Cross-Validation of the Foundation Pain Index with PROMIS-29 in Chronic Pain Patients

Purpose

Discovery and validation of pragmatic biomarkers represent significant advancements in the field of pain management. Evaluating relationships between objective biomarkers and patient-reported outcomes (PROs) is an effective way to gain mechanistic insight into the potential role of biochemistry in chronic pain. The aim of this study was to validate the Foundation Pain Index (FPI) by evaluating associations between deranged biochemical function and PROMIS-29 domains in individuals living with chronic pain.

Patients and Methods

PROMIS-29 scores and FPI test results were obtained from 298 patients with chronic pain in this retrospective, observational study. Statistical analysis was performed using clinical test data to evaluate relationships between deranged biochemical function and quality of life measures across 8 universal domains.

Results

FPI scores significantly associated with multiple PROMIS-29 domains including physical function, impact score, fatigue, pain interference, and depression (P < 0.05). Moreover, specific analytes that comprise the FPI significantly correlated with PROMIS-29 domains, including 5-hydroxyindolacetic acid (pain interference, physical function, and pain impact scores), hydroxymethylglutarate (physical function), homocysteine (pain impact scores), kynurenic acid (pain interference and physical function), and quinolinic acid (physical function) (P < 0.05).

Conclusion

Cross-validation of the FPI with PROMIS-29 domains further supports the role of deranged biochemical function in the etiology of chronic pain. Objective identification of atypical biochemical function and subsequent correction holds tremendous promise for the non-opioid management of pain. Continued research efforts will aim to determine the impact of biochemical optimization in pre-surgical periods and post-surgical outcomes in patients with chronic pain.

An Analysis of Biomarkers in Patients with Chronic Pain

BACKGROUND

Because of the subjective nature of current pain assessments, limited efficacy of treatment options and risks associated with opioid abuse and diversion, the need for objective data to assist with chronic pain management has never been greater. Successful identification of mechanistic biomarkers would not only improve our understanding and ability to accurately diagnose pain disorders but would also facilitate the development of disease-modifying pain drugs.

OBJECTIVES

The objective of this study was to determine and evaluate the prevalence of abnormal biomarker findings in a population of patients with chronic pain.

STUDY DESIGN

Retrospective, observational study.

SETTING

Data analysis of biomarker test results was performed at a single industry site (Ethos Research & Development, Newport, KY) from clinical samples collected and analyzed from July to December 2018.

METHODS

A novel, pain-specific biomarker test panel that evaluates biomarkers of systemic inflammation, oxidative stress, neurotransmitter turnover, and micronutrient status was employed to determine the prevalence of abnormal findings in 17,834 unique patient samples analyzed at a national reference laboratory (Ethos Laboratories, Newport, KY). Patient biomarker results were considered abnormal if they were outside of the 95% confidence interval reference ranges established using a healthy population of donors who had no history of chronic pain or opioid use.

RESULTS

A total of 77% of patients with chronic pain exhibited at least one abnormal biomarker result (n = 13,765). The most common abnormal biomarker finding was elevated quinolinic acid, which was observed in 29% of patients (n = 5,107). Elevated pyroglutamate, indicative of glutathione depletion, was observed in 19% of patients (n = 3,314). Elevated xanthurenic acid, indicative of vitamin B6 insufficiency, was observed in 17% of patients (3,025). Elevated levels of the acrolein metabolite 3-hydroxypropyl mercapturic acid were observed in 21% of patients (n = 3,667). Elevated methylmalonic acid, indicative of a vitamin B12 deficiency, was observed in 10% of patients (n = 1,827), whereas abnormally low levels of neurotransmitter metabolites were observed in 8% of patients (n = 1,456).

LIMITATIONS

Medications and/or conditions other than those associated with chronic pain were not evaluated as potential causes of abnormal biomarker findings.

