Distance to first symptoms measured by the 6-min walking test differentiates between treatment success and failure in patients with degenerative lumbar disorders

PURPOSE The smartphone-based 6-min walking test (6WT) is an established digital outcome measure in patients undergoing surgery for degenerative lumbar disorders (DLD). In addition to the 6WTs primary outcome measure, the 6-min walking distance (6WD), the patient's distance to first symptoms (DTFS) and time to first symptoms (TTFS) can be recorded. This is the first study to analyse the psychometric properties of the DTFS and TTFS. METHODS Forty-nine consecutive patients (55 ± 15.8 years) completed the 6WT pre- and 6 weeks (W6) postoperative. DTFS and TTFS were assessed for reliability and content validity using disease-specific patient-reported outcome measures. The Zurich Claudication Questionnaire patient satisfaction subscale was used as external criterion for treatment success. Internal and external responsiveness for both measures at W6 was evaluated. RESULTS There was a significant improvement in DTFS and TTFS from baseline to W6 (p < 0.001). Both measures demonstrated a good test-retest reliability (β = 0.86, 95% CI 0.81-0.90 and β = 0.83, 95% CI 0.76-0.87, both p < 0.001). The DTFS exceeded the 6WD capability to differentiate between satisfied (82%) and unsatisfied patients (18%) with an AUC of 0.75 (95% CI 0.53-0.98) vs. 0.70 (95% CI 0.52-0.90). The TTFS did not demonstrate meaningful discriminative abilities. CONCLUSION Change in DTFS can differentiate between satisfied and unsatisfied patients after spine surgery. Digital outcome measures on the 6WT metric provide spine surgeons and researchers with a mean to assess their patient's functional disability and response to surgical treatment in DLD

Smartphone-Based Self-Assessment of Objective Functional Impairment (6-Minute Walking Test) in Patients Undergoing Epidural Steroid Injection

Epidural steroid injection (ESI) represents a popular treatment option in patients with lumbar degenerative disc disease (DDD). The main objective of the article was to determine whether the 6-minute walking test (6WT) could assist in the discrimination between ESI responders and nonresponders. We used a validated 6WT smartphone application to assess self-measured objective functional impairment (OFI) in 3 patients with DDD undergoing ESI. Patient-reported outcome measures (PROMs), including the Core Outcome Measures Index and the Oswestry Disability Index, were obtained at baseline and at the 3-, 7-, and 28-day follow-up. Descriptive analyses were used to compare PROMs with OFI over time. Two patients responded well to the ESI, illustrated by clinically meaningful improvements in PROMs. This improvement was accompanied by a substantial increase in the 6WT distance (case I: 358 m vs. 517 m and case II: 296 m vs. 625 m). One patient reported only moderate improvement in leg pain and conflicting results in the other PROMs. The 6WT demonstrated a persistent OFI (487 m vs. 488 m). This patient was considered a nonresponder and underwent surgical treatment. This case series illustrates the feasibility of the smartphone-based 6WT as a tool to assess OFI in patients undergoing ESI for lumbar DDD

Predicting Functional Impairment in patients with chronic subdural hematoma treated with burr hole Trepanation - The FIT-score

Objective It remains difficult to estimate prolonged functional impairment in patients with chronic subdural hematoma (cSDH) treated with burr hole trepanation. We aim to establish a score that reliably predicts postoperative functional impairment. Patients and methods Retrospectively analysis of a prospective institutional database. cSDH patients operated in 2013–2016 were identified. Clinical outcome was dichotomized into presence (modified-Rankin-Scale (mRS) ≥ 2) or absence of functional impairment (mRS 0–1) at discharge and last follow-up. A score was developed, based on the effect sizes of a set of outcome predictors. Its accuracy was tested using Area Under the Receiver-Operating Characteristic (AUROC) curve analysis. The 2017 cohort served for internal validation. Results A cohort of 253 patients (mean age 75 years, 75% male) was analyzed, of which 77 patients (30%) remained functionally impaired. In multivariate analysis, severe motor deficits at admission (OR 5.84, 95% CI 2.71–12.59, p < 0.001), age (≥85 years: 5.53, 2.14–14.32, p < 0.0001) and disorientation at admission (2.65, 11.39–5.05, p = 0.003) were associated with persistent functional impairment. Based on those variables, we created the “Functional Impairment after burr hole Trepanation” (FIT-score), which showed an AUROC of 0.77 (95% CI 0.70–0.83) for impairment at discharge and 0.76 (0.70–0.82) for impairment at follow-up. Internal validation confirmed the model with an AUROC of 0.79 (0.68–0.91) at discharge and 0.77 (0.64–91) at follow-up. Conclusions The FIT-score is likely to assist the physician when counseling patients and relatives pertaining to the need for postoperative rehabilitation and mid- to long-term supportive home care

