Hypertension Screening in Children and Adolescents — National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, and Medical Expenditure Panel Survey, United States, 2007–2010

Mary G. George, MD

Xin Tong, MPH

Charles Wigington, MS

Cathleen Gillespie, MS

Yuling Hong, MD, PhD

Division for Heart Disease and Stroke Prevention, National Center for Chronic Disease Prevention and Health Promotion, CDC

Corresponding author: Mary G. George, Division for Heart Disease and Stroke Prevention, National Center for Chronic Disease Prevention and Health Promotion, CDC. Telephone: 770-488-8092; E-mail: mgeorge@cdc.gov.

Introduction

Hypertension and prehypertension have been increasing among children and adolescents since the 1990s (1,2). During 2003–2006, among children and adolescents aged 8–17 years, the prevalence of prehypertension was approximately 14% in boys and approximately 6% in girls, and the prevalence of hypertension was estimated to be 3%–4% in various studies (1,3,4). During 1997–2006, hospitalization rates for children and adolescents with a diagnosis of hypertension doubled, from approximately 18 cases per 100,000 pediatric hospital discharges in 1997 to approximately 35 cases per 100,000 in 2006 (5). Among children and adolescents with hypertension, as many as one in three has target organ damage, especially left ventricular hypertrophy (4,6). Accumulating evidence supports the theory that elevated blood pressure levels in adolescence are a precursor of elevated blood pressure in adulthood, making it important to identify elevated blood pressure in childhood (7). An analysis of the National Childhood Blood Pressure database found that 14% of adolescents with prehypertension developed elevated blood pressure within 2 years (8).

A Healthy People 2020 objective (objective HDS-5.2) is to reduce the prevalence of hypertension among children and adolescents by 10% (3). In 2004, the National High Blood Pressure Education Program (NHBPEP) Working Group on Children and Adolescents recommended that health-care providers measure blood pressure in children aged >3 years who are seen in a medical setting (9). The Bright Futures guidelines developed by the American Academy of Pediatrics (AAP) at the request of the Health Resources and Services Administration (HRSA) recommends that children and adolescents aged 3–17 years receive blood pressure screening during their annual preventive care visit (10,11). However, in 2006, only 85% of children and adolescents had a preventive health-care visit (12). The National Quality Forum (NQF) has endorsed blood pressure screening as a performance measure, with documentation in the medical record as to whether the result is abnormal for children during the year they reach age 13 years and again during the year they reach age 18 years (NQF #1552 and NQF #1553) (13).

The reports in this supplement provide the public and stakeholders responsible for infant, child, and adolescent health (including public health practitioners, parents or guardians and their employers, health plans, health professionals, schools, child care facilities, community groups, and voluntary associations) with easily understood and transparent information about the use of selected clinical preventive services that can improve the health of infants, children, and adolescents. The topic in this report is one of 11 topics selected on the basis of existing evidence-based clinical practice recommendations or guidelines for the preventive services and availability of data system(s) for monitoring (14). This report analyzes 2007–2010 data from the National Ambulatory Medical Care Survey (NAMCS), the National Hospital Ambulatory Medical Care Survey (NHAMCS), and the Medical Expenditure Panel Survey (MEPS) to estimate the prevalence of blood pressure measurement at visits among children and adolescents aged 3–17 years. These estimates can serve as a baseline to track the progress and impact of preventive blood pressure screening for children and adolescents. Public health plays an important role in working with the health care sector and other stakeholders to increase the use of this screening. Public health officials and clinicians can use these data to identify population groups that might benefit from additional strategies to access and receive recommended blood pressure screening in children and adolescents.

Methods

NAMCS/NHAMCS

To estimate the prevalence of blood pressure measurement by providers at visits among children and adolescents aged 3–17 years, CDC analyzed 2007–2010 data from NAMCS and NHAMCS (15). These two national surveys collect data annually on the provision of ambulatory care services to patients of all ages from office-based physicians and hospital outpatient departments. The methods and sampling frame of NAMCS and NHAMCS have been described in detail elsewhere (16). Only preventive care visits were included in this analysis, defined by answering "yes" to the question of whether this was a preventive care visit or by using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) clinical diagnoses of V20, V70.0, V70.3, V70.6, V70.8, or V70.9. In addition, only visits to pediatricians or general practice providers were included. Visits by persons with diagnoses of hypertension (defined by an ICD-9-CM clinical diagnosis of 401–405 or by checkbox those who had hypertension) were excluded.