CONCLUSIONS

A novel biomarker assay that measures objective correlates to the neurobiological processes underlying chronic pain reveals a high prevalence of atypical biochemistry in a population of patients with pain. Abnormal biomarker findings presented here provide objective support for the role of cytokine-mediated inflammation, oxidative stress, abnormally low production of neurotransmitters, and micronutrient deficiencies in the development or worsening of chronic pain. This unique panel of functional pain biomarkers provides practitioners with novel, objective insight into the underlying causes of pain, which will pave the way for truly personalized pain medicine. Correcting abnormal biomarker findings with targeted, nonopioid therapies to improve patient function and alleviate pain potentially could lessen the opioid burden and drastically reduce health care costs.

KEY WORDS

Biomarker, pain, inflamation, oxidative stress, neurotransmitter, micronutrient deficiency, Kynurenine Pathway.

Raspberry ketone fails to reduce adiposity beyond decreasing food intake in C57BL/6 mice fed a high-fat diet

As the incidence of obesity continues to increase, identifying novel nutritional therapies to enhance weight loss are needed. Raspberry ketone (RK; 4-(4-hydroxyphenyl) butan-2-one) is a bioactive phytochemical that is marketed as a weight loss supplement in the United States, yet there is scant scientific evidence demonstrating that RK promotes weight loss. The aim of the current study was to investigate the effect of RK on accumulation of adipose mass, hepatic lipid storage, and levels of plasma adiponectin in mice fed a high-fat (HF) diet. Mice were individually housed and fed a HF control diet (45% kcal from fat) for two weeks to induce weight gain, then assigned to HF control, high-dose (1.74% wt/wt) raspberry ketone (HRK), low-dose (0.25% wt/wt) raspberry ketone (LRK), or a pair-fed group (PF) fed similar food intake to LRK mice. Following five weeks of feeding, mice fed LRK and HRK diets showed reduced food intake and body weight compared to mice maintained on control diet. When normalized to body weight, mice fed HRK diet exhibited decreased inguinal fat mass and increased liver mass compared to the control group. Hepatic steatosis was lowest in mice fed HRK diet, whereas LRK diet did not have an effect when compared to the PF group. Plasma adiponectin concentration was unaffected by RK and pair-feeding. Our findings demonstrate that RK supplementation has limited benefit to adipose loss beyond reducing energy intake in mice fed a high-fat diet. The present study supports the need for appropriate study design when validating weight-loss supplements.

Citrus flavonoid, naringenin, increases locomotor activity and reduces diacylglycerol accumulation in skeletal muscle of obese ovariectomized mice

SCOPE

Estrogen deficiency has been associated with central obesity, muscle loss and metabolic syndrome in postmenopausal women. This study assessed naringenin accumulation in tissues and investigated the hypothesis that naringenin reverses diet-induced metabolic disturbances in obese ovariectomized mice.

METHODS AND RESULTS

In study 1, we measured naringenin concentrations in plasma, liver, perigonadal and subcutaneous adipose tissues, and muscle of ovariectomized C57BL/6J female mice after 11 weeks of naringenin supplementation. Naringenin accumulated 5-12 times more in mice fed a 3% naringenin diet than in mice fed a 1% naringenin diet. In study 2, ovariectomized mice were fed a high-fat diet (60 kcal% fat) for 11 weeks and half of the mice were then supplemented with 3% naringenin for another 11 weeks. Dietary naringenin suppressed weight gain, lowered hyperglycemia and decreased intra-abdominal adiposity evaluated by magnetic resonance imaging. Naringenin-fed mice exhibited elevated locomotor activity monitored by infrared beam breaks, maintained muscle mass and reduced muscle diacylglycerol content. Real-time PCR analysis in muscle revealed decreased mRNA level for genes involved in de novo lipogenesis, lipolysis and triglyceride synthesis/storage.

CONCLUSION

Long-term 3% naringenin supplementation resulted in significant naringenin accumulation in plasma and tissues, associated with attenuated metabolic dysregulation and muscle loss in obese ovariectomized mice.