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Influenza and Pneumonia Mortality Data Trends, California 2000-2007

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At a Glance

  • In 2007, influenza and pneumonia ranked as the 8th leading cause of death in California.
  • The age-adjusted death rate for influenza and pneumonia per 100,000 California residents in 2007 was 18.8, which represents a 35.6 percent decrease from a rate of 29.2 in 2000.
  • Blacks had the highest age-adjusted death rate for influenza and pneumonia, followed by Whites, Asians, and Hispanics during this period.
  • Both female and male age-adjusted death rates for influenza and pneumonia significantly declined from 2000 through 2007.
  • Influenza and Pneumonia deaths increased with age. Approximately 50 percent of all deaths occurred among California residents 85 and older; this increased to over 90 percent when measured from age 65.
  • Out of the 32 California counties that had reliable age-adjusted rates for each study year, 20 counties showed a statistically significant decrease in their influenza and pneumonia rates, while 12 counties did not show any statistically significant change.

The graph below illustrates a decrease in the U.S. and California age-adjusted death rates from 2000 to 2007.  Although the difference decreased over time, California age-adjusted death rates remained slightly higher than the national age-adjusted death rates during this period.

Influenza and Pneumonia Age-Adjusted Death Rates for California and U.S.

This report was authored by Alicia Van Hoy, MA, Research Analyst II.  Please contact PDATrends@cdph.ca.gov for further information.

Background

Among the leading causes of death in California, influenza and pneumonia ranked 8th from 2005 to 2007, which is a decrease from the previous four years when influenza and pneumonia ranked 6th. 1  The two diseases are traditionally classified together, as influenza frequently progresses to pneumonia.  Influenza is a contagious respiratory illness caused by the influenza virus, whereas pneumonia is an inflammation of the lungs often caused by bacteria, viruses, or other infectious agents.2  Since the influenza virus is continually mutating and severity can vary, the number of annual influenza deaths fluctuates.  

People considered at high risk for influenza and pneumonia include the elderly, the very young, and those with underlying health problems, such as chronic obstructive pulmonary disease, diabetes mellitus, congestive heart failure, and sickle cell disease.2  Adults aged 65 and older are more likely to have serious complications from influenza.  Throughout the study period, California residents who were 85 and older accounted for over 50 percent of influenza and pneumonia deaths and when measured from 65 and older accounted for 90 percent of these deaths (Table 1a (PDF)Opens a new browser window.).  It is anticipated the H1N1 influenza virus may affect the age distribution of these deaths for calendar years 2009 and 2010; however, no data is available at this time.

Vaccinations are effective in preventing influenza as well as some strains of bacterial pneumonia, and are recommended for high-risk groups.  The U.S. Department of Health and Human Services developed a 10-year plan to improve the health of the nation.  Known as Healthy People 2010 (HP2010), the plan includes objectives related to increasing the number of people vaccinated against influenza and pneumonia.3  In addition, Goal 1 in the California Department of Public Health Strategic Plan includes objectives to increase the proportion of adults who are vaccinated against influenza and pneumonia.4  Measuring the success of these objectives requires specific data collection methods not covered in this report.

Data on California resident deaths due to influenza and pneumonia from 2000 through 2007 are presented in this report.  The data are extracted from vital statistics records with the underlying cause of death attributable to influenza or pneumonia as defined by the International Classification of Diseases, Tenth Revision (ICD-10) codes J09-J18, in accordance with National Center for Health Statistics (NCHS) reports.5  This code range includes almost all infectious causes of pneumonia (bacterial, viral, fungal, and parasitic), but excludes aspiration pneumonia, lung abscesses, Legionnaire’s Disease, and SARS.

This report presents different measures of influenza and pneumonia mortality, including number of deaths; crude, age-specific, and age-adjusted death rates; and rate differentials and percent change.  The report presents data in four major sections.  The first section discusses the number of deaths by age, sex, and race.  It further examines crude, age-specific, and age-adjusted rates for all Californians.  The second section examines the total number of deaths, and crude, age-specific and age-adjusted rates by sex.  The third section reviews the total number of deaths, and crude, age-specific, and age-adjusted rates by race/ethnicity groups.  The last section of the report examines death trends among California residents at the county level.  In addition, data from the last year under consideration are analyzed in more depth. 

Detailed tables are also provided.  Table 1a (PDF)Opens a new browser window. shows raw counts by age groups and ethnicity.   Table 1b (PDF)Opens a new browser window. and Table 1c (PDF)Opens a new browser window. show the same information by sex and race/ethnicity for years 2000 through 2007.  Table 2a (PDF)Opens a new browser window. shows age-specific death rates by age group, and Table 2b (PDF)Opens a new browser window. and 2c (PDF)Opens a new browser window. show the same information by sex and race/ethnicity.  Table 3 (PDF)Opens a new browser window. shows age-adjusted rates and 95 percent confidence intervals by sex and race/ethnicity from 2000 2007.  Table 4 (PDF)Opens a new browser window. presents raw counts of deaths by county.  Table 5 (PDF)Opens a new browser window. displays age-adjusted rates by county of residence for 2000 through 2007, and Table 6 (PDF)Opens a new browser window. shows 95 percent confidence intervals for the age-adjusted rates in Table 5 (PDF)Opens a new browser window..

