American Journal of Hematology 81:927–932 (2006)
Hospitalization Rates and Costs of Care of Patients With Sickle-Cell Anemia in the State of Maryland in the Era of Hydroxyurea Sophie Lanzkron,1* Carlton Haywood Jr,2 Jodi B. Segal,1 and George J. Dover3 1
2
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 3 Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
The multicenter study of hydroxyurea (MSH) in sickle-cell anemia (SCA) demonstrated that patients treated with hydroxyurea (HU) had a 44% decrease in hospitalizations when compared with those taking placebo. A subsequent study looking at the cost-effectiveness of HU showed that decreased hospitalizations for painful crisis accounted for the majority of cost savings in those taking HU. The purpose of this study was to examine whether the expected decrease in hospital utilization occurred after the approval of HU in Maryland. We used data collected by the Maryland Health Services Cost Review Commission to obtain SCA discharge data for Maryland from FY1995 through FY2003. We also reviewed the inpatient and outpatient charts of all adults with SCA admitted to a large university hospital during 2003. Hospitalization rates for adults with SCA in Maryland have increased significantly since approval of HU. While the total costs of inpatient care in Maryland are estimated to have increased by 31% above inflation from 1995 to 2003, the costs of inpatient care for adult SCA patients has increased by almost 60% above inflation. By comparison, there has been no significant increase in the pediatric hospitalization rate. We found that 70% of patients in one hospital who were appropriate candidates for HU were not taking the medication. Hospital utilization among adults with SCA has increased significantly. There are likely many factors that have played a role in this increase. One factor that appears to be involved is the underutilization of HU. Am. J. Hematol. 81:927–932, 2006. C 2006 Wiley-Liss, Inc. V
Key words: sickle; costs; hydroxyurea
INTRODUCTION
The multicenter study of hydroxyurea for sicklecell anemia (MSH) was a randomized, placebo controlled study that demonstrated that patients with sickle-cell anemia (SCA) treated with hydroxyurea (HU) developed fewer complications than those who received placebo [1]. MSH demonstrated that in patients having three or more crises per year, HU decreased the number of crises by 44%, decreased the number of patients in whom chest syndrome developed and decreased the number of transfusions required. As a result of MSH, in 1998, HU became the first FDA approved medication for the treatment of patients with SCA. The current recommendations for the use of HU in patients with SCA are described in the most recent version of The Management of C 2006 Wiley-Liss, Inc. V
Sickle-Cell Disease published by the National Heart, Lung, and Blood Institute (NHLBI) [2]. Contract grant sponsor: National Research Service Award, Minority Predoctoral Fellowship Program, NIH, NHLBI; Contract grant number: 1 F31 HL082037-01; Contract grant sponsor: Johns Hopkins School of Medicine. *Correspondence to: Sophie Lanzkron, MD, Johns Hopkins University, 1830 E. Monument Street, Suite 7300, Baltimore, MD 21205. E-mail:
[email protected] Received for publication 16 November 2005; Accepted 17 May 2006 Published online 21 August 2006 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/ajh.20703
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In 2000, Moore et al. examined the cost-effectiveness of HU based on the clinical effect that was demonstrated in the MSH [3]. Using the data from the MSH, the investigators applied cost estimates to each unit of resource utilization. Hospitalization for painful crisis accounted for the majority of costs in both arms of the study. The investigators concluded that the cost savings from reducing hospitalizations and other clinical care costs easily offset the increased costs of monitoring of HU. The investigators noted that if every eligible patient in the US were taking HU, at a savings of $5,210 per patient per year of medical care costs, this could potentially lead to a total cost savings of almost $26 million. Given this observation, we examined three measures of hospital utilization to determine whether there has been a decrease in hospital utilization for adults with SCA in Maryland since the FDA approval of HU. First, we examined trends in adult SCA hospitalization rates from fiscal year 1995 (FY1995) to fiscal year 2003 (FY2003). We also examined trends in the total hospital costs incurred by adult and pediatric SCA patients in Maryland, and we examined trends in the mean length of stay (LOS) for these patients over the time period. Finally, we examined in more detail the characteristics of adults with SCA hospitalized in one university hospital in FY2003. This provided a description of a patient population using HU outside of a clinical trial setting.