The unit of analysis used was a patient visit. With the exception of physician and clinic specialty (obtained from the provider/facility induction interview and sampling frames), all data for this analysis were obtained through abstraction of patient visit records using a standardized patient record form. Key items included on the patient record form include major reason for visit (preventive care), a maximum of three ICD-9-CM diagnosis codes related to the visit, and systolic blood pressure. The presence or absence of a recorded systolic blood pressure was used as an indicator of blood pressure measurement. Univariate t-tests were used to examine differences in the prevalence of blood pressure measurement over time and also between subgroups within the combined 2009–2010 survey cycles.

A total of 2,963 patient visits (weighted estimate 53,748,445) met the inclusion criteria for 2007–2008, and 2,941 patient visits (weighted estimate 61,631,434) met the inclusion criteria for 2009–2010. Data from NAMCS and NHAMCS were combined, and two time intervals were selected for analysis: 2007–2008 and 2009–2010. Patient visit weights were used to extrapolate these findings to national estimates. A two-tailed t-test with a p-value of <0.05 was deemed statistically significant.

MEPS

To estimate the number of household respondents who recalled having the child's blood pressure measured among children and adolescents aged 3–17 years, CDC analyzed 2007–2010 data from MEPS Child Preventive Health section of the Household component. MEPS collects data from a sample of families and persons across the United States drawn from a nationally representative subsample of households that participated in the prior year's National Health Interview Survey (conducted by CDC's National Center for Health Statistics). The methods and sampling frame are described in detail elsewhere (17).

The unit of analysis was the child or adolescent. The study population comprised children and adolescents aged 3–17 years who were not institutionalized at any time during the study period and for whom complete data on blood pressure measurement and covariates of interest were available. The sample was limited to those children and adolescents who had made at least one nonemergency office or clinic visit during the year before the survey; 17% (n = 5,935) of the sample was excluded because no such clinic or office visit was reported. The designated household respondent answered questions about the child's health. Blood pressure measurement was determined by assessing whether the child or adolescent had ever had their blood pressure measured and, if it had been measured, how long ago it had been measured. Respondents had five options to answer how long ago blood pressure had been measured: "within the past year," "within the past 2 years," "more than 2 years ago," "don't know," or "refused." Only those respondents who were able to answer definitively "yes" or "no" when asked whether the child or adolescent's blood pressure had been measured in the past year were included in the analysis. Additional covariates included type of health insurance at the time of interview, whether the participant had a usual place to go for health care, the type of place usual health care was sought (i.e. "office," "hospital non-ER," or "hospital ER"), and poverty level, defined as family income as a percentage of the federal poverty level (FPL). Five categories were used for analysis: "poor," defined as <100% of FPL; "near poor," defined as 100%–124% of FPL; "low income," defined as 125%–199% of FPL; "middle income," defined as 200%–399% of FPL; and "high income," defined as ≥400% of FPL. For all questions, response options of "refused" and "don't know" were provided to minimize reporting bias in the survey. Univariate t-tests were used to examine differences in the prevalence of blood pressure measurement over time and also between subgroups within the combined 2009–2010 survey cycles. Statistically unstable results were suppressed (relative standard error >30%).

Data from MEPS were combined, and two periods were selected for analysis: 2007–2008 and 2009–2010. Participant weights were used to extrapolate these findings to national estimates. After those for whom blood pressure measurement data were missing (n = 1,502) and covariates of interest (n = 273) were excluded, 10,475 participants aged 3–17 years had made at least one nonemergency health-care visit in the previous year for 2007–2008, and 11,143 met this inclusion criteria for 2009–2010. A two-tailed t-test with a p-value of <0.05 was deemed statistically significant.

Results

NAMCS/NHAMCS

During 2007–2008 and 2009–2010, blood pressure measurement was documented for children and adolescents at 73.7% and 75.7% of preventive care clinic visits, respectively (p = 0.5) (Table 1). Blood pressure was recorded more often for visits by adolescents aged 11–17 years (81.9%) compared with children aged 3–10 years (71.6%; p<0.01). No difference was detected in blood pressure being recorded at visits by males or females. Preventive care visits by non-Hispanic whites had the highest rates of blood pressure recording (78.2%) compared with visits by members of other racial/ethnic groups, but rates were not significantly different. Preventive care visits by private pay patients had higher rates of blood pressure recording (79.6%) compared with visits by Medicaid or State Children's Health Insurance Program (SCHIP/CHIP) patients (69.1%; p<0.01). There was no difference in blood pressure recording at preventive care visits by pediatricians and general practice providers (p = 0.15).

