Utility of plain radiograph in low back pain of non-traumatic origin as seen at Kenyatta national hospital

Abstract

BACKGROUND Low back pain is a commonly recognized problem worldwide and is a major cause of debilitation to many patients. Plain radiography is used in many of these patients as an initial investigative and evaluative tool, as was evidenced by data from the Department of Radiology, University of Nairobi. However, it was not known how truly useful this investigation was in making definitive diagnosis for many of the causes of low back pain seen at KNH. This study sought to establish the utility of plain radiographs in arriving at diagnostic conclusions for patients presenting with low back pain of non-traumatic origin. OBJECTIVE: To determine diagnostic utility of plain radiographs in patients presenting with low back pain that is of non-trauma origin. MATERIALS AND METHODS: This was a prospective study conducted at the orthopaedic clinics and wards at the Kenyatta National Hospital from 1st February 2013 to 30th May 2013.One hundred and two (102) consecutive patients who presented to the orthopaedic clinics or admitted to the wards with low back pain of non-traumatic origin were recruited into the study after meeting the selection criteria. Data was collected by the principle investigator with the help of a research assistant using a structured questionnaire. Plain radiograph films ordered by the clinicians were reviewed for diagnostic yield by two qualified radiologists.The data was analyzed using Stata/1C computer program version 11.0 and presented using tables, charts and graphs. MAIN OUTCOME MEASURE: Determination of frequency of occurrence of radiographic findings in patients reporting low back pain not caused by trauma. RESULTS: In this study, the average age of patients presenting with low back pain was 50.9years, with a male to female ratio of 1:2.4. Majority of these patients (96%) presented with chronic low back pain. Most of the patients presented with sensorimotor deficit. There was a high rate of positive radiological findings (98%), possibly attributed to the chronicity of the presenting symptoms. The most common occurring findings included muscle spasm, osteoporosis, reduced lumbar lordosis, spondylosis, disc degenerative disease and osteophytes. transitional vertebrae and tumor metastasis. 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) Follow-up of these patients showed that 33% underwent further investigations to enhance diagnostic yield. CONCLUSION: This study showed that most of the patients present to KNH with chronic low back pain and have increased probability of having positive radiological findings. However, usefulness of plain radiography is limited by factors such as inter-rater variability, film quality, the underlying pathology, views taken, among others. As such, it is the recommendation of this study that clinicians should be encouraged to adhere to already established international protocols on referral of patients for radiography