Models of prevention


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Models of prevention

  1. 1. Concepts of Preventionand ControlBYARUN.M
  2. 2. (I) Prevention
  3. 3. The goals of medicine are to promotehealth, to preserve health, to restorehealth when it is impaired, and tominimize suffering and distress.These goals are embodied in theword "prevention"
  4. 4. Prevention; Definition and ConceptActions aimed at eradicating, eliminating orminimizing the impact of disease anddisability, or if none of these are feasible,retarding the progress of the disease anddisability.The concept of prevention is best definedin the context of levels, traditionally calledprimary, secondary and tertiary prevention.A fourth level, called primordial prevention,was later added.
  5. 5. Determinants of PreventionSuccessful prevention depends upon:a knowledge of causation,dynamics of transmission,identification of risk factors and risk groups,availability of prophylactic or early detectionand treatment measures,an organization for applying these measures toappropriate persons or groups, andcontinuous evaluation of and development ofprocedures applied
  6. 6. Preventable Causes of DiseaseBEINGSBiological factors and Behavioral FactorsEnvironmental factorsImmunologic factorsNutritional factorsGenetic factorsServices, Social factors, and Spiritualfactors[JF Jekel, Epidemiology, Biostatistics, and Preventive Medicine, 1996]
  7. 7. Leavell’s Levels of PreventionStage of disease Level of prevention Type of responsePre-disease Primary Prevention Health promotion andSpecific protectionLatent Disease Secondary prevention Pre-symptomaticDiagnosis andtreatmentSymptomatic Disease Tertiary prevention •Disability limitation forearly symptomatic disease•Rehabilitation for lateSymptomatic disease
  8. 8. Levels of preventionPrimordial preventionPrimary preventionSecondary preventionTertiary prevention
  9. 9. Primordial preventionPrimordial prevention consists ofactions and measures that inhibit theemergence of risk factors in the formof environmental, economic, social,and behavioral conditions and culturalpatterns of living etc.
  10. 10. Primordial prevention (cont.)It is the prevention of the emergence ordevelopment of risk factors in countries orpopulation groups in which they have notyet appearedFor example, many adult health problems(e.g., obesity, hypertension) have theirearly origins in childhood, because this isthe time when lifestyles are formed (forexample, smoking, eating patterns,physical exercise).
  11. 11. Primordial prevention (cont.)In primordial prevention, efforts aredirected towards discouragingchildren from adopting harmfullifestylesThe main intervention in primordialprevention is through individual andmass education
  12. 12. Primary preventionPrimary prevention can be defined as theaction taken prior to the onset of disease,which removes the possibility that thedisease will ever occur.It signifies intervention in the pre-pathogenesis phase of a disease or healthproblem.Primary prevention may be accomplishedby measures of “Health promotion” and“specific protection”
  13. 13. Primary prevention (cont.)It includes the concept of "positive health",a concept that encourages achievementand maintenance of "an acceptable level ofhealth that will enable every individual tolead a socially and economically productivelife".Primary prevention may be accomplishedby measures designed to promote generalhealth and well-being, and quality of life ofpeople or by specific protective measures.
  14. 14. Primary preventionSpecific protectionHealth promotionAchieved byHealth educationEnvironmental modificationsNutritional interventionsLife style and behavioral changesImmunization and seroprophylaxischemoprophylaxisUse of specific nutrients or supplementationsProtection against occupational hazardsSafety of drugs and foodsControl of environmental hazards,e.g. air pollution
  15. 15. Health promotionHealth promotion is “ the process ofenabling people to increase controlover the determinants of health andthereby improve their health”.
  16. 16. Approaches for Primary PreventionThe WHO has recommended thefollowing approaches for the primaryprevention of chronic diseases wherethe risk factors are established:a. Population (mass) strategyb. High -risk strategy
  17. 17. Population (mass) strategy“Population strategy" is directed at the wholepopulation irrespective of individual risk levels.For example, studies have shown that even asmall reduction in the average blood pressure orserum cholesterol of a population would produce alarge reduction in the incidence of cardiovasculardiseaseThe population approach is directed towardssocio-economic, behavioral and lifestyle changes
  18. 18. High -risk strategyThe high -risk strategy aims to bringpreventive care to individuals atspecial risk.This requires detection of individualsat high risk by the optimum use ofclinical methods.
  19. 19. Secondary preventionIt is defined as “ action which halts the progress of a diseaseat its incipient stage and prevents complications.”The specific interventions are: early diagnosis (e.g.screening tests, and case finding programs….) andadequate treatment.Secondary prevention attempts to arrest the diseaseprocess, restore health by seeking out unrecognized diseaseand treating it before irreversible pathological changes takeplace, and reverse communicability of infectious diseases.It thus protects others from in the community from acquiringthe infection and thus provide at once secondary preventionfor the infected ones and primary prevention for theirpotential contacts.
  20. 20. Secondary prevention (cont.)Secondary prevention attempts to arrestthe disease process, restore health byseeking out unrecognized disease andtreating it before irreversible pathologicalchanges take place, and reversecommunicability of infectious diseases.It thus protects others from in thecommunity from acquiring the infection andthus provide at once secondary preventionfor the infected ones and primaryprevention for their potential contacts.
  21. 21. Early diagnosis and treatmentWHO Expert Committee in 1973 definedearly detection of health disorders as “ thedetection of disturbances of homoeostaticand compensatory mechanism whilebiochemical, morphological and functionalchanges are still reversible.”The earlier the disease is diagnosed, andtreated the better it is for prognosis of thecase and in the prevention of theoccurrence of other secondary cases.
