Initial investigation into the reliability of NUCCA assessments returned much success with the Supine Leg Check (SLC) Pilot study. Donor contributions allowed for:
- Initiation of the study.
- Presentation of results at two conferences.
- Chiropractic Research Agenda Conference (ACC-RAC 2011),
- 3rd North American Congress of Epidemiology,
- Publication of results to two indexed peer-reviewed journals;
- Journal of Manipulative and Physical Therapeutics (JMPT – May 2011)
- Epidemiologic Perspectives & Innovations
Data analysis and interpretation protocols were developed for all future NUCCA assessment reliability studies. Funding the SLC Pilot Study allowed for important team building and infrastructure development to handle data and employ a biostatistician, which is necessary to proceed to a full-scale SLC reliability study.
Results from the pilot have allowed for sample size calculations to produce statistically significant outcomes and the ability to fine-tune the original pilot protocol to demonstrate overall increased reliability in performing the SLC. Sample size requirements depend on the question being asked and the underlying assumptions. Using assumptions of an underlying kappa (κ) of 0.45, a margin of error of .10 requires 358 observations, compensating for a 15% non-inclusion rate. Four hundred subjects are to be recruited to produce statistically significant results.
Inter-examiner reliability may be assumed to increase when the population is symptomatic and leg length inequalities exceed ¼-inch. Subjects with headaches, neck, and back pain will be recruited. Inter-examiner reliability is also highly dependent on the threshold set for defining leg length inequality. Strict definitions for examiner decision-making thresholds will be established and refined.
The prevalence of leg length inequality (LLI) in general populations has yet to be addressed. The potential of the full-scale SLC study may put some issues surrounding SLC reliability to rest.
Study Procedure
Our study procedure is meticulously designed to ensure accurate and reliable data collection. Two board-certified NUCCA practitioners will examine 100 subjects every other weekend for approximately two months. A diverse population is crucial for the validity of our results, and a study location will be secured to support this and capitalize on the area’s diversity. Subjects volunteering must be between the ages of 18 and 65 years, and an ideal demographic of subjects would consist of the following:
Subjects Percentage
- Male 40%
- Female 60%
Minority Inclusion
- Black American 10%
- Asian American 2%
- Native American 2%
- Caucasian 81%S
- Hispanic American 5%
The study protocol is centered on lessons learned from the SLC Pilot study to decrease examiner variability in their observations, thereby increasing their ability to agree on the amount of LLI seen. Using clinic-provided shoes reduces the chance that footwear changes examiner agreement. Shoes will be marked with a “L” for left and “R” for right to eliminate any likelihood of human error. Exam tables are identified as right or left as well. The data collection protocol developed for the pilot study will be used to ensure solid collection and protection of the examiner’s data.
The publication of our study results in indexed peer-reviewed journals will contribute to the body of knowledge in chiropractic and profoundly impact the credibility and effectiveness of the NUCCA correction.
Your potential support is crucial in achieving this significant milestone.