Mann Dr. Mann LR of <1 LR of 1 LR >1 LR INTERPRETATION decreased likelihood for disease no diagnostic value/no change increased likelihood for disease TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 29 of 79 TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or https://www.facebook.com/topnotchmedicalboardprep/ This handout is only valid for April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. NATURAL HISTORY OF DISEASE PREVENTIVE MEDICINE PREVENTIVE MEDICINE • Branch of medicine focused on keeping people well • Goals: disease prevention, health promotion • “Science and art of preventing disease, prolonging life, promoting physical and mental health and efficiency” BASIC CONCEPTS HEALTH WELLNESS HEALTHCARE state of complete physical, mental, social well-being and not necessarily the absence of disease or infirmity. (WHO) active process of becoming aware & making choices toward a healthy & fulfilling life healthy balance of mind, body & spirit that results in overall feeling of well-being prevention, treatment, management of illness and preservation of health through services offered by health care organizations and professionals. all goods and services designed to promote health, including preventive, curative and palliative PRE-DISEASE STAGE LATENT (ASYMPTOMATIC) STAGE SYMPTOMATIC DISEASE STAGE before disease process begins disease producing process is underway, but without symptoms disease advanced enough to produce clinical manifestations SOCIAL DETERMINANTS OF HEALTH • Nonmedical factors that influence health outcomes. • Conditions in which people are born, grow, live, work and age. • Shaped by distribution of money, power, resources • Responsible for health inequities within and between countries. • Examples: o Employment conditions o Access to health care o Working conditions o Gender equity o Social exclusion o Early childhood development o Access to housing o Globalization, and o Clean water and sanitation Urbanization o Social protection systems (e.g., SSS) LEVELS OF PREVENTION PRIMORDIAL Address broad health determinants rather than personal exposure to risk factors. Minimize future hazards to health Inhibit establishment of risk factors (environmental, economic, social, behavioral, cultural) Ex: outlawing alcohol in certain countries (campaign against drinking is under primary prevention); pictures on cigarette boxes being implemented under Tobacco Regulation Act; Seatbelt Use Acts PRIMARY Predisease Stage SECONDARY Latent Disease TERTIARY Symptomatic Disease Prevents onset & reduces incidence of disease; Health education & promotion; protective measures; environmental sanitation Ex: Vaccination, Malaria prophylaxis, nutritional supplements, health campaigns, occupational and automobile safety measures Early diagnosis and prompt treatment; Screening programs Disability limitation & rehabilitation “soften” impact of an ongoing illness/injury Ex: Self-breast examination; medication compliance to prevent heart attacks or strokes, pap smear, PSA Ex: PT and psychological rehabilitation in cases of deformities; cardiac or stroke rehab programs; post-op chemotherapy CONSEQUENCES OF DISEASE • as defined by WHO International Classification of Functioning, Disability and Health (ICF) IMPAIRMENT Micro level (organ) • functional limitation of activity © Topnotch Medical Board Prep Adapted from: Clinical Epidemiology: The Essentials, 5th Edition, Lippincott Williams & Wilkins, Philadelphia 2013 LEVELS OF PREVENTION Level Primordial Keywords “General Risk” Stage -- Summary Primary “Protection” Pre-disease No disease, no symptom Secondary “Early Detection” Screening Latent With disease, no symptom Tertiary “Complications” Symptomatic With disease, With symptom There are certain scenarios which all level of preventions can be applied, take hypertension as an example: • Primary prevention includes efforts to treat prehypertension through increasing physical activity and weight loss. • Secondary prevention involves treating a hypertensive patient. • Tertiary prevention involves treating a patient with symptoms from a hypertensive crisis to prevent a stroke. Dr. Mann LEVELS OF PREVENTION ✔GUIDE QUESTION _____1. Abstaining from tobacco _____2. Cardiac stress testing _____3. Tumor debulking for stage 4 cancer _____4. Practicing stress management _____5. Colonoscopy _____6. Smoking cessation after myocardial infarction _____7. Oral chemoprophylaxis with doxycycline for flood exposure _____8. Self-breast examination _____9. Physical therapy post-ischemic stroke _____10. Use of condom for STI prevention Answers: 1. Primary 2. Secondary 3. Tertiary 4. Primary 5. Secondary 6. Tertiary 7. Primary 8. Secondary 9. Tertiary 10. Primary • problem with a structure or organ of body (psychological, physiological, anatomical structure or function) DISABILITY Individual level (person) HANDICAP Macro level (societal) Examples: IMPAIRMENT Cataract Dyslexia TEMPORARY Total Disability – < 120 days, except where injury requires medical assistance > 120 days but < 240 days PERMANENT Total Disability – > 120 days, complete sight loss of BOTH eyes, loss of TWO limbs at or above ankle/wrist, permanent complete paralysis of two limbs, brain injury with incurable imbecility & insanity • environmental factor preventing filling of normal life role DISABILITY Inability to see/move around Inability to read HANDICAP Exclusion from work Failing in class RECOMMENDED PREVENTIVE MEASURES • Grade A Recommendation by U.S. Preventive Services Task Force: Cervical Cancer Screening Women aged 21-65 years Colorectal Cancer Adults aged 50-75 years Screening Folic Acid for Prevention Women planning or capable of of Neural Tube Defects pregnancy Hepatitis B Screening Pregnant Adolescents & adults 15-65 HIV Screening years with risk factors; Pregnant TOPNOTCH MEDICAL BOARD PREP PREVENTIVE MEDICINE AND PUBLIC HEALTH MAIN HANDOUT BY DR. MANN For inquiries visit www.topnotchboardprep.com.ph or email us at [email protected] This handout is only valid for the April 2024 PLE batch. This will be rendered obsolete for the next batch since we update our handouts regularly. Page 30 of 79