Chronic fatigue in the general population: Prevalence, natural course and associations with chronic pain (the HUNT pain study).

BACKGROUND: Fatigue and pain are both prevalent and frequently co-occur. No standard measure of fatigue exists, but most definitions include a continuum between high levels of energy and fatigue. There is limited knowledge about the course of fatigue in the general population and its association with functioning and other health outcomes. Our main aim was to identify trajectories of energy and fatigue in the general population and to investigate whether chronic pain is related to a negative prognosis of chronic fatigue. METHODS: Longitudinal latent class analysis was performed to classify 4771 individuals into trajectory groups based on five quarterly repeated measures. RESULTS: A five-cluster solution was identified: 'much energy' (n = 1471, [31%]), 'varying energy' (n = 1445, [30%]), 'some energy' (n = 921, [19%]), 'low energy' [chronic moderate fatigue] (n = 852, [18%]) and 'no energy' [chronic severe fatigue] (n = 82, [2%]). Individuals with chronic moderate fatigue who reported chronic pain had reduced probability of improvement over the following 3 years (OR = 0.67, 95% CI [0.52, 0.88]). CONCLUSIONS: Chronic fatigue is highly prevalent in the general population and a small proportion have chronic severe fatigue. When chronic pain co-occurs with chronic fatigue, improvement of chronic fatigue is less likely, indicating that these symptoms may perpetuate each other. SIGNIFICANCE STATEMENT: Understanding the close relationship between chronic pain and chronic fatigue is important as they both contribute to suffering and loss of functioning, may be related to the same underlying diseases, or in the absence of disease, may share common mechanisms. This study highlights the important role of chronic pain in relation to chronic fatigue, both by showing a strong association between the prevalence of the two conditions, and by showing that chronic pain is associated with a negative prognosis of chronic fatigue.

A Clinical Description of Chronic Pain in a General Population Using ICD-10 and ICD-11 (The HUNT Pain Examination Study).

The purpose was to present a total description, distribution, and ranking of chronic pain conditions in the general population. This was based on structured clinical examinations of a random sample from a population-based survey (HUNT3) with a calculated oversampling of participants with chronic pain. Supplemented with access to hospital reports, the examination was performed by experienced physicians and psychologists using a consistent definition of chronic pain as well as ICD-10- and the new ICD-11-classification. The main findings were that a higher proportion of the 551 participants had chronic pain assessed by clinical examination (399) than by self-report in a survey the same day (337). Among those with examination-verified chronic pain estimated from HUNT3 to represent 27.9% of the general population, 63% had chronic primary pain, 81% musculoskeletal pain, and 77% more than one chronic pain condition. When separating chronic primary from chronic secondary pain according to ICD-11, the weighted prevalence was 17.7% for chronic pain conditions of unknown and 10.2% of known cause. When all the participants' conditions were accounted for, the most prevalent was nonspecific low back (10.8%) and neck pain (7.6%). Participants with chronic primary pain did not have significantly more psychopathology than those with chronic secondary pain: 14.5% versus 12.5%. PERSPECTIVE: Since this study confirms the high prevalence in self-report surveys and indicates that two thirds of chronic pain conditions cannot be explained by underlying diseases, this huge health and societal problem should be solved primarily on a public health level directed toward prevention and rehabilitation.

Impact of pain and catastrophizing on the long-term course of depression in the general population: the HUNT pain study.

