2. Health status indicators based on vital statistics (Statistics Canada)

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Health region level rates are based on the boundaries in effect as of June 2003 unless otherwise noted.

2.1 Provincial vital and cancer statistics

Health indicators based on vital and cancer statistics are produced at the Canada, province and territorial level only, with long time series. These indicators may have different methodologies compared to the regional health indicators (refer to section 2.2). Data on provincial health and on regional health may be the same indicator, but the numbers or rates may differ because of their methodologies. One key difference is that the provincial indicators are based on single years of data, whereas regional level data are based on multiple year averages (refer to section 2.2). For this reason, in addition to certain additional methodological differences, comparisons between these two sources are not recommended.

These provincial health indicators include the Canada/province/territory–only time series data for life expectancy, low birth weight, age–standardized mortality rates, infant mortality, potential years of life lost and cancer incidence.

Age–standardized mortality and cancer incidence rates were based on place of residence. The formula for age–standardization is presented in a later section entitled “Age–standardized mortality rates”. Cancer incidence data from 2001 to 2004 are estimates produced by Health Canada.

Life expectancy is calculated using the Greville method, a widely recognized method of constructing a life table¹. These provincial/territorial life expectancy data were based on single years of mortality and population and were abridged life tables (i.e., 5 year age–sex groupings). Although their methodologies differ, the Greville, Chiang and Keyfitz methods of calculating life expectancy yield similar results². There are no special notes for the provincial vital statistics indicators of low birth weight and infant mortality outside of what is described in the Definitions and Data Sources document.

Potential years of life lost (PYLL) was calculated in the same fashion as the regional–level indicators of the same name, as described in section 2.2.9.

2.2 Regional-level vital statistics indicators

Rates are based on place of residence for indicators derived from birth and death events.

Indicators presented in this product (with the exception of province–only indicators, described above) which were derived from vital statistics, are based on three years of data in both numerator and denominator. For low birth weight, three years of birth data are used in both the numerator and denominator. For infant and perinatal mortality, three years of death or stillbirth data are divided by the same three years of birth data. For mortality, three years of death data (e.g., 2000 to 2002) are divided by three times the mid-year (e.g., 2001) population estimate. In all vital statistics table titles, the year mentioned simply refers to the middle year.

2.2.1 Regional level data quality measures: Confidence Intervals

All data presented have an associated 95% confidence interval (CI). The confidence interval illustrates the degree of variability associated with a rate. Wide confidence intervals indicate high variability, thus, these rates should be interpreted and compared with due caution. Some age–standardized rates were suppressed due to both a very small underlying count plus extremely high variability. Confidence intervals can also be used to determine whether a rate in one health region is statistically below, above or no different than the rate for the same indicator in another health region.

The confidence intervals for the age–standardized rates were produced using the variance derived using the Spiegelman method³ .

where is the standard population (refer to section 2.2.2), is the age–specific standard population, x is the age group (using 5-year age groups),  is the population estimate for the corresponding age group,  is the mean age–specific crude mortality rate and n is the number of years of data used.

Note that when using n years of data,  , where  is the number of deaths in age group x in year i .

The confidence intervals for the crude count, crude rate and birth–related data were produced via the Fleiss method⁴ . Take note that the lower confidence interval (CI) in this formula is constrained by zero, which means the difference between the rate and the lower CI is not always equal to the difference between the rate and the upper CI.

for the lower limit and

for the upper limit where n is the number of events, p is the proportion or rate, c is the standard error (1.96 at 95% confidence) and . Remember that n is comprised of three years worth of data, and , where pop is three years worth of life–years.

2.2.2 Age-standardized rates

Mortality rates, with the exception of crude rates, potential years of life lost (PYLL) and infant and perinatal mortality, as well as cancer incidence and certain CIHI –based data, are age–standardized using the direct method, and the 1991 Canadian Census population structure. The use of a standard population results in more meaningful rate comparisons, as it adjusts for variations in population age distributions over time and across different geographic areas.

