Session Information
Session Type: Abstract Submissions (ARHP)
Background/Purpose
Socioeconomic disparities in health outcomes among people with osteoarthritis are well documented, with some key limitations: existing studies limit their analyses to few outcome variables at a time and often evaluate socioeconomic status (SES) as a dichotomous exposure. As a result, there remains substantial uncertainty regarding the extent and nature of those health inequities. The data from the Osteoarthritis Initiative (OAI) allow us to comprehensively assess socioeconomic disparities in health outcomes within a large group of individuals at risk for or diagnosed with knee osteoarthritis.
Methods
This study includes 4081 OAI participants with full data on demographics, SES and health behaviors. Health outcomes included SF-12 measures of physical (PCS) and mental (MCS) health, the Center for Epidemiological Studies Depression scale (CESD), Western Ontario and McMaster Universities Arthritis Index (WOMAC) subscales for disability, pain and stiffness, Knee Injury and Osteoarthritis Outcome Scores (KOOS) for function and quality of life, and the amount of time needed to complete 20m and 400m walks. Our analyses focused on baseline measurements and used ordinary least squares regressions to evaluate the associations of health indicators with categories of family income and education, included separately and then simultaneously. All analyses were adjusted for race, sex and age, and standard errors were clustered by study site. Linear trends were assessed across income and education categories using linear contrasts.
Results
58% of sample respondents were women, 18% self-identified as African-Americans, and the mean age was 61 years. Participants had an average BMI of 29kg/m2, and nearly half (45%) ever smoked. 30% of all sample participants held a graduate degree and 24% reported family earnings over $100,000/year. There were graded associations of education and income with each of the health outcome measures, adjusted for age, race and sex (Table 1), with the exception that individuals who only partially attended graduate school experienced worse self-reported health than those with a college degree but no postgraduate schooling. Further adjustments for pack-years smoked, body mass index, alcohol use, comorbidities, marital status, current employment and study site did not substantially change the associations, while education and income remained independently associated with health outcomes when simultaneously included in models (Data not shown).
Conclusion
The health of OAI participants varied strongly according to their SES, in a gradient pattern of worsening health with lower levels of income and education. This may be the most comprehensive study of the health socioeconomic gradient in a population with OA or at risk for OA. Differences were not explained by health behaviors, and further studies should explore pathways related to the patterns described herein.
|
Table 1. Differences in adjusted means (from reference)1 for the associations of education and income with health outcome measures in the Osteoarthritis Initiative (N=4081), in separate ordinary least squares regression models adjusted for age, race, and sex |
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|
|
SF-12 |
CESD |
WOMAC1 |
KOOS |
Walk t (s) |
|||||
|
|
PCS2 |
MCS3 |
|
Pain |
Disability |
Stiffness |
Function |
QOL4 |
20m |
400m |
|
Income |
||||||||||
|
<$10K-25K |
-11.02‡ |
-7.76‡ |
9.12‡ |
3.82‡ |
12.71‡ |
1.28‡ |
-18.83‡ |
-15.94‡ |
2.51‡ |
38.84‡ |
|
$10K-25K |
-4.79‡ |
-4.45‡ |
5.27‡ |
1.57‡ |
5.04‡ |
0.57‡ |
-8.87‡ |
-7.17‡ |
1.62‡ |
28.29‡ |
|
$25K-50K |
-3.37‡ |
-2.59‡ |
2.93‡ |
1.01‡ |
3.07‡ |
0.45‡ |
-6.54‡ |
-4.74‡ |
0.92‡ |
17.61‡ |
|
$50K-100K |
-1.19† |
-1.07† |
1.28‡ |
0.29* |
0.92* |
0.19† |
-2.65* |
-2.07* |
0.30† |
7.21† |
|
linear trend (p)6 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
|
Education |
||||||||||
|
< High-school |
-7.24‡ |
-7.13‡ |
8.14‡ |
3.10‡ |
9.14‡ |
0.88‡ |
-12.24‡ |
-10.23‡ |
2.74‡ |
44.53‡ |
|
High-school |
-3.58‡ |
-1.92‡ |
3.26‡ |
1.90‡ |
5.38‡ |
0.65‡ |
-11.32‡ |
-6.81‡ |
0.97‡ |
17.58‡ |
|
Some college |
-3.42‡ |
-1.29‡ |
1.87‡ |
1.50‡ |
4.82‡ |
0.58‡ |
-8.73‡ |
-6.48‡ |
0.78‡ |
13.37‡ |
|
College |
-0.66 |
-0.36 |
0.56* |
0.32* |
0.9 |
0.15* |
-1.99 |
-0.84 |
0.23 |
5.61* |
|
Some grad. |
-1.73† |
-0.65 |
1.31† |
0.79‡ |
2.44‡ |
0.24* |
-5.01† |
-4.22† |
0.04 |
2.85 |
|
linear trend (p) |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
<0.001 |
0.005 |
<0.001 |
<0.001 |
<0.001 |
|
1 Referent categories are: ≥$100,000 (income) and graduate school (education). |
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Disclosure:
A. A. Baldassari,
None;
T. Schwartz,
None;
R. J. Cleveland,
None;
J. M. Jordan,
Algynomics,
5,
Samumed,
5,
Flexion,
5,
ClearView Healthcare Partners,
5,
Trinity Partners, LLC,
5;
L. F. Callahan,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/socioeconomic-disparities-in-health-outcomes-among-individuals-with-or-at-risk-for-osteoarthritis-from-the-united-states-data-from-the-osteoarthritis-initiative/