Pain that does not interfere with daily life—a new focus for population epidemiology and public health?

Association between the dietary inflammatory index and pain in US adults from NHANES

OBJECTIVES

The growing global burden of pain is gradually expanding from the medical field to public health. Dietary inflammatory potential correlates with inflammatory markers, and inflammation is one of the main mechanisms of pain.

METHODS

This study explored the association between dietary inflammatory index (DII) and pain from the NHANES database on DII and pain (neck pain, low back pain, joint pain, and headache or migraine) using logistic regression and stratified analysis.

RESULTS

The results show a stronger association between DII and joint pain (Q4 of DII adjusted-OR = 1.23, 95% CI = 1.08-1.40, P = 0.003) and headache or migraine (Q4 of DII adjusted-OR = 1.31, 95% CI = 1.15-1.48, P < 0.001), but no association is found in neck pain (Q4 of DII adjusted-OR = 1.03, 95% CI = 0.89-1.20, P = 0.65) and low back pain (Q4 of DII adjusted-OR = 1.04, 95% CI = 0.92-1.17, P = 0.54). After stratifying the data according to demographics, differences in the relationship between DII and pain are found at different levels of the population.

DISCUSSION

This study identifies high DII as a risk factor for joint pain and headache or migraine.

Worse health‐related quality of life, impaired functioning and psychiatric comorbidities are associated with excess mortality in patients with severe chronic pain

Background

Severe chronic pain that interferes with daily activities is associated with an increased risk of mortality. We assessed the overall mortality of tertiary chronic pain patients in comparison with the general population, with a special aim to analyse the association of health‐related quality of life (HRQoL) and its dimensions with the risk of death.

Methods

In this prospective observational follow‐up study, patients with non‐cancer chronic pain attended an outpatient multidisciplinary pain management (MPM) episode in a tertiary pain clinic in 2004–2012 and were followed until May 2019. Mortality between the patients and the general population was compared with standardized mortality ratios (SMR) in different age groups. Causes of death and comorbidities were compared among the deceased. Association of mortality and HRQoL and its dimensions, measured with the 15D instrument, was studied with Cox proportional hazards model.

Results

During a mean of 10.4‐year follow‐up of 1498 patients, 296 died. The SMR in the youngest age group (18–49 years) was significantly higher than that of the general population: 2.6 for males and 2.9 for females. Even elderly females (60–69 years) had elevated mortality (SMR 2.3). Low baseline HRQoL at the time of MPM, as well as poor ratings in the psychosocial dimensions of HRQoL, was associated with an increased risk of death.

Conclusions

Our results support the role of HRQoL measurement by a validated instrument such as the 15D in capturing both the physical and the psychological symptom burden, and consequently, an elevated risk of death, in patients with chronic pain.

Significance

Severe chronic pain is associated with elevated mortality. In patients in chronic pain under 50 years old, the mortality was 2.5–3 times higher than in the general population. Psychological distress appears to contribute to the increased mortality. Regular follow‐up by health‐related quality of life (HRQoL) measurement could be useful in identifying patients in chronic pain who are in need of intensive symptom management and to prevent early death.

Healthy working life expectancy at age 50 for people with and without osteoarthritis in local and national English populations

Retirement ages are rising in many countries to offset the challenges of population ageing, but osteoarthritis is an age-associated disease that is becoming more prevalent and may limit capacity to work until older ages. We aimed to assess the impact of osteoarthritis on healthy working life expectancy (HWLE) by comparing HWLE for people with and without osteoarthritis from ages 50 and 65 nationally and in a local area in England. Mortality-linked data for adults aged ≥ 50 years were used from six waves (2002-13) of the English Longitudinal Study of Ageing and from three time points of the North Staffordshire Osteoarthritis Project. HWLE was defined as the average number of years expected to be spent healthy (no limiting long-standing illness) and in paid work (employment or self-employment), and was estimated for people with and without osteoarthritis and by sex and occupation type using interpolated Markov chain multi-state modelling. HWLE from age 50 years was a third lower for people with osteoarthritis compared to people without osteoarthritis both nationally (5.68 95% CI [5.29, 6.07] years compared to 10.00 [9.74, 10.26]) and in North Staffordshire (4.31 [3.68, 4.94] years compared to 6.90 [6.57, 7.24]). HWLE from age 65 years for self-employed people with osteoarthritis exceeded HWLE for people without osteoarthritis in manual or non-manual occupations. Osteoarthritis was associated with a significantly shorter HWLE. People with osteoarthritis are likely to have significantly impaired working ability and capacity to work until older ages, especially in regions with poorer health and work outcomes.

How Pain Shapes Depression and Anxiety: A Hybrid Self-regulatory/Predictive Mind Perspective

Because many persons living with chronic pain achieve a relatively balanced lifestyle without experiencing functional disability, medical psychologists must explain the well-documented co-occurrence of pain complaints and DSM-5-disorders (including but not limited to depression and anxiety) in a significant subset of individuals. The question of differential resilience versus susceptibility has received modest theoretical and empirical attention, but remains open. In this review, I deconstruct the temporally extended pain adaptation process in order to address this vexing question, relying upon two complementary explanatory frames. The first is a motivational/cybernetic systems formulation labeled the Goal-Centered, Self-Regulatory, Automated Social Systems Psychology (GRASSP) model, erected upon feedback sensitive, goal-guided, hierarchically organized self-regulatory processes. Depression and anxiety presumably result from compromised regulatory functions undermining pain processing, goal pursuit, and everyday performance. The second perspective postulates a "Bayesian Brain"/"Predictive Mind" capable of unifying perception, action, and emotion via predictive processing. From a Bayesian perspective, predictive processing implies that our brains evolved to compare, without conscious direction, incoming environmental information against prior, model-based predictions in order to arrive at accurate perceptual representations of the world. Maladjustment results from failures of active inference. When applied to the perception of visceral information, the embodied process, termed interoceptive inference, can also yield pathogenic outcomes. The Bayesian model holds that depression and anxiety in individuals with pain result from error-prone (biased, rigid, or highly certain) prior evaluations of aversive feeling states and their relation to the external milieu. I consider how the hybrid conceptual framework advanced by the two models points to several novel and familiar avenues of intervention.

Behavioral Conceptualization and Treatment of Chronic Pain

Pain is considered a hardwired signal of bodily disturbance belonging to a basic motivational system that urges the individual to act and to restore the body's integrity, rather than just a sensory and emotional experience. Given its eminent survival value, pain is a strong motivator for learning. Response to repeated pain increases when harm risks are high (sensitization) and decreases in the absence of such risks (habituation). Discovering relations between pain and other events provides the possibility to predict (Pavlovian conditioning) and control (operant conditioning) harmful events. Avoidance is adaptive in the short term but paradoxically may have detrimental long-term effects. Pain and pain-related responses compete with other demands in the environment. Exposure-based treatments share the aim of facilitating or restoring the pursuit of individual valued life goals in the face of persistent pain, and further improvements in pain treatment may require a paradigm shift toward more personalized approaches.

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.