MEPS

During 2009–2010, over two thirds of respondents recalled blood pressure being measured at a nonemergency care physician or clinic visit (69.6%) among children and adolescents who had one or more nonemergency care physician or clinic visits during the previous year, compared with 66.0% in 2007–2008 (p = 0.001) (Table 2). In 2009–2010, blood pressure measurement was recalled more often for adolescents aged 11–17 years (80.2%) compared with children aged 3–10 years (62.2%; p<0.01). No difference was detected in recall of blood pressure measurement between males and females (p = 0.16), and recall of blood pressure being measured did not differ by race/ethnicity (p>0.05). Children and adolescents from families that were defined as near poor and low-income were less likely to report blood pressure screening than families defined as high income (p<0.05). Respondents living in the Northeast were more likely than those living in other regions of the country to recall blood pressure being measured (p<0.01). Respondents with private or public insurance were more likely to recall blood pressure being measured than those without insurance (p = 0.02 and <0.01 respectively). Seven percent of respondents said that the child did not have a usual source of care; these respondents were less likely to recall blood pressure being measured (55.6%) than those with a usual source (70.7%; p<0.01). Recall of blood pressure measurement did not differ by usual care location (p>0.05).

Discussion

The data provided in this report indicate the frequency of blood pressure screening at ambulatory care visits by children and adolescents, not the prevalence of hypertension. This might be the first report to compare the rate of household respondents' recall of whether blood pressure was measured in the year before the survey with provider responses as to whether blood pressure was recorded at preventive care visits for children and adolescents aged 3–17 years. During 2009–2010, responses from providers in NAMCS/NHAMCS and responses from household respondents in MEPS showed similar screening rates; providers reported measuring blood pressure at approximately 76% of visits, and household respondents recalled receipt of blood pressure measurement at approximately 70% of visits. A nonsignificant increase was noted in blood pressure being recorded at preventive care visits in 2009–2010 compared with 2007–2008 in NAMCS/NHAMCS, which is consistent with the increase in blood pressure measurement recall in MEPS for the same years. The nonsignificant difference in blood pressure screening among non-Hispanic whites and members of racial/ethnic groups other than non-Hispanic blacks and Hispanics might be attributable to the small sample size of other groups in both surveys. On the basis of this analysis, blood pressure screening rates among children and adolescents have increased from previous reports that used NAMCS/NHAMCS data for 2000–2001 (51%) (18) and MEPS data for 2004–2006 (66%) (19) and 2006–2007 (66%) (20). However, the NAMCS/NHAMCS data suggest that blood pressure measurement at preventive care visits among children and adolescents is slightly higher than that recalled by household respondents in MEPS.

Overall rates of blood pressure measurement at ambulatory care visits by children and adolescents continue to increase; however, the data provided in this report indicate that the most disadvantaged children and adolescents in terms of receipt of blood pressure measurement at preventive care visits are those using Medicaid or SCHIP/CHIP in the provider data and those <125% of FPL or living in the West in the household respondents' recall data. Younger children (aged 3–10 years) had a lower frequency of blood pressure measurement at care visits in the provider data as well as among household respondents' recall.

Although the U.S. Preventive Services Task Force (USPSTF) found insufficient evidence in 2002 to recommend for or against routine screening for high blood pressure in children and adolescents because of a lack of evidence on the benefits and harms of screening (21), the USPSTF assessment was made before the 2004 recommendations from NHBPEP. In 2004, the National Heart, Lung, and Blood Institute convened the NHBPEP Working Group on children and adolescents to provide guidance on definitions and diagnosis of high blood pressure in children and adolescents, on the basis of data from the National Health and Nutrition Examination Survey. In addition to recommending screening starting at age 3 years, the NHBPEP Working Group recommended that children and adolescents with prehypertension and hypertension be considered candidates for lifestyle interventions (i.e., weight reduction, increased physical activity, and adoption of healthy eating habits) to reduce blood pressure, with pharmacologic approaches reserved for children and adolescents with elevated blood pressure that does not respond to lifestyle interventions or for those who have secondary causes of hypertension (9). An updated review conducted by USPSTF in 2012 concluded that blood pressure screening in children and adolescents might be effective in identifying high blood pressure, but insufficient evidence exists on routine screening, and false positive rates might be high. Following the 2012 USPSTF review, the previous recommendation was not changed (22); however, reducing high blood pressure among children aged 8–17 years by 10% (from 3.5% to 3.2%) is a Healthy People 2020 objective (HDS-5.2) (3).

