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.