Chronic pain: One year prevalence and associated characteristics (the HUNT pain study)
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Tormod Landmark
,
Pål Romundstad
Abstract
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.
1 Introduction
In epidemiological studies, chronic pain is usually defined as pain lasting for more than three or six months [1]. However, the phrasing of the questions and the use of additional criteria to indicate severity of pain varies between studies, and among others, these factors may explain the large variation in prevalence, ranging from 11% to 64% [2, 3]. The wide variation in case ascertainment is problematic since it makes prevalence and associated burden estimates difficult to compare. Ultimately, this may have political consequences and negatively impact the credibility of the research [4].
Previous studies have shown both cross sectional and prospective relationships between chronic pain and various physical and mental aspects of self-reported health and functioning in the general population [5, 6, 7]. Others have reported high direct and indirect economic costs of chronic pain, in terms of health care utilisation and absence from employment [8, 9]. The estimated total costs range between 3% of the gross domestic product (GDP) in Ireland [10] and 10% of the GDP in Sweden [11]. However, these estimates are highly influenced by the methodology used, and there are large differences in social welfare policies between countries [9].
Although the prevalence of chronic pain is high in Norway, we have limited knowledge about its consequences [12, 13]. Those with chronic pain utilize large resources of the health care services, but the management of pain is reported to be inadequate [13]. Instatistics provided from the official registers, musculoskeletal disorders is given as the cause for approximately 35% and 30% of all sick leaves and disability pensions, respectively [14]. However, the validity of these diagnoses is uncertain; they are often provided by the primary physician and non-medical factors such as social problems, lack of education, and characteristics at work may contribute to the final conclusion [15, 16]. Chronic pain may also be an important cause for disability among subjects classified with other conditions than musculoskeletal disorders, such as mental disorders [17]. It is therefore important to study the relationship between chronic pain and disability in representative samples from the population.
In a previous study, longitudinal data on pain measured every third month over one year was used to estimate the prevalence of chronic pain [18]. The study confirmed a high prevalence, with almost one third of the adult Norwegian population being affected by chronic pain of at least moderate intensity. The aim of the current paper is to further investigate the importance of this finding by studying the consequences of chronic pain in terms of self-reported health and functioning, health care utilisation and work incapacity.
2 Methods
2.1 Participants and procedure
The present study is a component of a large population based health survey; the HUNT 3 Study. Between 2006 and 2008, the total population 20 years of age and older in Nord-Trandelag county in Norway (n = 94,194) was invited to participate, and a total of 50,827 (54%) individuals attended the study. The study population is fairly representative for Norway with respect to geography, economy, industry, sources of income, age and sex distribution and mortality, but the average income and educational level are slightly lower than in Norway as a whole [19].
We decided to invite a random sample of 6500 HUNT 3 participants from two municipalities, Levanger and Verdal, to a sub-study of pain (the HUNT pain study). The sequence in which participants entered the HUNT 3 Study was based on their residence district, and they were selected for the HUNT pain study in groups based on their attendance. Inclusion was stopped after having selected 6419 participants. These subjects received a questionnaire together with an information letter two months after they had entered the HUNT 3 Study and 4782 (75%) accepted the invitation. Thereafter they received postal questionnaires every three months for the following 12 months (five questionnaires in total). A reminder was mailed to non-responders together with another questionnaire after one month. If the reminder was not returned, but the individuals had not actively withdrawn from the study, another questionnaire was mailed at the end of the 12 month period.
The study was approved by the Regional Committee for Medical and Health Research Ethics Central-Norway and the Norwegian Data Inspectorate.
2.2 Questionnaires
Each mailing included the one week recall version of the SF-8 health survey [20]. The SF-8 health survey is a shorter version of the more common SF-36 health survey [21] and contains one item representing each of the following eight subscales: bodily pain, general health, mental health, vitality, physical functioning, social functioning and limitations in work due to physical (role physical) and emotional (role emotional) problems. The eight subscales may also be combined into two summary measures of physical and mental health. The scoring procedure ensures a mean score close to 50 and a standard deviation close to 10 for each scale, according to the US norm data [20]. In the present study, a mean score across all five measurements was constructed for each scale, to cover the 12 months study period.