California Total Population

The age-adjusted death rate of influenza and pneumonia significantly declined from 2000 to 2007.  In 2007, the age-adjusted death rate for influenza and pneumonia per 100,000 California residents was 18.8, which represented a decrease of 35.6 percent from a rate of 29.2 in 2000.  The chart below displays California age-adjusted death rates from 2000 through 2007 and a trend line.  For additional information about trend analysis, see Technical Notes.

Influenza and Pneumonia Age-Adjusted Death Rates, All Race/Ethnic Groups, California 2000-2007
  

The minor annual variability of influenza and pneumonia death rates between 2004 and 2005 was due to the peak dates of occurrence for the influenza season, which do not necessarily align with the calendar year.6  Refer to Table 3 (PDF)Opens a new browser window.for detailed influenza and pneumonia age adjusted rates.  

Age-Specific Death Rate

Except for those under 1, the risk of dying from influenza and pneumonia increases with age. The minimum and maximum age-specific death rates for age groups that had reliable rates during each year of study were as follows:

• Under 1 year (4.6 to 7.1)
• 25-34 years   (0.4 to 0.8)
• 35-44 years   (1.1 to 1.9)
• 45-54 years   (3.0 to 4.6)
• 55-64 years   (8.4 to 12.0)
• 65-74 years   (32.6 to 47.4)
• 75-84 years   (134.8 to 204.0)
• 85 and older  (582.3 to 947.9)

The age-specific death rate for persons in each age group showed slight year-to-year variations from 2000 through 2007.  Annual age-specific influenza and pneumonia death rates for the California population are displayed in Table 2a (PDF)Opens a new browser window.. For additional information about age-specific death rates and age groups, please see the Technical Notes.

Crude Death Rates

During this period, the actual risk of dying per 100,000 population, or crude rate, ranged from 17.2 to 24.5. (Table 2a (PDF)Opens a new browser window.). 

Crude death rates show the actual rate of dying in a given population, but because populations will vary in age distribution, crude rates do not provide a statistically valid method for comparing sex or race/ethnic groups, geographic areas, or multiple reporting periods.7   Please see age specific or age-adjusted death rates for comparisons.

Number of Deaths

From 2000 to 2007, California recorded 1,872,245 resident deaths, of which 61,523 deaths (3.3 percent) were attributed to influenza and pneumonia.  In 2007, California recorded 233,467 deaths of which 6,522 deaths (2.8 percent) were due to influenza and pneumonia.  The number of deaths by influenza and pneumonia of California residents decreased from 8,355 in 2000 to 6,522 in 2007. 

The number of deaths decreased every year relative to 2000, although slight increases occurred between 2002 and 2003 (86 deaths) and between 2004 and 2005 (206 deaths).  The increase in the number deaths between these years is primarily due to the occurrence of the influenza season peak dates.  Both nationally and in California, the 2003-2004 influenza season peaked at the end of 2003 whereas the 2004-2005 influenza season peaked in the beginning of 2005, resulting in a decrease of deaths during the calendar year of 2004. 6  The chart below illustrates the fluctuation in seasons 2002-2003 through 2005 2006 by week of deaths beginning with week 40 and ending at week 20, the end of the influenza season.

Traditionally, influenza circulates during winter months, but durations and timing can vary.  On the national level, CDC conducts surveillance during the influenza season, which usually begins October (week 40) and continues to mid-May (week 20).8  In addition, the Immunization Branch within the California Department of Public Health conducts influenza surveillance in California within the same time span, using inpatient, pharmacy, sentinel physician, and laboratory data. 9

 

Weekly Deaths Due to Influenza and Pneumonia, During Seasonal Flu Season, California 2000-2006

Number of Deaths by Sex

During 2000-2007, the number of females dying from influenza and pneumonia was 33,410 (54.3 percent), outnumbering male deaths at 28,113 (45.7 percent).  In 2007, females accounted for 54.0 percent (N=3,523) of deaths whereas males accounted for 46.0 percent (N=2,999).  This was consistent throughout the period. 