METHODS Data Collection
We used data collected by the Maryland Health Services Cost Review Commission (MHSCRC) to obtain SCA discharge data for the State from FY1995 through FY2003. The MHSCRC database collects annual statistics on the number of hospital discharges by hospital. Data collected include patient demographic characteristics, primary payer, secondary payer, principal diagnosis and other diagnoses (total of 15), length of stay, complexity, condition code, and charges. The database includes all hospitals in the State, except for Veterans Affairs facilities. We used International Classification of Disease-9-Clinical Modification codes (ICD-9-CM) codes recorded in the dataset to identify SCA inpatient data. We used the codes 282.61 (sickle-cell Hgb SS without crisis) and 282.62 (sickle-cell Hgb SS with crisis) in any of the 15 listed diagnoses to identify SCA admissions. We calculated the annual hospitalization rate as the number of discharges that included a diagnosis of SCA divided by the number of people estimated to be living with SCA in Maryland during the same year. This estimate was American Journal of Hematology DOI 10.1002/ajh
generated using 1990 and 2000 US census data [4] for an estimate of the number of African Americans in Maryland, and an estimated SCA prevalence of 1 in 600 African Americans [5]. To describe the total costs of hospitalized patients, we used the MHSCRC data and looked at total costs. This database breaks down costs as follows; routine charges (bed charges), operating room, pharmacy, radiology, laboratory, supplies, therapy, and other costs. To describe the characteristics of patients who were admitted to the university hospital in FY2003, we reviewed the inpatient and outpatient charts of all adults with sickle-cell disease (SCD) admitted in that year to Johns Hopkins Hospital (JHH), identified with the ICD-9-CM codes described earlier. We compared the data for SCA patients with fewer than three admissions to that of SCA patients with three or more admissions to determine whether there were differences between these two populations of patients. We used the indications described in the NHLBI management guide to identify individuals that would have been eligible for HU use [2]. Those indications include patients with hemoglobin SS or Sb0thal with frequent pain episodes, acute chest syndrome, severe vasoocclusive events, or severe symptomatic anemia. Statistical Methods
For the statewide analyses, Poisson regression techniques were used to test the statistical significance of the trends in SCA hospitalization rates in Maryland over the time period. Negative binomial regression models were used as appropriate for the hospitalization rate analyses when suggested by the results of goodness-of-fit tests. Ordinary least squares (OLS) regression models were used to test the trends in the mean length of stay (LOS) for all Maryland SCA patients over the time period, and to test the trend in SCA expenditures as a percentage of total Maryland hospital expenditures for the time period. We compared changes in the total cost of hospital care for SCA patients in Maryland in 1995 with those in 2003 by converting 1995 SCA costs into 2003 dollars using an inflation factor of 1.12 that we obtained from the producer price index. We then divided the cost of care in 2003 by the converted 1995 figure. The statistical package used was STATA 8.2 (StataCorp, College Station, TX). For the JHH FY2003 patient comparisons, we used t-tests, Mann-Whitney U tests, and chi-square tests as appropriate to test differences in gender, age, mean LOS, and mean costs per hospitalization between the patients with less than three and the patients with three or more admissions in the year.
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TABLE I. Discharge Data for Adults With Sickle-Cell Anemia in Maryland (MD): 1995 Through 2003
Year
Hospitalizations of patients with SCA (no.)
Estimated no. of adults with SCA
Hospitalizations per person*
1995 1996 1997 1998 1999 2000 2001 2002 2003
1,584 1,740 1,725 1730 1,858 1,797 1,940 2,203 2,355
1,574 1,606 1,637 1,670 1,701 1,733 1,765 1,797 1,829
1.006 1.083 1.054 1.036 1.092 1.037 1.099 1.226 1.288
ALOS**
Average cost per hospitalization per patient ($)***
Total hospital costs for adults with SCA ($)
Percentage of total hospital expenditures for adults in MD****
6.16 6.26 5.73 5.56 5.53 5.67 5.16 5.06 4.99
5,525 5,983 5,792 6,161 5,934 5,803 5,950 6,357 6,656
8,751,797 10,411,223 9,991,923 10,658,795 11,025,266 10,428,137 11,542,553 14,004,184 15,675,052
0.248 0.285 0.262 0.273 0.270 0.250 0.257 0.287 0.303
SCA, sickle-cell anemia; ALOS, average length of stay in days; Tests for trend: *P < 0.001; **P < 0.001; ***P ¼ 0.016; ****P ¼ 0.20.
RESULTS Maryland Hospital Discharge Data
Admission data for adults with SCA in Maryland from FY1995 through FY2003 are presented in Table I. There was a statistically significant increase in the absolute number of discharges for adults with SCA over the time period studied. Additionally, the hospitalization rate for adult African Americans with SCA increased from 1.006 in FY1995 to 1.29 in FY2003 (test for trend P < 0.001). The average length of hospital stay decreased from 6.16 days in FY1995 to 4.99 days in FY2003 (P < 0.001). The percentage of total statewide hospital costs due to adult SCA discharges increased from 0.25% in FY1995 to 0.30% in FY2003, though this increase was not statistically significant (P ¼ 0.200). The cost of care for adults with SCA in FY2003 was 60% higher than FY1995 costs even after adjusting for inflation (Table II). In comparison, total statewide adult hospital costs in FY2003 were 31% higher than FY1995 costs after adjusting for inflation. When we looked at the breakdown in costs, there was no one category that experienced any drastic change in its relative contribution to overall adult SCA costs (Fig. 1). We examined similar data for pediatric discharges and costs over the same time period. In children, there were no significant changes in hospitalization rates or mean LOS over the time period studied (Table III). There was a 40% increase in costs for pediatric SCA discharges in FY2003 compared to adjusted FY1995 costs, while total state-wide pediatric hospitalization costs in FY2003 were 20% higher than adjusted FY1995 costs (Table III). University Hospital Discharge Data
Data from patients admitted in FY2003 are shown in Table IV. In FY2003, there were 74 patients with
TABLE II. Increase in Hospitalization Costs in Maryland From 1995 to 2003: Adults and Children With SCA
Adults with SCA All adults Children with SCA All children
1995 Costsa
2003 Costs
9,802,012 3,948,840,390 1,951,089 375,622,805
15,675,052 5,178,470,560 2,720,957 451,037,201
Ratio of 2003 cost to adjusted 1995 cost 1.599 1.311 1.395 1.201
SCA, sickle-cell anemia. In 2003 dollars.