ABSTRACT: Pain and depression are episodic conditions that might take a chronic course. They are clearly related, but information on how they influence each other in the process of chronification is limited. Pain catastrophizing is hypothesized to play a role in the development of depression and chronic pain, but few longitudinal studies have investigated their association over a longer term. In this study, a random cohort from the general population (n = 4764) answered questions about pain, catastrophizing, and depression at 5 assessments in yearly intervals. Linear mixed models showed that within persons, increases in pain intensity and catastrophizing were independently associated with increases in depressive symptoms {mean change = -1.12, 95% confidence interval (CI) [-1.32 to -0.91] and -1.29, 95% CI [-1.52 to -1.05], respectively}. In prospective analyses restricted to individuals without depression above cutoff at baseline, chronic pain increased the risk of endorsing depression over the following 4 years (odds ratio = 2.01, 95% CI [1.71-2.37]). Seven percent showed a chronic course of depression, as indicated by scores above cutoff on at least 3 of 5 assessments. The number of years lived with chronic pain was associated with a chronic course of depression, with odds ratios increasing from 1.55 (95% CI [0.87-2.91]) to 14.19 (95% CI [8.99-22.41]) when reporting chronic pain on 2 vs 5 assessments compared with none. The results suggest that when pain intensity or catastrophizing change, depressive symptoms change in the same direction. When pain and catastrophizing become chronic, they seem to be mutually reinforcing determinants for chronic depression.

The Natural Course of Chronic Pain in a General Population: Stability and Change in an Eight-Wave Longitudinal Study Over Four Years (the HUNT Pain Study).

Epidemiological studies have to a little extent addressed the potential fluctuations of chronic pain over time, and there is a lack of information about the long-term course of pain using repeated measurements. We wanted to identify different trajectories of pain during 8 waves of follow-up over 4 years among individuals in the general population reporting pain lasting at least 6 months at baseline. Secondarily, we wanted to investigate whether biopsychosocial factors at baseline were associated with the different pain trajectories. Longitudinal Latent Class Analysis was performed to classify a random sample of 1905 participants from a larger population-based study (HUNT3) into groups based on their longitudinal pain severity reporting. A five-class solution gave the best fit. The terms chosen to describe the pain trajectories were: "fluctuating" (n = 586 [31%]), "persistent mild" (n = 449 [24%]), "persistent moderate" (n = 414 [22%]), "persistent severe" (n = 251 [13%]), and "gradual improvement" (n = 205 [11%]). In a multinomial logistic regression model using "gradual improvement" as the reference category, the "persistent moderate", "persistent severe", and "fluctuating" pain groups were associated with chronic widespread pain, elevated levels of catastrophizing, and poorer mental health. The "persistent mild" group was associated with sleep difficulties only. This study finds that although most individuals have a stable pain course, individuals in the largest distinct trajectory reports pain that fluctuate between mild and moderate levels, thus fluctuating under and above the chronic pain definition using moderate pain or more as a criterion. PERSPECTIVE: When examining the long-term course of chronic pain in the general population, 5 trajectories emerge. Although most individuals have stable pain, the largest distinct trajectory fluctuated under and above the chronic pain cut-off, using moderate pain or more as a criterion. A dichotomous categorization of chronic pain may be overly simplistic.

Development and course of chronic widespread pain: the role of time and pain characteristics (the HUNT pain study).

Chronic widespread pain (CWP) is common and associated with loss of functioning and health. Subjects with chronic nonwidespread pain (CnWP) are at increased risk of developing CWP, but few studies have described the nature of the development over time. We followed a random sample of 3105 participants from the population-based HUNT 3 study with 5 annual measurements of pain over 4 years. Although 29% reported CWP on at least 1 occasion, only 7% reported it consistently on 4 or 5 occasions. The average annual cumulative incidence was 5%, and the recovery rate was 38%. In mutual adjusted analysis, the risk of developing CWP from 1 year to the next was higher in subjects with chronic pain (relative risk [RR] = 2.4; 95% confidence interval [CI]: 1.8-3.4), 2 or more pain regions (RR = 3.3; 95% CI: 2.5-4.4), moderate pain or more (RR = 1.8; 95% CI: 1.5-2.6), and with comorbid chronic disease (RR = 1.6; 95% CI: 1.3-1.9). Developing CWP was associated with a modest concurrent change in self-reported mental and physical health. The risk of developing CWP between the fourth and fifth occasions was 80% lower for subjects without a history of CWP, compared to those with a history of CWP. For subjects without previous CWP, the development was associated with previously reported CnWP, but not with the number of occasions with CnWP, in analyses adjusted for sex, age, and pain severity. A substantial proportion of the new cases of CWP originates from subjects floating below and above the definition for CWP over time and, thus, does not seem to involve major transitions in health.

