State Trends in Health Risk Factors and Receipt of Clinical Preventive Services Among US Adults During the 1990s

Abstract

Context Monitoring trends is essential for evaluating past activities and guiding current preventive health program and policy efforts. Although tracking progress toward national health goals is helpful, use of national estimates is limited because most preventive health care activities, policies, and other efforts occur at the state or community level. There may be important state trends that are obscured by national data.

Objective To estimate state-specific trends for 5 health risk factors and 6 clinical preventive services.

Design Telephone surveys were conducted from 1991 through 2000 as part of the Behavioral Risk Factor Surveillance System.

Setting and Participants Randomly selected adults aged 18 years or older from 49 US states. Annual state sample sizes ranged from 1188 to 7543.

Main Outcome Measures Statistically significant changes (P<.01) in state prevalences of cigarette smoking, binge alcohol use, physical inactivity, obesity, safety belt use, and mammography; screening for cervical cancer, colorectal cancer, and cholesterol levels; and receipt of influenza and pneumococcal disease vaccination.

Results There were statistically significant increases in safety belt use for 39 of 47 states and receipt of mammography in the past 2 years for women aged 40 years or older for 43 of 47 states. For persons aged 65 years or older, there were increases in receipt of influenza vaccination for 44 of 49 states and ever receiving pneumococcal vaccination for 48 of 49 states. State trends were mixed for binge alcohol use (increasing in 19 of 47 states and declining in 3), physical inactivity (increasing in 3 of 48 states and declining in 11), and cholesterol screening (increasing in 13 of 47 states and decreasing in 5). Obesity increased in all states and smoking increased in 14 of 47 states (declining only in Minnesota). Cervical cancer screening increased in 8 of 48 states and colorectal cancer screening increased in 13 of 49 states. New York experienced improvements for 8 of 11 measures, while 7 of 11 measures improved in Delaware, Kentucky, and Maryland; in contrast, Alaska experienced improvements for no measures and at least 4 of 11 measures worsened in Iowa, North Dakota, and South Dakota.

Conclusions Most states experienced increases in safety belt use, mammography, and adult vaccinations. Trends for smoking and binge alcohol use are disturbing, and obesity data support previous findings. Trend data are useful for targeting state preventive health efforts.

It is well established that premature mortality can be reduced through changes in health risk factors and timely receipt of clinical preventive services. For instance, there is a strong scientific consensus that tobacco use, excessive alcohol use, physical inactivity, obesity, and failure to use safety belts increase mortality risk1-6 and that timely receipt of adult immunizations, screening for breast and cervical cancer, and screening for high blood cholesterol levels can reduce the risk of premature death.7-11

Population-based monitoring of progress toward health goals is a critical part of the assessment function of public health and a key role for health agencies.12 At the national level, monitoring of health trends is well established through the Healthy People initiative that began in 1980.13-15 Such information is essential for guiding current and future efforts to improve health. State improvements in preventive health depend on many factors, including socioeconomic status and other variables (eg, employment status, income level, and insurance status), state and local programs and policies, clinical standards of care, and the presence of consumers who are informed about prevention and health care services.

Although tracking progress toward national health goals is helpful, the use of national estimates is limited because most preventive health care activities, policies, and other efforts occur at the state or community level. Important state trends may exist that are obscured by national data.16,17 State mortality rates vary widely,18 as do the prevalence of health risk factors and receipt of clinical preventive services19; state mortality rates are known to correlate strongly with state risk factor estimates for certain measures, such as coronary heart disease20 and lung cancer (Suzanne Proctor, MSPH, written communication, National Center for Health Statistics, June 25, 2001).

A few studies have examined state-specific trends for health risk factors and receipt of clinical preventive services during part of the 1990s,17,21-26 but they focused on trends for specific measures (eg, obesity and mammography screening) rather than on a more comprehensive examination of multiple measures. These studies used different methods and years and did not account for the role of changes in demographics, thus limiting their usefulness. The purpose of this study was to provide a comprehensive overview of state trends during the 1990s, using a standard statistical approach, for 5 adult health risk factors and 6 clinical preventive services that are known to have a substantial impact on preventable morbidity and mortality in the United States. The trends we examined include cigarette smoking, binge alcohol use, physical inactivity, obesity, and safety belt use, as well as receipt of mammography, cervical cancer screening, colorectal cancer screening, cholesterol screening, and vaccination for influenza and for pneumococcal disease.

