Trial Outcomes & Findings for The SNAP Trial: SPRINT® Peripheral Nerve Stimulation for the Treatment of Neuropathic Post-Amputation Pain (NCT NCT03783689)

Last Updated: 2023-11-29

Results Overview

All subjects were asked to complete daily diaries to record their average residual limb pain and/or phantom pain intensities during the past 24 hours on each day of a 7-day period using an 11-point numerical rating scale where 0 represents "No Pain" and 10 represents "Pain as bad as you can imagine." The average pain scores were calculated across the 7-day period for each region of pain at baseline and across weeks 5 to 8 post-start of treatment. Percent reduction was then calculated for each subject's qualifying region of pain (residual limb and/or phantom limb pain with qualifying average pain intensity at baseline). To be considered a success, subjects must have experienced ≥ 50% reduction in all qualifying regions of pain compared to their 7-day baseline diary average pain score(s). The number of successes is presented.

Recruitment status

TERMINATED

Study phase

Target enrollment

38 participants

Primary outcome timeframe

Baseline and 5 to 8 weeks post-start of treatment (SOT)

Results posted on

2023-11-29

Participant Flow

After obtaining informed consent, subjects were evaluated for eligibility.

Participant milestones

Participant milestones
Measure	Group 1 (Treatment) Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Overall Study STARTED	19	19
Overall Study Safety Set	19	19
Overall Study Full Analysis Set	18	18
Overall Study Per Protocol Set	13	16
Overall Study Group 2 (Control Group Treatment Crossover)	0	9
Overall Study COMPLETED	10	14
Overall Study NOT COMPLETED	9	5

Reasons for withdrawal

Reasons for withdrawal
Measure	Group 1 (Treatment) Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Overall Study Adverse Event	2	0
Overall Study Lost to Follow-up	2	1
Overall Study Physician Decision	2	1
Overall Study Withdrawal by Subject	3	3

Baseline Characteristics

The SNAP Trial: SPRINT® Peripheral Nerve Stimulation for the Treatment of Neuropathic Post-Amputation Pain

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Group 1 (Treatment) n=19 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=19 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Total n=38 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Age, Categorical Between 18 and 65 years	14 Participants n=5 Participants	13 Participants n=7 Participants	27 Participants n=5 Participants
Age, Categorical >=65 years	5 Participants n=5 Participants	6 Participants n=7 Participants	11 Participants n=5 Participants
Age, Continuous	56.6 years STANDARD_DEVIATION 12.0 • n=5 Participants	62.0 years STANDARD_DEVIATION 10.5 • n=7 Participants	59.3 years STANDARD_DEVIATION 11.5 • n=5 Participants
Sex: Female, Male Female	4 Participants n=5 Participants	8 Participants n=7 Participants	12 Participants n=5 Participants
Sex: Female, Male Male	15 Participants n=5 Participants	11 Participants n=7 Participants	26 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	2 Participants n=5 Participants	1 Participants n=7 Participants	3 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	17 Participants n=5 Participants	18 Participants n=7 Participants	35 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	2 Participants n=5 Participants	0 Participants n=7 Participants	2 Participants n=5 Participants
Race (NIH/OMB) Asian	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	2 Participants n=5 Participants	3 Participants n=7 Participants	5 Participants n=5 Participants
Race (NIH/OMB) White	14 Participants n=5 Participants	15 Participants n=7 Participants	29 Participants n=5 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	1 Participants n=7 Participants	1 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Region of Enrollment United States	19 participants n=5 Participants	19 participants n=7 Participants	38 participants n=5 Participants
Employment Status Currently Working	3 Participants n=5 Participants	4 Participants n=7 Participants	7 Participants n=5 Participants
Employment Status Retired (not due to health)	4 Participants n=5 Participants	4 Participants n=7 Participants	8 Participants n=5 Participants
Employment Status Unemployed	1 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants
Employment Status Student	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants
Employment Status Disabled / Retired (due to health)	9 Participants n=5 Participants	10 Participants n=7 Participants	19 Participants n=5 Participants
Employment Status Other (self-employed)	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants
Location of Amputation Right Leg: Below Knee Amputation	7 Participants n=5 Participants	6 Participants n=7 Participants	13 Participants n=5 Participants
Location of Amputation Right Leg: Above Knee Amputation	3 Participants n=5 Participants	5 Participants n=7 Participants	8 Participants n=5 Participants
Location of Amputation Left Leg: Below Knee Amputation	7 Participants n=5 Participants	4 Participants n=7 Participants	11 Participants n=5 Participants
Location of Amputation Left Leg: Above Knee Amputation	2 Participants n=5 Participants	4 Participants n=7 Participants	6 Participants n=5 Participants

