Using the “primary” approach, we relied on only the first listed diagnosis code to classify patients in a group based on surgical indication. The first listed diagnosis code is sometimes deemed to be the most important reason for an admission, depending on the data source.
Using the “All Diagnoses” approach, we searched all listed diagnosis codes associated with a patient's admission and created non-mutually exclusive variables for each of the surgical indication groups. Essentially, each patient is characterized by a combination of 5 binary indicator variables that correspond to the diagnoses for back pain, disc herniation, spinal stenosis, spondylolisthesis and scoliosis. If any of the diagnosis codes for a given patient fits the definition for a particular surgical indication group, the indicator variable for that group is set to positive. Under this approach, a patient may have multiple diagnoses (e.g. a patient may have a positive indicator for stenosis and a positive indicator for spondylolisthesis). While this approach is useful for analyzing the overlap of surgical pathology, it is not practical for differentiating a population by a primary surgical indication because patients may be assigned to multiple groups.
The Hierarchical approach builds on the All Diagnoses approach. This involved searching all listed diagnosis codes associated with a patient's admission and grouping them into a mutually-exclusive hierarchy according to the strength of evidence for performing spinal fusion, ordered as: 1) muscle sprains/strains (least supported), 2) non-specific back pain (includes spondylosis and degenerative discs), 3) herniated disc (with or without myelopathy), 4) spinal stenosis, 5) spondylolisthesis, and 6) scoliosis (most supported). Evidence reviews suggest only weak support for fusion surgery in back pain due to degenerative discs, with no benefit over structured non-operative treatments. Fusion appears to be more effective for treating deformity, such as degenerative spondylolisthesis, fractures, and scoliosis, but has been shown to improve outcomes over decompression in patients with disc herniation or spinal stenosis.
Because SPORT only recruited lumbar surgical candidates, we used a separate set of indicator variables to restrict our analysis to those claims involving the thoracolumbar, lumbar, or lumbosacral regions. With the exception of select codes for orthopaedic devices and osteoporosis, diagnosis codes that were not specifically spine-related (e.g. “psychogenic pain”) were not included in the algorithm.
Using the “All Diagnoses” approach, we searched all listed diagnosis codes associated with a patient's admission and created non-mutually exclusive variables for each of the surgical indication groups. Essentially, each patient is characterized by a combination of 5 binary indicator variables that correspond to the diagnoses for back pain, disc herniation, spinal stenosis, spondylolisthesis and scoliosis. If any of the diagnosis codes for a given patient fits the definition for a particular surgical indication group, the indicator variable for that group is set to positive. Under this approach, a patient may have multiple diagnoses (e.g. a patient may have a positive indicator for stenosis and a positive indicator for spondylolisthesis). While this approach is useful for analyzing the overlap of surgical pathology, it is not practical for differentiating a population by a primary surgical indication because patients may be assigned to multiple groups.
The Hierarchical approach builds on the All Diagnoses approach. This involved searching all listed diagnosis codes associated with a patient's admission and grouping them into a mutually-exclusive hierarchy according to the strength of evidence for performing spinal fusion, ordered as: 1) muscle sprains/strains (least supported), 2) non-specific back pain (includes spondylosis and degenerative discs), 3) herniated disc (with or without myelopathy), 4) spinal stenosis, 5) spondylolisthesis, and 6) scoliosis (most supported). Evidence reviews suggest only weak support for fusion surgery in back pain due to degenerative discs, with no benefit over structured non-operative treatments. Fusion appears to be more effective for treating deformity, such as degenerative spondylolisthesis, fractures, and scoliosis, but has been shown to improve outcomes over decompression in patients with disc herniation or spinal stenosis.
Because SPORT only recruited lumbar surgical candidates, we used a separate set of indicator variables to restrict our analysis to those claims involving the thoracolumbar, lumbar, or lumbosacral regions. With the exception of select codes for orthopaedic devices and osteoporosis, diagnosis codes that were not specifically spine-related (e.g. “psychogenic pain”) were not included in the algorithm.
