European journal of pain : EJP
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There is limited knowledge on prognostic factors for developing chronic low back pain (LBP) at an early stage of LBP. The objectives of this study were to investigate the clinical course of pain and disability, and prognostic factors for non-recovery after 1-year, in patients seeking help for the first time due to acute LBP. An inception cohort study included 123 patients with acute LBP lasting less than 3 weeks and consulting primary care for the first time. ⋯ The proportions with sickness absence due to LBP at 6, 9, and 12 months were 7%, 8%, and 9%, respectively. At 12 months, 17% of patients had not fully recovered. Multivariate logistic regression analyses showed that high scores on a psychosocial screening (acute low back pain screening questionnaire) and emotional distress (Hopkin's symptom check list) were significantly associated with non-recovery at 12 months, with odds ratios of 4.4 (95% confidence interval 1.1-17.4) and 3.3 (1.1-10.2), respectively.
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Neuropeptide-expressing small diameter sensory neurones are thought to be vital in generating inflammatory hyperalgesic responses. Within the dorsal root ganglion (DRG), both the levels of the neuropeptide calcitonin gene-related peptide (CGRP) and the numbers of CGRP-immunoreactive (CGRP-IR) DRG neurones have been shown to increase in a number of acute adjuvant-induced inflammatory pain models. The aim of this study was to look specifically at changes in numbers of CGRP-IR DRG neurones in a chronic model of inflammatory joint pain following complete Freund's adjuvant (CFA) injection into the rat knee. ⋯ Following dosing of CFA-injected rats with rofecoxib (Vioxx) or paracetamol, there was a significant decrease in the number of ipsilateral CGRP-IR small and medium DRG neurones in rofecoxib- but not paracetamol-treated rats. These data also correlated with behavioural readouts where hypersensitivity and knee joint inflammation were significantly reduced by rofecoxib but not paracetamol treatment. In conclusion, these data show that changes in ipsilateral CGRP expression within small DRG neurones are consistent with behavioural readouts in both time course, rofecoxib and paracetamol studies in this model of chronic inflammatory pain.