The following question measures bodily pain in SF-8: “How much bodily pain have you had in the past week?” with response categories ranging from no pain to very mild, mild, moderate, severe or very severe pain. The question has shown robust psychometric properties and is recommended as a global measure of pain severity [22]. Chronic pain was defined as a score that indicated moderate or more intensive pain in at least three of the five consecutive measurements. This is the mid-point on the scale and would correspond to a score of 5 or more on an 11 point numerical rating scale (NRS). It has previously been shown that moderate pain is adequate to distinguish subjects with a complex pain condition from subjects with minor problems in population based samples [23]. At the HUNT 3 Study, the participants had answered the same question, but with a four week recall, before entering the present study, in addition to the following question: “Do you have bodily pain now which has lasted for more than 6 months?” These two questions were combined to an operational definition of chronic pain of at least moderate intensity during the past month and used to compare those who accepted the invitation to the HUNT pain study and completed all five pain measurements, and those who declined to participate in the HUNT pain study.
Health care utilisation during the past 12 months was measured by self report, and included seeing a general practitioner, seeing a medical specialist in or outside of hospital, being hospitalized, and seeing a physiotherapist, chiropractor, or other therapists giving massage, acupuncture or any alternative treatment. Reports covered the same 12 months period as the pain measurements.
Height and weight were measured, and body-mass index (BMI) was calculated as weight divided by height squared.
Information on income, education, disability pension awards and unemployment was obtained from Statistics Norway, which provided data from the National Education database (NUDB) and the Norwegian Labour and Welfare Administration (NAV) and linked this information with the health survey data by use of national identification numbers. Level of income is presented as quartiles of the household income divided by the squared number of household members. Information on the highest attained level of education was classified into three levels; as primary, secondary or tertiary education. Any person who was registered with a disability pension of 50% or more during the study period was coded as being work disabled. Any person who was registered as a job seeker was coded as unemployed. This category includes subjects who has been registered full time unemployed, part time unemployed, job seekers on benefits including vocational rehabilitation or other job seekers.
2.3 Statistical analyses
Descriptive statistics are given as numbers and percentages with 95% confidence intervals (CIs). Multivariable associations between demographic characteristics and chronic pain were calculated as prevalence ratios with 95% CIs using General linear models (GLM) for the binomial families, the binreg function in Stata. Associations between chronic pain as the predictor and seven of the SF-8 subscales (excluding pain) as outcomes were calculated using multiple linear regression with adjustment for sex and age. The adjusted differences in proportions of individuals reporting health care utilizations and work incapacity were calculated with GLM using the binreg function in Stata. Adjusted population attributable fractions (PAF) of health care use and work incapacity associated with chronic pain were calculated by using the punaf function in Stata and were based on the prevalence ratios from the GLM analyses. The association between chronic pain and disability pension was calculated among all subjects in working age (20–64 years). The association between chronic pain and unemployment were calculated among subjects in working age who were not receiving disability pension, i.e. the working force. All analyses were conducted using Stata version 11.0 for Windows (Stata Corporation, College Station, Texas).
3 Results
3.1 Comparison between participants and non-participants
Fig. 1 shows the flow of participants included in the HUNT pain study and the main analyses. Participants with complete pain reporting over the 12 month period (n = 3421) were older, more likely to be female and to have higher level of education compared to those who were invited, but declined to participate. The prevalence of chronic pain (29%), as measured in the HUNT 3 survey, was however, similar between groups.
3.2 Prevalence and characteristics of chronic pain
The total one year prevalence of chronic pain was 31% (95% CI 30–33), defined as reporting of moderate to severe pain in at least three of the five measurements (Table 1). Estimates were higher among women (36%; 95% CI 34–38) than men (25%; 95% CI 23–27), and among middle aged (34%; 95% CI 32–37) and older adults (35%; 95% CI 32–39), compared to younger adults (20%; 95% CI 17–23). Educational level and household income were inversely associated with the prevalence of chronic pain, and body mass index was positively associated. The prevalence among never smokers was 25% (95% CI 23–27), as compared to 34% (95% CI 32–37) among former smokers and 38% (95% CI 35–42) among current smokers. In the multivariable analyses, these estimates remained essentially unchanged (Table 1).
