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Chapter 10: Healthcare Statistics

Health Information Management Technology: An Applied Approach

Third Edition

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Descriptive Statistics

• Most common type of statistics encountered by health information technician

• Describe population

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Types of Data

• Measuremento Scales of measurement

•Nominal-level data•Ordinal-level data•Interval-level data•Ratio-level data

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Scales of Measurement

• Nominal-level datao Groups or categorieso Measures data by nameo Groups are mutually exclusiveo Example: race

• Ordinal-level datao Some ordero Order is meaningful – not numbero Example: staging pressure ulcer

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Scales of Measurement

• Interval-level datao Ordered and continuous datao Zero point is arbitrarily established

o Intervals between successive values are equal

o Example: temperature

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Scales of Measures

• Ratio-level datao Highest level of measuremento Defined unit of measureo Real zero valueo Intervals between successive values are equal

o Example: length of stay

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Discrete and Continuous Data

• Discrete variables: o Nominal or ordinal datao Fall into categorieso Example: Gender

• Continuous variableso Interval or ratio datao Includes fractionso Can perform mathematically calculations

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Ratios, Proportions, and Rates

• Indicate number of times something happens

• Examples: morbidity, mortality, and natality

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Ratio

• Quantities being compared may be completely independent or show part of wholeo Independent

•255 patients discharged alive, 15 died

o Part of whole•15 patients died out of 270 discharges

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Proportions

• Type of ratio• Quantity is part of whole

o Numerator is always included in denominator•2 patients have cancer / 2 patients with cancer + 8 without cancer = 0.2

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Rates

• Used to measure event over time.• May be used in performance improvement studies

• Number of cases occurring during a given time period / total cases or population at risk during the same time period

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Ratio, Proportion, and Rates

• Roundingo Policy should state 1 or 2 decimal points

o Round up at 5 or higher

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Measures of Central Tendency and Variability

• Mean• Median• Mode• Variability

o Rangeo Varianceo Standard deviation

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Frequency Distribution

• Values a variable can take and number of observations for each value

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Mean

• Arithmetic average of frequency distribution

• Disadvantageso Fractional valueso Sensitive to extreme measures

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Median

• Midpoint of a frequency distribution

• Advantageso Relatively easy to calculateo Based on whole distribution—not portion

o Outliers do not influence it

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Mode

• Most frequent observation• Advantages

o Easy to obtain and interpreto Not sensitive to extremeso Easy to communication and explain

• Disadvantageso Not descriptive when mode does not occur often and there is a large number of observations

o May be more than one modeo Does not provide information on entire distribution

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Range

• Difference between smallest and largest value

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Graphic Display of Data

• Presents large quantities of information• Purpose is to communicate information about data

• Graph shouldo Display datao Allow user to think about meaning of datao Avoid distortion of datao Encourage user to make comparisonso Reveal data at several levels—broad overview to fine detail

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Tables

• Orderly arrangement of values that groups data into rows and columns

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Characteristics of Tables

• Self-explanatory• All sources should be specified• Headings for columns and rows should be specific and understandable

• Row and column totals should have been checked for accuracy

• Enter zero or dash rather than leave cell blank

• Categories should be mutually exclusive and exhaustive

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Data Alignment

• Text in table should be aligned at lefto Heading may be centered

• Numeric values should be right aligned

• Decimals should be aligned

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Charts and Graphics

• Emphasize points and analyze and clarify relationships among variables

• Principleso Distortiono Proportion and scaleo Abbreviationso Coloro Print

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Bar Charts

• Displays data from one or more variables

• Bars may be horizontal or vertical

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Pie Chart

• Slices of pie show proportional contribution of each part

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Line Graph

• Display time trends• X-axis shows unit of time• Y-axis shows variable being plotted• Line connecting series of points• Several sets of data can be presented on one grapho Different lines

• Y-axis can be numbers or percent

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All Graphs Should:

• Be easy to read• Use proper scale• Complete and accurate title• Informative legend

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Histogram

• Displays frequency distribution

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Histogram vs. Bar Graph

• Bar grapho Data falls into groups or categorieso Categories are noncontinuous (discrete)

o Can be in fractions

• Histogramo Continuous variableso May be number or percent

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Frequency Polygon

• Graph depicting frequency of continuous data

• Line format• May have several frequency polygons on one graph

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Hospital Statistics

• Collect information on inpatient and outpatients on daily basis

• Monitor volume of students

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Standard Definitions

• Hospital inpatient• Hospital newborn inpatient• Inpatient hospitalization• Inpatient admission• Inpatient discharge• Hospital outpatient

