The guideline panel consists of 4 work groups to cover the 26 questions in this guideline. Senior and newer NASS Clinical Practice Guidelines members were placed in work groups to ensure that groups with newer members were balanced with members who have more guideline development experience. Each work group consisted of 3 to 5 members representing multidisciplinary backgrounds. The guideline panel includes representation from the fields of neurosurgery, orthopedic spine surgery, and spine research. NASS believes that having multidisciplinary teams involved in the guideline development process helps to minimize inadvertent biases in evaluating the literature and formulating recommendations.

Framing questions to ask in the guideline is critical to the guideline development process. The clinical questions from the original guideline, published in 2009, were reviewed and revised by trained guideline panelists. These panelists were asked to submit a list of new additional clinical questions that the guideline should address in addition to the questions included in the original guideline. Members were asked to use the acronym “PICO” when drafting questions if possible. “PICO” serves to guide the development of clinical questions that include all of the necessary components to build a literature search: “P” for the patient/problem; “I” for the intervention or indicator of interest (procedures, therapies, diagnostic tests, exposure, etc.); “C” for comparison and “O” for outcome of interest. The proposed questions were compiled into a master list and circulated to each member for review and comment. The draft clinical question list was then submitted to the NASS Health Policy Council, Evidence Analysis & Research Council, and Advocacy Council Chair for review. The councils submitted additional questions that may be useful for health policy or research purposes.

The draft list of clinical questions was made publicly available on the NASS website for a 30-day public comment period from June 8 to July 9, 2020. Additionally, stakeholders were invited through email solicitations to comment on the draft questions. Based on feedback, several revisions were incorporated in the clinical question list. After the comment period, an updated clinical question list with summarized changes was posted to the NASS website and circulated to all public comment period reviewers.

One of the most crucial elements of evidence analysis is the comprehensive literature search. Thorough assessment of the literature is the basis for the review of existing evidence and the formulation of evidence-based recommendations. In order to ensure a thorough literature search, NASS has instituted a Literature Search Protocol (Appendix A) which has been followed to identify literature for evaluation in guideline development. In keeping with the Literature Search Protocol, work group members have identified appropriate search terms and parameters to direct the literature search. Specific search strategies, including search terms, parameters and databases searched, are documented in the Technical Report associated with this document. The guideline definition and inclusion/exclusion criteria are outlined in the Introduction page . Methods were determined and agreed upon a priori and not changed after the literature search.

Once each work group identified search terms/parameters, the literature search was implemented by a work group with training and experience in systematic review search strategies, with oversight from a medical librarian, consistent with the Literature Search Protocol. Following these protocols ensures that NASS recommendations (1) are based on a thorough review of relevant literature; (2) are truly based on a uniform, comprehensive search strategy; and (3) represent the current best research evidence available. NASS maintains a search history in Endnote, for future use or reference.

Literature search results were uploaded into EndNote and Rayyan.1 At least two independent reviewers screened titles/abstracts to identify potential studies for inclusion. Full text articles were then reviewed for inclusion and allocated to the appropriate question(s). The reference list of included articles was also screened for eligible studies. Discrepancies were discussed until consensus was reached.

Members independently developed evidentiary tables summarizing study conclusions, identifying strengths and weaknesses (risk of bias), and assigning levels of evidence. In order to systematically control for potential biases, two or more work group members have reviewed each article selected and independently assigned levels of evidence to the literature using the NASS levels of evidence. Any discrepancies in scoring were resolved by discussion by two or more reviewers, and if necessary, arbitration with a larger group including work group authors, section chairs, and project lead. Final ratings were completed at a final meeting of section workgroup members including the section chair and project lead. Many articles have external funding sources (eg, government, research philanthropy, industry) and are described in the individual manuscript. When easily identifiable, industry funding was noted in the guideline article summaries. As a final step in the evidence analysis process, members have identified and documented gaps in the evidence to educate guideline readers about where evidence is lacking and help guide further needed research.

Work groups held virtual meetings to discuss the evidence-based answers to the clinical questions, the grades of recommendations and the incorporation of expert consensus. Expert consensus was incorporated only where Level I-IV evidence is insufficient and the work group has deemed that a recommendation is warranted. Transparency in the incorporation of consensus is crucial and all consensus-based recommendations made in this guideline very clearly indicate that Level I-IV evidence is insufficient to support a recommendation and that the recommendation is based only on expert consensus.

Consensus Development Process

For recommendations with a consensus grading, voting was conducted using a modification of the nominal group technique in which each work group member independently and anonymously ranked a recommendation on a scale ranging from 1 (“extremely inappropriate”) to 9 (“extremely appropriate”). Consensus was obtained when at least 80% of work group members ranked the recommendation as 7, 8 or 9. When the 80% threshold was not attained, up to three rounds of discussion and voting were held to resolve disagreements. If disagreements were not resolved after these rounds, no recommendation was adopted. After the recommendations were established, work group members developed the guideline content, addressing the literature supporting the recommendations.

Recommendation Development

In order to capture all relevant literature on this topic, the questions were formed to cover a broad population and did not necessarily focus on subcategorization. After the literature search was complete, a subcategory recommendation would be developed if there was enough evidence available to support. If the literature did not allow subcategorization, a general recommendation was made whenever possible.

Guideline sections were reviewed by the section work groups that developed them. The full guideline draft was then reviewed by the entire author group. Revisions to recommendations were considered only when substantiated by a preponderance of appropriate level evidence.

In order to assess clarity and perception of quality, members of NASS’ Clinical Practice Guidelines Committee who were not involved in the development of this guideline were invited to review the draft guideline. These external reviewers were given the opportunity to complete the Appraisal of Guidelines for Research & Evaluation II (AGREE II)2 instrument and provide open-ended comments. Additionally, a public comment period was open from October 15, 2024 to November 13, 2024. Members of the public, including but not limited to subject matter experts and societies, were eligible to complete a form with rating scales and open-ended questions in order to gather feedback on draft recommendations, assess readability, content, and feasibility (eg, facilitators and barriers to implementation), and improve the overall quality of the guideline. Revisions to recommendations were considered only when substantiated by a preponderance of appropriate level evidence.

After any evidence-based revisions were incorporated, the drafts were prepared for review and approval from the NASS Evidence Analysis & Research Council, followed by the NASS Board of Directors. Edits and revisions to recommendations and any other content were considered for incorporation only when substantiated by a preponderance of appropriate level evidence.

Following NASS Board approval, the guideline was slated for publication. No revisions were made after submission for publication, but comments have been and will be saved for the next iteration.

The guideline recommendations will be reviewed 3-5 years after publication, or according to the NASS’ topic selection and revision protocol. An EBM-trained multidisciplinary team will review and, when necessary, revise or rescind the guideline.