Methods
Source of Data
Data used in this study came from the Behavioral Risk Factor Surveillance System (BRFSS) from 1991 through 2000. Details of the BRFSS have been published elsewhere.27-29 The BRFSS is a state-based system of health surveys coordinated by the Centers for Disease Control and Prevention. Begun in 15 states in 1984, by 1994 all states were participating in the BRFSS. Data are obtained monthly by state health departments through telephone surveys of randomly selected persons aged 18 years or older.

The system obtains self-reported information primarily on health risk factors related to chronic disease and injury, including health risk behaviors, receipt of clinical preventive services, and health care access. In most states, the BRFSS is the sole source for these data. Results from 30 methodological studies suggest that most measures included in the BRFSS are both reliable and valid.30

For the study period from 1991 through 2000, the total sample size increased from 87 846 to 182 444 and the median state sample size increased from 1790 to 3338. Annual state sample sizes ranged from 1188 to 7543. Median annual response rates, based on persons actually reached by telephone, ranged from 84.1% in 1991 to 59.6% in 2000.

A change in the survey design in 1993 resulted in data collection at different intervals for certain topics. In all years, questions were asked on cigarette smoking, obesity, mammography, and cervical cancer screening (Papanicolaou test); in odd-numbered years for alcohol use, safety belt use, colorectal cancer screening, cholesterol screening, pneumococcal vaccination, and influenza vaccination; and in even-numbered years for physical inactivity (Table 1). Because of variation in the year in which states began to participate in the BRFSS and because of missing data for certain years, trend data are only available for selected measures for Arizona, Arkansas, Kansas, and Nevada and are not available for the District of Columbia and Wyoming.

To provide stable estimates of state trends, analyses were restricted to topics that were included on the survey by 1993 and for which data were collected for 4 or more years. Data on safety belt use were collected only through 1997. The questions used to define receipt of a Papanicolaou test changed in 1992; thus, analyses for these questions were restricted to 1992 through 2000.

Definitions
Definitions for the 5 health risk factors and the 6 clinical preventive services are listed in Table 1. We used definitions that are consistent with those used to measure national Healthy People 2000 objectives14,15,31,32 or that are commonly used within the respective subject areas.

Except for cigarette smoking, mammography, and colorectal cancer screening, the wording of survey questions was highly consistent across all years for all measures. In 1996, a question that was used to define current cigarette smoking was changed to make BRFSS questions comparable with other major national surveys (Table 1). Based on data from the National Health Interview Survey, this change increased the estimate of smoking prevalence by about 1 percentage point.33 Because of this question's change, we adjusted model-based prevalence estimates downward by 1 percentage point for the year 2000.

The introductory sentence to the mammography screening question was altered slightly in 1992 to describe a mammogram as a radiograph that involves pressing the breast between 2 plastic plates. This change resulted in a slight decrease in the prevalence of mammography use,34 but we did not adjust our data because the wording change occurred only in 1 year and the overall effects were minor. Because of changes in screening recommendations, the colorectal cancer screening question referred to proctoscopy in 1993 and 1995, proctoscopy or sigmoidoscopy in 1997, and sigmoidoscopy or colonoscopy in 1999. We were unable to examine trends for fecal occult blood testing, another method used for colorectal cancer screening, because these questions were not included until 1997.

To estimate alcohol use, we examined state trends in binge drinking, which was defined as consumption of 5 or more alcoholic beverages on 1 or more occasions in the past 30 days. Binge drinking is strongly associated with many health risk behaviors and adverse outcomes, including alcohol-impaired driving, unprotected sexual activity, and acute alcohol poisoning.2,35

There is no consensus on the most appropriate survey questions for assessing moderate or vigorous physical activity.36 Because of this lack of consensus, we chose to examine trends in physical inactivity, which we defined as participating in no leisure-time physical activity in the past 30 days. Using guidelines from the World Health Organization,37 we defined obesity as having a body mass index of at least 30 kg/m2. Safety belt use was defined as always using a safety belt because this definition produces estimates similar to those obtained from observational surveys.38,39

Recommendations differ on the optimal age for beginning routine breast cancer screening.40 In this study, we examined trends in receipt of mammography in the past 2 years for women aged 40 years or older. For receipt of cervical cancer screening within the past 3 years, analyses were restricted to women aged 18 years or older with an intact uterus. Cholesterol screening was defined as receipt of a blood cholesterol test within the past 5 years among persons aged 18 years or older.32 For receipt of influenza vaccination in the past year and ever receiving a pneumococcal vaccination, analyses were restricted to persons aged 65 years or older.31,32