Number of Influenza and Pneumonia Deaths, All Race/Ethnic Groups by Year, California 2000-2007

Number of Deaths by Race/Ethnicity

Of the 61,523 influenza and pneumonia deaths from 2000 through 2007, Whites accounted for 73.0 percent followed by Hispanics (12.0 percent), Asians (8.3 percent), Blacks (6.1 percent), American Indian (0.3 percent), Two or More Races (0.2 percent), and Pacific Islander (0.2 percent).  A similar pattern is seen in the 2007 race/ethnicity composition, which is the last year examined.  In 2007, out of the 6,522 deaths, there were 4,439 White deaths (68.1 percent) followed by 891 Hispanic deaths (13.7 percent), 690 Asian deaths (10.6 percent), 448 Black deaths (6.9 percent), 14 American Indian deaths (0.2 percent), 23 Two or More Races deaths (0.4 percent), and 17 Pacific Islander deaths (0.3 percent).  Percentages may not add to 100 percent due to rounding.

For additional information regarding the number of events, please see Technical Notes.


Age Distribution of Influenza and Pneumonia Deaths

The average age of a California resident who died of influenza and pneumonia between 2000 and 2007 was 81.4 years with a standard deviation of 14.1 years.  Almost 50 percent of influenza and pneumonia deaths occurred to people aged 85 and older, and when people aged 65 to 84 were included it rose to approximately 90 percent.

The chart below shows the age distributions of influence and pneumonia deaths.

 

Percentage of Influenza and Pneumonia Deaths by Age Group, All Race Groups, California 2000-2007

Male and Female Populations

Even though both male and female influenza and pneumonia age-adjusted death rates declined significantly between 2000 and 2007, males demonstrated a consistently higher age-adjusted death rate than females.  A trend analysis showed a statistically significant downward trend in influenza and pneumonia deaths for both males and females in California during this period.
 
The age-adjusted death rate among females in 2007 was 16.6, which represents a 36.4 percent decrease from a rate of 26.1 in 2000. The age-adjusted death rate among males in 2007 was 22.0, which denotes a 35.5 percent decrease from a rate of 34.1 in 2000.

For additional information about trend analysis, see Technical Notes.  Refer to Table 3 (PDF)Opens a new browser window. for detailed influenza and pneumonia age-adjusted rates and 95 percent confidence intervals.

 Influenza and Pneumonia Age-Adjusted Death Rates, All Race/Ethnic Groups by Sex, California 2000-2007

Age-Adjusted Death Rate by Race/Ethnicity and Sex

Influenza and pneumonia age-adjusted rates were generally higher for males than females within the same race/ethnic groups.  In examining overall trends by sex and race/ethnicity, there were year-to-year fluctuations in age-adjusted death rates by sex and race/ethnic groups.  The age-adjusted rates in the parentheses show the range of minimum and maximum annual rates per 100,000 over the study period.  Black males consistently had the highest mortality rate every year during the period ranging from (32.6 to 43.8), while Asian females continued to have the lowest rate (14.2 to 20.6).  Except for Black males, trend analysis for each sex and race/ethnic group showed a statistically significant downward trend in influenza and pneumonia deaths for California during this period.
 
Refer to Table 3 (PDF)Opens a new browser window. for detailed influenza and pneumonia age-adjusted rates and 95 percent confidence intervals for race/ethnic group populations by sex.  Rates for American Indian, Pacific Islanders and Two or More Races were unreliable during one or more years in the study, so their rates are not discussed here.  However, the rates are displayed in Table 3 (PDF)Opens a new browser window..

 Influenza and Pneumonia Age-Adjusted Death Rates by Race and Sex

Age-Specific Death Rates by Sex

The actual risk of dying from influenza and pneumonia increased with age.  For those age groups who had reliable data during the study period, age-specific death rates for both males and females became greater with increasing age.  For males and females aged 35 and older, the age-specific rates decreased in 2007 relative to 2000.  For males, the age group 45 to 54 showed the largest age specific rate decrease of 37.3 percent from 2000 to 2007.  For females, the age group 35 to 44 reflected the largest age-specific rate decrease of 52.9 percent between 2000 and 2007.  With the exception of the 35 to 44 age group in 2005, female age-specific rates were lower than male age-specific rates for all age categories and years, and this difference generally became greater with increasing age.

Annual age-specific death rates are displayed in Table 2b (PDF)Opens a new browser window.for males and Table 2c (PDF)Opens a new browser window. for females.

Crude Death Rate by Sex

During this period, the actual risk of dying per 100,000 population, or crude rate, ranged for males form 15.9 to 21.7 and females from 18.6 to 27.3.

Crude death rates show the actual rate of dying in a given population, but because populations will vary in age distribution, crude rates do not provide a statistically valid method for comparing sex or race/ethnic groups, geographic areas, or multiple reporting periods.7   Please see age-specific or age-adjusted death rates for comparisons.

Number of Deaths by Sex

Females accounted for more influenza and pneumonia deaths than males in each study year.  Of California’s 62,523 total influenza and pneumonia deaths from 2000 through 2007, females accounted for 54.3 percent of all deaths from influenza and pneumonia, whereas male accounted for 45.7 percent of influenza and pneumonia deaths. From 2000 to 2007, the number of California resident deaths from influenza and pneumonia decreased from 8,355 to 6,522, a decrease of 21.9 percent.  Male deaths decreased by 684 or 18.6 percent from 3,683 to 2,999.  Female deaths decreased by 1,149 or 24.6 percent from 4,672 to 3,523 (Table 1a-1c Opens a new browser window.). 

