The Influence of Comorbidity on Postoperative Outcomes Following Lumbar Decompression.

STUDY DESIGN Retrospective. OBJECTIVE Evaluate the association between comorbidity burden and reaching minimum clinically important difference (MCID) following lumbar decompression (LD). SUMMARY OF BACKGROUND DATA There is limited research on the influence of preoperative comorbidity burden on patient-reported outcome improvement following LD. METHODS A prospectively maintained surgical registry was retrospectively reviewed for eligible spine surgeries between 2015 and 2019. Inclusion criteria were primary, single, or multilevel LD. Patients were excluded for missing preoperative patient-reported outcome surveys. Stratification was based on Charlson Comorbidity Index (CCI) score: 0 points (no comorbidities), 1-2 points (low CCI), ≥3 points (high CCI). Demographics and perioperative characteristics were evaluated for differences. Linear regression assessed postoperative improvement for visual analogue scale (VAS) back, VAS leg, Oswestry disability index (ODI), Short Form-12 Physical Composite Score (SF-12 PCS), and Patient-Reported Outcomes Measurement Information System physical function (PROMIS-PF) scores through 1 year. Achievement rate of MCID was compared between groups and evaluated for significant predictors. RESULTS Three hundred fourteen patients were included (123 no comorbidities, 100 low CCI, 91 high CCI). Higher CCI patients were older, more likely to smoke, and have comorbid diseases (all P<0.001). Perioperative differences included increased operative time, levels decompressed, length of stay, and discharge day in the CCI≥3 group. No differences in the rate of achieving MCID for VAS back, VAS leg, and ODI. CCI≥3 subgroup had a lower rate of reaching MCID at 6 months for SF-12 PCS, at 6 weeks for PROMIS-PF, and the overall rate for both SF-12 PCS and PROMIS-PF (all P<0.05). Multilevel procedures was a predictor for MCID achievement for ODI. CONCLUSIONS Patients with increased comorbidities undergoing LD had an equivalent MCID achievement rate for pain and disability metrics through 1 year. High CCI patients did, however, have a lower rate of achieving MCID for their physical function surveys which suggests that comorbidity burden influences improvement in physical function following LD.