How to deal with non-detectable and outlying values in biomarker research: Best practices and recommendations for univariate imputation approaches

Investigating thyroid function and iodine status in adolescents with and without paediatric major depressive disorder

Depression has been associated with subclinical hypothyroidism and altered hypothalamic-pituitary-thyroid axis functioning. Adequate iodine nutrition is essential for healthy thyroid functioning. We therefore determined associations of iodine and thyroid status with paediatric major depressive disorder (pMDD) among Swiss adolescents and explored whether associations are sex-specific and mediated by stress. We conducted a matched case-control study in 95 adolescents with diagnosed pMDD and 95 healthy controls. We assessed depression severity using the Children's Depression Rating Scale-Revised and stress using the perceived stress scale (PSS) and measuring hair cortisol levels. We determined iodine status by measuring urinary iodine concentrations (UIC) and thyroid status by thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in serum. Median (IQR) UIC did not differ between cases (121 (87, 174) µg/l) and controls (114 (66, 183) μg/l, P = 0·3). Median TSH and FT4 were lower in cases than controls (TSH: 1·36 (0·91, 2·00) mlU/l v. 1·50 (1·18, 2·06) mlU/l, P = 0·039; FT4: 14·7 (12·9, 16·9) pmol/l v. 15·7 (14·3, 17·2) pmol/l, P = 0·004). The prevalence of hypothyroxinaemia (normal TSH; low FT4) was higher among female cases than controls (21 % v. 4%, P = 0·006). PSS scores were higher while hair cortisol was lower in cases than controls (PSS: 25 (20, 28) v. 11 (7, 15), P < 0·001; cortisol: 2·50 (1·34, 3·57) pg/mg v. 3·23 (1·79, 4·43) pg/mg, P = 0·044). After adjusting for confounders, the associations of TSH and hair cortisol with pMDD were no longer significant. Furthermore, TSH and FT4 were not associated with PSS scores and hair cortisol levels. Summarising, iodine nutrition was adequate for adolescents with and without pMDD. However, FT4 concentrations were lower in those with pMDD, and 1 in 5 female adolescents with pMDD were hypothyroxinaemic.

Effectiveness of Switching to Subcutaneous Infliximab in Ulcerative Colitis Patients Experiencing Intravenous Infliximab Failure

Background/Aims

Studies on elective switching to the subcutaneous (SC) formulation of infliximab revealed comparable efficacy and safety and higher infliximab level than those exhibited by intravenous (IV) infliximab. However, no studies have reported on the effectiveness of SC switching in ulcerative colitis (UC) patients who experienced IV infliximab failure during maintenance treatment.

Methods

This retrospective study included UC patients who had been switched to SC infliximab because of IV infliximab failure, between January 2021 and January 2023. Group A was defined as having clinically and biochemically active UC (secondary loss of response), and group B consisted of patients with stable symptoms but biochemically active UC.

Results

Twenty-three patients met the inclusion criteria: 15 in group A and eight in group B. The serum infliximab levels significantly increased after SC switching in both groups. The electively switched group also exhibited increased infliximab levels after SC switching. Patients in group A showed improved partial Mayo score with a significant decrease in fecal calprotectin and C-reactive protein after switching. In group B, the fecal calprotectin level significantly decreased without clinical relapse after switching. A high proportion of patients (≥80%) in both groups achieved clinical and/or biochemical responses at the last follow-up. During the follow-up period, only two patients in group A discontinued SC infliximab, and only one complained of severe injection site reaction.

Conclusions

In UC patients who experience IV infliximab failure during maintenance treatment, switching to SC infliximab may be a promising option because of better efficacy and safety.

Profile of uterine flush lipid mediators in cows with subclinical endometritis: pilot study

Subclinical endometritis affects reproductive outcomes and causes economic losses in dairy cows, thus, it is important to understand disease progression mechanisms and develop diagnostic procedures for better disease management. We measured the levels of 146 lipid mediators in uterine flush samples using lipid chromatography-mass spectrometry. We detected 25 lipid mediators in the uterine flush of both the control and subclinical endometritis cows; 15 of the 25 lipid mediators were AA-derived metabolites. Among the AA-derived metabolites, cyclooxygenase (COX)-generated mediators were the most abundant. Specifically, levels of 11β-13,14-dihydro-15-keto prostaglandin (PG) F2α, PGE2, PGA2, 13-hydroxyoctadecadienoic acid, and PGD1 were elevated in all the cows with subclinical endometritis. This study may provide new insights for the management of subclinical bovine endometritis.

The role of estrogen receptor gene polymorphisms in menopausal symptoms and estradiol levels in perimenopausal women - Findings from the Swiss Perimenopause Study

OBJECTIVES

Fluctuating estradiol (E2) levels seem to be associated with menopausal symptoms, though not all women suffer from these symptoms to the same extent despite experiencing these hormonal changes. This suggests underlying, interindividual mechanisms, such as single-nucleotide polymorphisms (SNPs) influencing estrogen receptors α and β, and the g-protein-coupled estrogen receptor (GPER). As research is scarce, we aimed to address this research gap by assessing genetic traits, E2 levels, and menopausal symptoms longitudinally.