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Inpatient Census Data

• Census reports patient activity for a 24 hour reporting periodo Inpatients admittedo Inpatients dischargedo Intrahospital transfers

• Take count at same time of data• Account for patients admitted and discharged on same day

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Inpatient Service Day

• Unit of measure for services received by one patient during a 24 hour period

• Daily inpatient census is equal to number of inpatient service days for a single day

• Compiled daily, weekly, monthly, and annually

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Inpatient Bed Occupancy Rate

• Also called percentage of occupancy

• Percentage of official beds occupied by hospital inpatients for given period of time

• Bed count• Bed count days• May be greater than 100%

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Length of Stay Data

• Calculated for each patient after discharge

• Calendar days from day of admission to discharge

• Adjust calculations for hospitalizations that cross calendar months

• Length of stay for patients admitted and discharged on same day is 1

• Total length of stay

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Hospital Death (Mortality Rate)

• Based on number of patients discharged alive and dead from facility

• Gross death rateo Proportion of all hospital discharges that ended in death

• Net death rateo Adjust death rate which excludes patients who died within 48 hours of admission

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Newborn Death Rate

• Newborns are included in hospital’s gross and net death rate

• Calculated separately• Includes only newborns born alive at the hospital

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Fetal Death Rate

• Death that occurs prior to fetus’s complete expulsion or extraction from mother in a hospital facilityo Any length of pregnancy

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Fetal Death Classifications

• Early fetal death: less than 20 weeks or weight of 500 grams or less

• Intermediate fetal death: at least 20 but less than 28 weeks or weight of between 501 and 1,000 grams

• Late fetal death: 28 weeks or weight of more than 1,000 grams

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Maternal Death Rate

• Death of any woman from any cause related to, or aggravated by, pregnancy or its management, regardless of duration or site of the pregnancyo Does not include accidental or incidental causes

• Typeso Direct maternal death rateo Indirect material death rate

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Autopsy Rates

• Examination of dead body to determine cause of death

• Types of autopsieso Hospital inpatient autopsyo Hospital autopsy

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Types of Autopsy Rates

• Gross autopsy rates• Net autopsy rate

o Removes coroner or medical examiner cases

• Hospital autopsy rateo Includes

•Bodies of inpatients who died in hospital excluding coroner or medical examiner

•Bodies of other hospital patients including ambulatory care, home health, and former hospital patients who died elsewhere but whose body is made available for autopsy

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Available for Autopsy Includes

• Autopsy is performed by hospital pathologists or designated physician on body of patient treated at some point in the hospital

• Report of autopsy is filed in health record and in hospital laboratory or pathology department

• Tissue specimens maintained in hospital lab

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Fetal Autopsy Rate

• Performed to determine cause of fetal loss

• Performed on intermediate or late fetal deaths

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Hospital Infection Rates

• Hospital-acquired infection rateso May be calculated for unit or entire hospital

• Postoperative infection rateo Clean surgical case

• Surgical procedure• Surgical operation

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Consultation Rate

• Consultation is when two or more physicians collaborate on patients diagnosis or treatment

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National Vital Statistics System

• Vital statisticso Collection and analysis of data related to: birth, death, marriage, divorce, fetal death, and induced terminations of pregnancy

o Used as part of effort to preserve and improve health of population

• National Vital Statistics Systemo Maintains official vital statistics of the United States

o Part of National Center for Health Statistics

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Vital Statistics

• Standard forms• Model procedures• Standard certificates

o Minimum basic data seto Revise about every 10 years

• Used ino Researcho Epidemiologyo Public health programs

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Certificate of Live Birth

• Collects information on child and parents

• Collects information on pregnancyo Not part of official birth certificate

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Death Certificate

• Used to compile causes of death• Contains

o Decedent informationo Place of death informationo Medical certificationo Disposition information

• Causes of death classified and coded by ICD-10

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Report of Fetal Death

• Completed when pregnancy results in stillbirth

• Containso Information on parentso History of pregnancyo Cause of fetal death

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Report of Induced Termination of Pregnancy

• Records information on:o Place of induced terminationo Type of termination procedureso Patient

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Linked Birth and Infant Death Data Set

• Explores relationships between infant death and risk factors

• Service provided by NCHS

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Population-Based Statistics

• Based on mortality and morbidity rateso Can infer health of population

• Birth rates and measures of infant mortality

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Birth Rates and Measure of Infant Mortality

• Live birtho Delivery of product of conception that shows any sign of life after complete removal from the mother