PRIMARY outcome

Timeframe: Baseline and 5 to 8 weeks post-start of treatment (SOT)

Population: Per Protocol Set presented.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Number of Subjects With ≥50% Reduction in Average Post-Amputation Pain (Residual Limb Pain [RLP] and/or Phantom Limb Pain [PLP])	6 Participants	3 Participants

PRIMARY outcome

Timeframe: Up to 14 months for each Group 1 subject and up to 18 months for each Group 2 subject (time from baseline to last study visit)

Population: Safety Set

At each study visit following the baseline assessment at Visit 1, subjects were questioned if any changes in their medical status or condition have occurred since their previous visit. If the subject experienced a change that was a study-related adverse event, an Adverse Event Form was completed by the site. The number of subjects that experienced at least one study-related adverse event is reported here.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=19 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=19 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Number of Subjects That Experienced at Least One Study-Related Adverse Event	10 Participants	6 Participants

SECONDARY outcome

Timeframe: Visit 1 (Baseline), Visit 7 (4-weeks post-start of treatment [SOT]), Visit 11 (8-weeks post-SOT), Visit 13 (3-months post-SOT), Visit 14 (6-months post-SOT), and Visit 16 (12-months post-SOT)

Population: Per Protocol Set presented. Data were not available for one Group 1 subject at Visit 14, three Group 1 subjects at Visit 16, and one Group 2 subject at Visit 7. In accordance with the planned study protocol, Group 2 subjects were not assessed for this outcome at 6- and 12-months due to crossover to receive active stimulation.

Question 9 of the Brief Pain Inventory-Short Form (BPI-9) is a 7-part question that assesses the level of interference that subjects experience in their daily lives due to pain. The 7 categories are general activity, mood, walking ability, normal work, relations with other people, sleep, and enjoyment of life. Subjects were asked to rate how much their post-amputation residual and/or phantom limb pains interfere with each aspect on an 11-point numerical scale where 0 represents "Does Not Interfere" and 10 represents "Completely Interferes." The average of these 7 scores was calculated for each subject at each time point. Percent reduction was then calculated for each subject's qualifying region of pain (residual limb and/or phantom limb pain with qualifying average pain intensity at baseline). To be considered a success, subjects must have experienced ≥ 50% reduction in all qualifying regions of pain compared to baseline. The number of successes is presented.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Pain Interference Visit 7: 4-weeks Post-SOT	7 Participants	6 Participants
Pain Interference Visit 11: 8-weeks Post-SOT	10 Participants	8 Participants
Pain Interference Visit 13: 3-months Post-SOT	10 Participants	6 Participants
Pain Interference Visit 14: 6-months Post-SOT	9 Participants	—
Pain Interference Visit 16: 12-months Post-SOT	6 Participants	—

SECONDARY outcome

Population: Per Protocol Set presented. Data were not available for one Group 2 subject at Visit 7, one Group 1 subject at Visit 14, and three Group 1 subjects at Visit 16. In accordance with the planned study protocol, Group 2 subjects were not assessed for this outcome at 6- and 12-months due to crossover to receive active stimulation.

