کمردرد مزمن، نمادی از آستانه پایین احساس درد در کارکنان شاغل در یک مجتمع صنعتی بزرگ

    Background: Job related Low Back Pain (LBP) is considered as the most common disabling musculo-skeletal complaint that can lead to compensation claims by workers. Although physical injuries at work place have been known as a reason for LBP, other factors such as a low pain threshold may contribute to the chronicity of LBP. This study aimed to determine the frequency of Fibromyalgia Syndrome (FMS) in workers with chronic LBP in a large industrial community and evaluate whether those with chronic LBP had a lower pain threshold compared to other workers. Methods: This cross-sectional study was performed in a large steel manufacturing plant between Sep. 2005 and Jan. 2006. Workers suffering from LBP most of the time for the past 3 months, with a severity index of ≥3 in numerical rating scale were recruited. Those with a history of taking corticosteroids, malignancy, severe kyphoscoliosis, inflammatory spinal diseases, or describing the maximum painful area above T12 were excluded. Workers without LBP presented for the routine annual examinations were selected as control group. Eighteen tender points were assessed by dolorimetry in case and control groups to determine the total myalgic score and the frequency of FMS according to American College of Rheumatology (ACR) classification criteria (1990). Descriptive statistics were used for expressing the data and Student t-test and chi-square were applied for comparing the variables, whenever appropriate. SPSS V.11.5 was used for data analysis.Results: Forty-five out of 150 workers with LBP met the study inclusion criteria and were enrolled into the study. Seventy-two workers were enrolled as control group. The mean (±SD) total myalgic scores were 1.4±0.5 and 1.2±0.2 in case and control groups, respectively (p=0.002). Four of the participants fulfilled the ACR 1990 criteria for FMS all in the case group.Conclusion: Lower pain threshold and higher prevalence of FMS in case group suggest that an overall susceptibility to pain may be a factor to chronicity of job related LBP. Clarification of this hypothesis would be important for further understanding of the pathophysiology of job related LBP. Subsequent studies are required to validate our findings.