 Number of Influenza and Pneumonia Deaths by Sex, All Race Ethnic Groups, California 2000-2007

Age Distribution of Deaths by Sex

The average age for death due to influenza and pneumonia for males was 79.3 years and 83.3 years for females during this period.  This means that, on average, males died four years earlier than females.  As indicated by the chart below, females who die from influenza and pneumonia are generally older in age than males.

Age Distribution of Influenza and Pneumonia Deaths by Sex, CA 2000-2007

Race/Ethnic Group Differences

Among race/ethnic groups with reliable rates in all years, Blacks had the highest age-adjusted death rate followed by Whites.  The age-adjusted rates for Asians and Hispanics closely mirrored each other with slight fluctuations.  Overall, the 2007 age-adjusted rates were lower than the 2000 rates for all race/ethnic groups with reliable rates.  The chart below illustrates a trend analysis, which shows a statistically significant downward trend in influenza and pneumonia death rates for Whites, Blacks, Hispanics, and Asians during the 2000 to 2007 period. 

Rates for American Indians, Pacific Islanders and Two or More Races were unreliable during one or more years in the study, so their rates are not discussed here.  However, the rates are displayed in Table 3 (PDF)Opens a new browser window.

Percentage of Influenza and Pneumonia Deaths by Race/Ethnicity, California 2000-2007 

Table 3 (PDF)Opens a new browser window.provides detailed influenza and pneumonia age-adjusted rates and 95 percent confidence intervals by race/ethnic groups.  More information about the race/ethnic groups studied is available in the Technical Notes.  

Specific results were as follows:

  • The Asian influenza and pneumonia age-adjusted death rate in 2000 and 2001 was consistent at 24.5.  The rate declined each subsequent year, except from 2004 and 2005 where there was a slight increase of 0.2.  In 2007, Asians reached their lowest rate during the study period, at 17.7.  
  • The Black influenza and pneumonia age-adjusted death rate has fluctuated within the    eight-year period.  In 2000, the Black age-adjusted rate was 33.0 per 100,000 California residents.  The 2001 rate rose to a high of 33.5, gradually declined to 28.5 by 2005, rose again to 29.4 in 2006, and then reached a low of 27.1 in 2007.
  • The Hispanic influenza and pneumonia age-adjusted death rate started at 24.1 in 2000, climbed to a 2001 high of 24.3, and then progressively declined, reaching a low of 16.2 in 2007.
  • The White influenza and pneumonia age-adjusted death rate decreased from year to year with the exception of 2004 and 2005 where there was a slight increase from 23.4 to 24.0.  However, the rate decline resumed in 2006 and 2007.  The White age-adjusted death rate was 19.3 in 2007, which was a decrease of 36.7 percent from the 2000 rate of 30.5.  

Age-Specific Death Rates by Race/Ethnicity 

The risk of dying from influenza and pneumonia increases with age. Age-specific death rates for all race/ethnic groups were higher in older age groups. Among age-specific death rates for all race/ethnic groups combined, those aged 55 and older decreased from 2000 to 2007 with some fluctuations year-to-year. The age-specific death rate by race/ethnicity from 2000 to 2007 for California residents 55 and older shows Blacks had the highest age-specific death rate for each year of study from age 55 through 84.

Prior to 2004, Whites had the highest age-specific rate among those 85 and older followed by Asians, Blacks and Hispanics. Beginning in 2004, year-to-year fluctuations are apparent within race/ethnic groups. In 2007, Blacks had the highest age-specific rate followed by Whites, Asians and Hispanics.

Annual age-specific influenza and pneumonia death rates by race/ethnic group are displayed in Table 2a (PDF)Opens a new browser window..

Crude Rates by Race/Ethnic Group

During this period, the actual risk of dying per 100,000 population, or crude rate, ranged for race/ethnic groups as follows:
• Asians, 14.9 to 15.9
• Blacks, 19.8 to 21.4
• Hispanics, 6.6 to 7.8
• Whites, 27.0 to 39.9

American Indians, Pacific Islanders and Two or More Races had unreliable crude death rates during one or more years of the study period and, therefore, are not included above.  Annual influenza and pneumonia crude death rates by race/ethnic group are displayed in Table 2a (PDF)Opens a new browser window. under the “All Ages” column.

Crude death rates show the actual rate of dying in a given population, but because populations will vary in age distribution, crude rates do not provide a statistically valid method for comparing sex or race/ethnic groups, geographic areas, or multiple reporting periods.7    Please see age specific or age-adjusted death rates for comparisons.