The Pain Disability Index (PDI) is a validated survey measuring the degree to which pain disrupts 7 categories of life activities on a scale from 0 to 10, with higher scores indicating greater disability. The 7 scores were summed for each subject to provide an overall pain disability score ranging from 0 to 70. A score of 0 indicates no disability while a score of 70 signifies that all of the activities in which the individual would normally be involved have been totally disrupted or prevented by pain. To be considered a success, subjects must have a ≥ 10-point reduction in their total PDI score at each time point compared to their baseline score. The number of subjects successful at each time point is reported.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Pain Disability Index (PDI) Visit 7: 4-weeks Post-SOT	10 Participants	9 Participants
Pain Disability Index (PDI) Visit 11: 8-weeks Post-SOT	10 Participants	9 Participants
Pain Disability Index (PDI) Visit 13: 3-months Post-SOT	12 Participants	5 Participants
Pain Disability Index (PDI) Visit 14: 6-months Post-SOT	10 Participants	—
Pain Disability Index (PDI) Visit 16: 12-months Post-SOT	6 Participants	—

SECONDARY outcome

Timeframe: Visit 7 (4-weeks post-Start of Therapy [SOT]), Visit 11 (8-weeks post-SOT), Visit 13 (3-months post-SOT), Visit 14 (6-months post-SOT), and Visit 16 (12-months post-SOT)

The Patient Global Impression of Change (PGIC) Survey asks subjects to rate their improvement with treatment on a 7-point scale ranging from -3 to 0 to +3, where -3 represents "very much worse," 0 is "no change," and +3 represents "very much improved" as compared to before stimulation treatment. The subjects combine all the components of their experience into one overall score. The mean rank score of each group was calculated for each time frame.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Patient Global Impression of Change (PGIC) Survey Visit 7: 4-weeks Post-SOT	1.8 score on a scale Standard Deviation 0.73	1.0 score on a scale Standard Deviation 1.1
Patient Global Impression of Change (PGIC) Survey Visit 11: 8-weeks Post-SOT	1.5 score on a scale Standard Deviation 0.66	0.88 score on a scale Standard Deviation 1.6
Patient Global Impression of Change (PGIC) Survey Visit 13: 3-months Post-SOT	1.2 score on a scale Standard Deviation 0.93	0.75 score on a scale Standard Deviation 1.2
Patient Global Impression of Change (PGIC) Survey Visit 14: 6-months Post-SOT	1.3 score on a scale Standard Deviation 1.4	—
Patient Global Impression of Change (PGIC) Survey Visit 16: 12-months Post-SOT	1.3 score on a scale Standard Deviation 1.3	—

SECONDARY outcome

Timeframe: Visit 1 (Baseline), Visit 7 (4-weeks post-Start of Treatment [SOT]), and Visit 11 (8-weeks post-SOT)

Population: Per Protocol Set presented. Data were not available for one Group 2 subject at Visit 7.

The Pain Catastrophizing Scale (PCS) questionnaire has 13 questions that assess rumination, magnification, and helplessness. Subjects are asked to think back on painful experiences in the past and reflect on how often they had specific thoughts or feelings. Each of the 13 questions is scored on a 5-point scale where 0 represents "not at all," and 4 represents "all the time." The scores from each question were summed for each subject to provide a total PCS score, with a possible range from 0 to 52 with higher scores indicating a greater tendency to catastrophize pain (i.e. a higher score indicates a worse outcome). The mean score for each time point is presented.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Pain Catastrophizing Scale (PCS) Visit 1: Baseline	17.6 score on a scale Standard Deviation 10.1	24.1 score on a scale Standard Deviation 11.6
Pain Catastrophizing Scale (PCS) Visit 7: 4-weeks Post-SOT	12.3 score on a scale Standard Deviation 10.0	17.2 score on a scale Standard Deviation 14.3
Pain Catastrophizing Scale (PCS) Visit 11: 8-weeks Post-SOT	8.3 score on a scale Standard Deviation 8.4	19.2 score on a scale Standard Deviation 15.4

SECONDARY outcome

Timeframe: Baseline, 1 to 4 weeks post-start of treatment (SOT), 5 to 8 weeks post-SOT, 3 months post-SOT, 6 months post-SOT, and 12 months post-SOT

Population: Per protocol set presented; only the six subjects that were using opioid analgesics at baseline were included in the analysis. Data were not available for two Group 1 subjects at 12-months post-SOT and for one Group 2 subject at 3-months post-SOT. In accordance with the planned study protocol, Group 2 subjects were not assessed for this outcome at 6- and 12-months due to crossover to receive active stimulation.

