Stability of Clinical Outcome Measures Following Anterior Cervical Spine Surgery

Transcription

1 Stability of Clinical Outcome Measures Following Anterior Cervical Spine Surgery Donna D. Ohnmeiss, Dr.Med., Richard D. Guyer, M.D., Jack E. Zigler, M.D., Scott L. Blumenthal, M.D. Disclosures: Ohnmeiss Employed by Texas Back Institute Research Foundation; Guyer: Royalties Alphatech, Stock Spinal Motion, Consulting and/or Scientific Advisory Board DePuy Synthes, K2M, Flexuspine, Spinal Kinetics, Nanovis, Crocker, MiMedx; Zigler: royalties Zimmer, stock Flexuspine, Expanding Ortho, Consulting and speaking DePuy Synthes, Ohnmeiss Nothing to disclose; Blumenthal: stock options Spinal Motion, Vertiflex, Anulex, FzioMed, Centinel Spine, Ranier, Consulting and/or Scientific Advisory Board Aesculap, Fziomed, Vertiflex, speaker Paradigm

2 Introduction Two-year follow-up is often thought of as the minimum required term for evaluating clinical outcomes, although rationale for such is not obvious Purpose: to investigate the stability of: Outcome measures over time following anterior cervical surgery for groups of patients in various studies Individual patient scores over time

3 Methods Literature search conducted to identify prospective studies involving anterior cervical spine surgery: In >100 patients Collecting data at multiple predefined time points Minimum 24 month follow-up

4 Methods Part 1: Literature reviewed to determine if significant changes in group outcome scores during follow-up Part 2: Using internal dataset, determined stability of individual patient s scores over time (pre-op, 6 wk, 3, 6, 12, 24 mo) Calculated percentage of patients with at least one 15 point change in NDI scores (minimal clinically important difference value)

5 Results 13 articles from 6 countries reviewed Topic: TDR and/or ACF Most frequently used assessments were NDI and VAS pain scales with SF-36 used in fewer studies Regardless of assessment, in no study was there statistically significant changes in mean scores after 3 mo follow-up, nor a trend toward worsening scores after 3 mo Also true of studies with follow-up extending beyond 2 yr

6 Results: Mean Scores in Literature Author N Topic Outcome measures Change Mummaneni, 2007 USA 276 TDR Prestige, ACF NDI, VAS, SF-36 Stable after 6 wk to 3 mo 265 ACF Heller, 2009 USA 242 TDR 221 ACF Bryan, ACF NDI, VAS, SF-36, composite success Stable after 6 wk to 3 mo except success with stabilized at 6 mo Murrey, 2009 USA 103 TDR 106 ACF ProDisc-C, ACF NDI, VAS, satisfaction Stable after 6 wk to 3 mo Coric, 2011 USA 136 TDR Kineflex-C, ACF NDI, VAS Stable after 6 wk to 3 mo 133 ACF Hisey, 2014 USA 179 TDR; 81 ACF 1 level Mobi-C NDI, VAS, SF-36, composite success Stable after 6 wk to 3 mo except success due to radiographic Davis, 2013 USA 225 TDR; 105 ACF 2 level Mobi-C NDI, VAS, SF-36, composite success scores Stable after 6 wk to 3 mo except success due to radiographic scores Phillips, 2013 USA 189 TDR PCM, ACF NDI, VAS, SF-36, Stable after 6 wk to 3 mo 153 ACF satisfaction Vaccaro, 2013 USA 151 TDR Secure-C NDI, VAS, SF-36 Stable after 6 wk to 3 mo 140 ACF Pitzen, 2009 Germany 132 ACF Anterior plates NDI, VAS Stable after 3 mo Schluessmann, TDR Multiple TDRs EQ-5D, COSS, VAS Stable after 3 mo Switzerland Huppert, 2011 France 231 TDR Mobi-C NDI, VAS, SF-36 Stable after 3 mo Fay, 2014 Taiwan 151 TDR Bryan, Prestige NDI, VAS, JOA, Nurik Stable after 6 mo (did not report earlier FU) Hou, 2014 China 149 TDR 196 ACF Discover, ACF NDI, VAS Stable after 3 mo

7 Mean NDI Scores (Internal Dataset) Mean NDI scores remained stable after 3 mo; however, the bars representing standard deviation indicated relatively high variation in scores Pre-op 6 wk 3 mo 6 mo 12 mo 24 mo

8 Individual NDI Scores When analyzing individual pts in the group (from whom stable mean scores were generated): 63.9% had at least one 15 point change in NDI scores between follow-up visits (value considered to be clinically relevant change) Among 55 patients completing all follow-up visits at 36, 48, and 60 mo, 69.0% had at least one 15 point change in NDI score

9 Discussion In the 13 studies reviewed, mean outcome scores for groups of patients improved significantly by 6 wk or 3 mo post-op and were stable during 2-year follow-up This occurred regardless of device, surgical technique, or outcome assessment used

10 Discussion For individual patient NDI scores, majority had at least one 15 point change during 24-mo follow-up suggesting that stable mean scores are produced by compensatory improving and worsening between individual patients Results suggest that while mean group scores are stable during follow-up, it should not be presumed that each patient s scores remain stable over time