Lower Extremity Motor Deficits Are Underappreciated in Patient-Reported Outcome Measures: Added Value of Objective Outcome Measures

Abstract

Purpose
The patient-reported outcome measure (PROM)-based evaluation in lumbar degenerative disc disease (DDD) is today's gold standard but has limitations. We studied the impact of lower extremity motor deficits (LEMDs) on PROMs and a new objective outcome measure.
Methods
We evaluated patients with lumbar DDD from a prospective two-center database. LEMDs were graded according to the British Medical Research Council (BMRC; 5 (normal) - 0 (no movement). The PROM-based evaluation included pain (VAS), disability (ODI & RMDI) and health-related quality of life (hrQoL; SF-12 PCS/MCS & EQ-5D index). Objective functional impairment (OFI) was determined as age- and sex-adjusted Timed-Up and Go (TUG) test value.
Results
One-hundred and five of 375 patients (28.0%) had a LEMD. Patients with LEMD had slightly higher disability (ODI 52.8 vs. 48.2, p=0.025; RMDI 12.6 vs. 11.3, p=0.034) but similar pain and hrQoL scores. OFI T-scores were significantly higher in patients with LEMD (144.2 vs. 124.3, p=0.006). When comparing patients with high- (BMRC 0-2) vs. low-grade LEMD (BMRC 3-4), no difference was evident for the PROM-based evaluation (all p>0.05) but patients with high-grade LEMD had markedly higher OFI T-scores (280.9 vs. 136.0, p=0.001). Patients with LEMD had longer TUG test times and OFI T-scores than matched controls without LEMDs.
Conclusion
Our data suggest that PROMs fail to sufficiently account for LEMD-associated disability, which is common and oftentimes bothersome to patients. The objective functional evaluation with the TUG test appears to be more sensitive to LEMD-associated disability. An objective functional evaluation of patients with LEMD appears reasonable.