Chronic pain management increasingly seeks objective biomarkers to complement subjective assessments. Ultra-weak photon emission (UPE), measurable via gas discharge visualization (GDV), has been proposed as a potential biomarker for various health conditions. However, the specificity of UPE measurements for pain versus comorbid conditions remains unexplored. This prospective cohort study followed 200 adults with electrodiagnostically confirmed neuropathic pain receiving cannabis therapy for 48 months. Assessments included the Numerical Rating Scale (NRS) for pain, Generalized Anxiety Disorder-7 (GAD-7) for anxiety, and Biowell UPE measurements. Cannabis therapy yielded 91.5% clinical response rate. However, UPE measurements showed striking differential validity: Biowell stress correlated strongly with GAD-7 (r = 0.579, p < 0.001) but negligibly with NRS (r = 0.093, p = 0.001), representing a 6.2-fold difference. Variance explained was 33.5% for anxiety versus 0.9% for pain. ROC analysis revealed good discrimination for clinical anxiety (AUC = 0.744) but poor discrimination for pain (AUC = 0.550). Mixed-effects modeling confirmed UPE stress predicted GAD-7 (b = 1.82, p < 0.001) but not NRS (b = −0.03, p = 0.84). These findings demonstrate that Biowell UPE measurements specifically capture psychological stress rather than nociceptive processes, with important implications for biomarker development in pain medicine. This study emphasizes the critical importance of validating proposed biomarkers against multiple related outcomes to establish specificity and appropriate clinical applications.

Background/Objectives: Reverse total shoulder arthroplasty (RTSA) is increasingly common, but large-scale studies on age-related differences in outcomes are limited. This study aims to evaluate epidemiological trends, clinical indications, and postoperative outcomes in patients under 65 undergoing RTSA. Methods: We analyzed data from the Nationwide Inpatient Sample (NIS) from 2016–2021, including 48,460 patients aged 35–64 undergoing shoulder arthroplasty. Patients were stratified into three age groups: 35–45, 46–55, and 56–65 years. We assessed trends, clinical indications, comorbidities, hospital stay metrics, and postoperative complications using chi-square tests, ANOVA, and multivariate logistic regression. Results: Procedure volumes increased from 2016 to 2019, peaking at 2007 cases, but declined in 2020 and 2021 (924 cases). The 56–65 age group consistently comprised the majority of procedures (81.7% in 2016 to 88.3% in 2021). Comorbidities like type 2 diabetes (5.9% to 22.8%), hypertension (27.9% to 55.3%), and dyslipidemia (10.3% to 40.5%) increased with age (p < 0.001). Rotator cuff tears were more prevalent in older patients (25% to 48.5%, p < 0.001), while instability was higher in the youngest group (8.8%, p < 0.001). Osteoarthritis was the most common indication, increasing with age (56.6% to 62.5%, p < 0.001). Cardiac complications increased with age (2.2% to 5.1%, p = 0.04). Female gender (OR = 1.548, p < 0.001), private insurance (OR = 1.570, p < 0.001), and small hospital size were associated with higher odds of cardiac complications. Native American race showed lower odds (OR = 0.308, p = 0.009) compared to White patients. Conclusions: Significant age-related differences exist in comorbidities, clinical indications, and postoperative complications following RTSA. Older patients had higher rates of comorbidities and cardiac complications, while younger patients presented with instability. These findings highlight the importance of age-specific perioperative management to optimize outcomes.