Abbott Proclaim 3660 Clinician Manual page 75

Programming parameters for tonic stimulation are based on long-term experience and
subject-optimization needs, while burst programming parameters for pulse width and
frequency were selected from feasibility studies and did not allow subject-specific
customization except for amplitude adjustment. Future studies that optimize burst
programming may show additional reduction in paresthesia.
Pain medication. The use of pain medications decreased more often during burst
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stimulation (32.3%) than during tonic stimulation (28.1%). In addition, the use of pain
medications increased less often during burst stimulation (9.4%) than during tonic
stimulation (12.5%).
Psychosocial measures. Based on the study exclusion criteria, only subjects with a BDI‡-II
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score of less than 24 could be enrolled. The exclusion of subjects with a BDI-II score of 24
or more most likely contributed to the observed low baseline scores for the other
psychosocial measures, as depression has been shown to be directly related to quality of life,
disability, and catastrophizing (Brenes, 2007; Currie & Wang, 2004; Richardson et al., 2009;
Tennen et al., 2006). Other pain studies that have shown clinically significant changes for
these domains have generally included such patients.
The baseline scores for the SF-36 physical component (28.6), ODI (49.1), and PCS (20.4) in
the study population were also below clinically relevant levels of impairment typically seen in
SCS candidates in quality of life, disability (Kumar et al., 2007), and catastrophizing
(Sullivan, 2009), respectively. Neither burst stimulation nor tonic stimulation produced
clinically meaningful changes for any of these psychosocial measures. Based on the baseline
scores, an improvement of the scores would not be expected.
Safety Conclusions
No device- or stimulation-related SAEs or any events categorized as unanticipated adverse device
effects (UADEs) were reported during the study. Fewer stimulation-related events occurred during
burst stimulation than tonic stimulation (13 events in 11 subjects and 16 events in 10 subjects,
respectively).
Benefit-Risk Conclusions
The probable benefits of the device are based on this clinical study for burst stimulation.
Effectiveness was demonstrated by the primary and powered secondary study endpoints. Burst
stimulation was also shown to be safe as described in the safety conclusions.
Limitations. The open label crossover design did not blind subjects as to whether they were
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receiving burst or tonic stimulation. The only randomized variable was the order in which a
subject would experience each stimulation mode—burst stimulation first or tonic stimulation
first. Blinding the stimulation mode was not feasible because subjects may have experienced
different sensations with each mode. Since the mode was not blinded, investigator and
subject bias may have affected the results for both tonic and burst stimulation modes.
In addition, the study design did not allow an assessment of the placebo response. Placebo
response is well known in pain studies due to the subjective nature of the pain assessment,
and the duration of the placebo response may be long lasting. Finally, subjects in the study
were required to maintain stable doses of their adjunctive pain medications. However, some
subjects in both groups required additional pain medications; these subjects were
considered non-responders for the stimulation mode in which they increased their
medications and were accounted for in the statistical plan.
Subjects had to complete a successful SCS trial using tonic stimulation before being
implanted with a permanent system and the success of tonic stimulation during the trial
period may have resulted in investigator and subject bias. Additionally, a washout phase was
not included before switching between stimulation modes.
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