Between June 2004 and August 2008, 131 patients were enrolled and randomized (). Sixty-eight patients were randomized to vertebroplasty and 63 to the control intervention; all received the allocated intervention. The baseline characteristics of the groups were similar (). One patient (1%) in the vertebroplasty group and two patients (3%) in the control group were lost to follow-up prior to one month. One patient (1%) in the vertebroplasty group and two patients (3%) in the control group crossed over prior to one month.
Enrollment, Randomization, and Follow-up of the Study Participants.
Baseline Characteristics of Study Participants.
The vertebroplasty and control groups did not differ significantly on either pre-specified primary outcomes of RDQ (treatment difference: 0.7; 95% CI, −1.3 to 2.8; P=0.49) or pain intensity (treatment difference: 0.7; 95% CI, −0.3 to 1.7; P=0.19) at one month (). Both groups showed substantial improvement in their back-related disability and pain immediately (three days) after the procedure, with comparable improvement between groups. The improvement in each group at three days was maintained at one month.
Treatment Comparisons on Primary Outcomes (Intent-to-Treat analyses).
The treatment groups did not differ significantly on any of the secondary outcomes, including measures of pain and quality of life, at one month (). Further, the groups did not differ in the post-specified proportion of patients achieving clinically meaningful improvement in back pain-related physical disability at one month (40% of vertebroplasty patients vs. 41% of control intervention patients, P=0.99). There was a trend (P=0.06) toward a higher rate of clinically meaningful improvement in pain in the vertebroplasty group (64%) versus the control group (48%).
Treatment Comparisons on Secondary Outcome Measures (Intent-to-Treat Analyses) at One Month.
By three months, 8 (12%) patients in the vertebroplasty group and 27 (43%) patients in the control group crossed over to the other group (P<0.001). The vertebroplasty patients who crossed over reported higher disability and pain at three and 14 days, as compared with the other patients (). Control intervention patients who crossed over showed some early improvement after the control procedure that disappeared by the one-month assessment. However, even after they received the alternative intervention, neither the control nor the vertebroplasty patients who crossed over improved by three months to the extent of non-crossover subjects.
Figure 3 Mean (95% confidence intervals) Roland-Morris Disability Questionnaire (RDQ) and pain numerical rating scores (average pain intensity, prior 24 hours) by treatment adherence over time. Treatment “crossover” was defined as having had the (more ...)
At 14 days, 63% of patients in the control group correctly guessed they had the control intervention, and 51% of patients in the vertebroplasty group correctly guessed they had the vertebroplasty. Both groups expressed similarly moderate confidence in their treatment guess on average (vertebroplasty mean=4.0, control mean=4.1; P=0.78). In the control group, 18 of 33 (55%) patients who adhered to treatment correctly guessed at 14 days that they had received the control intervention compared to 20 of 27 (74%) who eventually crossed over (P=0.12). Notably, among the eight vertebroplasty patients who crossed over to the control intervention, six (75%) guessed incorrectly at one month that they had received the control intervention.
In a post hoc subgroup analysis, the effect of treatment (vertebroplasty vs. control procedure) on one-month pain did not differ significantly across the three baseline pain duration categories (partial F-test P=0.58, 2 degrees of freedom). The treatment effect for patients with less than 13 weeks of pain (treatment difference: 0.8; 95% CI, −0.8 to 2.4; P=0.31) was similar to the results of the overall analysis. The treatment effect for patients with 14 – 26 weeks of pain was 1.3 (95% CI, −0.8 to 3.4; P=0.23) and that for patients with 27 – 52 weeks of pain was 0.0 (95% CI, −1.7 to 1.6; P=0.96).
One patient in the vertebroplasty group suffered injury to the thecal sac during the procedure, with resultant hospitalization. One patient in the control intervention group was hospitalized overnight after the procedure with tachycardia and rigors, of unclear etiology.