STUDY DESIGN

129 perimenopausal women (aged 40-56 years) participated in the 13-month longitudinal Swiss Perimenopause Study.

MAIN OUTCOME MEASURES

Menopausal symptoms were assessed fortnightly using the Menopause Rating Scale (MRS II). Salivary E2 levels were assessed 14 times over two non-consecutive months. Blood samples were collected using the dried blood spot (DBS) technique to analyze ESR1 rs2234693, ESR1 rs9340799, ESR2 rs1256049, ESR2 rs4906938, and GPER rs3808350. Group-based trajectory modeling was performed to identify interindividual trajectories of menopausal symptoms. Multinomial logistic regression models were employed to identify factors associated with these trajectories.

RESULTS

Four distinct trajectory groups of menopausal symptoms were identified (increase, moderate, rebound, decrease). ER gene polymorphisms and E2 fluctuation were significantly associated with group membership. Furthermore, ER gene polymorphisms modulated the effect of E2 fluctuations on menopausal symptom trajectory.

CONCLUSIONS

This study illuminates the multifaceted factors contributing to the individuality of the perimenopausal experience. ER gene polymorphisms emerged as integral factors by modulating the effect of E2 fluctuations on menopausal symptom trajectory. This underscores the intricate interplay of genetic factors, E2 fluctuations, and menopausal symptoms during perimenopause.

Stability and inter-family associations of hair endocannabinoid and N-acylethanolamines across the perinatal period in mothers, fathers, and children

Analysis of endocannabinoids (ECs) and N-acylethanolamines (NAEs) in hair is assumed to retrospectively assess long-term EC/NAE concentrations. To inform their use, this study investigated stability of EC/NAE hair concentrations in mothers, fathers, and their children across the perinatal period as well as associations between family members. In a prospective cohort study, EC (AEA, 1-AG/2-AG) and NAE (SEA, PEA, OEA) levels were quantified in hair samples taken four times in mothers (n = 336) and their partners (n = 225) from pregnancy to two years postpartum and in offspring (n = 319) from shortly after birth to two years postpartum. Across the perinatal period, maternal and paternal hair ECs/NAEs showed poor multiple-test consistency (16-36%) and variable relative stability, as well as inconsistent absolute stability for mothers. Regarding children, hair ECs/NAEs evidenced poor multiple-test consistency (4-19%), no absolute stability, and either no or variable relative stability. Hair ECs/NAEs showed small to medium significant associations across the perinatal period within couples and parent-child dyads. Findings suggest hair ECs/NAEs during the perinatal period possess variable stability in adults, albeit more stability in fathers than mothers in this time. This highlights the need to further investigate factors associated with changes in hair ECs/NAEs across time. The first two years of life may be a dynamic phase for the endocannabinoid system in children, potentially characterized by complex within-family correspondence that requires further systematic investigation.

The relationship between self-perceived fatigue, muscle endurance, and circulating markers of inflammation in participants of the Copenhagen aging and Midlife Biobank (CAMB)

BACKGROUND

Fatigue, low muscle endurance, muscle weakness and low-grade inflammation are strongly related to frailty at higher age. When signs of self-perceived fatigue and low muscle endurance are interrelated with low-grade inflammation at midlife, they might be used as early markers for frailty. This study investigated whether the interrelationships among self-perceived fatigue, muscle endurance and inflammation can be observed at midlife.

METHODS

A total of 965 participants of the Copenhagen Aging and Midlife Biobank (aged 52 ± 4 years, 536 males, 426 females) were assessed for self-perceived fatigue (20-item multidimensional fatigue inventory), muscle endurance (grip work), circulating markers of inflammation (hsCRP, IL-6, IL-10, TNF-alpha and IFN-γ), daily physical activity (PAS-2), body composition (%body fat assessed by bio-impedance) and self-reported health status. Participants were categorised (correcting for age and gender) according to high fatigue and/or low muscle endurance, differences in inflammatory profile between fatigue categories were assessed by ANCOVA (corrected for PAS-2, %body fat and presence of inflammatory conditions).

RESULTS

Overall, muscle endurance, fatigue and inflammatory markers were significantly interrelated. Higher levels of hsCRP (p < 0.001), IL-6 (p < 0.001), IL-10 (p = 0.035) and TNF-alpha (p = 0.028) were observed in participants presenting both low muscle endurance and high fatigue. IFN-γ was highest in those with high fatigue but normal muscle endurance (p = 0.015).

CONCLUSIONS

Middle-aged participants with higher fatigue in combination with low muscle endurance show higher levels of inflammation, independently from physical activity, body fat and inflammatory pathology. The underlying mechanisms should be identified and future studies should also investigate whether these individuals show early signs of reduced physiological reserve capacity, which in later life come to full expression by means of frailty.