Age standardized rates

Age (in years)	Standard population
Less than 1	403,061
1 to 4	1,550,285
5 to 9	1,953,045
10 to 14	1,913,115
15 to 19	1,926,090
20 to 24	2,109,452
25 to 29	2,529,239
30 to 34	2,598,289
35 to 39	2,344,872
40 to 44	2,138,891
45 to 49	1,674,153
50 to 54	1,339,902
55 to 59	1,238,441
60 to 64	1,190,217
65 to 69	1,084,588
70 to 74	834,024
75 to 79	622,221
80 to 84	382,303
85 to 89	192,410
90 and over	95,467
Source: Statistics Canada Cat. No. 84F0208XPB, Causes of Death 1997, Appendix 3

The formula for age–standardized death rate r is:

Where for age group i,  is the age–sex specific death count,  is the population size for a given cause of death and geographical area, and  is the weight for that group. Note that the same weight is used for each sex. To yield a rate per 100,000 population, r is multiplied by 100,000.

2.2.3 Geographic coding (geo-coding) to health regions

Birth and death data have been linked to health regions using postal codes reported with place of residence and converted to census geography using the automated geo–coding system (PCCF Plus)⁵ developed by the Health Statistics Division of Statistics Canada. These data were then aggregated to health region based on correspondence files⁶ developed by the Health Statistics Division with the cooperation of provincial Ministries of Health, Alberta Treasury and BC Stats.

Where postal codes were not available or invalid, additional steps were taken to assign records to health regions using the census subdivision codes for place of residence recorded on the national birth and death database. Stillbirth data, used to calculate perinatal mortality, were linked to health regions solely using census subdivision codes.

2.2.4 Birth statistics

Birth data on the Vital Statistics Database for Ontario are underestimated due to incomplete files. Thus, birth–related indicators (low birth weight, infant mortality and perinatal mortality), particularly for Ontario, should be interpreted with caution.

2.2.5 Life expectancy

This variable was calculated using the Chiang methodology for abridged life tables. The estimates are based on three years (for example, 2000–2002) of mortality data and the mid-year population estimates, as described above. Abridged life tables use five–year age groupings of both population and mortality rate inputs (as opposed to single year age breakdown). Since there is more variability in the number of events by age in smaller geographic areas, abridged life tables are more suitable for the adaptation to a sub–provincial level (health region). Chiang’s method in particular was chosen because it was relatively easy to adapt to the health region level data and included the calculation of standard error (in this case, addressing the variability of deaths from one year to the next).

2.2.6 Disability–free life expectancy

Estimates of disability–free life expectancy are calculated using Sullivan’s method⁷. Essentially, the latter generalizes Chiang’s method⁸.

Sullivan’s method is based on activity limitation rates within a population, according to sex and age group, in the calculation of life expectancy with disability. In the case of people living in health institutions, it was assumed that everyone had at least one activity limitation. For people living in other types of institutions, the hypothesis established is that the activity limitation rate by age group and sex was identical to the population in private households.

Disability–free life expectancy represents the difference between life expectancy and life expectancy with disability. The standard deviations of disability–free life expectancy estimates (and consequently the upper and lower limits of the confidence intervals associated with these estimates) are based on Colin Mathers’ method⁹. This method takes into account both the stochastic fluctuations in the observed death rates and the sampling variability of the activity limitation rates.

Note: The disability data for DFLE came from the 1996 Census of Population. Questions on disability in the Census of Population are generally used to capture the sample of post-censal Health and Activity Limitations Survey. Because of the decision not to conduct this survey in 1996, data on disability from the Census of population of 1996 were neither verified nor imputed. More precisely, no validation was undertaken to check the completeness or consistency of the data, and as a result, no corrections to the data were made. In addition, the data were not adjusted to account for population undercounts.

DFLE estimates will vary according to both the concepts from which they are based and the surveys from which the data are extracted.