Influenza and Pneumonia Number of Deaths by Race/Ethnicity

Of the 61,523 influenza and pneumonia deaths in 2000 to 2007, Whites accounted for 73.0 percent followed by Hispanics (12.0 percent), Asians (8.3 percent), Blacks (6.1 percent), American Indians (0.3 percent), Two or More Races (0.2 percent), and Pacific Islanders (0.2 percent). 

For additional information regarding the number of events, please see Technical Notes.

Age Distribution of Influenza and Pneumonia Deaths by Race/Ethnic Groups

There were differences in the average age of influenza and pneumonia deaths among race/ethnic groups.  For example, Pacific Islanders died an average 14 years earlier from influenza and pneumonia than Whites.  The average age and the number of deaths due to influenza and pneumonia between 2000 and 2007 was

  • 67.4 years for Pacific Islanders (N=104)
  • 70.5 years for Two or More Races  (N=133)
  • 75.0 years for American Indians (N=173)
  • 75.8 years for Blacks (N= 3,747)
  • 75.9 years for Hispanics (N=7,352)
  • 81.6 years for Asians (N=5,098)
  • 82.9 years for Whites (N= 44,915)

Over 90 percent of influenza and pneumonia deaths occurred to those aged 65 and over.  However, the percentage of death that occurred to people younger than 65 varied by race/ethnicity and some groups experienced more deaths at younger ages than other groups.  Specifically, the proportion of influenza and pneumonia deaths before 65 was:

  • More than 20 percent among American Indians, Pacific Islanders, and Two or More Races.
  • Between 10 and 20 percent among Blacks and Hispanics
  • Less than 10 percent among Asians and Whites. 

The chart below illustrates the differences between age groups by race/ethnicity.

 Age Distribution of Influenza and Pneumonia Deaths by Race/Ethnicity, CA 2000-2007

Sex Differences within Race/Ethnic Groups

Influenza and pneumonia age-adjusted rates were generally higher for males than females within the same race/ethnic groups.  In examining overall trends by sex and race/ethnicity, there were year-to-year fluctuations in age-adjusted death rates by sex and race/ethnic groups.  The age‑adjusted rates in the parentheses show the range of minimum and maximum annual rates per 100,000 over the study period.  Black males consistently had the highest mortality rate every year during the period, ranging from 32.6 to 43.8, while Asian females continued to have the lowest rate (14.2 to 20.6).  Except for Black males, trend analysis for each sex and race/ethnic group showed a statistically significant downward trend in influenza and pneumonia deaths for California during this period.

Refer to Table 3 (PDF)Opens a new browser window. for detailed influenza and pneumonia age-adjusted rates and 95 percent confidence intervals for race/ethnic group populations by sex.  Rates for American Indian, Pacific Islanders and Two or More Races were unreliable during one or more years in the study, so their rates are not discussed here.  However, the rates are displayed in Table 3 (PDF)Opens a new browser window..

 Influenza and Pneumonia Age-Adjusted Death Rates, by Race/Ethnic Group and Sex, California 2000-2007 

Age-Specific Death Rates by Race/Ethnicity and Sex

Age-specific death rates for all race/ethnic categories grouped by sex were higher in older age groups.  For more specific age-specific death rates, please see the Table 2b (PDF)Opens a new browser window. for males and Table 2c (PDF)Opens a new browser window. for females. 

Crude Death Rates by Race/Ethnicity and Sex

During this period, the actual risk of dying per 100,000 population, or crude rate, ranged for race/ethnic groups as were follows:
• Asians: males 14.9 to17.8, females 13.4 to 15.2
• Blacks: males 18.6 to 22.1, females 19.4 to 22.7
• Hispanics: males 5.8 to 7.4, females 7.4 to 8.6
• Whites: males 24.7 to 34.5, females 29.4 to 45.1

Annual influenza and pneumonia crude death rates by sex and race/ethnic group are also presented in Table 2b (PDF)Opens a new browser window. for males and Table 2c (PDF)Opens a new browser window. for females under the “All Ages” column.

Crude death rates show the actual rate of dying in a given population, but because populations will vary in age distribution, crude rates do not provide a statistically valid method for comparing sex or race/ethnic groups, geographic areas, or multiple reporting periods.7  Please see age specific or age-adjusted death rates for comparisons.

