Improvement following minimally invasive lumbar decompression in patients 80 years or older compared with younger age groups

Abstract

OBJECTIVE The objective of this study was to assess the outcomes of minimally invasive lumbar decompression in patients ≥ 80 years of age and compare them with those of younger age groups. METHODS This was a retrospective cohort study. Patients who underwent primary unilateral laminotomy for bilateral decompression (ULBD) (any number of levels) and had a minimum of 1 year of follow-up were included and divided into three groups by age: < 60 years, 60–79 years, and ≥ 80 years. The outcome measures were 1) patient-reported outcome measures (PROMs) (visual analog scale [VAS] back and leg, Oswestry Disability Index [ODI], 12-Item Short-Form Health Survey [SF-12] Physical Component Summary [PCS] and Mental Component Summary [MCS] scores, and Patient-Reported Outcomes Measurement Information System Physical Function [PROMIS PF]); 2) percentage of patients achieving the minimal clinically important difference (MCID) and the time taken to do so; and 3) complications and reoperations. Two postoperative time points were defined: early (< 6 months) and late (≥ 6 months). RESULTS A total of 345 patients (< 60 years: n = 94; 60–79 years: n = 208; ≥ 80 years: n = 43) were included in this study. The groups had significantly different average BMIs (least in patients aged ≥ 80 years), age-adjusted Charlson Comorbidity Indices (greatest in the ≥ 80-year age group), and operative times (greatest in 60- to 79-year age group). There was no difference in sex, number of operated levels, and estimated blood loss between groups. Compared with the preoperative values, the < 60-year and 60- to 79-year age groups showed a significant improvement in most PROMs at both the early and late time points. In contrast, the ≥ 80-year age group only showed significant improvement in PROMs at the late time point. Although there were significant differences between the groups in the magnitude of improvement (least improvement in ≥ 80-year age group) at the early time point in VAS back and leg, ODI, and SF-12 MCS, no significant difference was seen at the late time point except in ODI (least improvement in ≥ 80-year group). The overall MCID achievement rate decreased, moving from the < 60-year age group toward the ≥ 80-year age group at both the early (64% vs 51% vs 41% ) and late (72% vs 58% vs 52%) time points. The average time needed to achieve the MCID in pain and disability increased, moving from the < 60-year age group toward the ≥ 80-year age group (2 vs 3 vs 4 months). There was no significant difference seen between the groups in terms of complications and reoperations except in immediate postoperative complications (5.3% vs 4.8% vs 14%). CONCLUSIONS Although in this study minimally invasive decompression led to less and slower improvement in patients ≥ 80 years of age compared with their younger counterparts, there was significant improvement compared with the preoperative baseline.