We also considered possible consequences of chronic pain, including health related quality of life, health care utilisation, and work incapacity and unemployment. Table 2 shows that participants with chronic pain score consistently worse than participants without chronic pain for seven of the eight SF-8 health survey subscales (excluding bodily pain). After adjustment for sex and age, the mean differences ranged from 4 points (95% CI 3.7–4.4) for mental health, to 8.3 points (95% CI 8.0–8.7) for physical functioning. The differences were all in the range of 1–2.5 standard deviations for the no chronic pain group, and 0.6–1.2 standard deviations for the chronic pain group, indicating that the differences are likely to be clinically significant.
Flow of the participants included in the current study.
The proportion of participants seeking health care was high within the chronic pain group: 90 had seen a general practitioner during the 12 month study period, 53% had seen a medical specialist and 46% had seen other health professionals. The corresponding proportions for the group without chronic pain were 69%, 31% and 20%, respectively. After adjustment for sex and age, the differences remained basically unchanged (Table 3). The population attributable fraction (PAF) of chronic pain was 7% (95% CI 6–8) for seeing a general practitioner, 17% (95% CI 14–19) for seeing a medical specialist and 30% (95% CI 26–33) for other health professionals including seeing a physiotherapist, chiropractor or therapists providing alternative treatments.
In the chronic pain group 32% of those in working age were receiving disability pension, almost four times as many as that of the no chronic pain group (Table 3). The proportion of unemployed was 20% in the chronic pain group, twice as high as the no chronic pain group. The differences were only slightly attenuated when adjusting for sex and age. The population attributable fraction (PAF) suggested that 49% (95% CI 42–54) of the disability awards and 20% (13–27) of the unemployment were attributable to chronic pain.
Characteristics of the total sample and prevalence of chronic pain[a] according to sex, age, BMI, educational level, income and smoking in the HUNT pain study..
| Total sample | Chronicpainprevalence | Prevalence ratios[b] | ||||
|---|---|---|---|---|---|---|
| N | N | % | (95% CI) | PR | (95% CI) | |
| Overall | 3421 | 1069 | 31 | (30–33) | ||
| Sex | ||||||
| Female | 1931 | 701 | 36 | (34–38) | 1.00 | Ref |
| Male | 1490 | 368 | 25 | (23–27) | 0.66 | (0.60–0.73) |
| Age | ||||||
| 20–44 yrs | 829 | 166 | 20 | (17–23) | 1.00 | Ref |
| 45–64 yrs | 1696 | 585 | 34 | (32–37) | 1.58 | (1.37–1.84) |
| ≥65 yrs | 896 | 318 | 35 | (32–39) | 1.48 | (1.26–1.75) |
| BMI (kg/m2) | ||||||
| <25 | 1150 | 295 | 26 | (23–28) | 1.00 | Ref |
| 25–30 | 1502 | 450 | 30 | (28–32) | 1.13 | (1.01–1.28) |
| >30 | 695 | 301 | 43 | (40–47) | 1.46 | (1.28–1.65) |
| Education | ||||||
| Primary | 559 | 261 | 46 | (42–51) | 1.00 | Ref |
| Secondary | 1691 | 579 | 34 | (32–36) | 0.81 | (0.73–0.91) |
| Tertiary | 1162 | 228 | 20 | (17–22) | 0.48 | (0.41–0.56) |
| Income | ||||||
| Q4 (highest) | 888 | 212 | 24 | (21–27) | 1.00 | Ref |
| Q3 | 904 | 277 | 31 | (28–33) | 1.13 | (0.98–1.29) |
| Q2 | 833 | 293 | 35 | (32–38) | 1.26 | (1.09–1.44) |
| Q1 (lowest) | 796 | 287 | 36 | (33–39) | 1.00 | (0.85–1.16) |
| Smoking | ||||||
| Never | 1482 | 369 | 25 | (23–27) | 1.00 | Ref |
| Previous | 1054 | 363 | 34 | (32–37) | 1.30 | (1.16–1.46) |
| Current | 835 | 321 | 38 | (35–42) | 1.39 | (1.24–1.57) |
4 Discussion
In previous studies, the definitions and measurement of chronic pain have varied widely and so have the findings. Using a longitudinal design and measuring pain every three months over a 12 month period, we found that about one third had chronic pain. This estimate is within the range of what has been reported in previous studies [24]. The significance of these figures is shown by a clinically significant association with other measures of self-reported health and functioning, a substantial increase in the use of health care services and high drop out of the work force among those with chronic pain. Similar to our findings, previous studies suggest that demographic characteristics (sex, age, education) are related to chronic pain, indicated by fairly consistent associations [6, 12, 25, 26, 27]. Thus, the higher prevalence among women, the increasing prevalence with age, and the higher prevalence in people at the lower end of the socioeconomic status ladder, indicates where the burden of chronic pain is most prominent, and where efforts to change the situation should be emphasized. The strong relation with age, for example, begs for particular attention, especially due to the many challenges related to the ageing of the population.
