RESULTS
Patient and clinical characteristics
Of the more than 20,000 patients enrolled in the CHECK program, 373 had
SCD. Twelve outliers with inpatient expenditures more than $100,000 in
any CHECK year were excluded from analyses because such patients were
expected to have unique medical problems beyond their SCD5,33. Therefore, the analytic sample included 361
cases. Fifty-two percent of these 361 SCD patients were “engaged” for
CHECK services, which were tailored to their individual needs. Table 1
shows the demographics and comorbidities in these 361 participants
stratified by High utilization (n=32), Medium utilization (n=173) and
Low utilization (n=156) groups. Statistical tests were conducted across
risk utilization groups at baseline. Age and percent male did not differ
significantly across the three risk groups, nor did the percentage of
patients who were engaged versus enrolled in the CHECK program. Splenic
sequestration history was not significantly different across the three
risk groups. Only stroke and respiratory disease varied significantly
across the SCD hospitalization utilization risk groups: (Stroke, High
utilization risk group= 15.6%, Medium utilization risk group=4.6%, and
Low utilization risk group= 1.9%, p=.0007; Respiratory Disease High
utilization risk group= 81.2%, Medium utilization risk group=60.7%,
and Low utilization risk group= 46.2%, p<.001). For all the
comorbidities, symptoms were significantly highest in the High risk
group and lowest in the Low risk group
Analysis of inpatient expenditures
The utilization of acute care services was predicted to be associated
with total expenditures because published studies show that acute
inpatient expenditures are the dominant cost in SCD39,40. As expected, inpatient expenditures mirrored
the trends of total expenditures across the three risk group categories
(see Table 2). Many SCD patients had no inpatient expenditures. A
two-part analysis accommodated the semi-continuous expenditure data -
fitting a continuous model allowing for data with excess zeros. The
results suggested that the effect of utilization risk group on inpatient
expenditure varied by CHECK year. For utilization risk group
comparisons, the first part of the analysis estimated the percent
expenditure reduction for each CHECK year while the second part
estimated the odds of having zero expenditures for each CHECK year (see
Table 3).
The results suggested that the
effect of utilization risk on expenditure varied by CHECK year. In the
Baseline year, both Medium and Low utilization risk groups had lower
expenditures compared to High utilization risk groups. During the first
year in CHECK, the odds of having zero inpatient expenditures for
patients in the Low risk group was 7.34 times those in the High risk
group and the odds of having zero inpatient expenditure for patients in
the Medium risk group was 3.54 times those in the High risk group. At
baseline, 95% of patients in the low risk utilization group had zero
expenditure compared to 22% in the high risk group.
Looking at expenses a different way, Figure 1 shows the frequency
distribution of logarithm transformed expenditures for children in the
three tiers of utilization. High utilizers (n=32; Panel A) began with a
broad range of expenditures, then all but a few had reduced expenditures
over the next two years, ending with a bimodal distribution. Wilcoxon
pairwise tests suggested that inpatient expenditures during the second
year in CHECK were significantly lower compared to Baseline year
(adjusted p-value = 0.02). The other two comparisons (Year 1 compared to
Baseline year (p=0.209) and Year 2 compared to Year 1 (p=0.42)) were not
significantly different because the small sample size of high
utilization risk group limits statistical power.
Figure 1, Panel B shows that Medium utilizers (n=173) began with a
bimodal distribution. Inpatient expenditures during the second year in
CHECK were significantly reduced compared to the first year (p = 0.004)
and Baseline year (p = 0.002). The first year vs. baseline year was not
significant (p=0.675). Figure 1, Panel C shows that Low utilizers
(n=156) also began with a bimodal distribution of expenditures.
Expenditures for the low utilizer tier increased over time. As expected,
higher expenditures were associated with more hospital days; some were
elective hospitalizations such as tonsillectomy and others were
hospitalizations for unpredictable sickle cell complications. Using
pairwise comparisons, inpatient expenditures for the second and first
years in CHECK were significantly increased compared to the Baseline
year (p < 0.001). The second compared to the first-year
expenditures were not significantly different (p = 0.672).