Diagnostic Value of Plain Radiographs in Patients with Low Back Pain of Non-traumatic Origin at a National Teaching and Referal Hospitalin Kenya.

Background: Low back pain is a commonly recognized problem worldwide. Plain radiography is used in many of these patients as an initial investigative and evaluative tool. However, it was not known how truly useful this investigation was in making definitive diagnosis for non traumatic low back pain. The main objective of the study was to determine the value of plain radiographs in patients presenting with low back pain that is of non-traumatic origin.
Methods: A prospective study 102 consecutive patients with low back pain was conducted at the Kenyatta National Hospital (KNH) from 1^st February 2013 to 30^th May 2013. Data was collected using a structured questionnaire and analyzed. Plain radiograph films were reviewed by two qualified radiologists.
Results: The mean age of patients presenting with low back pain was 50.9years, with a male to female ratio of 1:2.4. Majority of the patient had chronic low back pain. There was a high rate of positive radiological findings (98%). The most common findings included muscle spasm, osteoporosis, reduced lumbar lordosis, spondylosis, disc degenerative disease and osteophytes. Assessment of inter-rater variability showed good level of agreement on presence of spondylolisthesis and vacuum phenomenon (k=0.71), moderate agreement on reduced disc space, reduced lumbar lordosis, spondylosis (k=0.42-0.56) and poor agreement on film quality, infections, tumor metastasis, osteophytes, prolapsed intervertebral disease (PID), osteoporosis, scoliosis, muscle spasm and sacroilitis (k=0.13-0.21)
Conclusion: Most of the patients presenting to KNH with low back pain have a chronic type and therefore have increased probability of having positive radiological findings. There was a poor ability to diagnose infectious causes, inflammatory conditions, transitional vertebrae and tumor metastasis. In such cases, more advanced imaging such as CT scan and MRI may be required.