Analysis of the direct cost of surgery for four diagnostic categories of adult spinal deformity

Background contextExisting literature on adult spinal deformity (ASD) offers little guidance regarding an evidence-based approach to care. To optimize the value of medical treatment, a thorough understanding of the cost of surgical treatment for ASD is required.PurposeTo evaluate four clinically and radiographically distinct groups of ASD and identify and compare the cost of surgical treatment among the groups.Study design/settingMulticenter retrospective study of consecutive surgeries for ASD.Patient sampleThree hundred twenty-five consecutive ASD patients treated between 2008 and 2010.Outcome measuresCost data were collected from hospital administrative records on the direct costs (DCs) incurred for the episode of surgical care, excluding overhead.MethodsBased on preoperative radiographs and history, patients were categorized into one of four diagnostic categories of deformity: primary idiopathic scoliosis (PIS), primary degenerative scoliosis (PDS), primary sagittal plane deformity (PSPD), and revision (R). Analysis of variance and generalized linear model regressions were used to analyze the DCs of surgery and to assess differences in costs across the four diagnostic categories considered.ResultsSignificant differences were observed in DC of surgery for different categories of ASD, with surgical treatment for PDS the most expensive followed in decreasing order by PSPD, PIS, and R (p<.01). Results further revealed a significant positive relationship between age and DC (p<.01) and a significant positive relationship between length of stay and DC (p<.01). Among PIS patients, for every incremental increase in levels fused, the expected DC increased by $3,997 (p=.00). Fusion to pelvis also significantly increased the DC of surgery for patients aged 18 to 29 years (p<.01) and 30 to 59 years (p<.01) but not for 60 years or more (p=.86).ConclusionsThere is an increasing DC of surgery with increasing age, length of hospital stay, length of fusion, and fusions to the pelvis. Revision surgery is the least expensive surgery on average and should therefore not preclude its consideration from a pure cost perspective.