Public health authorities and other stakeholders should work with health-care providers to increase blood pressure screening in children and adolescents. Few programs exist outside of provider educational efforts to improve blood pressure screening in children and adolescents. Medicare and Medicaid provide financial incentives to improve blood pressure screening in children and adolescents through Stages 1 and 2 of Meaningful Use* (for health information technology), in which providers are required to record blood pressure in the electronic medical record in patients aged ≥3 years (23). Health-care providers can use well-child visits and physical examinations for sports participation as opportunities to increase screening rates among children (22). Information in the literature on the cost-effectiveness of blood pressure screening in children and adolescents as recommended in the guidelines is scant. A recent modeling study on the cost-effectiveness of blood pressure screening in adolescents found that at the individual level, mass blood pressure screening followed by treatment for those with secondary hypertension was modestly cost-effective. Population-wide approaches of increasing physical activity classes and salt reduction campaigns have been demonstrated to be potentially more effective and more cost-effective than routine blood pressure screening and treatment for high blood pressure prevention and control among adolescents; however, routine screening is potentially more effective and less costly than selective screening or no screening (24). Another study demonstrated that the use of ambulatory blood pressure monitoring among children and adolescents with suspected hypertension was highly cost-effective because of the high prevalence of white coat hypertension in the pediatric population (25).

Ongoing changes in the U.S. health-care system offer opportunities to improve the use of clinical preventive services among infants, children, and adolescents. The Patient Protection and Affordable Care Act of 2010 (as amended by the Health Care and Education Reconciliation Act of 2010 and referred to collectively as the Affordable Care Act [ACA]) expands insurance coverage, consumer protections, and access to care and places a greater emphasis on prevention (26). As of September 23, 2010, ACA § 1001 requires nongrandfathered private health plans to cover, with no cost-sharing, a collection of four types of clinical preventive services, including 1) recommended services of USPSTF graded A (strongly recommended) or B (recommended) (27); 2) vaccinations recommended by the Advisory Committee on Immunization Practices (28); 3) services adopted for infants, children, and adolescents under the Bright Futures guidelines supported by HRSA and AAP (11) and those developed by the Discretionary Advisory Committee on Heritable Disorders in Newborns and Children (29); and 4) women's preventive services as provided in comprehensive guidelines supported by HRSA (30). The Bright Futures guidelines recommend blood pressure screening at multiple points as the child ages (11). State Medicaid programs cover hypertension screening as part of the Early and Periodic Screening, Diagnostic and Treatment benefit.

The Health Insurance Marketplace (or Health Insurance Exchange) began providing access to private health insurance for small employers and to persons and families interested in exploring their options for coverage, with policies taking effect as early as January 2014.† Federal tax credits are available on a sliding scale to assist those living at 100%–400% of FPL who purchase health insurance through the Marketplace (ACA § 1401). Insurance plans sold on the Marketplace must cover the four types of recommended clinical preventive services without cost-sharing, including hypertension screening (ACA § 1001). Health insurance coverage reforms under ACA could result in greater numbers of children and adolescents receiving blood pressure screening.

Limitations

The findings in this report are subject to at least five limitations. First, NAMCS and NHAMCS data were selected for preventive care visits only. Visits other than an annual care visit might have been included in the definition of a preventive care visit. This bias could lead to an under- or overestimation of blood pressure screening at preventive care visits. Second, blood pressure could have been taken at the preventive care visit but not recorded on the patient record form for NAMCS and NHAMCS. This bias could lead to an underestimation of blood pressure screening. Third, NAMCS and NHAMCS data are representative of patient visits rather than individual patients. Therefore, children who visit their doctors most frequently (e.g., those who are sicker) potentially could be represented more than once in the sample, although this would be unlikely because the analysis included only preventive care visits. In addition, services such as blood pressure measurement not provided at a given sampled visit might have been provided to the patient at another visit. Fourth, MEPS relies on a single household respondent's recall and is subject to recall bias. Finally, for recall of blood pressure measurement in MEPS, the household respondent might not have been present or might have been unable to witness whether the blood pressure was taken. This bias could lead to an underestimation of blood pressure screening from the MEPS survey. Although these two surveys are considered to be nationally representative, they did not survey an identical population. Therefore, caution should be used in comparing the results from the two surveys.

Conclusion

This study provides new information that household respondents' reports of blood pressure measurement in the year before the survey for children and adolescents are similar to provider reports of blood pressure measurement at preventive care visits (70% and 76% respectively) during the year of the survey. In addition, children and adolescents using Medicaid or those <200% of FPL appear to receive blood pressure screening less often than those with private insurance or those with higher income. Further studies are needed to confirm and/or track these findings of disparities in blood pressure screening among children and adolescents. Opportunities exist to address the Healthy People 2020 objective for reducing high blood pressure among children and adolescents by improving blood pressure screening at preventive care visits while at the same time addressing healthy lifestyle behaviors for children and adolescents.

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