Description of the variables
The characteristics of the patients and practitioners, the cause of referral (dissatisfaction with treatment outcome, determination of the appropriateness of the diagnosis or treatment, or the development of complications), treatment details, the mechanism and timing of the subsequent injury, and the outcomes were recorded. In addition, for those cases associated with complex regional pain syndrome (CRPS), a causative injury profile was included as well.
Chronic pain management claims were divided into two main categories based on the mode of treatment: invasive procedures and noninvasive pain management. Invasive procedures included nerve blocks, injections, ablative procedures, and implantation, maintenance, or removal of a device. If multiple treatments occurred, the case was categorized according to the treatment implicated in the complaint and the source of the alleged injury.
Invasive procedures were sub-classified according to the involved anatomic site; the spine, head and neck, upper extremities including the shoulder, trunk (chest, abdomen, and groin), and lower extremities. The spinal procedures were additionally sub-categorized into neuraxial procedures (epidural procedures including epiduroscopy, root blocks, and intrathecal procedures) and non-neuraxial procedures (paravertebral procedures such as facet joint blocks and vertebroplasty).
Noninvasive pain management was defined as diagnostic or therapeutic activities that did not require the use of needles or the insertion of a catheter or device. These included systemic medication management, physical therapy, and consultations.
Damaging events were defined as the mechanism by which an injury or complication occurred or allegedly occurred. These events were independently judged by each case file reviewer and grouped into the two categories depending on whether they were directly related to the procedure. Procedure-related events included needle trauma to the nerve or spinal cord, inadvertent intravascular injections, dural punctures, high block/total spinal block, pneumothorax, compressive hematoma events, and infections or abscesses. Events not directly related to the procedure included failure to diagnose, improper positioning, patient falls, deterioration of the patient's condition unrelated to the procedure, and failure to meet the patient's expectations.
The severity of the injury in each case was scored using the 10-point scale of the National Association of Insurance Commissioners (NAIC), which ranges from 0 (no obvious injury) to 9 (death) [
5]. The severity scores were grouped into three broad categories for analysis; temporary and non-disabling (score 0–5), permanently disabling injuries (score 6–8), and death (score 9). The severity of the injury reflected the latest assessment at the time the case was referred.
The NAIC severity scale includes the following categories (examples are in parentheses):
0: No obvious injury
1: Emotional only (fright, no physical damage)
2: Temporary insignificant (lacerations, contusions, minor scars, rash; no delay in recovery)
3: Temporary minor (infections, fracture, fall in hospital; delayed recovery)
4: Temporary major (burns, surgical material left, drug side effect, brain damage; delayed recovery)
5: Permanent minor (loss of fingers, loss or damage to organs; includes non-disabling injuries)
6: Permanent significant (deafness, loss of a limb, loss of an eye, loss of one organ)
7: Permanent major (paraplegia, blindness, loss of two limbs, brain damage)
8: Permanent grave (quadriplegia, severe brain damage, lifelong care or fatal prognosis)
9: Death