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Chapter 2 Evidence Based Public Health Background on cigarettes and health While tobacco was introduced to Europe as a new world crop in the early 16005 cigarette smoking did not begin until the development of the cigarette rolling machine byJames Duke in the 18805 Men were the rst mass consumers of cigarettes Cigarette smoking rst became popular among women in the 1920 the health problems of cigarette smoking were not fully recognized until decades after the habit became widespread Lung cancer deaths became to increase as smoking increased across states 5 basic questions we need to ask that together make up what we will call the evidencebased public health approach 39U PP N Problem what is the health problem Etology What isare the contributory causes Recommendations what works to reduce the health impacts implentations How can we get the job done Evaluation How well doesdo the interventions work in practice 5 questions provide a framework for de ning analyzing and addressing a wide range of public health issues and can be applied to cigarette smoking as an example PERIE process How can we describe a Health problem the rst step in addressing a health problem is to describe its burden of disease the occurrence of disability and death due to a disease 0 in public health disability is often called morbidity and death called mortality in addition to describing the burden of disease it is important to describe the course of disease 0 course of disease asks how often the disease occurs and how likely it is to be present currently and what happens once it occurs describing the course of a disease9 and burden requires the use of measurements two basic types of rates that are key to describing a disease incidence rates and prevalence incidence measures the chances of developing a disease over a period of time usually one year 0 often expressed as the number of events per 100000 people in the denominator Incident rate new cases of a disease in a vear of people in the atrisk population mortality rates are a special type of incidence rate that measure the incidence of death due to a disease during a particular year mortality rates are often used to measure burden of disease 0 when most people who develop a disease die from the disease the mortality and incidence rate are similar relationship between the incidence rate and the mortality rate is important because it estimates the chances of dying from the disease once it is diagnosed Prevalence living with a particular diseas in the atrisk population Prevalence is often useful when trying to assess the total impact or burden of a health problem in a population and can help identify the need for services when using rates to describe a problem we often use the rates of mortality and morbidity to describe the burden of disease 0 use the incidence prevalence and casefatality as the three key rates that together provide a description of the course of disease How understanding the distribution of disease helps us generate ideas or hypotheses about the cause of disease public health professionals epidemiologists investigate factors known as quotperson quot and quotplacequot to see if they can nd patterns associations in the frequency of a disease these are called group associations or ecological associations 0 person includes demographic characteristics that describe people such as age gender race and socioeconomic factors 0 quotplacequot implies geographic locations such as a city or state but it also includes connections between people such as a university community or a shared internet site when these types of factors occur more frequenctly among groups with the disease than among groups without the disease we call them risk factors or risk markets using cigarette smoking lung cancer example 0 in terms of person the increases in lung mortality observed in the 1930s through 19505 were far more dramatic among men than among women 0 in terms of place it was found that the relationship between cigarette smoking and lung cancer mortality was present throughout the uniteed states but was strongest in those states where cigarette smoking was most common How do epidemiologists investigate whether there is another explanation for the difference or changes in the distribution of disease Epidemiologists ask Are the differences or changes real or are they artifactual 3 basic reasons that changes in rates may be artifactual rather than real 0 Differences or changes in the interest in identifying the disease 0 Differences or changes in the ability to identify the disease 0 differences or changes in the de nition of the disease in describing the distribution of a problem epidemiologists ask are the differences or changes used to suggest group associations and generate hypotheses artifactual or real an additional step epidemiologists take when looking at rates is age adjustment to conduct age adjustment epidemiologists look at the rates of the disease in each age group and also the age distribution or the number of people in each age group in the population they then combine the rates for each age group taking into account or adjusting for the age distribution of a population What is the implication of a group association