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

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

Longitudinal smartphone-based self-assessment of objective functional impairment in patients undergoing surgery for lumbar degenerative disc disease: initial experience

BACKGROUND: The worldwide spread of smartphone usage enables new possibilities for longitudinal monitoring of objective functional impairment (OFI) in patients undergoing surgery for lumbar degenerative disc disease (DDD). METHODS: Three patients, undergoing elective surgery for lumbar DDD, self-assessed OFI using a recently validated 6-min walking test (6WT) smartphone application. Results are presented as raw 6-min walking distance (6WD) as well as in reference to age- and sex-specific healthy population reference values using standardized z-scores (number of standard deviations). In parallel, patient-reported outcome measures (PROMs), including numeric rating scale (NRS) leg-pain and Core Outcome Measures Index (COMI) were obtained before (pre) and 6 weeks (6 W) as well as 3 months (3 M) after surgery. Descriptive analyses were used to compare PROMs with repeated 6WT measurements over time. The feasibility and benefits of the longitudinal OFI measurements using the 6WT app are discussed. RESULTS: One patient presented a favorable outcome, reflected by a clinically meaningful improvement in PROMs. Correspondingly, the 6WT distance gradually improved above the normal population values ((pre 399 m (z-score - 1.96) vs. 6 W 494 m (- 0.85) vs. 3 M 557 m (- 0.1)). One patient experienced initial improvement at 6 W, followed by a decline in 6WD at 3 M which promoted further interventions with subsequent recovery ((358 m (z-score - 3.29) vs 440 m (- 2.2) vs 431 m (- 2.32) vs 471 m (- 1.78)). The last patient showed a lack of improvement in PROMs as well as in OFI (360 m (z-score 0.0) vs 401 m (0.30) vs 345 m (- 0.11)) resulting in secondary surgery. CONCLUSION: The longitudinal assessment of OFI using the 6WT app was feasible and provided the physician with a detailed history of patients' postoperative walking capacity complementing commonly used PROMs

Assessment of the Minimum Clinically Important Difference in the Smartphone-based 6-minute Walking Test After Surgery for Lumbar Degenerative Disc Disease

STUDY DESIGN Prospective cohort study. OBJECTIVE The aim of this study was to determine the minimum clinically important difference (MCID) of the 6-minute walking test (6WT) after surgery for lumbar degenerative disc disease (DDD). SUMMARY OF BACKGROUND DATA The smartphone-based 6WT is a valid and reliable tool to quantify objective functional impairment in patients with lumbar DDD. To date, the MCID of the 6WT has not been described in patients with DDD. METHODS We assessed patients pre- and 6-weeks postoperatively, analyzing both raw 6-minute walking distances (6WD; in meters) and standardized 6WT z scores. Three methods were applied to compute MCID values using established patient-reported outcomes measures (PROMs) as anchors (VAS back/leg pain, Zurich Claudication Questionnaire [ZCQ], Core Outcome Measures Index [COMI]): average change, minimum detectable change, and the change difference approach. RESULT We studied 49 patients (59% male) with a mean age of 55.5 ± 15.8 years. The computation methods revealed MCID values ranging from 81 m (z score of 0.9) based on the VAS back pain to 99 m (z score of 1.0) based on the ZCQ physical function scale. The average MCID of the 6WT was 92 m (z score of 1.0). Based on the average MCID of raw 6WD values or standardized z scores, 53% or 49% of patients classified as 6-week responders to surgery for lumbar DDD, respectively. CONCLUSION The MCID for the 6WT in lumbar DDD patients is variable, depending on the calculation technique. We propose a MCID of 92m (z score of 1.0), based on the average of all three methods. Using a z score as MCID allows for the standardization of clinically meaningful change and attenuates age- and sex-related differences.Level of Evidence: 3

