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INDEX |
TERMS, METHODS, AND COMPUTATIONAL EXAMPLESACQUIRED IMMUNODEFICIENCY SYNDROME (AIDS)(See HIV Disease.)
AGE-SPECIFIC FERTILITY RATE (ASFR)The rate of live births per 1,000 women for the specific age group. This is a more detailed measure than the crude birth rate, as it reflects variations in the birth rate by age groups of the female population.(See Statistical Computation under Fertility Rate for an example.)
AGE STANDARDIZATIONAge standardized is a method of calculation which adjusts a statistical measure for differences in the age/gender structures between populations. With standardized measures, more meaningful comparisons can be made between genders, different time periods, or geographic areas, because the age standardized statistic is calculated as if all populations had the same age/gender population distribution.(See Age Standardized Mortality Rate (ASMR), Standardized Mortality Ratio (SMR), Potential Years of Life Lost Standardized Rate (PYLLSR), and Potential Years of Life Lost Index (PYLLI); for an example, see Statistical Computation.)
AGE STANDARDIZED MORTALITY RATE (ASMR)A summary of age adjusted death rates by age and gender, which have been standardized to a "standard" population (1991 Canada Census) for the purpose of rate comparisons between genders, different time periods or different geographic locations. The ASMR is the theoretical number of deaths that would occur per 10,000 population, if the specific population had the same age structure as the standard population.(See Age Standardization and Standard Population; for an example, see Statistical Computation.)
AIDS(See HIV Disease.)
ALCOHOL-RELATED DEATHSAlcohol-related deaths are based on the ICD-10 diagnostic categories listed below, for which the resulting deaths are directly attributed to the use or abuse of alcohol.
Alcohol is considered to be a direct cause of death if one of the above conditions is listed as the underlying cause of death on the medical certification of death. If, however, any of the above conditions are listed on the certificate as antecedent causes giving rise to the underlying cause or other significant conditions contributing to the death, the death is considered to be indirectly related to alcohol. ICD-10 codes for deaths indirectly related to alcohol are listed below:
Refer to Glossary in previous annual reports for ICD-9 codes. [Return to top of page] ASFR(See Age Specific Fertility Rate.)
ASMR(See Age Standardized Mortality Rate.)
AVERAGE AGEThe average ages of brides, grooms, and mothers of newborns in this annual report are calculated based on information provided on marriage or birth registration forms. The average ages of the population living in data dissemination areas are based on the mid-year population estimates for five year age groups.
AVERAGE AGE POPULATIONThe average age of the population is a grouped average based on the mid-year population estimates for five-year age groups.
BIRTH ORDERDenotes the number position of the present birth relative to previous live births. That is, whether the live birth being counted is the 1st, 2nd, 3rd, etc. live born infant to a particular mother.
BIRTH RATE(See Crude Rates.)
BIRTH WEIGHTThe first weight of the fetus or newborn after birth. For live births this weight should be measured within the first hour of life before significant postnatal weight loss has occurred. Hospitals in BC measure weight in grams; the approximate equivalents in imperial measures are included below for comparisons to other jurisdictions. For statistical and risk assessment purposes, birth weights are grouped as:
BIRTHS(See Total Births.)
BREECH(See Mode of Delivery.)
CESAREAN(See Mode of Delivery.)
COMMUNITYA geographic area defined by a municipal (city, town, village, or district municipality) boundary. In this report, data are provided only for those communities that are incorporated.
CONFIDENCE INTERVAL(See Statistical Test.)CONGENITAL ANOMALIESPhysical defects that existed or date from birth.
CRUDE RATES
DEATH RATE(See Crude Rates.)
DRUG-INDUCED DEATHSDeaths due to drug-induced causes. This category of deaths excludes accidents, homicides, and other causes indirectly related to drug use, as well as alcohol-related deaths and smoking-attributable mortality. The causes of death classified as being drug-induced (as shown below) are based on those used by the National Center for Health Statistics1.
Refer to Glossary in previous annual reports for ICD-9 codes.
1 (National Center for Health Statistics (1993). Technical notes. Monthly Vital Statistics Report. 41 (Suppl. 7), 48).
EARLY NEONATAL DEATHDeath of a child under seven days of age.
ELDERLY GRAVIDAAny woman who was 35 years of age or older at the time of delivery of a live born infant.
EXPECTED DEATHSThe number of deaths expected for residents of a sub-provincial geographic area, based on the age-specific mortality rates for the province as a whole and the population age structure of the sub-provincial geographic area.(See Statistical Computation for an example.) EXPECTED LOW BIRTH WEIGHTThe number of live births with low birth weight (less than 2,500 grams) that would be expected to be born to residents of a sub-provincial geographic area, based on the low birth weight rate for the province as a whole, and the number of births in the sub-provincial geographic area.(See Statistical Calculation under Low Birth Weight Live Births for an example.)
