Biomarkers of chronic nonspecific pain syndrome: A cross-sectional hospital-based pilot study

Chronic nonspecific multiple-sites pain [CNMSP] of unknown etiology: Biopsychosocial method of evaluation for the primary care level

Background

Understanding and dealing with chronic nonspecific pain (CNP) is the important entity at primary care hospital. Chronic nonspecific multiple-site pain [CNMSP] of unknown etiology creates diagnostic and therapeutic challenges for primary care physicians due to lack of guidance regarding evaluation and treatment.

Aims and Objectives

To classify and formulate the evaluation, treatment strategies, and prediction of prognosis of patients with CNMSP of unknown etiology.

Methods

Patients present with CNMSP of more than 3-month duration without any obvious medical cause. The biopsychosocial [BPS] model with 3P model was applied to see the biological, psychological, and social factors behind persistence. Finally, patients were classified into four groups for evaluation response to treatment and relapse rates in 12-month follow-up.

Results

Of the total 243 patients of CNMSP, 243 [96.3%] were females. Sixty [24.7%] patients had short duration, and 183 [75.3%] had long duration. Headache was in 115 [47%], low back pain ± leg pain in 96 [39.4%], cervical pain ± shoulder/arm pain in 83 [34.1%], and diffuse body pain in 50 [20.5%] in various combinations. A total of 155 [63.8%] patients had high somatization-sensitization index (SSI), and 144 [59.3%] had low ferritin level. Group 1 [high SSI and low ferritin] had 37.9% of patients, group 2 [high SSI and normal ferritin] had 25.9% of patients, group 3 [low to medium SSI with low ferritin] had 21.4% of patients, and group 4 [low to medium SSI with normal ferritin] had 14.8% of patients. Response to pain symptoms was better in group 1, and relapse rate was higher in group 2.

Conclusion

CNMSP of unknown etiology itself is a heterogeneous entity, and assessment based on the BPS model can be very useful to understand the treatment plan and outcome of these patients.

Is nociplastic pain, a new pain category, associated with biochemical, hematological, and inflammatory parameters?

OBJECTIVE

The aim of the study was to evaluate the relationship between biochemical, hematological, and inflammatory parameters and pain in patients with nociplastic pain.

METHODS

In this cross-sectional study, a total of 8632 patients, aged between 20 and 65, were evaluated according to the nociplastic pain diagnosis criteria determined by IASP. Excluding individuals who did not meet the criteria for nociplastic pain, the study included a total of 660 participants. The biochemical, hematological, and inflammatory parameters of all individuals were examined. The pain levels of the patients were assessed using the Visual Analogue Scale (VAS). The patients were categorized based on nociplastic pain types and pain regions for evaluation.

RESULTS

In this study, the female gender was more prevalent both in all nociplastic pain categories and in all pain region groups (p < 0.05). In the nociplastic pain categories, it was observed that vitamin D levels were lower in patients with chronic widespread pain, while ferritin and C-reactive protein levels were higher in patients with chronic primary musculoskeletal pain. Among patients with chronic widespread pain with low hemoglobin and/or ferritin levels, the Visual Analog Scale activity score was higher. For patients with chronic widespread pain and low vitamin D levels and/or high erythrocyte sedimentation rate levels, the Visual Analog Scale rest score was higher. In patients with fibromyalgia and high parathyroid hormone levels, the Visual Analog Scale activity score was higher. For patients with fibromyalgia and high Neutrophil/Lymphocyte ratio levels, the Visual Analog Scale rest score was higher. In patients with chronic primary musculoskeletal pain and high erythrocyte sedimentation rate and/or C-reactive protein levels, the Visual Analog Scale activity score was higher. While vitamin B12 levels were found to be lower in patients with widespread pain, no significant relationship was identified between electrolytes, other blood count results, and nociplastic pain.

CONCLUSION

In our study, it was observed that levels of vitamin D in individuals with nociplastic pain were low, while erythrocyte sedimentation rate, C-reactive protein, and Neutrophil/Lymphocyte ratio were high, and hemoglobin and ferritin levels were elevated. Furthermore, these findings were found to be associated with both the presence of pain and the severity of pain assessed using the visual analog scale.

Early-Life Iron Deficiency Persistently Alters Nociception in Developing Mice

Clinical association studies have identified early-life iron deficiency (ID) as a risk factor for the development of chronic pain. While preclinical studies have shown that early-life ID persistently alters neuronal function in the central nervous system, a causal relationship between early-life ID and chronic pain has yet to be established. We sought to address this gap in knowledge by characterizing pain sensitivity in developing male and female C57Bl/6 mice that were exposed to dietary ID during early life. Dietary iron was reduced by ∼90% in dams between gestational day 14 and postnatal day (P)10, with dams fed an ingredient-matched, iron-sufficient diet serving as controls. While cutaneous mechanical and thermal withdrawal thresholds were not altered during the acute ID state at P10 and P21, ID mice were more sensitive to mechanical pressure at P21 independent of sex. During adulthood, when signs of ID had resolved, mechanical and thermal thresholds were similar between early-life ID and control groups, although male and female ID mice displayed increased thermal tolerance at an aversive (45 °C) temperature. Interestingly, while adult ID mice showed decreased formalin-induced nocifensive behaviors, they showed exacerbated mechanical hypersensitivity and increased paw guarding in response to hindpaw incision in both sexes. Collectively, these results suggest that early-life ID elicits persistent changes in nociceptive processing and appears capable of priming developing pain pathways. PERSPECTIVE: This study provides novel evidence that early-life ID evokes sex-independent effects on nociception in developing mice, including an exacerbation of postsurgical pain during adulthood. These findings represent a critical first step towards the long-term goal of improving health outcomes for pain patients with a prior history of ID.