Sources of Epidemiologic Data PDF

SOURCES OF EPIDEMIOLOGIC DATA Prepared by: Giane Paola T. Tanjuaquio, RMT  CONSIDERATIONS IN CHOOSING THE SOURCE OF DATA Research Objective Data Quality Sensitivity Issues Logistics  GENERAL TYPES OF DATA Primary Data: collected by the researcher firsthand Seconda...

SOURCES OF EPIDEMIOLOGIC DATA Prepared by: Giane Paola T. Tanjuaquio, RMT  CONSIDERATIONS IN CHOOSING THE SOURCE OF DATA Research Objective Data Quality Sensitivity Issues Logistics  GENERAL TYPES OF DATA Primary Data: collected by the researcher firsthand Secondary Data: derived from another source that may have other objectives for collecting the data  DATA SOURCES ACCORDING TO TYPE OF DATA Primary Secondary A. Queries A. Computerized Interviews bibliographic databases Questionnaires B. Surveillance data FGD Census B. Observations Registries Direct Hospital records With tools Insurance records  SECONDARY: CENSUS Advantage: o Info on population numbers and distributions by o age, sex and others o Allows small-area estimation and disaggregation like socioeconomic status Disadvantage: o Small number of health questions that can be included  SECONDARY: CIVIL REGISTRY Primary purpose: establishment of legal documents as required by law Major and most effective source of vital statistics **Cause of death together with International Classifications of Disease (ICD)  CIVIL REGISTRY: BIRTH STATISTICS Most visible evidence of a government’s existence of a person as a member of the society Uses of birth certificate data: o Calculation of birth rates o Maternal conditions, length of gestation, birthweight, congenital abnormalities. Problems: completeness of entries, unreliable data from the mother, neonatal defects undetected at birth  CIVIL REGISTRY: DEATH STATISTICS Mortality data have the advantage of being almost totally complete because deaths are unlikely to go unrecorded Cause of Death o Immediate cause of death: final disease, injury, complication o Antecedent cause of death: intervening event between immediate and underlying cause of death o Underlying cause of death: disease that initiated chain of morbid events  CIVIL REGISTRY: DEATH STATISTICS Uses of death certificate: o Calculation of mortality rates o Information on Cause of Death Problems: o Correctness of entries o Stigma associated with certain illnesses o Lack of standardization of diagnostic criteria o Change of coding for Cause of Death over time  NOTIFIABLE DISEASE STATISTICS Reportable diseases o Selected for being epidemic-prone o Targeted for eradication or elimination o Subject to international health regulation Uses o Monitor progress towards disease reduction targets o Measure achievements of disease prevention activities o Identify hidden outbreaks or problems so that early action may be taken  NOTIFIABLE DISEASE Category 1 o acute flaccid paralysis, anthrax, adverse event following immunization, human avian influenza, measles, meningococcal disease, neonatal tetanus, paralytic shellfish poisoning, rabies, SARS, outbreaks, clusters of diseases, unusual diseases or threats Category 2 o Acute blood diarrhea, acute encephalitis, acute hemorrhagic fever, acute viral hepatitis, bacterial meningitis, cholera, dengue, diphtheria, influenza-like, leptospirosis, Malaria, Non-neonatal tetanus, pertussis, typhoid and paratyphoid fever  INSTITUTION-BASED SURVEILLANCE DATA Within the Health Sector o Case reporting o Morbidity and mortality data o Availability and quality of services o Services delivered and commodities provided o Resources Beyond the Health Sector o Food and agricultural records o Occupational reports o Police records  DATA PRIVACY AND CONFIDENTIALITY Republic Act 10173: Data Privacy Act of 2012 Executive Order No. 2 s. 2016: Freedom of Information  SENSITIVE PERSONAL INFORMATION (RA 10173) Individual’s race, ethnic origin, marital status, age, political affiliations, etc. Individual’s health, education, genetic or sexual life of a person, etc. Issued by government agencies like SSS number, licenses, tax returns, etc.  DATA SHARING Voluntary release of information by one investigator or institution to another for purposes of scientific research Advantage: enhancement of knowledge Issues: o Loss of control over intellectual property o Loss of privacy and confidentiality of the research subject  DATA LINKAGE Joining data from two or more sources Requires interoperability of data sources o Talk with each other o Use of common identifying features to connect data records on a single individual  INTERNATIONAL CLASSIFICATION OF DISEASES (ICD) Diagnostic classification standard for all clinical and research purposes Assigns codes for diseases, disorders, injuries and other related health conditions o Easy Storage and Retrieval of Information o Track trends in diseases across time o Sharing and comparison of health data across countries  OTHER CLASSIFICATIONS International Classification of Functioning, Disability and Health (ICF) International Classification of Health Interventions (ICHI) MEASUREMENT AND ERRORS IN MEASUREMENT  MEASUREMENT A number or label assigned to empirical properties of a variable according to rules Numbers: numerals that have quantitative meaning Labels: attributes that have qualitative meaning  CLASSIFICATION (LABELS) Categorizing each subject into 2 or more mutually exclusive groups Examples: o Nutritional status o Severity of pain o Disease status  QUALITY OF MEASUREMENTS The fewer / smaller the errors, the better the measurements Errors o Misclassification o Deviation  OPERATIONAL DEFINITION Prerequisite for making measurements Example: WEIGHT o Contextual: measurement of gravitational force acting on an object o Operational: result of an object on a Newton spring scale  SOURCES OF ERRORS Observer: examiner, interviewer System: coding and classifying systems Subjects Instrument Data processing procedures  OBSERVER ERROR Differences or changes in the diagnostic criteria used by most clinicians Differences or changes in the application of diagnostic criteria by individual clinicians Prior knowledge  SYSTEM ERROR Defects or changes in o Classification of diseases / causes of death o Coding if diseases / causes of death  SUBJECT ERROR Behavioral o Recall problems o Unwillingness to disclose information Interactive responses o Response modified by the behavior of interviewer o Response modified by knowledge that one is being observed or studies Biologic variability o Random or short-term fluctuations in some biological factors  INSTRUMENT ERROR Equipment / mechanical instrument Single index instrument o Analytic or scaling problems of combining information from 2 or more items to form an overall index or indicator of the factor/disease Interview schedule/questionnaire: unclear instructions Abstraction form: not properly labeled, incomplete/ unclear Observation Checklist: incomplete/unclear  ABSTRACT AND CONCRETE VARIABLES Abstract o Not measured directly o Not easily defined o Measured by combining the results of 2 or more item scores into single index Concrete o Measured directly o Easily defined o Closely related to observed variables  INDICATORS OF VARIABLE Single o Obvious and has one indicator Composite o Not so obvious and can have multiple indicators Proxy indicator  INDICATORS OF VARIABLE Proxy indicator  DATA PROCESSING Human errors which involves o Processing o Data abstraction o Transcription o Improper use of software o Software viruses/bugs  CRITERIA FOR ASSESSING QUALITY OF MEASUREMENT Reliability: the extent to which the measurements obtained are reproducible or repeatable → Precision Validity: the extent to which measurements reflect the true values of the theoretical factors that the observed variable is supposed to measure → Accuracy  VALIDITY Sensitivity: proportion of people labelled positive by the test among those with the disease (confirmed) Specificity: proportion of people labelled negative by the test among those without the disease (confirmed) Predictive value (+): proportion of people who tested positive who have the disease (presumptive) Predictive value (-): proportion of people who tested negative among those without the disease (presumptive)