Subjects completed 7-day diaries in which they tracked their daily use of analgesic medications. Opioid analgesic usage was converted into a morphine equivalent dosage (MED), which is measured in units of morphine milligram equivalents (MME), for subjects who were using opioid analgesics at baseline. The average MED was calculated for each subject at each time point.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=3 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=3 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Pain Medication Usage Baseline	32.3 MME (Morphine Milligram Equivalents) Standard Deviation 37.2	14.4 MME (Morphine Milligram Equivalents) Standard Deviation 13.7
Pain Medication Usage 1 to 4 weeks Post-SOT	32.4 MME (Morphine Milligram Equivalents) Standard Deviation 36.9	16.3 MME (Morphine Milligram Equivalents) Standard Deviation 13.0
Pain Medication Usage 5 to 8 weeks Post-SOT	30.4 MME (Morphine Milligram Equivalents) Standard Deviation 38.7	12.4 MME (Morphine Milligram Equivalents) Standard Deviation 10.4
Pain Medication Usage 3-months Post-SOT	30.7 MME (Morphine Milligram Equivalents) Standard Deviation 38.9	9.0 MME (Morphine Milligram Equivalents) Standard Deviation 12.7
Pain Medication Usage 6-months Post-SOT	21.1 MME (Morphine Milligram Equivalents) Standard Deviation 21.5	—
Pain Medication Usage 12-months Post-SOT	45.0 MME (Morphine Milligram Equivalents) Standard Deviation 0.0	—

SECONDARY outcome

Timeframe: Baseline and 1 to 4 weeks post-start of treatment (SOT)

Population: Per Protocol Set presented. One Group 2 subject only had 3 days of diary data during week 3 post-SOT.

All subjects were asked to complete daily diaries to record their average residual limb pain and/or phantom pain intensities during the past 24 hours on each day of a 7-day period using an 11-point numerical rating scale where 0 represents "No Pain" and 10 represents "Pain as bad as you can imagine." The average pain scores were calculated across the 7-day period for each region of pain at baseline and across weeks 1 to 4 post-start of treatment (i.e., the first half of the 8-week treatment period). Percent reduction was then calculated for each subject's qualifying region of pain (residual limb and/or phantom limb pain with qualifying average pain intensity at baseline). To be considered a success, subjects must have experienced ≥ 50% reduction in all qualifying regions of pain compared to their 7-day baseline diary average pain score(s). The number of successes is presented.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Number of Subjects With ≥ 50% Reduction in Average Post-Amputation Pain (Residual Limb Pain [RLP] and/or Phantom Limb Pain [PLP]) 1 to 4 Weeks After Start of Treatment	3 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline and 5 to 8 weeks post-start of treatment (SOT)

Population: Per Protocol Set of subjects that qualified with residual limb pain presented.

All subjects were asked to complete daily diaries to record their average residual limb pain and/or phantom pain intensities during the past 24 hours on each day of a 7-day period using an 11-point numerical rating scale where 0 represents "No Pain" and 10 represents "Pain as bad as you can imagine." The average residual limb pain scores were calculated across the 7-day period at baseline and for weeks 5 to 8 post-start of treatment (for subjects with qualifying residual limb average pain intensity at baseline). Percent reduction from baseline was then calculated, and the number of subjects that experienced ≥ 50% reduction in residual limb pain are reported.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=10 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=13 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Number of Subjects With ≥ 50% Reduction in Average Residual Limb Pain (RLP) 5 to 8 Weeks After Start of Treatment	5 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline and 5 to 8 weeks post-start of treatment (SOT)

Population: Per Protocol Set of subjects that qualified with phantom limb pain presented.

All subjects were asked to complete daily diaries to record their average residual limb pain and/or phantom pain intensities during the past 24 hours on each day of a 7-day period using an 11-point numerical rating scale where 0 represents "No Pain" and 10 represents "Pain as bad as you can imagine." The average phantom limb pain scores were calculated across the 7-day period at baseline and for weeks 5 to 8 post-start of treatment (for subjects with qualifying phantom limb average pain intensity at baseline). Percent reduction from baseline was then calculated, and the number of subjects that experienced ≥ 50% reduction in phantom limb pain are reported.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=12 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=14 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Number of Subjects With ≥ 50% Reduction in Average Phantom Limb Pain (PLP) 5 to 8 Weeks After Start of Treatment	7 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline, 3-months post-Start of Treatment (SOT), 6-months post-SOT, and 12-months post-SOT

Population: Per Protocol Set presented. Data were not available for one Group 1 subject at 6-months and for three at 12-months. In accordance with the planned study protocol, Group 2 subjects were not assessed for this outcome at 6- and 12-months due to crossover to receive active stimulation.