Age Distribution of Influenza and Pneumonia Deaths by Race/Ethnicity and Sex

On average, men died earlier from influenza and pneumonia than women in all race/ethnic groups.  Men of Two or More Races had the lowest average age of influenza and pneumonia death and died an average of approximately 21 years earlier than White women, the longest surviving group.  The average ages of influenza and pneumonia death by sex and race/ethnicity for 2000 through 2007 were as follows:

• American Indian: males 73.8 years, females 76.1 years
• Asian: males 80.7 years, females 82.6 years
• Black: males 72.9 years, females 78.4 years
• Hispanic: males 72.9 years, females 78.6 years
• Pacific Islander: males 64.6 years, females 71.4 years
• Two or More Races: males 63.6 years, females 75.2 years
• White: males 80.8 years, females 84.5 years

The percentage of deaths that occurred to people under age 65 varied, and some groups experienced more deaths at younger ages than other groups.  Specifically, the proportion of influenza and pneumonia deaths before age 65 was:

• More than 30 percent among Pacific Islander males and females, and males of Two or More Races.
• Between 20 and 30 percent Black males, American Indian males, Hispanic males, and Two or More Races females.
• Between 10 and 20 percent Black females, American Indian females, and Hispanic females.
• Less than 10 percent Asian males and females, White males and females.

The two charts below shows the age distribution of influenza and pneumonia by race/ethnicity and sex.

 Age Distribution of Male Influenza and Pneumonia Deaths by Race/Ethnicity, CA 2000-2007 

 Age Distribution of Female Influenza and Pneumonia Deaths by Race/Ethnicity, CA 2000-2007

County of Residence Populations

Thirty-two of the 58 California counties had reliable influenza and pneumonia age-adjusted death rates for each study year.  Thirty-one counties had age-adjusted rates that were lower in 2007 than 2000, and one county demonstrated a higher rate.  San Diego County demonstrated the greatest drop in rates from 30.6 in 2000 to 9.8 in 2007, which represented a 68.0 percent decrease.  Sutter County was the only county that showed a slight increase, from an age adjusted rate of 26.0 in 2000 to 26.6 in 2007.

Out of 32 counties, 20 counties showed a statistically significant downward trend from 2000 to 2007.

Alameda (PDF)Opens a new browser window. Contra Costa (PDF)Opens a new browser window. Humboldt (PDF)Opens a new browser window. Los Angeles (PDF)Opens a new browser window. 
Marin (PDF)Opens a new browser window. Monterey (PDF)Opens a new browser window. Napa (PDF)Opens a new browser window. Orange (PDF)Opens a new browser window.
Placer (PDF)Opens a new browser window. Riverside (PDF)Opens a new browser window. Sacramento (PDF)Opens a new browser window. San Bernardino (PDF)Opens a new browser window.
San Diego (PDF)Opens a new browser window. San Francisco (PDF)Opens a new browser window. Santa Barbara (PDF)Opens a new browser window. Santa Clara (PDF)Opens a new browser window.
Sonoma (PDF)Opens a new browser window. Stanislaus (PDF)Opens a new browser window. Tulare (PDF)Opens a new browser window. Ventura (PDF)Opens a new browser window.

The remaining 12 counties did not show significant change from 2000 to 2007.

Butte (PDF)Opens a new browser window. Fresno (PDF)Opens a new browser window. Kern (PDF)Opens a new browser window. Merced (PDF)Opens a new browser window.
San Joaquin (PDF)Opens a new browser window. San Luis Obispo (PDF)Opens a new browser window. San Mateo (PDF)Opens a new browser window. Santa Cruz (PDF)Opens a new browser window.
Shasta (PDF)Opens a new browser window. Solano (PDF)Opens a new browser window. Sutter (PDF)Opens a new browser window. Yolo (PDF)Opens a new browser window.
 

Trend analyses were not performed in counties where rates for one or more years examined were unreliable.  The counties listed below were not included in trend analysis due to unreliable rates.

Amador (PDF)Opens a new browser window. Calaveras (PDF)Opens a new browser window. Colusa (PDF)Opens a new browser window. El Dorado (PDF)Opens a new browser window.
Del Norte (PDF)Opens a new browser window. Glenn (PDF)Opens a new browser window. Imperial (PDF)Opens a new browser window. Inyo (PDF)Opens a new browser window.
Kings (PDF)Opens a new browser window. Lake (PDF)Opens a new browser window. Lassen (PDF)Opens a new browser window. Madera (PDF)Opens a new browser window.
Mariposa (PDF)Opens a new browser window. Mendocino (PDF)Opens a new browser window. Modoc (PDF)Opens a new browser window. Mono (PDF)Opens a new browser window.
Nevada (PDF)Opens a new browser window. Plumas (PDF)Opens a new browser window. San Benito (PDF)Opens a new browser window. Sierra (PDF)Opens a new browser window.
Siskiyou (PDF)Opens a new browser window. Tehama (PDF)Opens a new browser window. Trinity (PDF)Opens a new browser window. Tuolumne (PDF)Opens a new browser window.
Yuba (PDF)Opens a new browser window.      

Alpine County did not have any influenza and pneumonia deaths within the study period.

California Map
 

In a closer look at 2007, 34 counties had reliable age-adjusted death rates.  Yolo County had the highest rate of 29.2, which was three times higher than the lowest rate of 9.8 in San Diego County.  Alpine, Mono, and Sierra counties had no deaths from influenza and pneumonia in 2007.