Catastrophizing, Solicitous Responses From Significant Others, and Function in Individuals With Neuropathic Pain, Osteoarthritis, or Spinal Pain in the General Population.

That certain psychological factors are negatively associated with function in patients with chronic pain is well established. However, few studies have evaluated these factors in individuals with chronic pain from the general population. The aims of this study were to: 1) evaluate the unique associations between catastrophizing and perceived solicitous responses and psychological function, physical function, and insomnia severity in individuals with neuropathic pain, osteoarthritis, or spinal pain in the general population; and 2) determine if diagnosis moderates the associations found. Five hundred fifty-one individuals from the general population underwent examinations with a physician and physiotherapist, and a total of 334 individuals were diagnosed with either neuropathic pain (n = 34), osteoarthritis (n = 78), or spinal pain (n = 222). Results showed that catastrophizing was significantly associated with reduced psychological and physical function, explaining 24% and 2% of the variance respectively, whereas catastrophizing as well as perceived solicitous responding were significantly and uniquely associated with insomnia severity, explaining 8% of the variance. Perceived solicitous responding was significantly negatively associated with insomnia severity. Moderator analyses indicated that: 1) the association between catastrophizing and psychological function was greater among individuals with spinal pain and neuropathic pain than those with osteoarthritis, and 2) the association between catastrophizing and insomnia was greater among individuals with spinal pain and osteoarthritis than those with neuropathic pain. No statistically significant interactions including perceived solicitous responses were found. The findings support earlier findings of an association between catastrophizing and function among individuals with chronic pain in the general population, and suggest that diagnosis may serve a moderating role in some of these associations. PERSPECTIVE: When examining persons with pain in the general population, catastrophizing is associated with several aspects of function, and diagnosis serves as a moderator for these associations. The replication of these associations in the general population support their reliability and generalizability.

Defining chronic pain in epidemiological studies: a systematic review and meta-analysis.

The objective was to document the operational definitions applied in epidemiological studies of chronic pain and to examine whether pain definitions and other methodological factors are systematically related to prevalence estimates. MEDLINE, EMBASE, and PsychINFO were searched for original research reports with study samples of at least 1000 individuals, excluding studies of less than 5 out of 15 selected body regions and studies solely concerned with specific pain conditions. Meta-analyses and meta-regressions were applied with random effects models; covariates were geography, sampling year, survey method, sampling frame, participation rate, percentage women of all participants, pain duration, and pain location. Of 6791 hits, 86 studies were included in the syntheses. The phrasing, content, and combinations of the chronic pain definition criteria were highly inconsistent, with virtually no 2 studies from independent research groups using the exact same criteria. Prevalence estimates ranged from 8.7% to 64.4%, with a pooled mean of 31%. Huge heterogeneity was shown in all forest plots. Prevalence estimates were significantly related to survey method (ß = -10.8 [95% confidence interval: -17.2 to -4.4]), but it only counted for a small fraction of the between-studies variation in the estimates. There were also interaction effect of survey method by sex (female-male prevalence ratio [95% confidence interval]: questionnaire = 1.20 [1.16 to 1.25], and interview = 1.38 [1.29 to 1.47]). The other covariates investigated were not significantly related to the prevalence estimates. Researchers and clinicians should be aware of the probability that interview survey method of collecting data may give lower chronic pain reporting than questionnaire survey method and that this effect may be stronger in men than women.

Effectiveness of Working Memory Training among Subjects Currently on Sick Leave Due to Complex Symptoms.