Statistical Analyses
Because all 11 of the outcomes we modeled were prevalences, we used logit models to evaluate state trends. Using logit models allowed us to evaluate trends while controlling for the effects age, sex, race/ethnicity, and education level have on the various outcomes. Thus, the unit of analysis in all models was the individual survey respondent. Respondents' answers were used to define dichotomous outcome variables. The independent variables in the models were year, age, sex, race/ethnicity (white non-Hispanic, black non-Hispanic, Hispanic, or other), and education level (less than high school graduate, high school graduate, and some college/college graduate). SUDAAN was used to take into account the complex survey design in the modeling.41

To determine the appropriateness of a linear trend, we added year2 (a quadratic term) to the models and examined its P value, setting the significance level at P<.01 because of the large sample sizes and the number of states. If the P value for the quadratic term was not less than .01, we assumed the trend was linear. Of the 525 total state trends examined, a total of 458 (87%) met our assumption of linearity. For these models, we removed the quadratic term, refit the models, and used the estimated β coefficients for year to calculate odds ratios (ORs). These ORs reflect the average annual change per year (or per 2 years) in overall state odds estimates for each outcome, controlling for the effects of demographic changes on each outcome. Odds ratios with 99% confidence intervals (CIs) that excluded the null value of 1 were considered statistically significant. β Coefficients with P<.01 were considered statistically significant.

For the 67 trends (13%) that violated the linearity assumption, we treated year as a categorical variable and used the contrast between the estimate available from the last year of the decade with the estimate from the first year of the decade. The β value for the contrast was used to calculate an OR that compared the overall odds estimate from the last year with the overall odds estimate from the first year of the decade. These ORs represent the average change across the entire decade using the first and last data points available, controlling for the effects of demographic changes on each outcome. β Coefficients with P<.01 were considered statistically significant.

Finally, we used our models to determine the predicted prevalence at the start and end of the decade for each measure in each state. Estimates were indirectly standardized to the age, sex, race/ethnicity, and education level of a typical person based on the pooled annual BRFSS sample population from all states.41,42 Although these model-based values are not the actual prevalence estimates, they allow for appropriate comparisons across states over time and are similar to published state estimates.30

Results
State trends during the 1990s for the 5 health risk factor measures are summarized in Table 2. Median state estimates showed a substantial increase in both obesity and safety belt use and a slight increase in binge alcohol use, and were essentially unchanged for physical inactivity and cigarette smoking.

Smoking prevalence decreased significantly only in Minnesota; in contrast, it was unchanged in 32 states and increased in 14 states primarily located in the Midwest (7 states) and South (4 states). Binge alcohol use declined in Arizona, Minnesota, and Pennsylvania, remained unchanged in 25 states, and increased in 19 states. Increases were concentrated primarily in the South (8 states) and Midwest (6 states), although baseline prevalence estimates were generally low in southern states. The prevalence of physical inactivity decreased in 11 states, increased in 3 states (Arizona, Minnesota, and Montana), and was unchanged in 34 states; about half the states registering declines were in the South. The prevalence of obesity increased in all states, and safety belt use increased in 39 of 47 states.

The pattern for receipt of clinical preventive services was different from that for health risk factors (Table 3). Median state estimates increased substantially for mammography, influenza immunization, and pneumococcal immunization, as most states experienced increases for these measures. In contrast, median estimates increased only slightly for colorectal cancer, cervical cancer, and cholesterol screening. Receipt of mammography for women aged 40 years or older in the prior 2 years increased significantly in 43 of 47 states (all except Alaska, Colorado, Minnesota, and Washington). Receipt of cervical cancer screening increased in 8 of 48 states, all of which were in the Northeast or South (Connecticut, Delaware, Kentucky, Maryland, Massachusetts, New York, Pennsylvania, and Rhode Island).

The use of colorectal cancer screening increased in 13 of 49 states, with 11 of these states in the Northeast or South. Trends in the receipt of cholesterol screening demonstrated a mixed picture, as increases occurred in 13 of 47 states (11 of which were in the South), but declines in screening occurred in Iowa, Minnesota, North Dakota, South Dakota, and Washington state. The trend in the increased use of vaccinations among persons aged 65 years or older was almost nationwide. Increases in the receipt of influenza vaccination in the past year occurred in 44 of 49 states, and the percentage of the older population who had ever received pneumococcal vaccination increased in 48 of 49 states.