  22. 22. Tertiary preventionIt is used when the disease process hasadvanced beyond its early stages.It is defined as “all the measures availableto reduce or limit impairments anddisabilities, and to promote the patients’adjustment to irremediable conditions.”Intervention that should be accomplished inthe stage of tertiary prevention aredisability limitation, and rehabilitation.
  23. 23. Disability limitationdiseaseimpairmentdisabilityhandicap
  24. 24. ImpairmentImpairment is “any loss orabnormality of psychological,physiological or anatomical structureor function.”
  25. 25. DisabilityDisability is “any restriction or lack ofability to perform an activity in themanner or within the rangeconsidered normal for the humanbeing.”
  26. 26. HandicapHandicap is termed as “adisadvantage for a given individual,resulting from an impairment ordisability, that limits or prevents thefulfillment of a role in the communitythat is normal (depending on age,sex, and social and cultural factors)for that individual.”
  27. 27. RehabilitationRehabilitation is “ the combined andcoordinated use of medical, social,educational, and vocational measuresfor training and retraining theindividual to the highest possible levelof functional ability.”
  28. 28. RehabilitationMedicalrehabilitationVocationalrehabilitationSocialrehabilitationPsychologicalrehabilitation
  29. 29. Strategy for PreventionAssessExposureIdentifyPopulationsat HighDisease Risk(based on demography /family history,host factors..)ConductResearch onMechanisms(including the study ofgenetic susceptibility)ApplyPopulation-BasedInterventionProgramsEvaluateInterventionProgramsModify ExistingInterventionProgramsInterventionAssessmentEpidemiology Division
  30. 30. (II) Control
  31. 31. ControlConcept of control:The term disease control describes ongoingoperations aimed at reducing:The incidence of diseaseThe duration of disease and consequently therisk of transmissionThe effects of infection, including both thephysical and psychosocial complicationsThe financial burden to the community.
  32. 32. Control activities focus on primaryprevention or secondary prevention,but most programs combine both.controleliminationeradication
  33. 33. Disease EliminationBetween control and eradication, anintermediate goal has been described,called "regional elimination"The term "elimination" is used to describeinterruption of transmission of disease, asfor example, elimination of measles, polioand diphtheria from large geographicregions or areasRegional elimination is now seen as animportant precursor of eradication
  34. 34. Disease EradicationEradication literally means to "tear out by roots".It is the process of “Termination of all transmissionof infection by extermination of the infectiousagent through surveillance and containment”.Eradication is an absolute process, an "all ornone" phenomenon, restricted to termination of aninfection from the whole world. It implies thatdisease will no longer occur in a population.To-date, only one disease has been eradicated,that is smallpox.
  35. 35. MonitoringMonitoring is "the performance andanalysis of routine measurements aimed atdetecting changes in the environment orhealth status of population" (Thus we havemonitoring of air pollution, water quality,growth and nutritional status, etc).It also refers to on -going measurement ofperformance of a health service or a healthprofessional, or of the extent to whichpatients comply with or adhere to advicefrom health professionals.
  36. 36. Surveillancesurveillance means to watch over withgreat attention, authority and often withsuspicionAccording to another, surveillance isdefined as "the continuous scrutiny(inspection) of the factors that determinethe occurrence and distribution of diseaseand other conditions of ill-health"
  37. 37. Objectives of SurveillanceThe main objectives of surveillance are:(a) to provide information about new and changing trendsin the health status of a population, e.g., morbidity,mortality, nutritional status or other indicators andenvironmental hazards, health practices and otherfactors that may affect health(b) to provide feed-back which may be expected tomodify the policy and the system itself and lead toredefinition of objectives, and(c) provide timely warning of public health disasters sothat interventions can be mobilized.
  38. 38. Control of infectious diseases (the 4“C”sControlCases Contacts Carriers CommunityDiagnosisnotificationisolationdisinfectiontreatmentfollow upreleaseobservation detectionEpidemiologicalInvestigation &containmentstandardstrictprotective
  39. 39. Evaluation of controlEvaluation is the process by which results are comparedwith the intended objectives, or more simply the assessmentof how well a program is performing.Evaluation should always be considered during the planningand implementation stages of a program or activity.Evaluation may be crucial in identifying the health benefitsderived (impact on morbidity, mortality, sequelae, patientsatisfaction).Evaluation can be useful inidentifying performancedifficulties.Evaluation studies may also be carried out to generateinformation for other purposes, e.g., to attract attention to aproblem, extension of control activities, training and patientmanagement, etc.
  40. 40. To summarizeThe goals of medicine are to promote health, to preservehealth, to restore health when it is impaired, and to minimizesuffering and distress.These goals are embodied in the word "prevention"Successful prevention depends upon a knowledge ofcausation, dynamics of transmission, identification of riskfactors and risk groups, availability of prophylactic or earlydetection and treatment measures, an organization forapplying these measures to appropriate persons or groups,and continuous evaluation of and development ofprocedures appliedThe objective of preventive medicine is to intercept oroppose the "cause" and thereby the disease process. Thisepidemiological concept permits the inclusion of treatmentas one of the modes of intervention
  41. 41. QuizMatch the following statements. Each option maybe selected once, more than once, or not at all:(a) performing carotid endarterectomy in a patientwith transient ischemic attack(b) recommending regular physical activity to apatient with no known medical problem(C) vaccinating a health care worker againsthepatitis B(d) giving isoniazid for 1 yr to a 28-year-oldmedical student with a positive PPD tuberculinskin test.1. primary prevention 2. secondary prevention3. tertiary prevention 4. health promotion
  42. 42. ThankYou