Introduction: The current study examined if adaptive working memory training (Cogmed QM) has the potential to improve inhibitory control, working memory capacity, and perceptions of memory functioning in a group of patients currently on sick leave due to symptoms of pain, insomnia, fatigue, depression and anxiety. Participants who were referred to a vocational rehabilitation center volunteered to take part in the study. Methods: Participants were randomly assigned to either a training condition (N = 25) or a control condition (N = 29). Participants in the training condition received working memory training in addition to the clinical intervention offered as part of the rehabilitation program, while participants in the control condition received treatment as usual i.e., the rehabilitation program only. Inhibitory control was measured by The Stop Signal Task, working memory was assessed by the Spatial Working Memory Test, while perceptions of memory functioning were assessed by The Everyday Memory Questionnaire-Revised. Results: Participants in the training group showed a significant improvement on the post-tests of inhibitory control when compared with the comparison group (p = 0.025). The groups did not differ on the post-tests of working memory. Both groups reported less memory problems at post-testing, but there was no sizeable difference between the two groups. Conclusions: Results indicate that working memory training does not improve general working memory capacity per se. Nor does it seem to give any added effects in terms of targeting and improving self-perceived memory functioning. Results do, however, provide evidence to suggest that inhibitory control is accessible and susceptible to modification by adaptive working memory training.

Chronic pain: One year prevalence and associated characteristics (the HUNT pain study).

Background The reported prevalence of chronic pain ranges from 11% to 64%, and although consistently high, the calculated economic burden estimates also vary widely between studies. There is no standard way of classifying chronic pain. We have repeated measurements of pain in a longitudinal population study to improve validity ofthe case ascertainment. In this paper, associations between chronic pain and demographic characteristics, self reported health and functioning, work Incapacity and health care use were investigated in a sample from the general Norwegian population. Methods A random sample of 6419 participants from a population study (the HUNT 3 Study) was invited to report pain every three months during a 12 month period. Chronic pain was defined as moderate pain or more (on the SF-8 verbal rating scale) in at least three out of five consecutive measurements. Self reported health and functioning was measured by seven of the eight subscales on the SF-8 health survey (bodily pain was excluded). Health care utilisation during the past 12 months was measured by self report, and included seeing a general practitioner, seeing a medical specialist and seeing other therapists. The survey data was combined with information on income, education, disability pension awards and unemployment by Statistics Norway, which provided data from the National Education database (NUDB) and the Norwegian Labour and Welfare Administration (NAV). Results The total prevalence of chronic pain was 36% (95% CI34-38) among women and 25% (95% CI 22-26) among men. The prevalence increased with age, was higher among people with high BMI, and in people with low income and low educational level. Smoking was also associated with a higher prevalence of chronic pain. Subjects in the chronic pain group had a self-reported health and functioning in the range of 1-2.5 standard deviations below that of those without chronic pain. Among the chronic pain group 52% (95% CI 49-55), of participants reported having seen a medical specialist during the 12 month study period and 49%(95% CI 46-52) had seen other health professionals. The corresponding proportions for the group without chronic pain were 32% (95% CI 29-34) and 22% (95% CI 20-25), respectively. Work incapacity was strongly associated with chronic pain: compared with those not having chronic pain, the probability of being a receiver of disability pension was four times higher for those with chronic pain and the probability of being unemployed was twice has high for those with chronic pain. The population attributable fraction (PAF) suggested that 49% (95% CI 42-54) of the disability pension awards and 20% (13-27) of the unemployment were attributable to chronic pain. Conclusion and implications Chronic pain is a major challenge for authorities and health care providers both on a national, regional and local level and it is an open question how the problem can best be dealt with. However, a better integration of the various treatments and an adequate availability of multidisciplinary treatment seem to be important.

Longitudinal associations between exercise and pain in the general population--the HUNT pain study.

