Interexaminer Reliability of Three Methods of Combining Test Results to Determine Side of Sacral Restriction, Sacral Base Position, and Innominate Bone PositionFrom the Department of Physical Medicine and Rehabilitation (Tong, Heyman, Lado, Isser); and the Spine Program (Tong, Heyman), University of Michigan in Ann Arbor. No funding was received from any pharmaceutical or equipment companies. Address correspondence to: Henry C. Tong, MD, Michigan Head & Spine Institute, Southfield Michigan, 29275 Northwestern Hwy, Ste 100, Southfield, MI 48034-5700. E-mail: hctong2{at}medscape.com Context: Sacroiliac joint dysfunction is diagnosed based on the combined results of several palpatory examinations. Previous studies have compared the interexaminer reliability of only one of these methods of diagnosis. Objective: To compare the interexaminer reliability of three methods of combining palpatory examinations to determine the side of sacroiliac joint dysfunction, sacral base position, and innominate bone position. Design: Blinded single-cohort reliability study.
Methods: Patients with low back pain underwent two identical sets of
palpatory examinations given by two physicians, separately, at a university
spine center. The results of each set were compiled and interpreted by three
methods: using the test result with the highest interexaminer reliability
(method 1), requiring at least one test result to be abnormal for the variable
to be abnormal (method 2), and requiring all test results to be abnormal for
the variable to be abnormal (method 3). The
Results: There were 24 subjects (mean age, 68.3 years), of which 15
(62%) were women. The Conclusion: Using the results of the most reliable examination consistently has the best interexaminer reliability.
A recent review article on the validity and reliability of tests for low-back dysfunction concluded that no single test has been adequately studied to be able to determine its validity and reliability.1 Similar judgments were expressed in two other review articles, which concluded that sacroiliac joint (SIJ) mobility tests were not proven to be reliable.2,3
It has been suggested that interexaminer reliability may be improved by
combining results from several tests into a composite multitest score
(MTS).4
Haas4 noted, based
on probability calculations, that the expected rate of agreement is lowest
when a middle threshold value is used (eg, three of five tests are required to
yield positive results before the MTS is considered positive). Thus, the
Two studies did present the reliability of individual tests and the MTS.9,10 Keating et al9 evaluated 46 subjects and showed only slightly stronger reliability with the MTS. Boline et al10 did not show improvement with the MTS. These two studies suggest that MTSs do not improve interexaminer reliability when compared with the individual test results.9,10 However, these studies only looked at one method of combining the individual test results. The effect of MTSs on the interexaminer reliability of diagnoses for the sacral and innominate bone positions was not examined by any of the studies mentioned previously.110 When treating patients using a directed manual treatment program, it is not enough to simply determine the presence of an SIJ dysfunction. The results of at least two of the individual palpatory examinations need to be combined to obtain diagnoses for the sacral and innominate bone positions.11
The purpose of the current study is to compare the interexaminer reliability of three methods of combining the results of osteopathic palpatory examinations to determine the side of SIJ dysfunction, sacral base position, and innominate bone position.
Between December 2002 and April 2003, new patients seen at a university spine center each underwent two separate evaluations by two physicians performing identical palpatory examinations. The first evaluator (H.C.T.) was aware of the patients' clinical histories, while a second evaluator (O.G.H., D.A.L., or M.M.I.) was blinded to these histories and current medical status as well as the results obtained by the first examiner. Subjects were included in the study if they had a chief complaint of low back pain. Subjects were excluded from the study if they could not tolerate the physical examination as a result of pain. Demographic variables, including age, sex, height, and weight, were recorded. Palpatory examinations were conducted to evaluate three variables: the presence and side of SIJ dysfunction, the sacral position, and the innominate bone position (Figure). For all of the tests, examiners used their dominant eyes as recommended by Greenman.11 The institutional review board of the University of Michigan Medical School in Ann Arbor approved the study, and informed consent was obtained from all subjects.
Diagnostic Methods
The resulting data from the three different models were then combined to determine the side of SIJ dysfunction, sacral position, and innominate bone position.
Statistical Analysis
Twenty-four subjects were chosen chronologically. No subject was excluded from the study as a result of exclusion criteria. The demographics of the subjects are described in Table 1. The mean age of participants was 68.3 years, and 15 patients (62%) were women. The mean height of participants was 1.7 m, the mean weight was 78.3 kg, and the mean body mass index was 27.8 kg/m2.
