Influence of Preoperative 12-Item Short Form Mental Composite Score on Clinical Outcomes in an Isthmic Spondylolisthesis Population Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion

Objective: To determine preoperative 12-Item Short Form Health Survey (SF-12) Mental Component Summary (MCS) influence on minimally important clinical difference (MCID) and patient-reported outcome measures in patients with isthmic spondylolisthesis receiving minimally invasive transforaminal lumbar interbody fusion.

Methods: Patients with isthmic spondylolisthesis undergoing primary, single-level minimally invasive transforaminal lumbar interbody fusion at L5-S1 were retrospectively identified and divided into preoperative SF-12 MCS <50 and SF-12 MCS ≥50 groups. Visual analog scale (VAS) back/leg, Oswestry Disability Index (ODI), SF-12 Physical Composite Score (PCS), and Patient-Reported Outcome Measurement Information System physical function (PROMIS-PF) were assessed. Improvements from preoperative score were analyzed via paired samples t test. Patient-reported outcome measures and MCID attainment between groups were evaluated using linear regression and χ², respectively.

Results: SF-12 MCS <50 and SF-12 MCS ≥50 groups included 35 and 26 patients, respectively. SF-12 MCS < 50 group had inferior scores for all VAS back time points except 6 weeks, all VAS leg time points except 6 weeks/1 year, all ODI time points, SF-12 PCS at 6 months/2 years, and PROMIS-PF at preoperative/6 months (all P ≤ 0.049). SF-12 MCS <50 group improved for VAS back/leg to 1 year, ODI and SF-12 PCS from 12 weeks to 1 year, and PROMIS-PF at 1 year only (all P ≤ 0.047). SF-12 MCS ≥50 group improved for VAS back from 12 weeks to 1 year, SF-12 PCS 6 months to 2 years, and VAS leg, ODI, and PROMIS-PF 12 weeks to 2 years (all P ≤ 0.018). MCID attainment differed for ODI at 6 weeks and PROMIS-PF at 12 weeks only (both P ≤ 0.035).

Conclusions: Patients with SF-12 MCS <50 demonstrated fewer long-term improvements from preoperative to 2 years and inferior patient-reported outcome measures at most time points for pain and disability following minimally invasive transforaminal lumbar interbody fusion. MCID attainment largely did not differ by preoperative mental functioning.