Premature Mortality Trends 2000-2007 DS 09-09000
The methods used to analyze vital statistics data are important qualifiers providing the basis for data interpretation.
Years of Potential Life Lost (YPLL-75) YPLL-75 is the number of years of potential life lost before age 75. In the past, years of potential life lost before age 65 (YPLL-65) were calculated. However, this measure was replaced in the mid-1990s because of longer average life expectancy in the American population.3 YPLL-75 is obtained by subtracting the age at the time of death from 75. For example, 29 year-old woman who dies from HIV disease would yield 46 years of potential life lost. A 73-year-old man who dies from chronic lower respiratory disease would be counted as two years of potential life lost.
Crude rates for YPLL-75 are calculated by adding the total number of years lost and dividing by the population. This report primarily uses age-adjusted YPLL-75 rates. Compared to crude rates, age-adjusted rates more accurately identify changes in premature mortality occurring over time because age-adjusted rates control for differences in the age distributions of different populations.4 Age-adjusted rates for YPLL-75 are computed by separating years lost into their respective age groups based on the age of the decedent, and computing age-specific rates based on the age group populations. These age-specific YPLL-75 rates are then weighted according to the 2000 U.S. standard population and a single rate is calculated. The following age groups were used to compute age-adjusted YPLL-75 rates: under 1 year, 1-4 years, 5-14 years, 15-24 years, 25-34 years, 35-44 years, 45-54 years, 55-64 years, and 65-74 years.
As with any vital statistics data, caution needs to be exercised when analyzing small numbers, including the rates derived from them. Rates calculated from a small number of deaths and/or population tend to be unreliable and subject to significant variation. YPLL-75 rates based on fewer than 20 deaths are considered unreliable. These rates are not shown in Table 1 (PDF) and are indicated with a dash (-). Unreliable YPLL-75 rates by county of residence in Table 3 (PDF), are displayed in red text and italics and are provided only as a point of information for further investigation.
Numerator data are taken from California Department of Public Health death records, and denominator data are obtained from the California Department of Finance population estimates. The 2000 U.S. standard population was used for calculating age-adjustments in accordance with statistical policy implemented by NCHS.5 Age-adjusted death rates are not comparable when rates are calculated with different population standards, e.g., the 1940 standard population.
The causes of death selected for the YPLL-75 report are based on the following ICD-10 codes: Malignant Neoplasms (C00-C97); Unintentional Injuries (V01-X59,Y85-Y86); Diseases of Heart (I00-I09,I11,I13,I20-I51); Homicide (U01-U02,X85-Y09,Y87.1); Conditions Originating in the Perinatal Period (P00-P96); Suicide (U03,X60-X84,Y87.0); Congenital Malformations (Q00-Q99); Chronic Liver Disease and Cirrhosis (K70,K73-K74); Cerebrovascular Disease (I60-I69); Diabetes Mellitus (E10-E14); Chronic Lower Respiratory Diseases (J40-J47); Human Immunodeficiency Virus Disease (B20-B24); Influenza and Pneumonia (J09-J18); Viral Hepatitis (B15-B19); Nephritis, Nephrotic Syndrome and Nephrosis (N00-N07,N17-N19,N25-N27); and Sudden Infant Death Syndrome (R95).
Deaths by place of residence—The data include only those deaths occurring among residents of California, regardless of the place of death.
International Classification of Diseases, Tenth Revision (ICD-10)—Beginning in 1999, cause of death has been reported using ICD-10.6 For more information, see the National Center for Health Statistics ICD-10 page: http://www.cdc.gov/nchs/icd.htm.
Race/Ethnicity— Beginning in 2000, the federal race/ethnicity reporting guidelines changed, which permitted more than one race to be recorded on death certificates. California initiated use of the new guidelines on January 1, 2000, and collects up to three races per certificate. To be consistent with population data, current reports tabulate race of decedent using all races identified on the certificate.
To meet the U.S. Office of Management and Budget minimum standards for race and ethnicity data collection and reporting, and with the population data obtained from the Department of Finance, this report presents Hispanic and the following non-Hispanic race/ethnic groups: American Indian, Asian, Black, Pacific Islander, White, and Two or More Races. Hispanic origin of decedents is determined first and includes decedents of any race group or groups. Non-Hispanic decedents who were reported with two or three races are subsequently placed in the Two or More Races group. Single non-Hispanic race groups are defined as follows: the “American Indian” race group includes Aleut, American Indian, and Eskimo; the “Asian” race group includes Asian Indian, Asian (specified/unspecified), Cambodian, Chinese, Filipino, Hmong, Japanese, Korean, Laotian, Thai, and Vietnamese; the “Pacific Islander” race group includes Guamanian, Hawaiian, Samoan, and Other Pacific Islander; the “White” race group includes White, Other (specified), Not Stated, and Unknown.
Caution should be exercised in the interpretation of mortality data by race/ethnicity. Misclassification of race/ethnicity on death certificates may contribute to underreporting of deaths in American Indians, Asians, Hispanics, and Pacific Islanders.7 This could contribute to artificially low rates for these groups as well as for the Two or More Races group. Race groups’ data that are not individually displayed on the tables due to unreliable rates are collectively included the state data totals.
Trend Analysis—In this report, linear regression was performed to establish the presence of statistically significant trends over the period examined. The trends identified in the report as statistically significant are those for which an F test yielded a p-value less than or equal to .05 and had R-square values greater than .50 unless otherwise specified. Trend analyses were not performed in cases where rates for one or more years examined were unreliable.