Research Methodology

Research Methodology


Inclusion/exclusion criteria

  • Includes all elective spine procedures
  • Excludes emergency cases, hospital/trauma consults, peripheral nerve, cranial, and spinal cord stimulator cases
  • Validated through insurance billing records to ensure all eligible patients are included


Patient profile

  • Demographics, conservative treatments, co-morbidities (other medical conditions), previous spine surgeries
  • Self-reported by patient, previous PCP/provider notes
  • Data collected through individual chart review


Primary diagnosis

  • Defined as the primary indication or reason for surgery
  • Documented by surgeon, imaging studies
  • Data collected through individual chart review


Surgical summary

  • Date, length of stay, OR time, levels treated, procedure, instrumentation
  • Documented by surgeon, anesthesiologist, and nurses in hospital anesthesiology reports, operative notes, discharge summaries, and intra-operative data collection forms


Complications: intraoperative

  • Documented by surgeon in operative notes
  • Examples:
    • Incidental durotomy (hole in dura)
    • Cardiopulmonary
    • Excessive blood loss/vascular injury
    • Injury to bowel, bladder, or spinal cord
    • Tension pneumothorax (air) or hemothorax (blood) in chest cavity causing problems breathing


Complications: medical

  • Any medical complication within 30 days of surgery
  • Examples:
    • Death
    • Urinary tract infection (UTI)
    • Urinary retention
    • DVT (clot in leg)
    • Pulmonary embolus (PE)
    • Anemia requiring transfusion
    • Prolonged hospital stay
    • Pneumonia
    • Myocardial infarction (MI)/heart attack
    • Stroke
    • Exacerbation of underlying medical conditions (worsening COPD)
    • Serious reactions to medications
    • Excludes:
      • Visit to ER without hospital admission
      • Constipation
      • Nausea
      • Small bump under incision without hematoma
      • Minor medication allergies


Complications: procedure related (no 30 day time limit)

  • Examples:
    • Subsidence or loss of correction requiring revision
    • Hardware failure
    • Pseudoarthroses (failure to fuse)
    • Discitis (disc space infection)
    • Retrograde ejaculation
    • Vascular injury
    • Superficial wound dehiscence (breakdown, without infection)
    • Wound infection (superficial or deep)
    • New motor weakness 1 grade or more (1/2 – 1 grade = minor, > 1 grade major)
    • Hematoma requiring intervention (superficial, asymptomatic excluded)
    • Loss of alignment or stability requiring surgery
    • Any unplanned return to OR (excluding exploratory with negative findings)
    • Excludes:
      • Subsidence without failed fusion
      • “Side effects” lasting less than 3 months
      • New numbness or tingling without weakness
      • Recurrent disc herniation


Complications specific to cervical procedures:

  • Examples
  1. Same as those listed above
  2. Prolonged dysphagia: unresolved after 3 months (< 3 months not considered a complication, it’s a common side effect)
  3. Excessive pre-vertebral swelling in early post-op period requiring readmit (if already discharged), steroids, observation, or NG/PEG tube for dysphagia, respiratory difficulties, or both
  4. Hoarseness
  5. New weakness
  • Excluded:  As above


Follow-up rates

  • In real world without financial incentives associated with studies at academic institutions, it’s often difficult to get patients to follow-up. Issues such as changes in insurance plans/coverage,  relocation, loss of insurance, or unpaid balance often hinder proper follow-up
  • Complications may not be the most complete if not reported by patient or other providers, affected by those lost to follow-up