A Single-Center Retrospective Analysis Investigating the Effect of Timing of Vertebral Augmentation on Pain Outcomes.

Background: Approximately 700,000 individuals experience osteoporotic vertebral compression fractures (OVCF) every year in the United States. Chronic complications from patients and increasing economic burdens continue to be major problems with OVCFs. Multiple treatment options for OVCF are available, including conservative management, surgical intervention, and minimally invasive vertebral augmentation. Prior studies have investigated the utility of vertebral augmentation techniques such as percutaneous vertebroplasty (PVP), balloon vertebroplasty (BVP), and vertebral augmentation with the KivaTM implant on patient mortality with favorable results. The optimal time from OVCF occurrence to vertebral augmentation continues to be a topic of investigation.

Objectives: To further investigate the effect of the timing of vertebral augmentation on pain outcomes.

Study Design: A retrospective cohort chart review study.

Setting: A single academic center in Albuquerque, New Mexico.

Methods: One hundred twenty-six consecutive patient encounters with OVCF diagnosed on imaging and treated with PVP, BVP, or vertebral augmentation with a KivaTM implant between 01/01/2004 and 11/28/2016 were analyzed. The time between fracture and intervention was categorized into < 6 weeks, 6-12 weeks, and >= 12 weeks. Pain scores were measured before and after treatment using the numeric pain rating scale. Statistical analysis using Wilcoxon-Mann-Whitney and Kruskal-Wallis tests were used as appropriate, and effect sizes were described with the Hodges-Lehmann estimates of difference.

Results: The 3 vertebral augmentation procedures compared in this study did not demonstrate statistically significant differences in pain score reduction (P = 0.949). The < 12 weeks group had a median and interquartile range (IQR) pain improvement of 3 (IQR 1,6) versus 1 (IQR 0,4) in the >= 12 weeks group (P = 0.018). Further analysis showed that the median and IQR pain improvement for the < 6 weeks group was 3 (IQR 1,7), for the 6-12 weeks group was 3 (IQR 1,4), and for the >= 12 weeks group was 1 (IQR 0,4). The overall effect of the time category on pain improvement was statistically significant for these groups (P = 0.040). Comparisons between groups only showed differences between the < 6 weeks and >= 12 weeks groups (P = 0.013), with an estimated median difference of 2 (95% CI 0,3). There was no statistically significant relationship between fill percentage and pain relief (P = 0.291).

Limitations: This is a retrospective cohort study from a single academic center with a limited sample size that lacked a control group and procedural blinding. There was also substantial heterogeneity among patients, fractures, operators, and techniques. Pain relief outcomes are subjective and can be biased by patients as well as physician reporting.

Conclusions: Early intervention (< 12 weeks) with vertebral augmentation in patients with OVCF is associated with improved pain scores when compared to later intervention (> 12 weeks). Very early intervention (< 6 weeks) confers a greater advantage when compared to later intervention (> 12 weeks).