Detailed yearly counts are displayed in Table 4 (PDF)Opens a new browser window..  Age-adjusted rates by county of residence are shown in Table 5 (PDF)Opens a new browser window. with corresponding 95% confidence intervals displayed in Table 6 (PDF)Opens a new browser window..

Technical Notes

Number of Events – The number of events provides a description of how a disease affects a population, but it is not useful for examining trends or comparison across groups because the number of events largely depends on population size.7

Crude Rates, Age-Specific Rates, and Age-Adjusted Rates – The crude death rate (number of deaths per population size) is a widely used mortality measure.7 This rate represents the average chance of dying during a specified period for persons in the entire population.  However, crude death rates are influenced by the age distribution of the population.  As such, crude death rate comparisons over time or between groups may be misleading if the populations being compared differ in age composition.

The age specific death rate is defined as the number of deaths occurring in a specified age group divided by the population of the age group, usually expressed per 100,000 population.  Age-specific death rates allow one to compare mortality risk among groups or over time within a particular age group.  Although effective in eliminating the effect of differences in age composition, age-specific comparisons can be cumbersome, because they require a relatively large number of comparisons, one for each age group.10

To control for the effect of age on death rates and provide a single measure, age-adjusted death rates are used.7 Age-adjusted rates are computed by separating deaths into their respective age groups based on the age of the decedent, and computing age-specific rates.  These age-specific rates are then weighted according to the 2000 U.S. Standard Population, and are summed to produce the age-adjusted rate.  Age-adjusted death rates are highly effective for making comparisons among population groups and among geographical areas because they remove the effects of dissimilar age distribution.

Three important caveats apply when using age adjusted rates.  First, the age-adjusted death rate does not reflect the mortality risk of a “real” population.  The actual risk of mortality is represented by the crude death rate.  The numerical value of an age-adjusted death rate depends on the standard used and, as a result, is not meaningful by itself.  Age-adjusted death rates are appropriate only when comparing groups or examining trends across multiple time periods.  A comparison of age-adjusted death rates among groups or periods over time will reflect differences in the average risk of mortality.

Second, age adjusting may mask important information if the age-specific rates between comparison groups do not have a consistent relationship.  As an example, Anderson and Rosenberg (1998)7 demonstrate that the trend in the age-adjusted death rate for cancer does not reflect the complexities in the underlying age-specific rates.  As averages, age-adjusted rates, like other averages, may be misleading, especially when age-specific rates reflect divergent trends over time.  However, usually age-specific rates move roughly in parallel.  Thus, age-adjusted death rates are a widely accepted and useful convention for analyzing trends. 

Finally, because age-adjusted death rates are averages, they represent merely the beginning of an analytical strategy that should proceed to age-specific analyses, and then to an examination of additional sociodemographic, temporal, and geographical variables.

Data Sources – Numerator data are taken from California Department of Public Health death records, and denominator population data are obtained from the Department of Finance 2007 race/ethnic population estimates with age and sex detail, July 2007.  The 2000 U.S. Standard Population was used for calculating age-adjustments in accordance with statistical policy implemented by NCHS.7 Age-adjusted death rates are not comparable when rates are calculated with different population standards, e.g., the 1940 standard population.

Variability of Rates – Rates are sensitive to size variations in both the numerator (the number of vital events that occurred) and the denominator (the estimated population at risk).  For example, in small counties a numerator variation of only a few cases might cause a relatively large shift in a rate, while in a large county such a small change possibly will cause no difference in the rate.  Likewise, a minor revision in a small county population estimate may cause a relatively major change in a county’s vital event rate.  Therefore, caution needs to be exercised when analyzing small numbers, including the rates derived from them. 

Age-specific rates that have fewer than 20 deaths are considered unreliable (Tables 2a-2c).  These rates are not shown and are indicated with an asterisk (*).  Unreliable age-adjusted rates by race/ethnicity and sex (Table 3) and county of residence (Table 5), are displayed with an asterisk (*) and are provided only as a point of information for further investigation.  Events based on no events are denoted with a dash (-).

Sampling Error and Vital Statistics – Vital events are essentially a complete count, because more than 99 percent of all vital events are registered.  Although this number is not subject to sampling error, it may be affected by nonsampling errors in the registration process. 

Nevertheless, the number of vital events is subject to random variation and a probable range of values can be estimated from the actual figures, according to certain statistical assumptions. This is because the number of vital events that actually occurred can be thought of as one outcome in a large series of possible results that could have occurred under the same (or similar) circumstances. 

A 95 percent confidence interval is the range of values for a measurement that would be expected in 95 out of 100 cases.  The confidence intervals are the highest and lowest values of the range.  Confidence intervals tell you how much a measurement could vary under the same (or similar) circumstances. 