Assessment of the Minimum Clinically Important Difference in the Smartphone-Based 6-Minute Walking Test after Surgery for Lumbar Degenerative Disc Disease

STUDY DESIGN Prospective cohort study. OBJECTIVE The aim of this study was to determine the minimum clinically important difference (MCID) of the 6-minute walking test (6WT) after surgery for lumbar degenerative disc disease (DDD). SUMMARY OF BACKGROUND DATA The smartphone-based 6WT is a valid and reliable tool to quantify objective functional impairment in patients with lumbar DDD. To date, the MCID of the 6WT has not been described in patients with DDD. METHODS We assessed patients pre- and 6-weeks postoperatively, analyzing both raw 6-minute walking distances (6WD; in meters) and standardized 6WT z scores. Three methods were applied to compute MCID values using established patient-reported outcomes measures (PROMs) as anchors (VAS back/leg pain, Zurich Claudication Questionnaire [ZCQ], Core Outcome Measures Index [COMI]): average change, minimum detectable change, and the change difference approach. RESULT We studied 49 patients (59% male) with a mean age of 55.5 ± 15.8 years. The computation methods revealed MCID values ranging from 81 m (z score of 0.9) based on the VAS back pain to 99 m (z score of 1.0) based on the ZCQ physical function scale. The average MCID of the 6WT was 92 m (z score of 1.0). Based on the average MCID of raw 6WD values or standardized z scores, 53% or 49% of patients classified as 6-week responders to surgery for lumbar DDD, respectively. CONCLUSION The MCID for the 6WT in lumbar DDD patients is variable, depending on the calculation technique. We propose a MCID of 92m (z score of 1.0), based on the average of all three methods. Using a z score as MCID allows for the standardization of clinically meaningful change and attenuates age- and sex-related differences.Level of Evidence: 3

External Validation of the Timed Up and Go Test as Measure of Objective Functional Impairment in Patients With Lumbar Degenerative Disc Disease

BACKGROUND The Timed Up and Go (TUG) test is the most commonly applied objective measure of functional impairment in patients with lumbar degenerative disc disease (DDD). OBJECTIVE To demonstrate external content validity of the TUG test. METHODS Consecutive adult patients, scheduled for elective lumbar spine surgery, were screened for enrollment into a prospective observational study. Disease severity was estimated by patient-reported outcome measures (PROMs; Visual Analog Scales [VAS], Core Outcome Measures Index [COMI] back, Zurich Claudication Questionnaire [ZCQ]) and the TUG test. Pearson correlation coefficients (PCCs) were used to describe the relationship between logarithmic TUG test raw values and PROMs. RESULTS A total of 70 patients (mean age 55.9 ± 15.4 yr; 38.6% female; 27.1% previous spine surgery; 28.6% lower extremity motor deficits) with lumbar disc herniation (50%), lumbar spinal stenosis (34.3%), or instability requiring spinal fusion (15.7%) were included. The mean TUG test time was 10.8 ± 4.4 s; age- and sex-adjusted objective functional impairment (OFI) T-score was 134.2 ± 36.9. A total of 12 (17.1%) patients had mild, 14 (20%) moderate, and 9 (12.9%) severe OFI, while 35 (50%) had TUG test results within the normal population range (no OFI). PCCs between TUG test time and VAS back pain were r = 0.37 (P = .002), VAS leg pain r = 0.37 (P = .002), COMI back r = 0.50 (P < .001), ZCQ symptom severity r = 0.41 (P < .001), and ZCQ physical function r = 0.36 (P = .002). CONCLUSION This external validation demonstrated similar OFI rates and PCCs between logarithmic TUG test results and PROMs compared to the original article from 2016. These findings support the TUG test being a quick, easy-to-use objective test, which provides the physician with a robust estimate of pain and functional impairment

