RESUMO
BACKGROUND AND AIMS: Chronic low back pain (chronic LBP) is the number one cause for years lived with disability among 301 diseases and injuries analyzed by The Global Burden of Disease study 2013. Insomnia is highly prevalent among people with chronic LBP. To explain the sleep-pain relationship, theoretical models propose that insomnia symptoms may be associated with increased basal inflammation, operationalized as c-reactive protein (CRP) and lead to further pain and disrupted sleep. We aimed to determine the associations between insomnia, chronic LBP, and inflammation (operationalized as CRP), whilst controlling for age, body mass index, smoking, physical activity, depression, anxiety and osteoarthritis. METHODS: A cross-sectional analysis of the third Nord-Trøndelag Health Study (2006-2008), a rural population survey of 50,666 participants in Norway aged 20-96 years. Insomnia (dichotomous) was defined according to the Diagnostic and Statistical Manual of Mental Disorders 5th Edition, and chronic LBP (dichotomous) as low back pain or stiffness lasting at least 3 months. Data for CRP were obtained from non-fasting serum samples and assessed via latex immunoassay methodology. We excluded participants with the following self-reported chronic somatic diseases: chronic heart failure, chronic obstructive pulmonary disease, rheumatoid arthritis, fibromyalgia or ankylosing spondylosis. Possible associations between presence of insomnia and presence of chronic LBP (dependent), and the level of CRP and presence of chronic LBP (dependent), were assessed using logistic regression models. The possible association between insomnia and CRP (dependent) was assessed using linear regression. Multivariable analyses were conducted adjusting for confounders stated in our aim that achieved p ≤ 0.2 in univariate regressions. We performed stratified analyses for participants with "Normal" (<3 mg/L) "Elevated" (3-10 mg/L) and "Very High" (>10 mg/L) levels of CRP. RESULTS: In our total included sample (n = 30,669, median age 52.6, 54% female), 6.1% had insomnia (n = 1,871), 21.4% had chronic LBP (n = 6,559), and 2.4% had both (n = 719). Twenty four thousand two hundred eighty-eight (79%) participants had "Normal" CRP, 5,275 (17%) had "Elevated" CRP, and 1,136 (4%) had "Very High" CRP. For participants with "Normal" levels of CRP, insomnia was associated with higher levels of CRP (adjusted B = 0.04, 95%CI [0.00-0.08], p = 0.046), but not for people with "Elevated" or "Very High" levels of CRP. There was an association between CRP and presence of chronic LBP in the total sample (adjusted OR = 1.01, [1.00-1.01], p = 0.013) and for people with "Normal" CRP (1.05, [1.00-1.10, p = 0.034]. Insomnia was associated with the presence of chronic LBP in the total sample (adjusted OR = 1.99, 95%CI [1.79-2.21], <0.001) and for people with "Normal", "Elevated" and "Very High". CONCLUSIONS: Individuals with insomnia have twice the odds of reporting chronic LBP. Insomnia, CRP and chronic LBP appear to be linked but the role of CRP appears to be limited. Longitudinal studies may help further explore the causal inference between insomnia chronic LBP, and inflammation. IMPLICATIONS: Given the strong relationship between insomnia and chronic LBP, screening and management of comorbid insomnia and chronic LBP should be considered in clinical practice. Further longitudinal studies are required to explore whether the presence of insomnia and increased inflammation affects the development of chronic LBP.
RESUMO
STUDY DESIGN: A systematic literature review of outcome questionnaires designed for assessing functional status or disability in patients with low back pain. OBJECTIVES: To provide a comprehensive overview of all functioning/disability questionnaires used in recent years and to explore how the main concept(s) was described or defined in the original paper, the content or the domains of disability, and the measurement properties of the questionnaires. SUMMARY OF BACKGROUND DATA: A number of clinical tools designed for evaluating the functional status of patients with low back pain have been developed. Only a few have been reviewed earlier, and there has been little focus on the content reflected in the questionnaires. METHODS: Papers including questionnaires for assessing disability, function, activity limitations, or participation restrictions in adult patients with low back pain were searched in the MEDLINE and CINAHL databases for the period from January 1996 to January 2002. Two independent and blinded researchers read and selected abstracts and questionnaires. The content of the included questionnaires was classified according to World Health Organization's International Classification of Functioning, Disability and Health. The measurement properties were analyzed according to recommended guidelines. RESULTS: A total of 36 back-specific questionnaires were identified. When distinguishing among a bodily, personal, and social perspective of functioning, 4 main types of content were identified. Most of the outcome questionnaires had a mixed content reflecting various constructs such as pain and symptoms, sleep disturbances, psychological dysfunctions, physical impairments, and social functions. Nine questionnaires assessed solely activities of daily living. For one-third of the questionnaires, the measurement properties were reported in only the original study. CONCLUSIONS: Although most questionnaires had their main focus on activity limitations, a considerable variation with respect to the main concept and content was found. Only a few of the questionnaires can be considered acceptably validated.
