This article represents the first step toward a better understanding of inpatient healthcare utilization in children with hypertension. Mean hospitalization charges for children with hypertension have increased by 50% and account for an estimated $3.1 billion in inpatient healthcare charges from 1997 to 2006. The frequency of hypertension discharges rose significantly in children. Other published studies have demonstrated an increase in frequency of hypertension among children in outpatient and community settings in the United States.12,13
Taken together, one might postulate that a fraction of all cases of hypertension may be hospitalized, and the increase in hypertension in the outpatient setting is directly related to observed trends in the inpatient environment.
Our study found a higher frequency of hypertension discharges in 10- to 18-year olds as compared with 2- to 9-year olds. One may hypothesize that the higher frequency of hypertension discharges seen in the 10- to 18-year–old group in our study may be because of the rise in obesity prevalence as reported in the literature, especially among adolescents.14,15
Several studies have demonstrated an association between childhood obesity and pediatric hypertension.13,16
Sorof and Daniels17
reported that children who are obese are at 3-fold higher risk of developing hypertension than nonobese children. Although we found that only 9.3% of claims with hypertension also have a code for obesity, of those with obesity and hypertension jointly coded, 9% were 2 to 9 years old and 91% were 10 to 18 years old. Analyses using discharge data may be limited by the accuracy of coding, which could affect the ability to identify obesity. This may be especially relevant because obesity is not typically reimbursable, thereby resulting in a lower likelihood of coding obesity as a discharge diagnosis.18,19
The KID database does not capture body mass index data. These data would be required to further explore this potential association.
Demographic and socioeconomic factors were examined as potential determinants of hypertension healthcare utilization. We found that boys and blacks were more likely than girls and other races to be hospitalized with hypertension. This is consistent with pediatric studies in the outpatient setting and studies in adults.12,13
Blacks have been shown to be at higher risk of hypertension across the life span and, therefore, may be at increased risk for hypertension-associated hospitalizations. In addition, blacks have a blunted nocturnal dip, which may contribute to an increased cardiovascular load compared with white Americans.20–22
Our study analyzed median income by zip code as the marker of socioeconomic status. We did not find an association, but this may have reflected the insensitive nature of this socioeconomic status surrogate.
A few studies have examined medical expenditures of pediatric hypertension in the ambulatory setting.9,23
Swartz et al23
investigated the cost effectiveness of ambulatory blood pressure monitoring in the evaluation of 267 children with hypertension in a single medical center between 2005 and 2006. The charge for outpatient evaluation of a hypertensive child was $3420 for the initial evaluation. In a study comparing total cost of obesity-related pediatric hypertension with a randomly selected control group in the South Carolina Medicaid system, the costs of outpatient and inpatient services were significantly higher in the obese hypertensives compared with the controls ($28596 versus $15242).9
Although our analysis was restricted to the available inpatient charge data, our results are reflective of all payer types and all causes of pediatric hypertension.
Although there are numerous studies evaluating the trends of hypertension prevalence among children in outpatient settings, to our knowledge, there have been no published reports on inpatient healthcare utilization for pediatric hypertension and the contribution of ESRD to inpatient charges. In adults, the total US expenditure in 1998 attributable to hypertension was $108.8 billion.8
Of this total, 21% was attributed to a hypertension diagnosis, 27% to a cardiovascular condition, and 52% to all other conditions. Although ESRD was included in the all other conditions group, the exact contribution of ESRD to the overall hypertension expenditure remains unclear.8
Thamer et al24
examined medical care costs among adults with renal failure, including those with chronic renal failure and ESRD in 1991. They found that hypertensive patients with renal failure were 10 times more likely to be hospitalized, and their LOS was ≈1 day longer than patients without renal failure. Our findings among pediatric hospitalizations are similar to the existing adult data in that hypertensive children with ESRD tend to have a significant increase in charges.