External Validation of the Minimum Clinically Important Difference in the Timed-Up-and-Go (TUG) Test after Surgery for Lumbar Degenerative Disc Disease

STUDY DESIGN: Prospective observational cohort study. OBJECTIVE: To provide external validation of the minimum clinically important difference (MCID) of the Timed-Up-and-Go (TUG) test. SUMMARY OF BACKGROUND DATA: The TUG test is one of the best explored and most frequently applied objective task-based functional outcome measure in patients with lumbar degenerative disc disease (DDD). The increased use of the TUG test is based on its solid psychometric properties, however, an external validation of the originally determined MCID is lacking. METHODS: N = 49 patients with lumbar DDD, scheduled for elective spine surgery, were assessed pre- and 6-weeks (W6) postoperative. MCID values were calculate for raw TUG test times (in s) and standardized TUG z-scores using three different computation methods and the following established patient-reported outcome measures (PROMs) as anchors: Visual Analog Scales (VAS), Core Outcome Measures Index (COMI) Back, Zurich Claudication Questionnaire (ZCQ)). RESULTS: The three computation methods generated a range of MCID values, depending on the PROM used as anchor, from 0.9 s (z-score of 0.3) based on the VAS leg pain to 3.0 s (z-score of 2.7) based on the ZCQ physical function scale. The average MCID of the TUG test across all anchors and computation methods was 2.1 s (z-score of 1.5). According to the average MCID of raw TUG test values or TUG z-scores, 41% and 43% of patients classified as W6 responders to surgery, respectively. CONCLUSION: This study confirms the ordinally reported TUG MCID values in patients undergoing surgery for lumbar. A TUG test time change of 2.1 s (or TUG z-score change of 1.5) indicates an objective and clinically meaningful change in functional status. This report facilitates the interpretation of TUG test results in clinical routine as well as in research.Level of Evidence: 3

Objective outcome measures may demonstrate continued change in functional recovery in patients with ceiling effects of subjective patient-reported outcome measures after surgery for lumbar degenerative disorders

BACKGROUND CONTEXT The 6-minute walking test (6WT) has been previously shown to be a reliable and valid outcome measure. It is unclear if the 6WT may further help to detect differences in well performing patients that reach a ceiling effect in PROMs after surgery. PURPOSE To evaluate changes and timing of change in objective functional impairment (OFI) as measured with the smartphone-based 6WT in relation to patient-reported outcome measures (PROMs) after surgery for degenerative lumbar disorders (DLD). STUDY DESIGN Prospective observational cohort study. PATIENT SAMPLE Fifty consecutive patients undergoing surgery for DLD. OUTCOME MEASURES Patients self-determined their OFI using the 6WT application (6WT-app) and completed a set of paper-based PROMs before, 6 weeks and 3 months after surgery. METHODS Fifty patients undergoing surgery for DLD were assessed preoperatively (baseline), 6 weeks (6W) and 3 months (3M) postoperatively. Paired sample t-tests were used to establish significant changes in raw 6-minute walking distance (6WD) and standardized Z-scores, as well as PROMs. Pearson correlation coefficient was used to define the relationship between 6WT and PROMs. Floor and ceiling effects were assessed for each PROM (visual analogue scale [VAS], core outcome measure index [COMI], Zurich claudication questionnaire [ZCQ]). RESULTS Mean 6WT results improved from 377 m (standard deviation - SD 137; Z-score: 1.8, SD 1.8) to 490 m (SD 126; -0.7, SD 1.5) and 518 m (SD 112; -0.4, SD 1.41; all p<.05) at 6W and 3M follow-up. No significant improvement was observed between 6W and 3M for the ZCQ, VAS back and leg pain. While correlation between 6WT and all PROMs were weak at baseline, correlation coefficient increased to moderate at 3M. A considerable ceiling effect (best possible score) was observed, most notably for the ZCQ physical performance, VAS back and leg pain in 24%, 20%, and 16% of patient at 6W and in 30%, 24%, and 28% at 3M. CONCLUSIONS Objective functional tests can describe the continued change in the physical recovery of a patient and may help to detect differences in well performing groups as well as in cases where patients' PROM results cannot further improve because of a ceiling effect