Population
The MHS provides medical treatment to approximately 9.4 million US military service members, their families, and retirees [
12], and has two mechanisms for healthcare delivery. Direct care is provided to beneficiaries in military hospitals and clinics. Purchased care encompasses care in the civilian sector, and is associated with TRICARE health insurance. Due to perceived differences in obtaining medical care in different countries served by the MHS, the search was limited to patients and providers in the direct care system within the United States.
Data source
Data for this study were extracted from the Military Health System Data Repository (MDR) for adult patients (between ages 18–64) with an International Classification of Disease Ninth Edition (ICD-9) diagnosis code of nonspecific low back pain (724.2). We considered adding additional ICD-9 codes, but this would have further exposed our analysis to additional uncontrollable variables. For example, adding ICD-9 codes specific to radiculopathy could expose us to additional red flags which would not make our analysis valid for imaging. Furthermore, a vast majority of patients presenting with acute low back pain were coded for code 724.2, creating an appropriate sample size. Specifically, we identified 288,077 patients diagnosed with lumbago (ICD-9724.2) in fiscal year 2015. A six month walk-back from the initial diagnosis date was used to ensure an acute incidence and no previous history of lumbago, resulting in 244,333 acute low back pain patients. Further measures were used to remove data quality issues with the reported provider specialty, and only encounters with Physicians, Physician Assistants, Nurse Practitioners, and Physician Residents were selected for our final study populations and analyses; 195,844. Treatments (NSAIDs, Opiates, CT, Radiography, and MRI) were matched to acute low back pain encounters within four weeks of diagnosis date, consistent with the DoD/VA Clinical Practice Guideline. In FY 2015, the patient population with ICD-9724.2 were treated by 10,232 providers.
Treating provider characteristics include provider type (physician, NP, or PA), clinical specialty, military branch of service (Army, Navy, or Air Force), personnel category (active duty, civilian, contractor), and the TRICARE region where the provider is employed. Patient characteristics include age, gender, beneficiary category (active duty, retiree, or dependent), and marital status.
Measurement indicators
The DoD/VHA Clinical Guidelines for this diagnoses and treatment were applied in this study as a benchmark for comparing provider type and category. Specifically, identifying if imaging or pharmaceuticals were prescribed within four weeks of an initial diagnosis of Lumbago. In narrowing our focus to a single ICD-9 diagnosis and only the first four weeks of treatment, we isolated a very specific part of the CPG for adherence. The imaging procedures were selected from the DoD/VHA Clinical Guidelines for diagnosis and treatment of low back pain include radiography, CT, or MRI, which were captured at the provider level, and the proportion attributable to each provider for these categories was also captured. The same process was performed to identify factors associated with prescription of NSAIDs or opioids for low back pain.
Statistical analysis
Separate binomial logistic regression models were used to calculate the odds for prescribing non-steroidal anti-inflammatory drugs (NSAID), opiates, plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI). These models were adjusted for provider military service (Army, Navy, Air Force, and Other), personnel category (whether the provider was military Active Duty, a Civil Servant, Contractor, or Other), and geographic region (in 2015, TRICARE had three regions in the Continental United States that include West, North, and South). Models were adjusted for patient characteristics, to include age, gender, and beneficiary category (Active Duty, Military Dependent, Military Retiree, and Inactive Guard / Reserve). Data management and statistical analyses were performed using SAS software.