Determination of the patient acceptable symptom state for the Japanese Orthopaedic Association Score in patients undergoing anterior cervical discectomy and fusion for cervical spondylotic myelopathy

Abstract

BACKGROUND CONTEXTThe patient acceptable symptom state (PASS) has gained attention as a valuable interpretation tool in spine research. While the PASS for the Japanese Orthopaedic Association (JOA) score has been recently proposed, previous analyses demonstrated a weak discriminative ability for the suggested threshold. PURPOSETo define the PASS for the JOA score in patients undergoing anterior cervical discectomy and fusion (ACDF) for cervical spondylotic myelopathy (CSM). STUDY DESIGNRetrospective review of prospectively collected registry data. PATIENT SAMPLE378 patients who underwent ACDF for cervical myelopathy between 2005 and 2014. OUTCOME MEASURESThe main outcome measure was the JOA score. The PASS anchor question was adapted from the NASS questionnaire, “How would you rate the overall results of your treatment?” and the validation question was adapted from same questionnaire, “Has the surgery for your neck condition met your expectation so far?” METHODSPatients were assessed preoperatively, 6 months and 2 years postoperatively using the JOA. Responses to the anchor question were dichotomized and used as the external criterion in receiver operating characteristics (ROC) analysis to define thresholds on the JOA that corresponded to a PASS at 2 years postoperatively. Sensitivity analyses were carried out for various subgroups (based on age, gender, body mass index, comorbidities), preoperative myelopathy severity, time of follow-up (6 months and 2 years) and an alternate definition of PASS. RESULTSOf the 378 patients, 312 (83%) completed 2-year follow-up, of which, 78.5% reported their current state as acceptable. The areas under the curve (AUC) for the ROCs were 0.72 to 0.83 for all analyses, indicating a good discriminative ability of the JOA when assessing if a satisfactory state was attained. The PASS threshold was ≥13.25 points at 6 months (AUC 0.74, sensitivity 78%, specificity 59%) and ≥14.25 points at 2 years (AUC 0.76, sensitivity 74%, specificity 66%). Sensitivity analyses revealed that the 14.25-point threshold on the JOA was robust. PASS responders were approximately 6 times more likely to be satisfied (adjusted OR 6.18, 95% CI 2.87–13.30) and 8 times more likely to have their expectation fulfilled (adjusted OR 8.23, 95% CI 3.81–17.77) compared with non-responders. CONCLUSIONSThis study validates the PASS threshold of 14.25 on the JOA in a robust analysis of a large cohort undergoing ACDF. This knowledge will enable clinicians to identify patients who have attained a satisfactory functional status after surgery for CSM and allow researchers to interpret studies utilizing the JOA from a patient-centered perspective.