We found that obesity and smoking were associated with a higher prevalence of chronic pain. We have also reported elsewhere that lower level of exercise was associated with a higher prevalence of chronic pain [28]. The results of others have not been consistent, and it has been suggested that patterns of causality for these factors are complex [29, 30, 31]. Nonetheless, the findings should increase our awareness that lifestyle factors may influence the occurrence of chronic pain.
The responses to the SF-8 health survey suggest that people with chronic pain have low scores on self-reported functioning, and on general and mental health, and similar findings have been reported by others [6, 7]. Although reduced general functioning may be a consequence of chronic pain, it has also been suggested that poor social and physical functioning may predict the onset of chronic pain [5]. In relation to mental health and vitality, associations with chronic pain are also likely to be complex [27, 32]. However, the close association with different dimensions of self-reported health and functioning underscores the multidimensionality of chronic pain, and the challenge it poses on many levels.
Comparisons between the no chronic pain group and the chronic pain group on the SF-8 subscales (excluding pain).
| No chronic pain | Chronic pain | Difference[a] | (5% CI) | |||
|---|---|---|---|---|---|---|
| N | Mean (sd) | N | Mean (sd) | |||
| General health | 2335 | 49.5 (4.9) | 1052 | 41.1 (5.1) | 8.0 | (7.7–8.4) |
| Physical functioning | 2335 | 50.8 (3.7) | 1059 | 42.8 (6.0) | 7.6 | (7.3–7.9) |
| Role physical | 2330 | 51.7 (3.3) | 1051 | 43.1 (6.7) | 8.3 | (8.0–8.7) |
| Vitality | 2342 | 50.1 (6.2) | 1065 | 42.2 (6.4) | 7.7 | (7.2–8.1) |
| Mental health | 2322 | 53.0 (4.2) | 1058 | 49.0 (6.4) | 4.0 | (3.7–4.4) |
| Role emotional | 2314 | 50.3 (3.1) | 1045 | 45.1 (5.9) | 5.1 | (4.8–5.4) |
| Social functioning | 2331 | 52.5 (3.4) | 1053 | 46.7 (5.9) | 5.6 | (5.3–5.9) |
Comparisons between the no chronic pain group and the chronic pain group on the proportions seeking health care and being work incapacitated.
| No chronic pain | Chronic pain | Difference[a] | (95% CI) | PAF[b] | (95% CI) | |||
|---|---|---|---|---|---|---|---|---|
| N | (%) | N | (%) | |||||
| Health care | ||||||||
| General practitioner | 1634 | (69) | 959 | (90) | 18.6 | (16.0–21.2) | 0.07 | (0.06–0.08) |
| Medical specialist | 736 | (31) | 564 | (53) | 20.5 | (16.9–24.1) | 0.17 | (0.14–0.19) |
| Other professional | 468 | (20) | 495 | (46) | 26.4 | (23.9–29.9) | 0.30 | (0.26–0.33) |
| Work incapacity | ||||||||
| Disability pension[c] | 135 | (8) | 274 | (32) | 22.1 | (18.4–25.8) | 0.49 | (0.42–0.54) |
| Unemployment[d] | 161 | (10) | 94 | (20) | 9.9 | (6.1–13.7) | 0.20 | (0.13–0.27) |
In our study, disability pension was far more common among those reporting chronic pain, and reflects the high prevalence of musculoskeletal complaints that is represented in the disability statistics [14]. The high impact of chronic pain on work capacity was also indicated in a pan European study showing that almost 60% of those with chronic pain reported reduced ability to perform work outside home [13]. It has previously also been shown that widespread pain is a strong risk factor for disability pension, and that the risk for disability increases with increasing number of pain sites affected [17, 33].
The higher proportion of unemployed individuals among those with chronic pain indicates that the sick leave and disability statistics does not capture all those who have lost work capacity due to chronic pain. This is also indicated by findings showing that pain complaints are major causes for reduced performance at work [34].
