Insurance Status Correlates With Patient-reported Baseline Symptoms of Spinal Stenosis

Nurse handing insurance card to patient with clipboard on table

The Centers for Medicare & Medicaid Services and other insurers now use patient-reported outcome measures (PROMs) as quality metrics in performance analyses and to negotiate reimbursement. Therefore, it’s important to determine what factors influence PROMs before and after treatment.

Several studies of patients undergoing joint arthroplasty and insured by Medicaid report systematically worse PROM scores than patients with other insurance. In the first study of its type, researchers at Brigham and Women’s Hospital found the same is true among patients with lumbar spinal stenosis.

Andrew J. Schoenfeld, MD, MSc, a surgeon in the Department of Orthopaedic Surgery at the Brigham, Andrew K. Simpson, MD, MBA, MHS, director of minimally invasive spine surgery in the department, Alexander M. Crawford, MD, a resident in the department, and colleagues report the data in Spine (Phila Pa 1976).


The researchers retrospectively studied 608 adults with lumbar spinal stenosis, mean age 63. At their initial visit, they completed PROMs in the Patient-Reported Outcomes Measurement Information System (PROMIS) plus visual analog scales (VAS) for leg and low back pain.

Most patients were commercially insured (47%) or insured through Medicare (46.7%); 6.1% had Medicaid and one patient was insured through Veterans Affairs.

PROM Scores by Insurance Type

Unadjusted analysis

Except on the leg pain VAS, all PROM scores were significantly different between insurance groups. Patients with Medicaid consistently reported the worst scores.

When patients insured through Medicaid were compared against commercially insured patients, the differences in PROM scores met or exceeded the minimal clinically important differences wherever differences existed.

Adjusted analysis

The findings were largely maintained after adjustment for potential confounders. Across most PROMs, patients insured through Medicaid reported significantly worse scores than commercially insured patients:

  • PROMIS Physical Function (incidence rate ratio (IRR), 0.90; P=0.003)
  • PROMIS 10 Physical Global (IRR, 0.88; P=0.001)
  • PROMIS Pain Intensity (IRR, 1.09; P=0.002)
  • PROMIS Pain Interference (IRR, 1.05; P=0.024)
  • PROMIS Mental (IRR, 0.85; P<0.001)
  • PROMIS Anxiety (IRR, 1.10; P=0.002)
  • PROMIS Depression (IRR, 1.07; P=0.037)
  • VAS low back pain (IRR, 1.23; P=0.03)

The results were similar when patients insured by Medicaid were compared against those insured through Medicare, except the two groups had similar VAS low back pain scores.

Clinical and Policy Implications

Medicaid insurance generally indicates disadvantaged socioeconomic status, which is often tied to delayed health care and inadequate access to specialists. Treating physicians should consider that patients insured through Medicaid may be more likely to present at an advanced stage of spinal stenosis and be more inclined than others to want interventional and/or surgical modalities of pain control.

The findings of this study also have significant implications for decision-makers who establish standards for performance and reimbursement. It seems to be necessary to account for differences in PROM scores between groups, even within the same patient population.

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