EXPECTED POTENTIAL YEARS OF LIFE LOSTThe number of potential years of life lost (to age 75, as in this report) expected for residents of a sub-provincial geographic area based on the age-specific mortality rates for the province as a whole and the population age structure of the sub-provincial geographic area.(See Statistical Computation under Potential Years of Life Lost Index for an example.)
FERTILITY RATEThe number of live births occurring in a given time period divided by the number of women of child-bearing age for residents of a geographic area. BC rates are per 1,000 women aged 15 to 44. Canadian rates are per 1,000 women aged 15 to 49.(See Total Fertility Rate.)
FORCEPS(See Mode of Delivery.)
GESTATIONAL AGEFetal age or duration of pregnancy measured from the first day of the last normal menstrual period. Gestational age is expressed in completed days or completed weeks (e.g., events occurring 280 to 286 days after the onset of the last normal menstrual period are considered to have occurred at 40 weeks of gestation).
Measurements of fetal growth, as they represent continuous variables, are expressed in relation to a specific
week of gestational age as follows:
HEALTH AUTHORITY(HA)A geographic subdivision of the province used by the Ministry of Health for administrative purposes. The appendices 1 and 3 include data by 6 health authorities. Figure 2 presents a map of the province by HAs.
HEALTH SERVICE DELIVERY AREA (HSDA)A geographic subdivision of the province used by the Health Authorities for administrative purposes. The appendices 1 and 3 include data by 16 Health Service Delivery Areas. Figure 2 presents a map of the province by HSDAs.
HIV DISEASEIn 1987, the World Health Organization added new codes to the International Classification of Diseases (ICD) to identify Acquired Immunodeficiency Syndrome (AIDS) and Human Immunodeficiency Virus (HIV). In ICD-10, these conditions are coded to B20-B24 and are called HIV disease.Refer to Glossary in previous annual reports for ICD-9 codes.
HUMAN IMMUNODEFICIENCY VIRUS (HIV)The virus that causes HIV disease.
ICD-9 CODESThe World Health Organization's International Classification of Diseases, Ninth Revision. This version of ICD was used by the B.C. Vital Statistics Agency for coding of birth complications and causes of death from 1979 until 1999.
ICD-10 CODESThe World Health Organization's International Classification of Diseases and Related Health Problems, Tenth Revision, implemented by the B.C. Vital Statistics Agency on January 1, 2000. The Preamble to Appendix 2 presents a summary of ICD-10.
INFANT MORTALITYDeath of children under one year of age.
INFANT MORTALITY RATEThe number of deaths of children under one year of age expressed as a rate per 1,000 live births. The infant mortality rate is an internationally accepted indicator of the health status of a population.
LBW(See Low Birth Weight.)
LHA(See Local Health Area.)
LIFE EXPECTANCYLife expectancy at age 0 represents the mean number of years a birth cohort (persons born in the same year) may expect to live given the present mortality experience of a population. The life expectancy for a population is a summary measure that reflects the mortality rates for all ages combined, weighted in accordance with a life-table population structure. Life expectancy is an internationally accepted indicator of the health status of a population.
LIVE BIRTHThe Vital Statistics Act defines a live birth as "The complete expulsion or extraction from its mother, irrespective of the duration of the pregnancy, of a product of conception in which, after the expulsion or extraction, there is:(a) breathing; (b) beating of the heart; (c) pulsation of the umbilical cord; or (d) unmistakable movement of voluntary muscle, whether or not the umbilical cord has been cut or the placenta attached."
LOCAL HEALTH AREAA geographic subdivision of the province used by the Ministries of Health for data dissemination purposes, which can be aggregated into Health Authorities (HA), or Health Service Delivery Areas (HSDA). In the tables in this report, four pairs of LHAs have been combined for ease of data presentation. Figure 1 presents a map of the province by local health areas.
LOW BIRTH WEIGHT (LBW)A birth weight of less than 2,500 grams. Low birth weight babies have increased risks of morbidity and premature death.
LOW BIRTH WEIGHT RATEThe number of low birth weight live born babies per 1,000 live births.
MARRIAGE RATE(See Crude Rates.)
MEDICALLY TREATABLE DISEASES, DEATHS DUE TODeaths due to medically treatable diseases are based on Charlton's2classification. The disease categories (shown below) are ones for which mortality could potentially have been avoided through appropriate medical intervention. The calculation of this measure is based on deaths of a specified age where the underlying cause stated on the medical certificate of death falls into one of these categories.
2 Charlton, J.R.H. (1987). Avoidable Deaths and Diseases as Monitors of Health Promotion. In Abelin,T., Z.J. Brzezinski, & V. Carstairs (Eds.), Measurement in Health Promotion and Protection (pp. 467-479). Copenhagen, Denmark: World Health Organization, Regional Office for Europe.