• Crude birth rate

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Infant Mortality

• Neonatal mortality rateo Up to 28 days of life

• Postneonatal mortality rateo 28 days up to, but not including one year

• Infant death rateo Under one year of age

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Death (Mortality) Rates

• Crude death rateo Measure of actual or observed mortality in a given population

• Cause-specific death rateo Rate of death due to specified causeo May be calculated for entire population, age, gender, or race

• Case fatality rateo Probability of death among diagnosed cases of a disease

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Death (Mortality) Rates

• Proportionate mortality ratioo Measure of mortality due to specific cause for a specific time period

• Maternal mortality rateo Deaths associated with pregnancy for specific community for a specific period of time

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Measures of Morbidity

• Measures to describe presence of disease in community or specific location

• Incidence rateo Frequency of disease in different populations

• Prevalence rateo Proportion of persons in population who have particular disease at a specific point in time or over specified period of time

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National Notifiable Diseases Surveillance System

• Notifiable diseaseo Regular, frequent, and timely information on individuals cases is necessary to prevent and control disease

o Council of State and Territorial Epidemiologists and CDC determine which diseases are reported

o State reporting to CDC is optional

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External Sources of Healthcare Data

• Benchmarking• CDC Resources

o Cancer Surveillance, Epidemiology, and End Results (SEER)

o Fatal Accident Reporting (FARS)o Data 2010o Injury Data and Resourceso Leading Causes of Deatho Mortalityo Natality

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National Center for Health Statistics

• Part of CDC• Examples of NVSS data

o Birtho Mortalityo Linked births/infant deaths

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National Health Care Survey

• National Ambulatory Medicare Care Survey

• National Hospital Ambulatory Medical Care Survey

• National Hospital Discharge Survey• National Survey of Ambulatory Surgery• National Home and Hospice Care Survey• National Nursing Home Survey

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Agency for Healthcare Research and Quality

• Agency of HHS• Mission

o Improve outcomes and quality of healthcare

o Strengthen quality measurement and improvement

o Reduce costs of healthcareo Address patient safety and medical errorso Broaden access to effective services

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Healthcare Cost and Utilization Project (HCUP)

• AHRQ database• Used for benchmarking• Data collected by states data organizations, state hospital associations, private data organizations, and federal government

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Internal Use of Statistics and Patient Data for Research

• Data is turned into information foro Joint Commission standardso State licensing requirementso Evaluation of healthcare providerso Improve organizational performance

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Introduction to the Institutional Review Board

• Required of organizations that conduct research on human subjects

• Committee that protects rights and welfare of research subjectso Functions as ethics committee

• Evaluates risk versus benefits• Informed consent

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Federal Regulation Requires Human Subjects to be Given:

• Description of researching including purpose, timeframe of subject involvement, description of procedures to be followed, and what is experimental

• Description of reasonably foreseeable risks or discomforts

• Benefits to subject or others• Disclosure of any appropriate alternative procedures or treatment

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Federal Regulation Requires Human Subjects to be Given:

• Confidentiality of records• When risk is more than minimal, statement on compensation or medical treatment available if injury occurs

• Who to contact for answers• Statement that participation is voluntary with no penalties for discontinuing participation

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Privacy Considerations in Clinical and Biomedical Research

• HIPAA Privacy Ruleo Protected Health Informationo Defines means by which human research subjects are informed of how health information will be used or disclosed

o Rights to informationo Protects privacy while allowing access to researchers

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Privacy Rule Authorization

• PHI to be used or disclosed• Who is authorized to use or disclose PHI

• Who the covered entity may make the request use or disclosure

• Description of purpose• Expiration date or event• Signature and date

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Privacy Rule Authorization

• Right to revoke authorization at anytime and must be provided with procedure to do so

• If treatment, payment, enrollment, or eligibility of benefits are contingent on authorization and consequences for refusing to sign

• Any potential risk that PHI will be redisclosed by recipient and no longer protected by Privacy rule

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Data Interpretation Issues

• Data can be misinterpretedo Errors in calculationso Errors in presentation of data

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Misleading Presentation of Numbers

• Decisions are made based on data• Making up data• Misinformation

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Ignoring the Baseline

• Comparing raw numbers without adjusting baseline

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Selection Bias

• Sample does not represent population

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Graphical Misrepresentations

• Graphs can be manipulated

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Ethical Guidelines in Statistics

• Data collection, calculation, display, and interpretation must be appropriate and accurate

• Should follow rules of IRB• Use appropriate statistical methods and techniques

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American Statistical Association’s Ethical Guidelines for Statistical Practice

• Present findings and interpretation honestly and objectively

• Avoid untrue, deceptive, or undocumented statementsDisclose any financial or other interests that may affect, or appear to affect, their professional statements