BACKGROUND: Population-based studies have reported conflicting findings on the relationship between physical activity and pain, and most studies reporting a relationship are cross sectional. Temporal relationships are therefore difficult to infer and associations may be subject to confounding from a variety of other factors. The aim of the current study was to investigate the association between exercise and pain longitudinally and to use within subjects analyses to remove between subjects confounding. METHODS: In the population-based HUNT 3 study, participants reported both pain and level of exercise. A random sub-sample of 6419 participants was in addition invited to report their last week pain and exercise every three months over a 12 month period (five measurements in total). We used multilevel mixed effects linear regression analyses to prospectively estimate the association between regular levels of exercise (measured in HUNT 3) and subsequent longitudinal reporting of pain. We also estimated within-subjects associations (i.e. the variation in pain as a function of variation in exercise, over time, within individuals) to avoid confounding from between subject factors. RESULTS: Among those invited to participate (N = 6419), 4219 subjects returned at least two questionnaires. Compared with subjects who reported no or light exercise, those who reported moderate levels of exercise or more at baseline, reported less pain in repeated measures over a 12 month period in analyses adjusted for age, sex,education and smoking. Adjusting for baseline level of pain distinctly attenuated the findings. Within subjects, an increase in exercise was accompanied by a concurrent reduction in intensity of pain. However, we found no indication that exercise level at one occasion was related to pain reporting three months later. CONCLUSION: This longitudinal population-based study indicates that exercise is associated with lower level of pain and that this association is close in time.

Contextual and time dependent pain in fibromyalgia: an explorative study.

BACKGROUND: Little is known about contextual effects on chronic pain, and how vulnerability factors influence pain in different contexts. We wanted to examine if fibromyalgia (FM) pain varied between two social contexts, i.e. at home versus in a doctor office, when it was measured the same day, and if pain was stable for 14 years when measured in similar contexts (doctor office). Our secondary aim was to explore if pain vulnerability factors varied in the two different contexts. FINDINGS: Fifty-five female FM patients were included in the study and scored pain in both contexts at baseline. Their age ranged between 21-68 years (mean 45.7), mean education level was 11 years and mean FM-duration was 15.6 years. Their mean pain was perceived significantly lower at home than in a doctor context the same day. However, pain was much more stable when measured in two similar contexts 14 year apart where 30 subjects (54.5%) completed. Predictor analyses revealed that pain vulnerability factors apparently varied by home and doctor contexts. CONCLUSION: Pain and pain predictors seem to vary by contexts and time, with less pain at home than to a doctor the same day, but with unchanged pain in the same context after 14 years. Thus, contextual pain cues should be accounted for when pain is measured and treated, e.g. by focusing more on home-measured pain and by optimizing the doctor office context. This explorative study should be followed up by a larger full-scale study.

Estimating the prevalence of chronic pain: validation of recall against longitudinal reporting (the HUNT pain study).

Methods for classifying chronic pain in population studies are highly variable, and prevalence estimates ranges from 11% to 64%. Limited knowledge about the persistence of pain and the validity of recall questions defining chronic pain make findings difficult to interpret and compare. The primary aim of the current study was to characterize the persistence of pain in the general population and to validate recall measures against longitudinal reporting of pain. A random sample of 6419 participants from a population study (the HUNT 3 study in Norway) was invited to report pain on the SF-8 verbal pain rating scale every 3 months over a 12-month period and to report pain lasting more than 6 months at 12-month follow-up. Complete data were obtained from 3364 participants. Pain reporting was highly stable (intraclass correlation 0.66, 95% confidence interval 0.65 to 0.67), and the prevalence of chronic pain varied considerably according to level of severity and persistence: 31% reported mild pain or more, whereas 2% reported severe pain on 4 of 4 consecutive measurements. When defined as moderate pain or more on at least 3 of 4 consecutive measurements, the prevalence was 26%. Compared with the longitudinal classification, a cross-sectional measure of moderate pain or more during the last week on the SF-8 scale presented a sensitivity of 82% and a specificity of 84%, and a sensitivity of 80% and a specificity of 90% when combined with a 6-month recall question. Thus pain reporting in the general population is stable and cross-sectional measures may give valid prevalence estimates of chronic pain.

Associations between recreational exercise and chronic pain in the general population: evidence from the HUNT 3 study.