With multivariate analysis, younger age, male sex, other insurance status, and care at a teaching institution were all associated with higher charges. It is likely that patients treated at teaching institutions have more severe disease and complications, requiring more complex health care. In addition, those with “other” insurance status may represent a population that is paying out of pocket, which may also incur greater expense in comparison with patients with some form of insurance-based discount.25–27
In this study, those in the lowest median income by region and blacks had lower charges compared with the reference groups. Using the US government census data, 38% of children were in the low income bracket in 2006.28
In comparison, ≈30% of pediatric hypertension hospitalizations occurred in the lowest median income by zip code. We found that the LOS was approximately a half-day shorter for those with the lowest compared with the highest median income by zip code. The underlying cause for this LOS difference requires additional study but may explain the charge differential found in the multivariate analysis. Nearly 30% of discharges with a diagnosis of hypertension in the HCUP-KID were black compared with the 15% in the US census.28
The present study found that the LOS for blacks was slightly shorter compared with whites (7.9 days and 8.1 days, respectively). The lower hypertension charges associated with black children may be because of the possibility that these patients have poorer control in the home environment and, therefore, require more frequent, shorter hospitalizations.
The greatest strength of this study was the magnitude of the KID database. The use of a national billing claims database offered data not limited by single-center or single-payer biases. In addition, it provided a large amount of data that allowed us to move beyond demographics and to examine complicated hypertension represented as ESRD and its contribution to charges.
This study had several limitations. First, KID-weighted estimates is a limitation in our analysis of trends. This is especially true for 1997 and 2000, in which only 22 and 27 states reported, respectively. In addition, certain states regularly restrict their participation in HCUP-KID, including Georgia, Virginia, Michigan, and Illinois. Although generating sampling weights using the American Hospital Association universe of hospitals reasonably corrects for these sampling restrictions, the estimates would likely have a better representation if reporting was more uniform. It is important to understand these differences in sampling frame and data collection when using the KID for trend analysis.10
Other potential confounding factors in the increase in healthcare expenditure noted in this study include recommendations to use emerging costly technologies to evaluate hypertension, such as computed tomography angiography, magnetic resonance angiography, and sleep studies.29
The HCUP-KID database does not provide data on specific resources used for care of patients. In 2004, the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents provided new management guidelines that have significantly changed the approach to children with elevated blood pressure.30
These guidelines may have had significant impact on healthcare utilization, especially on screening and recognition of hypertension. This study found an increase in hypertension-related discharges at teaching hospitals, whereas those in nonteaching hospitals remained relatively constant. The increases in hospital charges in teaching institutions compared with nonteaching environments may in part reflect differential case ascertainment.
As with other studies using data derived from medical claims, this study may be limited by the accuracy and consistency of medical biller coding. Our decision to keep the examination of hypertension ICD-9 codes broad was attributed to the possible subjectivity of the person assigning billing code, making it difficult to decipher primary hypertension from secondary hypertension. Perhaps this distinction can be better made with the new ICD-10 coding system.
Another limitation of this study is the availability of only inpatient information within KID. These discharge data include repeat hospitalizations and, thus, do not reflect unique patients. As a result, we cannot make conclusions on prevalence of pediatric hypertension or on medical care charges per capita. In addition, these data reflect charges and not actual cost of treating pediatric hypertension.
Healthcare utilization studies help us to understand the magnitude and economic burden of health conditions. This study expands our understanding of the impact of hypertension in children in the hospital setting and augments previous ambulatory literature. Children with hypertension in the inpatient setting are likely to have either severe hypertension or hypertension that complicates a coexisting condition. This study shows that, across this inpatient landscape, the frequency of hypertension hospitalizations is rising, the fraction of charges attributed to hypertension are increasing, and hospitalization of children with hypertension and ESRD resulted in significant increases in healthcare charges. A more detailed evaluation of resource use for hypertensive children in the outpatient setting will complement this study to provide a more complete description of hypertension-related healthcare utilization and charges.