The figures clearly tell us that chronic pain is a substantial obstacle to maintain work capacity for a large number of individuals. However, the relation of chronic pain with disability is likely to involve other factors as well, including psychological, social, economic and occupational [35]. We need more knowledge about how this problem should be managed. Few studies have investigated the benefits of treatment on return to work. However, it has been shown that integrated care directed at patients with chronic low back pain and their work place, have beneficial effects that may prevent disability [36].
A large proportion of participants with chronic pain in our study reported some form of health care utilisation. Although our data are based on self report, the findings show that chronic pain is a considerable strain on the health care system. The findings are also in correspondence with a Danish study using data from national registers and showed that hospital admissions, in hospital days and number of contacts with primary care were about twice as high for the chronic pain group compared with the control group [8]. The management of chronic pain has been described as a chaotic component of contemporary medicine; many medical specialities are involved, and little is known about the cost-effectiveness of various treatments [37, 38]. Data also suggest increasing costs, without evidence for any corresponding improvement in health and functioning [39]. Simultaneously, it has been shown that a small proportion of patients accounts for a very high proportion of the costs [40, 10].
In the prevention and treatment of chronic pain, it may be appropriate to target a range of lifestyle factors, including obesity, smoking, and exercise. Although the evidence is not conclusive, several prospective studies have suggested that the prevalence of chronic pain may be reduced by modifying these factors [29, 30, 31].
The complexity of pain suggests that improving the integration of various treatment efforts may be beneficial. Multidisciplinary treatment involves a team of health professionals including physicians, psychologists, physical therapists, nurses, occupational therapists and other specialists, working together in pain clinics to address the physiological, psychological and social dimensions of pain. Such treatments have been shown to be more effective than standard treatments and other non-multidisciplinary treatments [41, 42]. Even though cost effectiveness studies are rare and their findings have been difficult to summarize, several studies now suggest that the economic costs of multidisciplinary treatments are outweighed by their gains, in particular by reducing the high indirect costs of chronic pain [43, 36, 44]. Among those with the highest health care utilisation, multidisciplinary treatment may also have a positive effect on the health care costs.
In a previous paper, using the same dataset, we reported the prevalence of pain employing different criteria for persistence and stability. As expected the prevalence estimates varied greatly according to the criteria employed [18]. However, a cut-off at moderate pain using the SF-8 bodily pain scale on a single time point corresponded well with the longitudinal estimate of chronic pain of at least moderate intensity. Taken together, these two studies show that the prevalence of chronic pain is high, have substantial social and economic consequences, and maybe validly estimated in cross sectional studies with a measure that may readily be standardized across studies.
Our study has some limitations. The average age of the study population was slightly higher than in the general population, and educational level was somewhat higher. The prevalence of chronic pain reported in this study may therefore not be representative of the total population. The external validity of the associations being studied is less likely to be influenced by the non response, however [45]. In our sample the reporting of chronic pain was remarkably stable over the 12 months period [18]. A certain proportion of the participants may have experience large fluctuations in pain and it has been suggested that fluctuations in pain are associated with functioning and disability [22]. However, the hypothesis has received little empirical attention and may be an important issue for future studies. The cut-off at moderate to severe pain reported at three separate measurements to indicate chronic pain may be questionable. For example, it is possible that the pain in some participants maybe better characterized as recurrent than persistent pain.
5 Conclusion
In this population study, almost one third consistently reported clinically significant pain during 12 months of longitudinal reporting. The pain was strongly associated with self reported health status, use of health care resources and loss of employment. This 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.
Highlights
Chronic pain affects about one third of the adult Norwegian population and is associated with:
A substantial reduction in the self reported health and functioning.
A doubling of subjects seeking help from medical specialists or other health care providers.
A high risk for lost work capacity.
DOI of refers to article: http://dx.doi.org/10.1016/j.sjpain.2013.08.002
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Funding source
The research council of Norway and the liaison committee between the central Norway regional health authorities and NTNU.
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Conflict of interest: None declared.
