Improvement following minimally invasive lumbar decompression in patients 80 years or older compared with younger age groups
Authors: Shahi Pratyush , Song Junho , Dalal Sidhant , Melissaridou Dimitra , Shinn Daniel J. , Araghi Kasra , Mai Eric , Sheha Evan , Dowdell James , Qureshi Sheeraz A. , Iyer Sravisht 
Published: July 2022

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.