MODE OF DELIVERY
MVA DEATHSMotor Vehicle Accidental Deaths.
NATURAL POPULATION GROWTHThe component increase in a population due to the number of live births less deaths. This increase may often be expressed as a rate, such as per 1,000 population.
NEONATAL DEATHDeath of a child under 28 days of age.OBSERVED DEATHSThe actual number of deaths that occurred in the province to residents of a geographic area in a specified time period.
OBSERVED LOW BIRTH WEIGHT LIVE BIRTHSThe actual number of low birth weight live births that occurred in the province to residents of a geographic area in a specified time period.
OBSERVED PYLLThe actual number of potential years of life lost (to age 75) from deaths that occurred in the province to residents of a geographic area in a specified time period.
OUT-OF-WEDLOCK BIRTHSBirths where the mother of the baby is not lawfully married to the father of the baby.
P-VALUE(See Statistical Test.)PERINATALPertaining to or occurring in the period shortly before, during, and after birth.
POPULATIONMid-year population estimates used in the preparation of this report were obtained from BC STATS, Ministry of Management Services.
POST NEONATAL DEATHDeath of a child between the ages of 28 days and less than one year.
POST-TERM(See Gestational Age.)
POTENTIAL YEARS OF LIFE LOST (PYLL)The number of years of life lost when a person dies before a specified age (75 years). In this report, all deaths are assumed to occur at the midpoint of five-year age groups.(See Statistical Computation for an example.) PRE-TERM(See Gestational Age.)
PYLL INDEX (PYLLI)The ratio of an area's observed PYLL to its expected PYLL. This is a health status indicator.(See Statistical Computation for an example.)
PYLL STANDARDIZED RATE (PYLLSR)An age-standardized measure of an area's PYLL, expressed in terms of a rate per 1,000 population, adjusted to a standard population (1991 Canada Census). This is a health status indicator.(See Statistical Computation for an example.)
PYLLI(See PYLL Index.)
PYLLSR(See PYLL Standardized Rate.)
QUINTILEA ranking is derived by dividing a group (e.g., LHAs within British Columbia) into five subgroups, each with equal numbers of LHAs. These divisions are derived from a ranking of the group members according to the value of a measure, such as the SMR or the PYLLI.
SAM(See Smoking-attributable Mortality.)
SAM(%)(See Smoking-attributable Mortality.)
SIDSSudden Infant Death Syndrome.
SMOKING-ATTRIBUTABLE MORTALITY (SAM)The absence on death certifications of complete and reliable data on smoking as a contributing factor requires that estimation or other techniques be used to approximate the extent of smoking-attributable deaths. Estimation methods, while not precise, may at least provide a general indication of the extent of such deaths. The method used here is based on the concept of attributable risk.
To define attributable risk mathematically, consider d0 and d1 respectively to represent the death rates, in a
given time period, in two cohorts from a population - those not exposed and those exposed to a given risk
factor. The attributable risk of this factor, AR1 , would then be:
The number of adult (35+ years of age) smoking deaths in British Columbia were estimated for 19 diseases.
Smoking-attributable deaths are derived by multiplying the smoking-attributable mortality percentage
expressed as a decimal fraction by the number of deaths in each cause of death category listed below.
Relative-risk data from the American Society's Cancer Prevention Study (CPS-II) 1982-19883 were selected for use, as they have been widely used for similar analyses. The data from the CPS-II established the age groups and the classification of smokers (current, former, and never) for which smoking prevalence data were required. The relative risk age categories were for 35+, or 35-64 and 65+. BC prevalence rates for smoking were provided in the Tobacco Use in BC (1997) survey commissioned by the BC and Yukon Health and Stroke Foundation4. Refer to Glossary in previous annual reports for ICD-9 codes.
3 Centres for Disease Control. (1990). Smoking and health: A national status report. (DHSS publication no. (CDC) 87-8396). 2nd Edition. Rockville, MD: U.S. Department of Health and Human Services. 4 Detailed information from the Tobacco Use in BC, ANGUS REID GROUP survey results, September 1997.
SMR(See Standardized Mortality Ratio.)
STANDARD POPULATIONA reference population of known age distribution used in the calculation of standardized indicators to adjust for variations in population age structures in different geographic areas or time periods. For SMR and PYLLI calculations the standard population is the British Columbia population for the year(s) concerned. The 1991 Canadian Census is used as the standard population in the calculation of ASMR and PYLLSR.
STANDARDIZED MORTALITY RATIO (SMR)The ratio of the number of deaths occurring to residents of a geographic area (e.g., LHA) to the expected number of deaths in that area based on provincial age-specific mortality rates. The SMR is a good measure for comparing mortality data that are based on a small number of cases or for readily comparing mortality data by geographical area. SMR is an internationally recognized health status indicator.(See Age Standardization and Standard Population ; for an example see Statistical Computation.)