a
SCA regularly treated as outpatients at the sicklecell center within this hospital. Fourteen (19%) were taking HU and six of these 14 patients were hospitalized in FY2003. In total, 52 of the 74 SCA patients were admitted with a total of 676 hospital days. Thirty-eight patients (73%) had fewer than three admissions, while 14 patients (27%) were admitted three or more times. This 27% of patients accounted for 60% of the total hospital days for all patients with SCA, and 55% of total SCA hospital charges. The mean age of those individuals admitted in FY2003 was 31.2 with a median of 27.5 years. The mean and median ages of adults admitted to this institution in FY1995 for SCA was similar. There was no statistical difference in the mean and median ages of those patients admitted less than three times, and those patients admitted three or more times. Of the 14 patients admitted three or more times, one was admitted for complications related to surgery, one was admitted with wound infection, and two were pregnant. These patients, therefore, were not candidates for HU. Of the 10 remaining patients, all were admitted with vasoocclusive crisis (VOC) and only three of these patients were on HU. Of the 38 patients admitted fewer than three times, 29 were admitted at least once with a VOC. Only three American Journal of Hematology DOI 10.1002/ajh
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Fig. 1. Breakdown of total hospital costs 1995 compared to 2003 for adults with sickle-cell anemia. There was no one category that experienced any drastic change in its relative contribution to overall costs. TABLE III. Discharge Data for Children With SCA in Maryland: 1995 Through 2003
Year
Hospitalizations of children with SCA (no.)
Estimated no. of children with SCA
Hospitalizations per child
1995 1996 1997 1998 1999 2000 2001 2002 2003
398 394 406 413 426 401 456 433 456
718 735 751 768 784 801 818 834 851
0.55 0.54 0.54 0.54 0.54 0.50 0.56 0.52 0.54
ALOS
Total hospital costs for children with SCA ($)
% Total hospital expenditures for children in Maryland
3.50 3.78 3.61 4.17 3.83 4.23 3.90 3.40 3.44
1,742,044 1,935,739 1,898,028 2,538,337 2,225,489 2,193,972 2,635,798 2,342,555 2,720,957
0.519 0.574 0.515 0.707 0.592 0.585 0.682 0.542 0.603
SCA, sickle-cell anemia; ALOS, average length of stay in days.
patients in this group were taking HU and they were admitted with VOC. There was no difference in mean costs per admission or in length of stay per admission between those admitted three times or more and those admitted fewer than three times. Using the NHLBI management guide criteria for HU use, 70% of the patients admitted with SCA would have been eligible for HU therapy, but were not taking it. The reasons that individuals were not taking HU varied, four of seven had no regular outpatient follow-up. Two had adherence issues related to side effects, and one patient started HU during FY2003. This patient had six admissions prior to starting HU and two after. DISCUSSION
The number of adult SCA discharges in Maryland has significantly increased over the time period studied. The average length of stay for adults with SCA has significantly decreased over this same time period. While the total costs of inpatient care in Maryland are estimated to have increased by 31% above inflation from 1995 to 2003, the costs of inpatient care American Journal of Hematology DOI 10.1002/ajh
for adult SCA patients has increased by almost 60% above inflation. By comparison, there has been no significant increase in the number of pediatric discharges over the same time period. At an estimated increase of 40% above inflation from 1995 to 2003, the costs of inpatient care for pediatric SCA patients, while not as large of an increase as adult hospitalizations, is still nearly twice the increase estimated in the general pediatric population in Maryland. There are many potential explanations for the increase in hospital utilization. One explanation may be that because patients are now taking HU they are living longer and are admitted for other complications of their disease. This would be similar to the increase in hospital admissions that has been seen for people with congestive heart failure that is thought to be due, in part, to improvements in survival of patients after acute myocardial infarction [6,7]. Improved survival and an aging population is not likely the cause of increased hospital utilization in our university hospital setting, as the median age of patients did not change between FY1995 and FY2003. Another possibility is that fewer specialists familiar with the outpatient treatment of patients
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TABLE IV. Characteristics of Adult Patients With SCA Admitted to an Urban University Hospital in 2003 All SCA patients Total patients (%) Total hospital days (%) Total Admits (%) Total charges (%) Number on HU (%) Mean age (median)
52 676 118 1303118 6 (12) 31.2 (27.5)
3 admissions/year 14 (27) 406 (60) 68 (58) 717976 (55) 3 28.2* (25.5)**