The evidence for an association between leisure-time physical activity and prevalence of pain is insufficient. This study investigated associations between frequency, duration, and intensity of recreational exercise and chronic pain in a cross-sectional survey of the adult population of a Norwegian county (the Nord-Trøndelag Health Study; HUNT 3). Of the 94,194 invited to participate, complete data were obtained from 46,533 participants. Separate analyses were performed for the working-age population (20-64 years) and the older population (65 years or more). When defined as pain lasting longer than 6 months, and of at least moderate intensity during the past month, the overall prevalence of chronic pain was 29%. We found that increased frequency, duration, and intensity of exercise were associated with less chronic pain in analyses adjusted for age, education, and smoking. For those aged 20-64 years, the prevalence of chronic pain was 10-12% lower for those exercising 1-3 times a week for at least 30 minutes duration or of moderate intensity, relative to those not exercising. Dependent on the load of exercise, the prevalence of chronic pain was 21-38% lower among older women who exercised, relative to those not exercising. Similar, but somewhat weaker, associations were seen for older men. This study shows consistent and linear associations between frequency, duration, and intensity of recreational exercise and chronic pain for the older population, and associations without an apparent linear shape for the working-age population.

Associations between physical activity and physical and mental health--a HUNT 3 study.

PURPOSE: Health-related quality of life (HRQoL) has been characterized as the ultimate goal for health interventions such as physical activity (PA). We assessed how frequency, duration, and intensity of PA were related to HRQoL in younger (<65 yr) and older (≥65 yr) females and males. METHODS: This population-based cross-sectional study explored associations between frequency, duration, and intensity of PA and physical and mental health. HRQoL was measured by SF-8 Health Survey. Frequency and duration were assessed by items validated in a previous HUNT study, and intensity was assessed by Borg RPE scale. Associations between PA and physical and mental health were estimated using general linear modeling. RESULTS: A total of 4500 participants (56% females), age 19-91 yr, with mean age of 53±15 yr, were included. Of these, 40% were less active than recommended by international guidelines. In general, mean physical health (PCS-8) in females and males was 47.4±9.7 and 48.8±8.9, and mental health (MCS-8) was 50.5±8.0 and 51.9±7.3, respectively. Age-adjusted association between PA and HRQoL was stronger for physical than mental health in both genders and age groups. The largest differences were between no exercise and exercise groups at any level for frequency, duration, and intensity of PA. We found no substantial gender differences in association between PA and HRQoL, but association was stronger in older (≥65 yr) than younger (<65 yr) females and males. Adjusting for socioeconomic factors and factors such as presence of diseases, body mass index, smoking habits, cohabitation, and disablement did not change the results. CONCLUSIONS: The study suggests that exercising at any level is associated with better physical and mental health in both genders compared with no exercise, particularly among the older individuals.

Defense mechanisms in patients with fibromyalgia and major depressive disorder

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Background and objectives: Fibromyalgia (FM) and depression has been suggested to share a common underlying etiology. Few studies have investigated the role of emotional regulation processes in FM compared to depressive disorders. The purpose of the current study was to explore the use of defense mechanisms in FM patients with and without comorbid lifetime depressive disorder (LDD), and to compare their use of defenses to healthy control subjects and patients with Major Depressive Disorder (MDD).Methods: A total of 91 participants were included (17 with FM and LDD, 25 with FM but not LDD, 24 with MDD, and 25 healthy controls). Depressive disorders were identified by using the Structured Clinical Interview for DSM Axis I disorders (SCID-I). All diagnosis of FM were confirmed to meet the American College of Rheumatology’s criteria for FM. The Life Style Index (LSI) was used to measure defense mechanisms. Results and Conclusions: Group comparisons indicated that MDD patients and FM patients with LDD made significantly more use of defenses than healthy controls, whereas FM patients without LDD made significantly less use of defenses than both MDD patients and FM patients with LDD, but did not differ from healthy controls. Follow up analyses indicated significant main effects for the defense mechanisms of regression, compensation and displacement. This study suggests that FM and depression do not share common risk factors in terms of restricted affects or avoidance of conflicted feelings (AU)