Confidence intervals based on 100 deaths or more – When there were 100 deaths or more, a normal approximation was used to calculate confidence intervals.

Confidence intervals based on fewer than 100 deaths – When there were fewer than 100 deaths, a gamma distribution was used to calculate confidence intervals.

Detailed procedures and examples for each type of calculation are given in Technical Notes of  Deaths: Final Data for 2006; National Vital Statistics Reports; National Center for Health Statistics, 2009. 6 

Cause of Death – One of the most important uses for vital statistics data is the study of trends by cause of death. Vital statistics trend research yields valuable information about population health status, emerging public health problems, and at-risk populations, which can be used to develop strategies and allocate resources to improve public health.

Cause-of-death statistics are derived from the medical information reported on the
death certificate by the certifying physician or coroner.  The medical portion of the death certificate has fields for up to four causes of death (immediate, two intervening, and underlying) plus additional fields for recording contributing causes of death.  Up to 20 causes can be entered onto a single death certificate.  The cause-of-death field selected for coding and tabulation in this report is the "underlying cause of death."  This is generally defined as the disease, injury, or complication that initiated the morbid events sequence leading directly to death. 

Deaths by Place of Residence – Mortality data analysis in this report are based on records for all California resident deaths occurring in the fifty states, the District of Columbia, US territories, and Canada; all other worldwide resident deaths are excluded.  Deaths to non-California residents were excluded from analysis.

Age Groups – The following age groups were used to compute age-specific and age-adjusted 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, 65-74 years, 75-84 years, and 85 and older.  

International Classification of Diseases, Tenth Revision (ICD-10) – Beginning in 1999, cause of death has been reported using ICD-10. 11 For more information, see the National Center for Health Statistics ICD-10 page at http://www.cdc.gov/nchs/icd.htm.

Race/Ethnicity –  Beginning in 2000, the federal race/ethnicity reporting guidelines changed to allow 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.12This could contribute to artificially low rates for these groups and the Two or More Races group.  Race groups’ data that are not individually displayed on the tables or figures 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.

References

1 State of California, Department of Public Health. Death Records, 2000-2007.

2 American Lung Association. Pneumonia Fact Sheet. April 2006. URL http://www.lungusa.org/ Accessed September 09, 2009.

3 U.S. Department of Health and Human Services. Healthy People 2010 Objectives (Second Edition, in Two Volumes).  Washington, D.C. January 2001.

4 State of California, Department of Public Health.  Strategic Plan 2008-2010.  July 2008.  URL: http://www.cdph.ca.gov/Documents/CDPH-Strategic-Plan.pdf (PDF)Opens a new browser window. Accessed September 10, 2010.

5 Centers for Disease Control and Prevention. Instructions for Classifying the Underlying Cause of Death, 2008. NCHS Instruction Manual, Part 2a. National Center for Health Statistics. Hyattsville, Maryland. January 2008. URL http://www.cdc.gov/nchs/data/dvs/2a2008Final.pdf (PDF, 2.6MB)Opens a new browser window.Accessed September 09, 2009.

6 Hernon M, Hoyert DL, Murphy SL, Xu J, Kochanek KD, Tejeda-Vera B. Deaths: Final Data for 2006. National Vital Statistics Reports; Vol. 57, No. 14, National Center for Health Statistics Reports. April 2009. URL http://www.cdc.gov/nchs/data/nvsr/nvsr57/nvsr57_14.pdf (PDF)Opens a new browser window.Accessed November 09, 2009.

7 Anderson RN, Rosenberg HM. Age Standardization of Death Rates: Implementation of the Year 2000 Standard. National Vital Statistics Reports; Vol. 47, No. 3. National Center for Health Statistics. Hyattsville, Maryland. 1998.

8 Centers for Disease Control and Prevention .  The Flu Season.  URL: http://www.cdc.gov/flu/about/season/flu-season.htm  Accessed December 7, 2009.

9 State of California, Department of Public Health, Immunization Branch.  California Influenza Surveillance Project.  URL:  http://www.cdph.ca.gov/programs/vrdl/Pages/CaliforniaInfluenzaSurveillanceProject.aspx Accessed September 10, 2010.

10 Curtin L and Klein R. Direct Standardization (Age-Adjusted Death Rates). Healthy People 2000 Statistical Notes; No. 6 - Revised. National Center for Health Statistics. Hyattsville, Maryland. 1995. URL http://www.cdc.gov/nchs/data/statnt/statnt06rv.pdf (PDF)Opens a new browser window.Accessed August 19, 2009.

11 World Health Organization. International Statistical Classification of Diseases and Related Health Problems. Tenth Revision. Geneva: World Health Organization. 1992.

12 Rosenberg HM, et al. Quality of Death Rates by Race and Hispanic Origin: A Summary of Current Research, 1999. Vital and Health Statistics, Series 2, No. 128. National Center for Health Statistics. September 1999.

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