Group associations are established by investigations that use information on groups or a population without having information on the speci c individuals within the group These studies are called population comparisons or ecological studies Group associations as a hypothesis that requires investigation at the individual level Group associations can be misleading if they suggest relationships that do not exist at the individual level confounding variables Etiology how do we establish contributory cause Understanding the reasons for disease is fundamental to the prevention of disability and death these reasons are referred to as etiology or causation evidencebased public health approach relies on epidemiological research studies to establish a contributory cause which requires 0 the quotcausequot is associated with the quoteffectquot at the individual level 0 the quotcausequot precedes the quoteffect quot in time altering the quotcausequot alters the quoteffectquot these three de nitive requirements are ideally established using three different types of studies all of which relate potential quotcauses quot to potential quoteffectsquot at the individual level retrospective studies cohort studies or prospective studies randomized controlled trials or experimental studies retrospective studies cohort studies or prospective studies and randomized controlled trials or experimental studies case control studies are most useful for establishing requirement number one that is the quotcausequot is associated with the quoteffectquot at the individual level When a factor such as cigarettes has been demonstrated to be associated on an individual basis with an outcome such as lung cancer this is referred to as a risk factor 0 ex 1940s and early 505 a number of case control studies established that individuals who developed lung cancer were more likely to be regular smokers vs Similar individuals who didn39t smoke these cases controlstudies established requirement number one the case is associated with the quoteffectquot Cohort Studies most useful for establishing requirement number two the quotcausequot precedes the quoteffectquot ex those with the potential quotcausequot or risk factor cigarette smoking and those without the potential quotcase are followed over time to determine who develops the quoteffectquot lung cancer randomized controlled trials are most useful for establishing requirement number threealtering the quotCausequot alters the quoteffectquot 0 chance process known as quotrandomizationquot or quotrandom assignmentquot are used where individuals are assigned to be exposed or into exposed to the potential quotcausequot ie cigarette smoking 0 individuals with and without the potential quotcausequot are followed over time to determine who develops the quoteffectquot 0 once there was a strong suspicion that cigarettes might cause lung cancer randomized controlled trials were not practical or ethical as a method for establishing cigarette smoking as a contributory cause of lung cancer Ful lling Requirements for establishing contributory cause or ef cacy Hypothesis generationD group association populationecological studies 0 Requirement 1D individual association casecontrol studies 0 Requirement ZD quotcausequot precedes quoteffectquot cohort studies 0 Requirement 3 D Altering the quotcausequot alters the quoteffect Randomized Controlled trials or natural experiments 0 contributory cause or ef cacy supportive criterion consistency strength dose response biological plausibility What can we do if we cannot demonstrate all three requirements to de nitively establish contributory cause in evidencebased public health use of supportive or ancillary criteria to make scienti c judgments about cause and effect 0 strength of the relationship implies we are interested in knowing how closely related the risk factor cigarette smoking is to the disease lung cancer The risk for those with the risk factor is greatly increased compared to those without the risk factor strength of relationship is measured by calculating the relative risk the probability of developing the disease if the risk factor is present compared to the probability of developing the disease if the risk factor is not present Ex Relative risk probabilitv of lung cancer for cioarette smokers probability of lung cancer for nonsmokers o Doseresponse relationship higher levels of exposure andor longer duration of exposure to the quotcausequot is associated with increased probability of the quoteffect Ex studies of cigarettes and lung cancer establish that smoking half a pack a day over an extended period of time increases the risk compared to not smoking smoking one pack per day and two packs per day further increase the risk consistency of the relationship consistency implies that studies in different geographic areas and among a wide range of groups produce similar results among populations of varying socioeconomic and cultural backgrounds 0 Biological plausibility implies that we can explain the occurrence of disease based upon known and accepted biological mechanisms EX we can explain the occurrence of lung cancer by the fact that cigarette smoke contains a wide range of potentially toxic chemicals that reach the locations in the body when lung