DFLE (Volume 2001, No’s. 1 and 2): For these issues, disability was defined as “having any activity limitation or handicap”.

DFLE (Volume 2001, No. 3 and beyond): Disability is defined as “having an activity limitation that affects activities at home, work or at school”. This differs from previous Health Indicators issues by excluding limitations that only affect activities other than home, work or school as well as respondents who stated that they had some form of handicap other than an activity limitation.

2.2.7 Disability-adjusted life expectancy (DALE)

Disability–adjusted life expectancy (DALE) is similar to DFLE , in that they are both measures of quality of life lived and both are based on mortality and disability data. However, DALE is an expectation of life weighted to account for four health states defined in terms of disability. These health states are, in order of greatest to least weight:

• (1) having no activity limitations;
• (2) having activity limitations in leisure time activities and/or transportation;
• (3) having activity limitations at work, home and/or school; and
• (4) institutionalization in a health care facility. Specifically, state #1 has a weight of 1.0; state #2 has a weight of 0.8; state #3 has a weight of 0.65; and state #4 has a weight of 0.5. The sum of life expectancies of persons in a specific age group within a given geography, based on their health states, produces the value of DALE for that specific age group.

The calculation of the confidence intervals for DALE is based on Colin Mathers’ method. Specifically, for any particular age group,

Where  is the standard error, LE denotes life expectancy and 'state n' refers to the specific health state.

2.2.8 Deaths due to medically treatable diseases

The definitions of medically treatable diseases were taken from a paper written by WW Holland¹⁰. This was based on earlier work from JRH Charlton¹¹. The types of medically treatable diseases mentioned in Charlton originally came from a paper by DD Rutstein¹².

All results were age-standardized according to the age group considered for reasonable odds of survival. These age-standardized rates per 100,000 reflect these age groups, not the total population.

The method of calculating confidence intervals was the Spiegelman method (refer to section 2.2.1).

2.2.9 Potential years of life lost

In this publication, death was considered premature if the person died before age 75. This is more reflective of life expectancies in recent years and is more reflective of international standards. Many previous Statistics Canada publications provide PYLL data based on death before age 70. Additionally, PYLL can be presented as an age-standardized rate or as a crude rate; in this publication, it is presented as a crude rate. As well, the denominator can be based on population aged 0 to 74 or for the total population. In this publication, the denominator is based on the former.

In this publication, a PYLL rate was produced, where the weights are taken as proportions of the years lost per death within each age group over the total years lost in all age groups. Each death event is multiplied by its age–specific weight. The sum of all these values represents the total PYLL. The PYLL rate is PYLL per 100,000 population aged 0 to 74. The use of weights allows for the calculation of confidence intervals. The confidence intervals for each PYLL rate were produced by the Spiegelman method (refer to section 2.2.1).

Potential years of life lost rates

Age group	Years lost	Weight
Less than 1	74.9	74.9/636.9
1 to 4	72.0	72.0/636.9
5 to 9	67.5	67.5/636.9
10 to 14	62.5	62.5/636.9
15 to 19	57.5	57.5/636.9
20 to 24	52.5	52.5/636.9
25 to 29	47.5	47.5/636.9
30 to 34	42.5	42.5/636.9
35 to 39	37.5	37.5/636.9
40 to 44	32.5	32.5/636.9
45 to 49	27.5	27.5/636.9
50 to 54	22.5	22.5/636.9
55 to 59	17.5	17.5/636.9
60 to 64	12.5	12.5/636.9
65 to 69	7.5	7.5/636.9
70 to 74	2.5	2.5/636.9
Sum	636.9	1.0

This publication only presents PYLL rates based on the sum of all age groups. Thus, the rate is calculated as follows:

Where  is the sum of PYLL for ages 0 to 74 for the three years of data, w is a weight of 1, and ' POP' is the population aged 0–74 for the middle year of the three years.

To calculate the age-specific PYLL rates:

where i is the specific 5-year age group.

For more information on vital statistics: Birth database (3231), death database (3233).