131. The role of surgery on pain in degenerative cervical myelopathy: a pooled analysis of the CSM-NA, CSM-I, and CSM-Protect clinical trials

BACKGROUND CONTEXT Controversy exists regarding the optimal approach to surgically treat degenerative cervical myelopathy (DCM). Moreover, patients with mild DCM may be more sensitive to slight changes in physical function when treated using different surgical approaches. PURPOSE To compare the effect of anterior and posterior surgical approaches for DCM in general and in patients with mild DCM, in particular. STUDY DESIGN/SETTING Ambispective cohort study of prospectively accrued data. PATIENT SAMPLE Individuals with DCM that underwent surgical decompression between 2005 to 2018 were identified from a harmonized, prospective, multicenter database of the AO Spine CSM-North America, CSM-International, and CSM-Protect clinical studies. OUTCOME MEASURES Primary outcomes were changes in short form 36 Physical Component Summary score (SF36-PCS) and mJOA score at 12 months. Secondary outcomes were change in total Neck Disability Index (NDI) score and SF36 Mental Component Summary score (SF36-MCS). METHODS Two comparison cohorts were created: 1) anterior surgery (ie, discectomy and corpectomy with or without fusion) and 2) posterior surgery (ie, laminectomy and laminoplasty with or without fusion). Unbalanced baseline variables were matched with 1:1 nearest-neighbour propensity score matching without replacement. Afterwards, one-stage mixed-effects meta-analysis with study and treatment exposure as random effects was performed and reported with mean differences and 95% confidence intervals. A subgroup analysis planned a priori in mild DCM patients (mJOA 15-17) was performed. RESULTS From a total of 1,031 patients with DCM, a well-matched cohort of 634 patients who received anterior vs posterior surgery was included for analysis. Patients who received anterior surgery did not significantly differ from those with posterior surgery in change of mJOA (MD: 0.035, 95% CI [-0.39–0.46]). However, anterior surgical patients had a significantly higher SF36-PCS score of 2.08 points, which did not reach MCID (MD: 2.08, 95% CI [0.51–3.32]). SF36-MCS scores (MD: -0.36, 95% CI [-2.43–1.71]) and NDI (-2.52, 95% CI [-5.44–0.41]) were not significantly different. From 194 mild DCM patients, a well-matched cohort of 68 patients were included for analysis. Mild DCM patients that received anterior surgery had 9.0 points greater SF-PCS improvement at 12 months compared to posterior surgery patients (MD: 9.04, 95% CI [4.14–13.94]). Improvement in mJOA was also significantly greater by 0.9 points (MD: 0.89, 95% CI [0.07–1.70]), both of which reached MCID. SF36-MCS (MD: 5.11, 95% CI [-0.13–10.35]) and NDI [-8.76, 95% CI [-17.48– -0.028]) were not significantly different, or did not reach MCID. CONCLUSIONS In general, anterior and posterior approaches for DCM result in similar gains in recovery of function or patient-reported physical functioning. However, in mild DCM, when surgery is clinically indicated, anterior surgery is associated with clinically important benefits in functional recovery and patient-reported physical functioning when compared with posterior techniques. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. Controversy exists regarding the optimal approach to surgically treat degenerative cervical myelopathy (DCM). Moreover, patients with mild DCM may be more sensitive to slight changes in physical function when treated using different surgical approaches. To compare the effect of anterior and posterior surgical approaches for DCM in general and in patients with mild DCM, in particular. Ambispective cohort study of prospectively accrued data. Individuals with DCM that underwent surgical decompression between 2005 to 2018 were identified from a harmonized, prospective, multicenter database of the AO Spine CSM-North America, CSM-International, and CSM-Protect clinical studies. Primary outcomes were changes in short form 36 Physical Component Summary score (SF36-PCS) and mJOA score at 12 months. Secondary outcomes were change in total Neck Disability Index (NDI) score and SF36 Mental Component Summary score (SF36-MCS). Two comparison cohorts were created: 1) anterior surgery (ie, discectomy and corpectomy with or without fusion) and 2) posterior surgery (ie, laminectomy and laminoplasty with or without fusion). Unbalanced baseline variables were matched with 1:1 nearest-neighbour propensity score matching without replacement. Afterwards, one-stage mixed-effects meta-analysis with study and treatment exposure as random effects was performed and reported with mean differences and 95% confidence intervals. A subgroup analysis planned a priori in mild DCM patients (mJOA 15-17) was performed. From a total of 1,031 patients with DCM, a well-matched cohort of 634 patients who received anterior vs posterior surgery was included for analysis. Patients who received anterior surgery did not significantly differ from those with posterior surgery in change of mJOA (MD: 0.035, 95% CI [-0.39–0.46]). However, anterior surgical patients had a significantly higher SF36-PCS score of 2.08 points, which did not reach MCID (MD: 2.08, 95% CI [0.51–3.32]). SF36-MCS scores (MD: -0.36, 95% CI [-2.43–1.71]) and NDI (-2.52, 95% CI [-5.44–0.41]) were not significantly different. From 194 mild DCM patients, a well-matched cohort of 68 patients were included for analysis. Mild DCM patients that received anterior surgery had 9.0 points greater SF-PCS improvement at 12 months compared to posterior surgery patients (MD: 9.04, 95% CI [4.14–13.94]). Improvement in mJOA was also significantly greater by 0.9 points (MD: 0.89, 95% CI [0.07–1.70]), both of which reached MCID. SF36-MCS (MD: 5.11, 95% CI [-0.13–10.35]) and NDI [-8.76, 95% CI [-17.48– -0.028]) were not significantly different, or did not reach MCID. In general, anterior and posterior approaches for DCM result in similar gains in recovery of function or patient-reported physical functioning. However, in mild DCM, when surgery is clinically indicated, anterior surgery is associated with clinically important benefits in functional recovery and patient-reported physical functioning when compared with posterior techniques.