Title: Validation of the Osteoporosis SelfAssessment Tool in Men with Rheumatoid Arthritis
1Validation of the Osteoporosis Self-Assessment
Tool in Men with Rheumatoid Arthritis
- Justin Peng MD, John S. Richards MD, Gail Kerr MD
- Georgetown University and VAMC, Washington DC
2Purpose
- The Osteoporosis Self-Assessment Tool (OST) is a
simplified instrument that incorporates weight
and age to predict patients at risk for
osteoporosis. - We tested the validity and predictive value of
the OST index in a male cohort of patients with
rheumatoid arthritis.
3Background - Osteoporosis
Osteoporosis is the end result of years of bone
loss, which is always due to a mismatch between
bone resorption and bone formation.
4Background
- Rheumatoid Arthritis (RA) is a major risk factor
for - Osteoporosis.
- Although more common in women, men suffer from
fragility - fractures and have a worse outcome.
- Indications for dual energy x-ray absorptiometry
(DXA) in - males are vague and based on expert opinion
rather than - clinical trials.
- The Osteoporosis Self-Assessment Tool (OST) is a
screening - tool originally developed to identify Asian
women at risk for - osteoporosis.
5Background
- OST Index Weight (Kg) Age x 0.2 (remove
- decimal)
- OST Risk Categories
- gt 4 Low Risk
- -1 to 3 Moderate Risk
- lt -2 High Risk
- This study evaluates the utility of the OST Index
to - predict osteoporosis/osteopenia in a cohort
of male - subjects with RA
6Methods
- The Veterans Affairs Rheumatoid Arthritis
Registry (VARA) is a - database of veterans with RA, 90 of whom are
male. - Male patients in the VARA database who had a dual
energy x- - ray absorptiometry (DXA) scan were included in
the study. - Bone mineral density (BMD) results for each
subject were - standardized using published formulas and
T-scores calculated - T-scores were classified as normal, osteopenia
and - osteoporosis according to the WHO criteria
- The OST index was calculated for each subject at
the time of - DXA.
7Methods
- Sensitivity, specificity, and predictive values
of the different OST categories for low BMD were
calculated - The association of the OST index with low BMD was
adjusted for measures of disease activity /
severity and select comorbid diseases using
separate multivariable logistic regression model.
8Statistics
- Sensitivity
- The probability that a diseased patient has a
positive test result - Specificity
- The probability that a nondiseased person will
have a negative test result - Positive Predictive Value
- The probability that a patient with a positive
test result has the disease - Negative Predictive Value
- The probability that a patient with a negative
test result is disease free
9Statistics
PPV A / (A B) NPV D / (C D)
Sensitivity A / (A C) Specificity D / (B
D)
10Results
- 264 of 780 males in the cohort had a DXA
- Mean age was 66.2 and 81 were Caucasians
- Subjects with DXA were more likely to smoke (p lt
- 0.019)
- No difference in demographics, RA disease
- duration, activity or severity and comorbid
diseases - in those with DXA vs. those without DXA
11Results
Table 1 - Distribution of OST Index in Male VARA
Patients
12Results
Figure 1 Predictive Value of The Different OST
Risk Groups for Predicting Low BMD
13Table 2 - Univariate Associations of OST Index
with Reduced BMD (Osteopenia/Osteoporosis)
Subgroup Analysis
14Table 3 - Multivariable Associations of OST Index
with Reduced BMD (Osteopenia/Osteoporosis)
Adjusting for Measures of Disease
Activity/Severity
15Table 4 - Multivariable Associations of OST Index
with Reduced BMD (Osteopenia/Osteoporosis)
Adjusting for Select Comorbidity
16Limitations
- Possible selection bias with DXA ascertainment
- Limited sample sizes for subgroup comparisons
(particularly for younger patients, never
smokers, and Non-Hispanic Blacks)
17Conclusions
- Although lacking sensitivity in this
retrospective study of male - RA patients, a High Risk OST Index was
predictive of low BMD - The association of the OST Index with low BMD
appeared to - be consistent across subgroups, although the
association was - attenuated in younger men and never smokers
- The association of the OST Index with low BMD was
- independent of measures of disease activity /
severity and the - presence of select comorbid conditions
- A prospective trial in a larger cohort is needed
to assess the - predictive value of the OST Index in
inflammatory rheumatic - diseases and if ethnic or age specific cutoffs
are required
18References
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Intern Med 1993119963-8 - Poor G , Atkinson EJ, Lewallen DG et al.
Age-related hip fractures in men clinical
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Int19955419-26 - Binkley N, Bilezikian JP, Kendler DL et al J Clin
Densitom 200694-14 - Koh LK, Ben Sedrine W, Torralba TP et al.
Oseoporosis Int. 20011212699-705 - Looker AC, Wahner HW, Dunn WL et al. Osteoporosis
Int 19988468-489
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