Although lower extremity fractures are frequent events in men with spinal cord injury (SCI), there is very little information regarding their impact in this population.
The objectives of this project were to describe lower extremity fracture risk factors and fracture care in Veterans with SCI, to determine the impact of these fractures on mortality and morbidity, and to examine treatment patterns (surgical vs. nonsurgical) for the acute fracture. These objectives were accomplished by the following specific aims.
Specific Aim 1: Determine the impact of lower extremity fractures on mortality in Veterans with a traumatic SCI.
Specific Aim 2: Determine the impact of lower extremity fractures on morbidity in Veterans with a traumatic SCI.
Specific Aim 3: Describe utilization of health care delivery systems for an incident lower extremity fracture in Veterans with a traumatic SCI.
Specific Aim 4: Identify treatment patterns following an incident lower extremity fracture in Veterans with a traumatic SCI and determine whether these are associated with differences in mortality following the fracture.
Specific Aim 5: Determine the association of anticonvulsant use with lower extremity fractures in Veterans with a traumatic SCI.
Specific Aim 6: Identify prescription patterns for pharmacological therapies for osteoporosis following an incident lower extremity fracture in Veterans with a traumatic SCI.
For all specific aims using administrative databases, we included the cohort of male Veterans with a traumatic SCI of at least two years' duration identified from the VA Spinal Cord Dysfunction (SCD) Registry from FY2002-FY2007, and defined fractures using International Statistical Classification of Diseases, 9th revision codes for fractures of the lower extremity including: femoral neck (820.x), intertrochanteric (820.21, 820.31), sub trochanteric (820.22, 820.32), pelvis (808.x), femur (820.x, 821.x), patella (822.x), and tibia/fibula (823.x) using National Patient Care Database (NPCD) data. Only incident fractures were included, defined as no encounters with the same 3-digit ICD-9 codes within a 120-day time period prior to the identified fracture. For Specific Aims 1-2, fracture cases were those with an incident lower extremity nontraumatic fracture between FY2002-FY2007, and controls with no incident fracture during this time period who had at least one episode of VA health care utilization in the same year as the fracture case were selected. 1027 fracture cases and 1027 propensity matched controls (matched for demographic factors (age, race), SCI-related fractures (level of injury, duration of injury, completeness of injury), socioeconomic status (using surrogate of SCI-related service connection status (yes/no)), and co-morbidities (by Charlson co-morbidity scores)) were included. The variables included in the propensity score matching were obtained from the VA SCD Registry data and/or NPCD files. Fracture cases were followed for up to five years post fracture, and controls were followed for five years post index date, with the index date for the controls set to the fracture date of the cases. Mortality data were obtained from the National Death Index (NDI) of the National Center for Health Statistics and the VA Vital Status File. We examined post fracture morbidities including respiratory complications, pressure ulcerations, thromboembolism, delirium, and cardiac arrhythmias in the one year following the fracture. We obtained morbidity data from the Austin databases using ICD-9 codes for each morbidity examined. Cox proportional hazards were used to determine differences in mortality and morbidity in the fracture cases compared with the nonfracture controls. To further characterize morbidity and mortality and to understand risk factors and care patterns for these fractures (Specific Aim 3), a detailed chart review of all lower extremity fracture cases identified at four VA sites with SCI centers (Hines, Durham, Puget Sound, Memphis) was performed.
For Specific Aim 4, we utilized ICD-9 codes of 79.0x, 791.x, 792.x, 793.x, 78.5, 79.35, 79.16, 78.57, 79.35, 81.51, 81.52 to identify surgical treatment of fractures (n=100) and described characteristics of surgically treated fracture cases compared with those not surgically treated for the incident fracture (n=956). We examined mortality by type of treatment (surgical vs. nonsurgical) in overall models and then in models adjusted for descriptive variables. Logistic regression was utilized to determine whether there were significant differences in mortality by treatment group. We also used the chart review sample, as described above, to further understand the management of fractures in the setting of chronic SCI.
For Specific Aim 5, we utilized the VA pharmacy benefits management group to identify anticonvulsant use (yes vs. no); and, among anticonvulsant use, the type of anticonvulsant used (P450 inducing vs. not) and monotherapy vs. polytherapy. We used Cox proportional hazards to characterize the association of anticonvulsant use with fracture case status. We also examined the relationship of other medications used (opioids and then thiazides) with fracture status in this population. For Specific Aim 6, we used the chart review data to identify receipt of osteoporosis therapies in the one year following the incident fracture.