Acknowledgement
The Nord-Trøndelag Health Study (The HUNT study) is a collaboration between HUNT Research Centre (Faculty of Medicine, Norwegian University of Science and Technology NTNU), Nord-Trøndelag County Council and The Norwegian Institute of Public Health. The HUNT pain study and this work were funded by the Research Council of Norway. We thank all the participants, and the staff who contributed in the data collection: Berit Bjelkåsen, Vanja Strømsnes, Cinzia Marini, Ingunn Johansen, & Aleksandra Szczepanek. A special thanks to Karin Tulluan for her participation in the data collection and in administering the database.
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© 2013 Scandiavian Association for the Study of Pain
Articles in the same Issue
- Editorial comment
- Chronic pain – The invisible disease? Not anymore!
- Clinical pain research
- New objective findings after whiplash injuries: High blood flow in painful cervical soft tissue: An ultrasound pilot study
- Editorial comment
- Chronic pain is strongly associated with work disability
- Observational studies
- Chronic pain: One year prevalence and associated characteristics (the HUNT pain study)
- Editorial comment
- Pain rehabilitation in general practice in rural areas? It works!
- Clinical pain research
- Effectiveness of multidisciplinary rehabilitation treatment for patients with chronic pain in a primary health care unit
- Editorial comment
- Mirror-therapy: An important tool in the management of Complex Regional Pain Syndrome (CRPS)
- Topical review
- Mirror therapy for Complex Regional Pain Syndrome (CRPS)—A literature review and an illustrative case report
- Editorial comment
- New insight in migraine pathogenesis: Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the circulation after sumatriptan
- Original experimental
- Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the circulation after sumatriptan
- Editorial comment
- Statistical pearls: Importance of effect-size, blinding, randomization, publication bias, and the overestimated p-values
- Topical review
- Significance tests in clinical research—Challenges and pitfalls
- Editorial comment
- Biomarkers of pain – Zemblanity?
- Topical review
- Mechanistic, translational, quantitative pain assessment tools in profiling of pain patients and for development of new analgesic compounds
- Editorial comment
- Chronic Benign Paroxysmal Positional Vertigo (BPPV): A possible cause of chronic, otherwise unexplained neck-pain, headache, and widespread pain and fatigue, which may respond positively to repeated particle repositioning manoeuvres (PRM)
- Observational studies
- Pain and other symptoms in patients with chronic benign paroxysmal positional vertigo (BPPV)
- Editorial comment
- The most important step forward in modern medicine, “a giant leap for mankind”: Insensibility to pain during surgery and painful procedures
- Topical review
- In praise of anesthesia: Two case studies of pain and suffering during major surgical procedures with and without anesthesia in the United States Civil War-1861–65
- Editorial comment
- Intravenous non-opioids for immediate postop pain relief in day-case programmes: Paracetamol (acetaminophen) and ketorolac are good choices reducing opioid needs and opioid side-effects
- Clinical pain research
- Intravenous acetaminophen vs. ketorolac for postoperative analgesia after ambulatory parathyroidectomy
- Editorial comment
- Scandinavian Association for the Study of Pain 2013—Annual scientific meeting abstracts of pain research presentations and greetings from incoming President
- Abstracts
- Why does the impact of multidisciplinary pain management on quality of life differ so much between chronic pain patients?
- Abstracts
- Health care utilization in chronic pain—A population based study
- Abstracts
- Pain treatment in rural Ghana—A qualitative study
- Abstracts
- Pain psychology specialist training 2012–2014
- Abstracts
- Pain assessment, documentation, and management in a university hospital
- Abstracts
- Promising effects of donepezil when added to patients treated with gabapentin for neuropathic pain
- Abstracts
- A pediatric patients’ pain evaluation in the emergency unit
- Abstracts
- Proteomic analysis of cerebrospinal fluid gives insight into the pain relief of spinal cord stimulation
- Abstracts
- The DQB1(*)03:02 HLA haplotype is associated with increased risk of chronic pain after inguinal hernia surgery and lumbar disc herniation
- Abstracts
- On the pharmacological effects of two lidocaine concentrations tested on spontaneous and evoked pain in human painful neuroma: A new clinical model of neuropathic pain
- Abstracts
- The mineralocorticoid receptor antagonist spironolactone enhances morphine antinociception
- Abstracts
- Expression of calcium/calmodulin-dependent protein kinase II in dorsal root ganglia in diabetic rats 6 months and 1 year after diabetes induction
- Abstracts
- Histamine in the locus coeruleus attenuates neuropathic hypersensitivity
- Abstracts
- Pronociceptive effects of a TRPA1 channel agonist methylglyoxal in healthy control and diabetic animals
- Abstracts
- Human inducible pluripotent stem cell-derived sensory neurons express multiple functional ion channels and GPCRs
Articles in the same Issue
- Editorial comment
- Chronic pain – The invisible disease? Not anymore!