cancer occurs Implications of Contributory Cause important to understand what the existence of a contributory cause implies and what it does not imply ex some individuals never smoke and still develop cancer D cigarette smoking is a contributory cause of lung cancer but not a necessary cause 0 some smoke cigarettes all their lives and do not develop lung cancerlj cigarettes are not a quotsufficient causequot of lung cancer the existence of a contributory cause implies that the quotcausequot increases the chances that the quoteffectquot will develop Its presence does not guarantee that the disease will develop also the absence of cigarette smoking does not guarantee the disease will not develop RECOMMENDATIONS what works to reduce the health impact ln evidencebased public health action should be grounded in recommendations that incorporate evidence 0 evidence serves not only to establish contributory cause but is also central to determining whether or not speci c interventions work recommendations are summaries of the evidence about which interventions work to reduce the health impacts 0 the requirements of contributory cause are the same as those for establishing that an intervention works or has efficacy on the particular population studied 0 recommendations go beyond ef cacy or bene ts and take into account harms or safety Evidencebased recommendations ask about the research evidence supporting the bene ts and harms of potential interventions Evidencebased recommendations are based upon two types of criteria each of which is given a quotscorequot 0 the quality of the evidence scored based in large part upon the types of investigations and how well the investigation was conducted quality of the evidence also determines whether the data collected during an intervention are relevant to its use in a particular population or setting ex data from young adults may not be relevant to children or the elderly quality of the evidence in evidencebased public health is scored as quotgood fair or poorquot 0 good quality of evidence evidence ful lls all the criteria for quality 0 poor quality evidence implies that there are fatal aws in the evidence and recommendations cannot be made 0 fair quality of evidence lies in between having no fatal aws and ful lling all the criteria for quality 0 the magnitude of the impact asks the question How much of the disability andor death due to the disease can be potentially removed by the intervention takes into account the potential bene ts as well as harms of an intervention 0 bene ts harms net bene ts scored substantial moderate small and zeronegative substantial impact may imply that the intervention works extremely well for a small number of people may also imply that the intervention has a modest net bene t for any one individual but can be applied to large numbers of people Evidencebased recommendations combine the score for the quality of the evidence with the score for the impact of the intervention The strength of the recommendations are given grades as follows AMust strong recommendation B Should in general the intervention should be used unless there are go od reasons or contraindications for not doing so C May the use ofjudgment is often needed on an individualby individual basis Individual recommendations depend on the speci cs of an individual39s situation risktaking attitudes and values o D Don39t there is enough evidence to recommend against using the interventions o I Indeterminant insuf cient or I don39t know the evidence is inadequate to make a recommendation for or against the use of the intervention at the present time classi cation of recommendations table Magnitude of the impact Quality of Net bene t Net Bene t Net Bene t Net Bene t the Substantial Moderate Small Zeronegativ evidence e Good A B C D Fair B B C D Poor I I I I insuf cient evidence in addition to recommendations we need to decide the best ways to put the recommendations into practice implementation Issues of ethics culture politics and risktaking attitudes can and should have major impacts on implementation IMPLEMENTATION HOW TO GET THE JOB DONE strong recommendations based upon the evidence are ideally the basis of implementation however it may not be practical or ethical to obtain the evidence needed to establish contributory cause and develop evidencebased implementation 0 One method for examining the options for implementation uses a structure we call the quot WhenWhohow approach when asks about the timing in the course of disease in which an intervention occurs timing allows us to categorize interventions as primary secondary and tertiary Primary interventions take place before the onset of the disease aim of preventing disease Secondary interventions occur after the development of a disease or risk factor but before symptoms appear aimed at early detection of disease or reducing risk factors while the patient is asymptomatic Tertiary interventions occur after the initial occurrence of symptoms but before irreversible disability aim to prevent irreversible consequences of the disease cigarette example primary interventions aim to prevent cigarette smoking secondary interventions aim to reverse the course of disease by smoking cessation efforts or screening to detect early disease