Correlation Between the Oswestry Disability Index and the North American Spine Surgery Patient Satisfaction Index

Abstract

The Oswestry Disability Index (ODI) is a widely used patient-reported outcome instrument in lumbar spine surgery, but its relationship to the increasingly scrutinized but still heterogeneous patient satisfaction metrics has not been well described. One popular metric is the North American Spine Society (NASS) patient satisfaction index. This study aimed to determine whether change in ODI predicts patient satisfaction. Adult patients at a neurosurgery spine clinic completed the ODI and NASS questionnaires at various times in their care between September 2014 and November 2018. Scores were retrospectively analyzed using ordinal logistic regression. One thousand thirty-seven patients were identified (mean age 59.3 ± 14.7 years, 54.2% male). At 3, 12, and 24 months postoperatively, 684 (84.5%), 400 (83.3%), and 215 (80.9%) patients, respectively, expressed satisfaction (NASS score 1 or 2). Mean ± standard deviation improvements in ODI at 3, 12, and 24 months postoperatively were 16.8 ± 17.5 (n=675), 18.4 ± 17.5 (n= 396), and 19.7 ± 17.7 (n= 213). For every unit improvement in ODI, the odds of selecting the next most satisfied NASS score at 3, 12, and 24 months postoperatively increased by 6.8% (95% confidence interval [CI] 5.6%-8.1%), 5.8% (95% CI 4.4%-7.1%), and 6.0% (95% CI 4.2%-7.9%), respectively. Every 10-unit improvement increased the odds, respectively, by 93.8% (95% CI 73.2%-117.0%), 75.0% (95% CI 53.8%-99.1%), and 79.4% (95% CI 50.3%-114.1%). Improvements in ODI are predictive of increased patient satisfaction as defined by the NASS index. A 10-point improvement in ODI nearly doubled the odds of increased satisfaction 3 months postoperatively.