Background/Purpose:
Low socioeconomic status (SES) is associated with negative health outcomes and higher healthcare costs in general populations, but the impact of SES on costs in systemic sclerosis (SSc) is unknown. To address this knowledge gap, we examined the relationship between SES at diagnosis, and direct medical costs for 5 years after diagnosis, in a general population-based context. We hypothesized that baseline SES would be associated with higher costs.
Methods:
Data Source: Our administrative data captured all provincially funded outpatient encounters and hospitalizations (1990-2010), and all dispensed medications (1996-2010) regardless of funding source, in the province of British Columbia.
Sample: We assembled a general population-based cohort of all incident cases of SSc who received care from 1996-2010, based on the following validated algorithm: a) two ICD-9-CM codes for SSc at least 2 months apart but within a 2 year period by a non-rheumatologist physician; or b) one ICD code by a rheumatologist or hospitalization. Statistics Canada neighborhood income quintile data for the year of SSc diagnosis was used to define SES.
Cost Calculation: Costs for outpatient services and prescriptions were summed directly from billing data. Case-mix methodology was used for hospitalizations.
Statistical Analysis: Early mortality is common in SSc and likely associated with high costs before death, but failure to account for this censoring will underestimate the long-term costs of SSc. To address this, follow-up was divided into 90-day periods with costs per-period weighted by the person-specific inverse probability of being alive in each period. A generalized linear model was used to
1) Evaluate the relationship between SES and direct medical costs, after adjusting for sex, age and baseline Charlson’s comorbidity index; and
2) Predict the cumulative 5-year costs (adjusted for censoring) for cases in each SES group.
Parametric bootstrapping was used to obtain 95% confidence intervals (CI). Costs are reported in 2010 Canadian dollars.
Results:
We identified 1,116 incident SSc cases (83% female, mean age 56.2 years) contributing 3,392 person-years. 5-year costs totaled $36,559,914 with 24% from outpatient, 48% from hospital and 28% from medications.
Age (p=0.0278), Charlson’s co-morbidity score (p < 0.0001) and being in the lowest (p=0.0364) or middle (p=0.0015) SES quintile (vs. the highest) were significantly associated with costs. Predicted cumulative 5-year costs for the lowest-SES cases were 42% greater than the highest-SES ($55,035 vs. $38,664). Highest-SES cases had the lowest medication costs (see Table). Cases in the middle SES quintile at diagnosis had the highest outpatient, hospital and overall costs.
Conclusion:
The long-term healthcare costs of SSc cases are substantial (averaging $51,643 per-person over 5 years), and associated with SES, being 42% greater, on-average, for the lowest-SES than the highest.
|
Socioeconomic Quintile at Diagnosis |
N Cases |
N Female (%) |
Mean Age at Diagnosis (SD) |
Median Baseline Charlson Comorbidity Score (IQR) |
N Months of Follow-Up |
N 90-Day Costing Periods |
N Ever-Hospitalized (%) |
Unadjusted Overall Costs |
Covariate-Adjusted Mean Per-Person Predicted Costs (95% CI) |
|||
|
Outpatient |
Hospital |
Medication |
Overall |
|||||||||
|
All |
1,116 |
922 (83%) |
56.2 (14.6) |
0 (1) |
40,707 |
13,569 |
595 (53%) |
$51,643 |
– |
– |
– |
– |
|
1=Lowest |
220 |
178 (81%) |
55.0 (14.1) |
1 (2) |
7,899 |
2,633 |
134 (61%) |
$55,680 |
$11,373 ($11,005 – $11,741)
|
$14,899 ($12,380 – $17,418)
|
$17,161 ($16,340 – $17,982)
|
$55,035 ($52,516 – $57,554)
|
|
2 |
212 |
176 (83%) |
55.0 (15.0) |
0 (1) |
7,599 |
2,533 |
118 (56%) |
$43,680 |
$10,607 ($10,104 – $11,111)
|
$8,750 ($7,167 – $10,332)
|
$13,377 ($12,769 – $13,985)
|
$43,169 ($41,369 – $44,968)
|
|
3=Middle |
239 |
204 (85%) |
56.6 (15.3) |
0 (1) |
8,688 |
2,896 |
116 (49%) |
$59,872 |
$14,251 ($13,536 – $14,965)
|
$15,801 ($13,403 – $18,199)
|
$14,963 ($14,477 – $15,449)
|
$65,054 ($60,939 – $69,170)
|
|
4 |
230 |
189 (82%) |
56.4 (14.4) |
1 (1) |
8,484 |
2,828 |
125 (54%) |
$54,007 |
$10,670 ($10,265 – $11,075)
|
$10,230 ($8,405 – $12,056)
|
$17,794 ($16,975 – $18,612)
|
$51,381 ($49,054 – $53,708)
|
|
5=Highest |
215 |
175 (81%) |
58.0 (14.0) |
0 (1) |
8,037 |
2,679 |
102 (47%) |
$43,870 |
$11,033 ($10,632 – $11,434)
|
$9,124 ($7,768 – $10,481) |
$11,979 ($11,557 – $12,402) |
$38,664 ($37,159 – $40,169) |
Disclosure:
N. McCormick,
None;
M. Sadatsafavi,
None;
W. Chen,
None;
C. A. Marra,
None;
J. A. Avina-Zubieta,
None.
ACR Meeting Abstracts - https://acrabstracts.org/abstract/is-socioeconomic-status-at-diagnosis-associated-with-long-term-direct-medical-costs-in-systemic-sclerosis-a-general-population-based-cohort-study/