STATISTICAL COMPUTATIONThe following provides the reader with computational examples of how various measures are calculated. In the examples, LHAs have been employed as the geographic unit of analysis. All data shown in the examples are hypothetical.
For the Local Health Area:  [Return to top of page]
For the Local Health Area:
For the Local Health Area:
For the Local Health Area:    
For the Local Health Area:  Where: O = observed PYLL; E = expected PYLL; dij = observed deaths in age group i and gender j; eij = expected deaths in age group i and gender j; Yij = age at midpoint of age group i and gender j; pij = LHA population for age group i and gender j; Pij = provincial population for age group i and gender j; Dij = provincial deaths for age group i and gender j. 1) Observed PYLL (O) The number of potential years of life lost (PYLL) based on the number and age at death of deaths that occurred in the LHA. For example, for age group under one year of age and gender j, the observed PYLL are: Observed PYLL=deaths x age factor= dij(75-Yij)= 3 x 74.5 = 223.5 2) Expected PYLL (E) The number of potential years of life lost (PYLL) expected for residents of the LHA based on the PYLL from the expected deaths in the age group. For example, for age group under one year of age and gender j, the expected PYLL are:
Expected PYLL = expected deaths x age factor = eij(75-Yij) = Dij/Pij x pij x (75-Yij) 
Note that this method is both age and gender standardized. For the Local Health Area:  Where: dij = observed deaths in age group i and gender j; and eij = expected deaths in age group i and gender j. 1) Observed Deaths (d) The actual number of deaths that occurred in the LHA. For example, for age group under one year of age, the observed deaths are three. 2) Expected Deaths (e) The number of deaths expected for residents of the LHA based on the age specific mortality rates for the province as a whole and the population age structure of the LHA. For age group under one year, the expected deaths are:  Where: pij = LHA population for age group i and gender j; Dij = provincial death for age group i; and gender j; and Pij = provincial population for age group I and gender j.
STATISTICAL TEST
(a) p-value less than or equal to a reject null hypothesis at level a, (b) p-value > a do not reject the null hypothesis at level a,
and we call the data statistically significant when the null hypothesis is rejected and not significant
otherwise.
  Where: Rl = Rate for LHA l; Rp = Rate for the province; Ol = Observed number for LHA l; and Op = Observed number for the province.
If the Lower Limit > 0, then Rl is statistically significantly higher than Rp;
Where:
 Where: Ôl = Ol if Ol> El; otherwise Ôl = Ol + 1
STILLBIRTHThe Vital Statistics Act defines a stillbirth as "The complete expulsion or extraction from its mother after at least 20 weeks of pregnancy, or after attaining a weight of at least 500 grams, of a product of conception in which, after the expulsion or extraction, there is no breathing, beating of the heart, pulsation of the umbilical cord, or unmistakable movement of voluntary muscle."The definition of a stillbirth has changed over the years. From July 1, 1962 until January 1, 1986, the definition of a stillbirth did not include the phrase "or after attaining a weight of at least 500 grams. " From 1950 until July 1, 1962, the definition of a stillbirth was: the birth of a viable fetus after at least 28 weeks pregnancy in which pulmonary respiration does not occur, whether death occurs before, during, or after birth.
STILLBIRTH RATE(See Crude Rates.)
TEENAGE MOTHERSMothers less than 20 years of age.
TERM(See Gestational Age.)
TFR(See Total Fertility Rate.)
TOTAL BIRTHSThe number of live births plus stillbirths.
TOTAL FERTILITY RATE (TFR)The rate is calculated by summing all of the age-specific birth rates multiplied by the number of years by which the age-specific birth rates are grouped (this assumes the same number of women in each age group). "The total fertility rate indicates the number of births that a group of 1,000 women would have if they experienced, during their childbearing years (i.e., age 15 to 44 years), the age-specific birth rates observed in a given calendar year. It is a hypothetical measure that shows the implications of current levels of fertility by age for completed family size." (National Center for Health Statistics. Supplements to the monthly vital statistics report: advance reports, 1987. National Center for Health Statistics. Vital Health Stat 24 (4) p. 5. 1990.)(See Statistical Computation for an example.)
TOTAL PYLLThe total number of potential years of life lost prior to an established cut-off point of 75 years.
VERY LOW BIRTH WEIGHTA birth weight of less than 1,500 grams.
UCOD(See Underlying Cause of Death)
UNDERLYING CAUSE OF DEATH (UCOD)The World Health Organization defines the underlying cause of death as "(a) the disease of injury which initiated the train of events leading directly to death, or (b) the circumstances of the accident or violence which produced the fatal injury."
VACUUM(See Mode of Delivery.)
VERTEX(See Mode of Delivery.)
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