tertiary intervention diagnose and treat diseases caused by smoking in order to prevent permanent disability or death Who asks at whom should we direct the intervention individuals groups vulnerable groups or everyone in community or population How three types information education motivation incentives and obligation requirements When Who Howa Level 1 primary prior to 1 individual 1 Information 5 disease or 2 atrisk Education condition group 2 Motivationncenti 2 Secondary prior 3 General ves to symptoms populatio 3 Obligation 3 Tertiary prior to ncommu requirement irreversible nity complications Evaluation Evaluating results Important to evaluate whether an intervention or a combination of interventions has been successful in reducing the problem also critical to measure how much the problem has been eliminated by the intervention 5 and what is the nature of the problem that still remains traditionally evaluation has asked before and after questions in recent years the process of evaluation has been extended to attempt to address how well speci c interventions work and are accepted in practice REAIM framework is used to evaluate such factors Reach Effectiveness Adoption Implementation and Maintenance 0 quotREquot evaluating the potential of the intervention for those it is designed to include or reach as well as those it has the potential to reach in practices Interventions are often applied far beyond the groups for whom they have been designed or investigated 0 quotAIMquot factors examine the acceptance of the intervention in clinical or public health practice in the short and long runs S u m m a ry Question to ask EvidenceBased Public Health Approach 1 Problem What is the health problem 0 What is the burden of a disease or other health problem 0 What is the course of a disease or other health problem 0 Does the distribution of the health problem help generate hypothesis 2 EtiologyWhat are the contributory causes 0 Has an association been established at the individual level 0 Does the cause precede the effect 0 Has altering the cause been shown to alter the effect if not use ancillary criteria 3 Recommendation what works to reduce the health impact 0 What is the quality of the evidence for the intervention 0 What is the impact of the intervention in terms of bene ts and harms 0 What grade should be given to indicate the strength of the recommendation 4 ImplementationsHow can we get the job done 0 When should the implementation occur 0 At whom should the implementation be directed o How should the intervention 5 be implemented 5 EvaluationHow well does the intervention work in practice life expectancy in US 81 women 76 Men average 7847 does health equal wealth culture factors race infant mortality gives you an idea of how the nation is doing as a whole 54 million number of uninsured people in America expensive part time workers tedious age preexisting conditions no longer a factor because of Obama care employer doesn39t provide undocumented unemployed 45 millionD number of people that live below the poverty line 23000 for a family of 4 number has gone up since 20008 50 of whom are children 13 millionljnumber of people who get food stamps family of four about 649 thriftiest individual spends about 146week on groceries 12 individuals social determinants of health 1 where people are born grow up work age socioeconomic status a all of the things that make you who you are built environment manmade space where you live work or play Factors that determine disease disability and death Behavior smokes rislq behavior bodily harm nutrition sleep patterns exercise safety daily habits that you have that may cause your life to be altered for the worst Infection direct cause of diseases Genetics outcomefamily history predisposition based on raceethnicity Geography location lived increases frequency of diseases Environment dangerous factorviolence clean water and air Medical care access to quality care Socioeconomic status intrinsic factors education transportation Population Health Transitions Demographic idea of extended life spans over a period as well as decrease in death rate of children under 1 Epidemiological socioeconomic shifts as well as built in environment increase of disease Nutritional poorly balanced diet D increase in processed foods PER approach Problem Etiology Recommendation Implementation Burden of disease Mortality vs Morbidiy mortality refers to death rates while morbidity refers to the chronic diseases that one may live with Distribution of disease incidence new infection prevalence burden of a health problem infant mortality 611000 4 factors that epidemiologists focus on 1 Group Association 2 person factors age race gender socioeconomic status 3 place factors refers to geography 4 risk indicators Lung Cancer history of smoking 1950 stress reliever working man warpatriotism celebrities health professionals very social no surgeon General smoking was accepted everywhere heavily promoted in the South post industrial revolution women became part of work force and began to smoke as well cigarettes have been heavily regulated between this time 2015 educational campaigns commercial surgeon warning higth stigmatized heavily taxed smoking ban second hand smoke quothealthierquot cigarettes