Smartphone-recorded real-world physical performance compared to standardized capacity-based outcome in patients with sciatica.

[BACKGROUND CONTEXT] Degenerative lumbar disorders (DLD) accompanied by sciatica frequently impair mobility and reduce functional capacity. Although patient-reported outcome measures (PROMs) and standardized tests are widely applied, real-world indicators of physical activity remain insufficiently examined. Modern smartphones can continuously record step counts, offering an accessible means of assessing daily movement patterns. However, the reliability of this approach in individuals with DLD-related sciatica has not yet been clearly determined.

[PURPOSE] This study aimed to assess whether smartphone-derived daily step count accurately reflects real-life physical performance in patients with sciatica secondary to DLD and to explore how it correlates with established subjective and objective outcome measures.

[STUDY DESIGN] Prospective observational cohort study PATIENT SAMPLE: 50 patients with sciatica secondary to DLD scheduled for microsurgery OUTCOME MEASURES: Physical performance was determined using smartphone-based daily step count, physical capacity by the 6-minute Walking Test application (6WT-app) and subjective disability by a set of paper-based patient-reported outcome measures (PROMs) prior to microsurgery.

[METHODS] Participants' step counts, 6WT results, and PROMs (COMI-Back, ODI) were analyzed. Activity data were standardized using age- and sex-specific reference values (z-scores) to categorize impairment levels. Correlations among all measures were calculated using Spearman coefficients.

[RESULTS] Mean daily step count was 4602 steps (SD 1074, z-score -1.1), and mean 6WT distance was 398 meters (SD 88, z-score -1.4). Most patients (58%) showed moderate impairment in both metrics. Step count correlated strongly with 6WT (r = 0.70) and moderately with ODI (r = -0.63) and COMI-Back (r = -0.65), with weaker correlations for back (r = -0.50) and leg pain (r = -0.30). Stratification revealed small discrepancies between physical capacity and real-life performance, suggesting that both variables might capture distinct aspects of disability CONCLUSION: Smartphone-based step counting provides a valid, objective indicator of physical performance in sciatica patients with DLD. Its association with both functional test results and self-reported disability suggests that smartphone data can serve as a practical complement to existing evaluation methods.