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Published on: August 2, 2024
Serum 25-Hydroxyvitamin D Status and 12-Week Functional Outcomes After Extracorporeal Shock Wave Therapy for Lateral
1Department of Orthopedic Surgery, Kyung Hee University College of Medicine, Kyung Hee University Hospital at Gangdong, Seoul 05278, Republic of Korea.
Background/Objectives:
Serum 25-hydroxyvitamin D [25(OH)D] is a clinically used biomarker of vitamin D nutritional status, although it is also influenced by sunlight exposure, supplementation, season, and other host factors. Short-term functional status after extracorporeal shock wave therapy (ESWT) for lateral epicondylitis varies. We evaluated whether serum 25(OH)D level and status were associated with 12-week functional outcomes among ESWT-treated patients.
Methods:
This single-center retrospective cohort included 62 adults with lateral epicondylitis who received outpatient ESWT and had baseline and 12-week assessments. Baseline variables included grip strength ratio, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score, serum 25(OH)D measured using the Architect 25-OH D vitamin kit, common extensor tendon (CET) thickness, age, sex, and body mass index. Multivariable linear regression was used in an analysis-of-covariance framework. Serum 25(OH)D was assessed continuously and as <20 versus ≥20 ng/mL in exploratory threshold analysis.
Results:
Serum 25(OH)D was 21.0 ± 8.4 ng/mL; 30 patients (48.4%) had <20 ng/mL, 22 (35.5%) had 20-29.9 ng/mL, and 10 (16.1%) had ≥30 ng/mL. QuickDASH decreased from 42.0 ± 17.4 to 27.0 ± 13.7, and grip strength ratio increased from 0.58 ± 0.14 to 0.76 ± 0.14. Higher serum 25(OH)D was associated with lower 12-week QuickDASH after adjustment (β per 10 ng/mL = -4.04, 95% CI -7.17 to -0.91; p = 0.012). Additionally, 25(OH)D <20 ng/mL was associated with higher 12-week QuickDASH (β = 6.43, 95% CI 1.17 to 11.69; p = 0.017). Serum 25(OH)D was not clearly associated with 12-week grip strength ratio.
Conclusions:
Lower serum 25(OH)D, interpreted as a vitamin D nutritional-status marker rather than as a nutrition-specific causal exposure, was associated with worse 12-week patient-reported function, but not grip strength ratio. The <20 ng/mL threshold analysis was exploratory and was not powered for subgroup inference. These findings should be interpreted as observational and hypothesis-generating.