- Clinical pain research
- New objective findings after whiplash injuries: High blood flow in painful cervical soft tissue: An ultrasound pilot study
- Editorial comment
- Chronic pain is strongly associated with work disability
- Observational studies
- Chronic pain: One year prevalence and associated characteristics (the HUNT pain study)
- Editorial comment
- Pain rehabilitation in general practice in rural areas? It works!
- Clinical pain research
- Effectiveness of multidisciplinary rehabilitation treatment for patients with chronic pain in a primary health care unit
- Editorial comment
- Mirror-therapy: An important tool in the management of Complex Regional Pain Syndrome (CRPS)
- Topical review
- Mirror therapy for Complex Regional Pain Syndrome (CRPS)—A literature review and an illustrative case report
- Editorial comment
- New insight in migraine pathogenesis: Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the circulation after sumatriptan
- Original experimental
- Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the circulation after sumatriptan
- Editorial comment
- Statistical pearls: Importance of effect-size, blinding, randomization, publication bias, and the overestimated p-values
- Topical review
- Significance tests in clinical research—Challenges and pitfalls
- Editorial comment
- Biomarkers of pain – Zemblanity?
- Topical review
- Mechanistic, translational, quantitative pain assessment tools in profiling of pain patients and for development of new analgesic compounds
- Editorial comment
- Chronic Benign Paroxysmal Positional Vertigo (BPPV): A possible cause of chronic, otherwise unexplained neck-pain, headache, and widespread pain and fatigue, which may respond positively to repeated particle repositioning manoeuvres (PRM)
- Observational studies
- Pain and other symptoms in patients with chronic benign paroxysmal positional vertigo (BPPV)
- Editorial comment
- The most important step forward in modern medicine, “a giant leap for mankind”: Insensibility to pain during surgery and painful procedures
- Topical review
- In praise of anesthesia: Two case studies of pain and suffering during major surgical procedures with and without anesthesia in the United States Civil War-1861–65
- Editorial comment
- Intravenous non-opioids for immediate postop pain relief in day-case programmes: Paracetamol (acetaminophen) and ketorolac are good choices reducing opioid needs and opioid side-effects
- Clinical pain research
- Intravenous acetaminophen vs. ketorolac for postoperative analgesia after ambulatory parathyroidectomy
- Editorial comment
- Scandinavian Association for the Study of Pain 2013—Annual scientific meeting abstracts of pain research presentations and greetings from incoming President
- Abstracts
- Why does the impact of multidisciplinary pain management on quality of life differ so much between chronic pain patients?
- Abstracts
- Health care utilization in chronic pain—A population based study
- Abstracts
- Pain treatment in rural Ghana—A qualitative study
- Abstracts
- Pain psychology specialist training 2012–2014
- Abstracts
- Pain assessment, documentation, and management in a university hospital
- Abstracts
- Promising effects of donepezil when added to patients treated with gabapentin for neuropathic pain
- Abstracts
- A pediatric patients’ pain evaluation in the emergency unit
- Abstracts
- Proteomic analysis of cerebrospinal fluid gives insight into the pain relief of spinal cord stimulation
- Abstracts
- The DQB1(*)03:02 HLA haplotype is associated with increased risk of chronic pain after inguinal hernia surgery and lumbar disc herniation
- Abstracts
- On the pharmacological effects of two lidocaine concentrations tested on spontaneous and evoked pain in human painful neuroma: A new clinical model of neuropathic pain
- Abstracts
- The mineralocorticoid receptor antagonist spironolactone enhances morphine antinociception
- Abstracts
- Expression of calcium/calmodulin-dependent protein kinase II in dorsal root ganglia in diabetic rats 6 months and 1 year after diabetes induction
- Abstracts
- Histamine in the locus coeruleus attenuates neuropathic hypersensitivity
- Abstracts
- Pronociceptive effects of a TRPA1 channel agonist methylglyoxal in healthy control and diabetic animals
- Abstracts
- Human inducible pluripotent stem cell-derived sensory neurons express multiple functional ion channels and GPCRs