Our project identified a number of important findings relative to fractures in the SCI population. First, there was no significant effect of incident lower extremity fractures on mortality for up to five years following the fracture (HR: 1.16; 95% CI 0.96-1.39). However, morbidity complications, including respiratory complications, pressure ulcerations, UTIs, thromboembolism and delirium, were significantly increased at one month post fracture compared with controls (p < 0.03 for all). Almost 1/3 of all fractures occurred during transfers, particularly while using a wheelchair. Surgical treatment for lower extremity fractures occurred in approximately 10% of patients. However, there was no differential association of fracture treatment pattern (surgical vs. nonsurgical) on one year mortality, with 5 (5%) of the surgically treated population and 36 (6%) of the nonsurgically treated population dying within one year of the fracture (p=0.36). Compared with non-users of anticonvulsants, there was a significant positive relationship with fractures by overall use of anticonvulsants (HR 1.33; 95% CI 1.16-1.53), by polytherapy compared with monotherapy (HR 1.27; 95% CI 1.07-1.54), but not by anticonvulsant type. Similarly, opioid use, which occurred in 70% of the cohort, was positively associated with fracture risk (HR 1.82; 95% CI 1.59-2.09). Thiazide use was also common in this cohort, with 22% of the cohort using thiazide diuretics. There was a statistically significant inverse relationship between thiazide use and risk for lower extremity fractures (HR 0.74; 95% CI 0.59-0.93). In the year post fracture, 31% of patients received calcium and 36% vitamin D supplements; however, only 7% received a bisphosphonate and <1% received calcitonin or teriparatide.
We have identified a number of key areas that can be targeted to improve quality of care and outcomes for Veterans with SCI with respect to fractures. To start, fracture prevention should focus on preventing transfer-related falls, particularly while using a wheelchair. Although there is no increased mortality following lower extremity fractures in SCI, these fractures are associated with substantial complications, particularly in the first month following the fracture. The majority of lower extremity fractures can be treated with medical management; however, in those that do require surgery, this management is not associated with greater mortality. Use of opioids and anticonvulsants are associated with increased fracture risk; however, importantly, use of thiazide diuretics are inversely associated with fracture risk. Provision of pharmacological therapies for osteoporosis following fractures in SCI beyond calcium and vitamin D supplementation is rarely done at present.
- Burns SP, Weaver F, Chin A, Svircev J, Carbone L. Cervical stenosis in spinal cord injury and disorders. The journal of spinal cord medicine. 2016 Jul 1; 39(4):471-5.
- Bailey LA, Weaver FM, Chin A, Carbone LD. Estimation of a recurrent event gap time distribution: an application to morbidity outcomes following lower extremity fracture in Veterans with spinal cord injury. Health Services and Outcomes Research Methodology. 2015 Mar 1; 15(1):1-22.
- Akhigbe T, Chin AS, Svircev JN, Hoenig H, Burns SP, Weaver FM, Bailey L, Carbone L. A retrospective review of lower extremity fracture care in patients with spinal cord injury. The journal of spinal cord medicine. 2015 Jan 1; 38(1):2-9.
- Carbone LD, Chin AS, Lee TA, Burns SP, Svircev JN, Hoenig HM, Bailey L, Weaver FM. Thiazide use is associated with reduced risk for incident lower extremity fractures in men with spinal cord injury. Archives of physical medicine and rehabilitation. 2014 Jun 1; 95(6):1015-20.
- Carbone L, Chin AS, Lee TA, Burns SP, Svircev JN, Hoenig H, Akhigbe T, Thomas F, Bailey L, Weaver F. The association of anticonvulsant use with fractures in spinal cord injury. American journal of physical medicine & rehabilitation / Association of Academic Physiatrists. 2013 Dec 1; 92(12):1037-46; quiz 1047-50.
- Carbone LD, Chin AS, Burns SP, Svircev JN, Hoenig H, Heggeness M, Weaver F. Morbidity following lower extremity fractures in men with spinal cord injury. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2013 Aug 1; 24(8):2261-7.
- Bailey LA, Carbone L, Chin A, Burns S, Svircev J, Hoenig H, Weaver FM. Overview of Estimators in Survival Analysis for Recurrent Event Data: An Application to Morbidity Outcomes in Veterans with Spinal Cord Injury. Poster session presented at: Health Policy Statistics Annual International Conference; 2013 Oct 10; Chicago, IL.
- Jessee R, Weaver FM, Chin A, Burns S, Svircev J, Hoenig H, Heggeness M, Carbone L. Management of lower extremity fractures in men with spinal cord injuries. Paper presented at: Southern Regional Societies Annual Meeting; 2013 Feb 22; New Orleans, LA.
- Carbone L, Chin A, Lee TA, Burns S, Svircev J, Hoening H, Akhigbe T, Weaver FM. Anticonvulsant and Opioid Use and Fractures in Veterans with Spinal Cord Injury. Poster session presented at: American Society for Bone and Mineral Research Annual Meeting; 2011 Sep 17; San Diego, CA.
Health Systems, Acute and Combat-Related Injury, Brain and Spinal Cord Injuries and Disorders, Musculoskeletal Disorders
Epidemiology, Treatment - Observational, Prevention
Patient outcomes, Practice patterns, Spinal cord injury