An observational study in Complex Regional Pain Syndrome I (CRPS I), sponsored by Ambros Therapeutics, Inc.. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-29.
Sponsored by Ambros Therapeutics, Inc. · Observational
The goal of this observational study is to learn about how well neridronate keeps working in the months after treatment. For 12 or up to 24 months while the registry is open participants will answer online survey questions about their CRPS pain, medication use or procedures done and how CRPS affects what they are able to do.
The primary objective of the registry is to evaluate the long-term effectiveness of IV neridronate across three outcome domains in participants who qualified in CRPS-RISE with early, warm CRPS-1 and a positive triple phase bone scan, following prior treatment with four infusions of neridronate 100 mg IV over approximately a 10-day period. The three outcome domains include, patient report of health status, CRPS-1 related clinical events, and disability status.
No neridronate treatment will be given as part of the registry and limited safety information will be collected. Participants will have received neridronate either through CRPS-RISE and/or through the Open Label Extension.
205 studies on the registry are indexed under Complex Regional Pain Syndromes; 55 are open to participants now.
This study's planned enrollment of 270 is above the median of 55 across 43 observational studies indexed under Complex Regional Pain Syndromes.
Browse Complex Regional Pain Syndromes studies →Ambros Therapeutics, Inc. is the lead sponsor of 3 studies on the registry; 3 are open to participants now.
Counted across the registry records on this site, refreshed daily.
The registry target population for provisional enrollment includes all participants in CRPS-RISE, the parent trial of the Registry. After the completion of the last participant's last visit in CRPS-RISE and the unblinding of the trial, the Enrolled Study Cohort will be participants confirmed to have completed a four-infusion course of neridronate. The Enrolled Study Cohort will also include participants in the Open Label Extension study.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Participants from CRPS-RISE
Completed CRPS-RISE with a final trial visit at Week 6 (Visit 8) or later.
Participants who meet both criteria will be provisionally enrolled pending post-trial unblinding and be included in the Provisionally Enrolled Study Cohort.
After CRPS-RISE last patient last visit unblinding, only participants who meet the following neridronate exposure criterion #3 will continue in registry follow-up and be included in the Enrolled Study Cohort:
Participants from the Open Label Extension (OLE)
Exclusion Criteria:
There are no exclusion criteria.
Participants provisionally enrolled in the registry. (Note: Participants provisionally enrolled who do not meet this neridronate-exposure criterion will not continue registry follow-up.)
Participants who have consented to participate and meet all inclusion criteria including confirmation of completing four infusions of neridronate.
Change from baseline to each registry assessment of average pain in the past 24 hours.
Average pain (24-hour recall) reported on an 11-point numeric rating scale. This is recorded every 90 days from entry.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Time to loss of benefit where benefit is 50% reduction in average pain intensity from baseline to Week 12 of the CRPS-RISE trial.
Each patient reported registry assessment of average pain in the past 24 hours will use an 11 point numeric rating scale. The analysis will be limited to participants who experienced benefit. Data will be summarized as Kaplan-Meier estimates.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Change from baseline to each registry assessment in CRPS Severity Score Self-Report (CSS-SR) total score and individual items.
The CSS-SR is designed as a patient self-report questionnaire to assess the severity of CRPS signs and symptoms using plain language to assess 13 concepts.
Time frame: Every 3 months from entry to up to 24 months of participation.
Change from baseline to each registry assessment in Patient Global Impression of Severity (PGI-S).
The 6-point PGI-S is an overall assessment of the participant's perception of the severity of their CRPS condition at the time of the assessment. Participants will respond to the question "How would you rate the symptoms of your CPRS at this time." Possible responses are scored from 0 to 5 representing none, minimal, mild, moderate, severe, very severe.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Change from baseline to each registry assessment in each of the Short Form 12 Health Survey (SF-12, Acute Version 2) domains, Physical Component Score (PCS), Mental Component Score (MCS), and individual items.
The SF-12 is a widely used measure of general health status used in observational studies across a broad range of disease areas. It is a shortened version of the SF-36 V2.0 and yields 8 domain scores and a Physical Component Summary and Mental Component Summary. Each domain score is calculated by transforming raw responses to a 0-100 scale, where higher scores indicate better health status.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Change from baseline to each registry assessment in Daily Sleep Interference Scale (DSIS) in the past 24 hours on an 11-point numeric rating scale.
The DSIS is a single-item scale that assesses "how much did your pain interfere with your sleep during the past 24 hours?" (0 = did not interfere; 10 = completely interfered
Time frame: Every 3 months from enrollment until up to 2 years after entry.
CRPS-1 Related Clinical Events during the 3 months preceding each registry assessment.
The CRPS-1 Treatment Checklist was developed for this registry to assess commonly used pharmacologic treatments (e.g., opioids, neuropathic pain agents, ketamine, NSAIDs, bisphosphonates, corticosteroids, and topicals),interventional procedures (e.g., spinal cord or dorsal root ganglion stimulation, peripheral nerve stimulation, stellate/lumbar sympathetic blocks, sympathetic ablation/sympathectomy, intrathecal pump implant, and Bier block), and non-invasive rehabilitation therapies (e.g., physical therapy, occupational therapy, mirror visual feedback, psychological therapies, scrambler therapies or acupuncture). Participants select all CRPS-related treatments used in the past 3 months. The checklist will also record participation in the open-label clinical trial and is intended for descriptive evaluation of long-term CRPS-1 treatments with a focus on resource intensive events. The outcome domain assesses the long-term effectiveness of neridronate through patient reports.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Disability Status
During the 3 months preceding each registry assessment the participant reported applying for or being on short-term disability, long-term disability, or workers compensation. As a binary endpoint, it will be summarized as frequencies and percentages. The domain assesses the long-term effectiveness of neridronate through patient reports of short-term disability, long-term disability, and workers compensation.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Healthcare Use and Costs (Provisional)
The potential for inclusion of linked health care claims and electronic health record data will be enabled by having participants consent to tokenizing their identifying information.
Time frame: Every 3 months from enrollment until up to 2 years after entry.
Plan to share: Undecided
No publications or documents are linked to this record.
Start is estimated for Sep 2026; primary completion for Apr 2029, 30 months later.
Of 18 observational studies under Complex Regional Pain Syndromes, half reached primary completion within 68 months of starting (the median), counting those still running; a quarter within 13 and three quarters within 147. This study's planned 30 months is below that.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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