Session Information
Date: Sunday, November 5, 2017
Title: Systemic Lupus Erythematosus – Clinical Aspects and Treatment Poster I: Biomarkers and Outcomes
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose:
Obesity is more common in patients with SLE compared to the general population. The prevalence of obesity among SLE patients is between 28 and 50 percent. We hypothesized that a higher body mass index was associated with elevated ESR after adjusting for disease activity, prednisone and immunosuppressive use.
Methods:
Our analysis is based on 2246 different patients who were observed from 1 to 137 visits. The median number of visits per patient was 15.
The “between-person” association addresses the question of whether those who tend to have high BMI also tend to have high ESR. To assess this, we calculated the person-specific mean ERS values and plotted them against the person-specific mean BMIs. \We fit crude and adjusted models to estimate the slope in the expectation of mean ESR per unit difference in mean BMI. The results are shown in Table 1.
The within-person analysis addresses the question of whether a person tends to have higher ESR when his/her BMI is lower than his average BMI. To assess this, for each visit, we calculated the difference between the BMI level at that visit and the person’s average of BMI. Then we modelled the relationship between these differences in BMI and the difference between the person’s ESR at each visit and the person’s average ESR.
Results:
Table 1: Difference in person-specific mean ESR per 1 unit difference in person-specific mean BMI
|
Model |
Effect |
Unadjusted |
Adjusted1 |
|||
|
Estimated difference in mean ESR per 1 unit difference in mean BMI (95% CI) |
P-value |
Estimated difference in mean ESR per 1unit difference in mean BMI (95% CI) |
P-value |
|||
|
Model 1 Pooling across Sex |
BMI |
0.6 (0.4, 0.7) |
<0.0001 |
|
0.5 (0.4, 0.6) |
<0.0001 |
|
Model 2 Allowing different association by sex |
BMI |
0.6 (0.5, 0.7) |
<0.0001 |
|
0.5 (0.4, 0.7) |
<0.0001 |
|
Female |
5.0 (-12.2, 22.2) |
0.57 |
|
3.2 (-12.1, 18.5) |
0.68 |
|
|
BMI*Sex |
-0.5 (-1.1, 0.2) |
0.14 |
|
-0.3 (-0.9, 0.2) |
0.24 |
|
1 Adjusted for age, age-squared, race, mean disease activity, mean prednisone dose, proportion of time on immunosuppressant medication.
Table 2: Difference in ESR at each visit per 1 unit difference in between the person’s BMI at that visit and the person’s average BMI.
|
Model |
Effect |
Unadjusted |
Adjusted1 |
|||
|
Estimated difference in ESR (relative to a person’s average ESR) as a function of differences in a person’s BMI (relative to that person’s average BMI) |
P-value |
Estimated difference in ESR (relative to a person’s average ESR) as a function of differences in a person’s BMI (relative to that person’s average BMI) |
P-value |
|||
|
Model 1: Pooling across Sex |
BMI -mean BMI |
0.04 (-0.01, 0.10) |
0.15 |
0.09 (0.03, 0.15) |
0.004 |
|
|
Model 2 Allowing different association by sex |
BMI -mean BMI |
0.05 (-0.01, 0.11) |
0.12 |
|
0.09 (0.03, 0.15) |
0.004 |
|
Females |
0.004 (-0.54, 0.54) |
0.99 |
|
0.26 (-0.30, 0.82) |
0.36 |
|
|
BMI -mean BMI *Sex |
-0.07 (-0.31, 0.16) |
0.55 |
|
-0.04 (-0.28, 0.21) |
0.78 |
|
1 Adjusted for age, age-squared, race, disease activity, prednisone dose, immunosuppressant use.
Conclusion:
Patients whose mean BMI is 10 points higher have a mean ESR that is 6mm/hour higher (p<0.0001). The association between BMI and ESR does not vary by sex and is not affected by adjusting for covariates.
We also found a significant within person association between ESR and BMI: a 1 unit increase in BMI increases the expected ESR by 0.09mm/hour (p=0.004).
Careful interpretation of clinical data is necessary in obese patients- an elevated ESR may not be a manifestation of disease activity.
To cite this abstract in AMA style:
Stojan G, Barr E, Petri M. Elevated Erythrocyte Sedimentation Rate Among Obese Patients with SLE- Not Always a Marker of Disease Activity [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/elevated-erythrocyte-sedimentation-rate-among-obese-patients-with-sle-not-always-a-marker-of-disease-activity/. Accessed .« Back to 2017 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/elevated-erythrocyte-sedimentation-rate-among-obese-patients-with-sle-not-always-a-marker-of-disease-activity/