In January 2005, the oversight responsibility of the Post-Approval Studies Program was transferred to the Division of Epidemiology (DEPI) of the Office of Surveillance and Biometrics (OSB)/Center for Devices and Radiological Health (CDRH).
The CDRH Post-Approval Studies Program encompasses design, tracking, oversight, and review responsibilities for studies mandated as a condition of approval of a premarket approval (PMA) application, protocol development product (PDP) application, or humanitarian device exemption (HDE) application. The program helps ensure that well-designed post-approval studies (PAS) are conducted effectively and efficiently and in the least burdensome manner.
CDRH has established an automated, internal tracking system that efficiently identifies the reporting status of active PAS studies ordered since January 1, 2005 based on study timelines incorporated in study protocols and agreed upon by the CDRH and applicants. This system represents CDRH's effort to ensure that all PAS commitments are fulfilled in a timely manner.
In addition, CDRH launched this publicly available webpage to keep all stakeholders informed of the progress of each PAS. The webpage displays general information regarding each PAS, as well as the overall study status (based on protocol-driven timelines and the adequacy of the data) and the applicant's reporting status for each submission due.
The Long-Term Outcomes Study (LTOS) is a prospective, multi-center study of patients who received the
X-STOP device in the pre-market trial, crossover study (COS) or continued access program (CAP).
Study Population Description
The study population is comprised of patients aged 50 years and older who have lumbar
spinal stenosis, suffers symptoms of neurogenic intermittent claudication, have moderately impaired physical function, and are able to relieve their symptoms when they bend forward or flex their spines. This device is indicated for treatment of patients aged 50 or older suffering from neurogenic intermittent claudication secondary to a confirmed diagnosis of lumbar spinal stenosis (with X-Ray, MRI, and/or CT evidence of thickened ligamentum flavum, narrowed lateral recess and/or central canal narrowing). The X STOP is indicated for those patients with moderately impaired physical function who experience relief in flexion from their symptoms of leg/buttock/groin pain, with or without back pain, and have undergone a regimen of at least 6 months of nonoperative treatment. The X STOP may be implanted at one or two lumbar levels in patients in whom operative treatment is indicated at no more than two levels.
The sample size is 155 potential patients who participated in the IDE.
The primary effectiveness endpoint is treatment response, defined as follows:- Clinically significant improvement (by at
least 5 points) in the Symptom Severity (SS) Domain of the ZCQ compared to the preoperative baseline.-Clinically significant improvement (by at least 0.5 points) in the Physical Function (PF) domain of the ZCQ compared to the preoperative baseline score
-Patient satisfaction with treatment defined by Patient Satisfaction score at the five-year postoperative evaluation.- No additional surgery for lumbar stenosis performed.- No dislodgement of the implant. - No device-related complications. Secondary effectiveness endpoints encompass mean individual ZCQ domain scores and mean SF-36 scores.Radiographic examination will permit the assessment of the maintenance of distraction. Distraction will be maintained if the distance between the spinous processes is not reduced by more than 4 mm from the distance observed at the six-week clinical assessment.
Followup Visits and Length of Followup
The duration of patient follow-up will be 5 years. The follow-up schedule for the study
is delineated below:- 24 months following initial enrollment for those patients actively participating in either the CAP or COS at the time of LTOS study initiation- 36 months for all CAP/COS patients following enrollment into their original IDE study- 48 months for all CAP/COS patients following enrollment into their original IDE study - 60 months for all CAP/COS patients following enrollment into their original IDE study, > 60 months, for all Pivotal Trial patients following their IDE study enrollment into the X-STOP group. All patients in the Pivotal Trial have already reached their fifth postoperative year; therefore they will have in excess of 60 months device experience at their next follow-up visiT. At every office visit, patients will complete the ZCQ and the SF-36 prior to physician examination. Patients will undergo a complete clinical examination with emphasis on the neurological assessment for strength, reflexes, sensation, and pain related to the diseased intervertebral space.
Radiographic examination, anterior/posterior (AP) and lateral x-rays, will be performed on all LTOS patients at their 5 year postoperative visit. Radiographic examination will also be performed on LTOS patients at 24 months. Data collected from the radiographic examinations will include the position of the X-STOP, the status of the X-STOP, the status of the spinous process, laminae and facets, and the distance between the tips of the spinous processes.