1. Endocrine and Bone Health Care of Boys with Duchenne Muscular Dystrophy in the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet)
Shiny Thomas1, Stephen W. Erickson2, Emma Ciafaloni3, Deborah J. Fox1, Joyce Oleszek4, Shree Pandya3, Yedatore Venkatesh5, Christina Westfield1, David R. Weber3 and the MD STARnet
1New York State Department of Health; 2RTI International, Research Triangle Park, NC; 3University of Rochester Medical Center, NY; 4University of Colorado-Denver, Denver, CO; 5University of South Carolina School of Medicine, Columbia, SC
BACKGROUND
DXA USE BY CALENDAR YEAR
PATIENT CHARACTERISTICS BY SURVEILLANCE SITE
Steroid treatment is associated with poor bone health and endocrine problems including slow growth, late puberty, and weight gain. There are limited studies on the management of these complications in patients with Duchenne muscular dystrophy (DMD).
CHARACTERISTICS CO IA
wNY AZ GA p n
160 93 74
170
186
Age at start of study, yrs
18.9 ± 5.1
8.9 ± 5.8
8.9 ± 5.4
8.7 ± 5.4
7.8 ± 4.1
0.22
Diagnosis age, yrs
4.5 ± 2.8
4.2 ± 2.7
4.4 ± 3.4
4.4 ± 2.8
4.8 ± 2.8
0.59
Age at last visit, yrs
14.7 ± 6.5
14.89 ± 6.8
15.39 ± 6.3
14.54 ± 6.0
13.5 ± 5.0
0.14
Steroid exposure
49 (30.6)
25 (26.9)
17 (23)
35 (20.6)
35 (18.8)
0.09
Fracture
67 (41.9)
37 (39.8)
37 (50)
55 (32.4)
55 (29.6)
<0.01
Ambulatory2
133 (83.7)
74 (80.4)
45 (60.8)
111(66.9)
132 (71.7)
Race
White
Hispanic
Black
86 (53.8)
53 (33.1)
5 (3.1)
71 (76.3)
7 (7.5)
3 (3.2)
50 (67.6)
4 (5.4)
6 (8.1)
73 (42.9)
66 (38.8)
2 (1.2)
117 (62.9)
28 (15.1)
31 (16.7)
DXA Scan
47 (29.3)
50 (43.0)
29 (39)
24 (14.0)
24 (13.0)
Endocrine Consult
6 (3.8)
9 (9.7)
5 (6.8)
4 (2.4)
8 (4.3)
0.08
OBJECTIVE
The goal of this study was to determine the use of bone health screening, endocrinology referral, and endocrine and bone health medications in the care of boys with DMD.
METHODS
1. Study Design
Population based cohort study of boys with DMD
2. Study Sample
DMD classification as “definite” or “probable”
DMD phenotype: high, medium and low probability
Lived in Colorado, Iowa, Arizona, Georgia, W. New York
Data from January 1, 2002 to December 31, 2011
Death dates available
3. Data Source
Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) surveillance program
Inpatient and outpatient medical records reviewed
4. Study Variables
Presence of a bone density (DXA) scan
Endocrine and bone health medications including calcium, vitamin D, bisphosphonates, growth hormone, testosterone, insulin, and metformin
Documentation of a visit to an endocrinologist
Other variables of interest: steroid use, demographics, anthropometrics, fractures and surveillance site
5. Statistical Analysis
Descriptive statistics to report frequencies & percentages
Means and tests for trends
Odds ratio (OR) to identify clinical predictors of participants that received DXA
[The OR is the odds that a DXA occurred in the presence of an exposure, compared to the odds that the outcome occurred without the exposure].
1 mean ± SD, all such values
2Denominator=675, based on availability of mobility information
ENDOCRINE AND BONE MEDICATION USE
SUMMARY OF KEY RESULTS
Despite the known complications of DMD and steroid use on the endocrine and skeletal systems, our study found that less than 5% of patients were evaluated by an endocrinologist and only ¼ had a DXA bone density screening test performed over the period
With the exception of calcium and vitamin D, the percentage of cases treated with endocrine or bone health medication was very low
History of fracture and duration of disease were found to be associated with greater odds of a DXA scan having been performed, suggesting that DXA scans were being performed more frequently in high risk individuals
A higher percentage of cases in our study were treated with bisphosphonates (13%) than were seen by an endocrinologist (5%) which highlights the variability in the type of specialists who oversee bone health care
We also uncovered evidence of racial disparity in DXA utilization; further studies will be needed to identify barriers to DXA use so that adequate access to bone health screening can be provided to all patients
CLINICAL PREDICTORS OF DXA USE
CLINICAL PREDICTORS
OR (95% CI) p
Fracture
2.8 ( )
<0.001
Steroid exposure
1.5 ( )
0.10
DMD duration, yrs
1.1 ( )
0.02
Diagnosis age, yrs
1.0 ( )
0.39
Race
White
Ref
Black
0.4 ( )
0.09
Hispanic/Latino
0.5 ( )
<0.01
Other/unknown
1.3 ( )
0.33
Insurance
1.0 ( )
0.96
Surveillance Site
Georgia (GA)
Arizona (AZ)
1.0 ( )
0.99
Western New York (wNY-12 counties)
2.4 ( )
Colorado (CO)
3.9 ( )
Iowa (IA)
3.0 ( )
STRENGTHS AND LIMITATIONS
PATIENT CHARACTERISTICS
Strengths
Large number of patients from across the US
Data came directly from medical records and are expected to reflect true clinical practice
Limitations
Clinical data recorded in the medical record may be incomplete
This study ended in 2012; therefore the results may differ from current practice
Chart review for patients seen after 2012 is ongoing
Sample Size, n
683
Age at start of study, yrs
8.2 ± 5.1
Age at last visit, yrs
14.4 ± 6.0
Age at diagnosis, yrs
4.5 ± 2.9
Racial Group
White, n (%)
397 (58.1)
Hispanic, n (%)
158 (23.3)
Black, n (%)
47 (6.9)
Ambulatory1, n (%)
5063 (75.0)
Loss of ambulation2, n (%)
2763 (40.9)
Steroid use, n (%)
389 (57.0)
Fracture, n (%)
251 (36.7)
CONCLUSION
This is the first multi-center study to describe the use of bone health and endocrine screening tests and treatments in boys with DMD. We found that a low percentage of boys were seen by an endocrinologist, had bone density evaluated by DXA, or were treated with an endocrine or bone health medication. We think that these results could be very helpful to providers focusing on improving the care of boys with DMD.
1 At start of study follow up
2 Percentage of ambulatory participants at start who lost ambulation
3 Denominator=675, based on availability of mobility information
Acknowledgment
This publication was supported by the Cooperative Agreement numbers, DD000187, DD000189, DD000190, DD000191, DD001126, DD001123, DD and DD funded by the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Diseases Control and Prevention or the Department of Health and Human Services.