The interexaminer reliability of each palpatory examination is summarized
in Table 2. Of the
examinations for SIJ dysfunction, the standing stork test had the best
interexaminer reliability, with a
The interexaminer reliability of the resulting sacral position diagnosis
and innominate bone position diagnosis for the three diagnostic methods are
summarized in Table 3.
The interexaminer reliability of sacral position when divided into all nine
possible categories was incalculable due to the large number of categories and
small number of subjects. Consequently, we calculated the interexaminer
reliability of sacral positioning as characterized by the two components that
determine sacral position: sacral base position (normal, anterior, or
posterior) and side of dysfunction (bilateral, left, or right). The
interexaminer reliability of sacral base position for all three methods was
poor to fair, with
Post hoc analysis was performed because it was noted that one of the
secondary examiners consistently had poor correlation with the initial
examiner. Because of this finding, the data were reanalyzed, excluding the
subjects seen by the examiner in the second group. As shown in
Table 2, the
interexaminer reliability of all of the tests improved with the remaining 18
subjects. Specifically, the
Several different palpatory examinations are used to evaluate joint motion as well as joint position to detect any abnormality. It has been suggested that combining results from several tests to form a composite MTS will increase interexaminer reliability.4 In fact, Haas4 recommends that if an MTS is used, based on expected random chance agreements, an intermediate threshold score should be used to "ensure moderate agreement." However, this theory has not been tested with empiric data to ascertain if it maximizes the interexaminer reliability of MTS. Maximizing interexaminer reliability is essential, as most of the studies evaluating palpatory examinations of the sacrum and pelvis have shown poor to fair interexaminer reliability.1 When they noted poor interexaminer reliability, Flynn et al15 correctly decided not to include palpatory examinations in their analyses. Dreyfuss et al16 noted poor interexaminer reliability with the palpatory examinations yet still used their results in the analyses. However, they did not explain whether they used the physician's findings or the chiropractor's findings, calling into question the validity of their conclusion that the palpatory examination had poor sensitivity and specificity in determining SIJ pain.16 The current study found that using the test with the best interexaminer reliability (method 1) consistently yielded the score with the highest interexaminer reliability. For example, the standing stork test had the best interexaminer reliability in testing for SIJ dysfunction. Using looser criteria (method 2) had slighter better interexaminer reliability to determine the side of SIJ dysfunction. However, this method also had significantly worse reliability when determining the innominate bone position. Using stricter criteria (method 3) consistently had the worst interexaminer reliability for both sides of SIJ dysfunction and innominate bone position. Previously mentioned studies either did not give the interexaminer reliability of the individual tests5,7,17 or they evaluated the interexaminer reliability of only one method of combining multiple palpatory examination results.9,18 Our study does not support the recommendation by Haas4 that an intermediate range threshold should be used. However, because of the small number of subjects in our study, the present analysis cannot definitively refute Haas' recommendation. Our findings suggest that maximizing the interexaminer reliability is a prerequisite to conducting studies that truly evaluate the sensitivity and specificity of the palpatory examination, and thus validate this aspect of osteopathic medicine. In addition, maximizing interexaminer reliability is important for clinical care because prescribed manual treatments are based on the results of the palpatory examination. By using the most reliable method to diagnose the cause of low back pain, the physician can be more confident in his or her treatment decisions. Our study has several strengths. Interexaminer reliability was evaluated for a variety of palpatory examinations and diagnostic methods. In addition, we examined the interexaminer reliability of examinations that detect sacral position and innominate bone position in addition to SIJ. When interpreting the results of this study, several limitations should be considered. First, the results need to be replicated by other studies. A larger study with more tests to further evaluate this issue is planned by the authors. Also, even though the medial malleolus symmetry test has better reliability than the supine anterior superior iliac spine symmetry test, the former test may not be a valid measure of innominate bone position if the subject has a significant leg length discrepancy. Finally, interexaminer reliability is not the only factor to determine what integration method should be used to diagnose structural dysfunction. Sensitivity and specificity may take precedence over reliability in certain instances. Our study shows that the maximum interexaminer reliability occurs when only the result of the most reliable test is used to determine the side of SIJ dysfunction, sacral base position, and innominate bone position. Therefore, this method should be used when making clinical management decisions to ensure that the most appropriate treatment is implemented for each patient.
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