All subjects were asked to complete daily diaries to record their average residual limb pain and/or phantom limb pain intensities during the past 24 hours on each day of a 7-day period using an 11-point numerical rating scale where 0 represents "No Pain" and 10 represents "Pain as bad as you can imagine." The average pain scores were calculated across the 7-day period for each region of pain at baseline and at 3, 6, and 12 months post-start of treatment. Percent reduction was then calculated for each subject's qualifying region of pain (residual limb and/or phantom limb pain with qualifying average pain intensity at baseline) at each time point. To be considered a success, subjects must have experienced ≥ 50% reduction in all qualifying regions of pain compared to their 7-day baseline diary average pain score(s). The number of successes is presented.

Outcome measures

Outcome measures
Measure	Group 1 (Treatment) n=13 Participants Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=16 Participants Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.
Durability of Treatment Effect on Average Post-Amputation Pain Intensity (Residual Limb Pain [RLP] and/or Phantom Limb Pain [PLP]) 3-months Post-SOT	4 Participants	3 Participants
Durability of Treatment Effect on Average Post-Amputation Pain Intensity (Residual Limb Pain [RLP] and/or Phantom Limb Pain [PLP]) 6-months Post-SOT	4 Participants	0 Participants
Durability of Treatment Effect on Average Post-Amputation Pain Intensity (Residual Limb Pain [RLP] and/or Phantom Limb Pain [PLP]) 12-months Post-SOT	3 Participants	0 Participants

Adverse Events

Group 1 (Treatment)

Serious events: 0 serious events

Other events: 10 other events

Deaths: 0 deaths

Group 2 (Control)

Serious events: 0 serious events

Other events: 6 other events

Deaths: 0 deaths

Group 2 (Control Group Treatment Crossover)

Serious events: 0 serious events

Other events: 2 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Other adverse events
Measure	Group 1 (Treatment) n=19 participants at risk Subjects in Group 1 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received electrical stimulation for up to 8 weeks via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control) n=19 participants at risk Subjects in Group 2 were consented and met all eligibility criteria prior to randomization. These subjects had Leads placed in their residual limb and received up to 8 weeks of sham stimulation. Three months after start of sham treatment, subjects were given the option to crossover and receive stimulation therapy via the SPRINT Peripheral Nerve Stimulation (PNS) System.	Group 2 (Control Group Treatment Crossover) n=9 participants at risk Subjects who were consented and randomized to Group 2 (Control), received sham stimulation treatment, and crossed over to receive active stimulation treatment.
Skin and subcutaneous tissue disorders Skin irritation	36.8% 7/19 • Number of events 9 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	26.3% 5/19 • Number of events 6 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	22.2% 2/9 • Number of events 2 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.
Skin and subcutaneous tissue disorders Itching at bandage site	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	11.1% 1/9 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.
Skin and subcutaneous tissue disorders Discoloration/bruising	15.8% 3/19 • Number of events 4 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/9 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.
Skin and subcutaneous tissue disorders Skin infection	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/19 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/9 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.
Skin and subcutaneous tissue disorders Skin tear at pad site	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/19 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/9 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.
Musculoskeletal and connective tissue disorders Pain at lead site	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/19 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/9 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.
Musculoskeletal and connective tissue disorders Uncomfortable stimulation	5.3% 1/19 • Number of events 1 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/19 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.	0.00% 0/9 • Each participant enrolled was assessed for adverse events from the time of informed consent through their final study visit. For subjects in Group 1, the total assessment period was approximately 14 months for each participant. Each Group 2 subject that did not crossover to receive stimulation treatment was assessed for approximately 5 months. Group 2 subjects that crossed over to receive treatment were each assessed for approximately 18 months.

Additional Information

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