The role of sex hormones, oral contraceptive use, and its parameters on visuospatial abilities, verbal fluency, and verbal memory

Sex hormones can cross the blood-brain barrier and access brain regions underlying higher-order cognition. Containing synthetic sex hormones, oral contraceptives (OC) have been found to modulate visuospatial and verbal abilities, though inconsistencies have been found in the literature. Among possible explanations, certain OC use parameters (progestin androgenicity, synthetic hormone levels, duration of use) have not received consistent consideration. Thus, the objectives were to (1) examine group differences between men, combined OC users, and naturally cycling women (NC women; not using OC) in visuospatial abilities, verbal fluency, and verbal memory and (2) investigate the contribution of endogenous and exogenous sex hormones on these effects. We also aimed to (3) identify OC use parameters relevant to cognitive outcomes. In total, 70 combined OC users, 53 early follicular (EF) women, 43 pre-ovulatory (PO) women, and 47 men underwent cognitive tests. Performance was compared based on hormonal milieus (OC, EF, PO, men) and OC users' contraceptive androgenicity (anti, low, high). Correlations between performance, hormone levels and OC use duration were also conducted. OC use dampened the sex difference that typically favors men in 3D visuospatial abilities, whereas its duration of use positively predicted verbal fluency. Androgenicity and hormone levels did not predict performance in any task. These results highlight the importance of considering OC use duration. Results also did not support a role for androgenicity in cognition. Importantly, combined OC use (including prolonged use) does not impair visuospatial, verbal, and memory functions in a healthy young sample.

Morphologic alterations of the fear circuitry: the role of sex hormones and oral contraceptives

Background

Endogenous sex hormones and oral contraceptives (OCs) have been shown to influence key regions implicated in fear processing. While OC use has been found to impact brain morphology, methodological challenges remain to be addressed, such as avoiding selection bias between OC users and non-users, as well as examining potential lasting effects of OC intake.

Objective

We investigated the current and lasting effects of OC use, as well as the interplay between the current hormonal milieu and history of hormonal contraception use on structural correlates of the fear circuitry. We also examined the role of endogenous and exogenous sex hormones within this network.

Methods

We recruited healthy adults aged 23-35 who identified as women currently using (n = 62) or having used (n = 37) solely combined OCs, women who never used any hormonal contraceptives (n = 40), or men (n = 41). Salivary endogenous sex hormones and current users' salivary ethinyl estradiol (EE) were assessed using liquid chromatography - tandem mass spectrometry. Using structural magnetic resonance imaging, we extracted surface-based gray matter volumes (GMVs) and cortical thickness (CT) for regions of interest of the fear circuitry. Exploratory whole-brain analyses were conducted with surface-based and voxel-based morphometry methods.

Results

Compared to men, all three groups of women exhibited a larger GMV of the dorsal anterior cingulate cortex, while only current users showed a thinner ventromedial prefrontal cortex. Irrespective of the menstrual cycle phase, never users exhibited a thicker right anterior insular cortex than past users. While associations with endogenous sex hormones remain unclear, we showed that EE dosage in current users had a greater influence on brain anatomy compared to salivary EE levels and progestin androgenicity, with lower doses being associated with smaller cortical GMVs.

Discussion

Our results highlight a sex difference for the dorsal anterior cingulate cortex GMV (a fear-promoting region), as well as a reduced CT of the ventromedial prefrontal cortex (a fear-inhibiting region) specific to current OC use. Precisely, this finding was driven by lower EE doses. These findings may represent structural vulnerabilities to anxiety and stress-related disorders. We showed little evidence of durable anatomical effects, suggesting that OC intake can (reversibly) affect fear-related brain morphology.

Sympathetic nervous system responses to acute psychosocial stress in male physicians with clinical burnout

BACKGROUND

Occupational burnout has been associated with an increased risk of cardiovascular disease, with sympathetic nervous system (SNS) dysfunction as one explanation. This study examined the effects of burnout on responses of SNS activity measures to acute psychosocial stress in male physicians, a population at risk for burnout.

METHODS

Study participants were 60 male physicians, 30 with clinical burnout, assessed with the Maslach Burnout Inventory, and 30 without burnout (controls). All participants underwent the 15-min Trier Social Stress Test. Heart rate, blood pressure, salivary alpha-amylase, and plasma levels of epinephrine (EPI) and norepinephrine were assessed pre-stress, immediately post-stress, and 15 min and 45 min post-stress.

RESULTS

Physicians with burnout and controls differed in EPI changes over time, controlling for age, job stress and anxiety symptoms (F (3,147) = 5.18, p = .002 for 'Time by Group' interaction; η2p = .096). Burnout was associated with a smaller increase in EPI from pre-stress to immediately post-stress (r(54) = -.40, p = .004). The emotional exhaustion dimension of burnout was a significant driver of this effect. The area under the curve with respect to increase in EPI was also smaller in the burnout group (F (1,49) = 6.06, p = .017, η2p = .110). Group differences were not significant for the other SNS activity measures.

CONCLUSIONS

Burnout may be linked to dysfunction of the sympathoadrenal medullary (SAM) system, when exposed to acute psychosocial stress. In keeping with the allostatic load concept, an insufficient SAM stress response in burnout could potentially contribute to cardiovascular disease.

Association Between Blood Calcium, Magnesium, and Non-alcoholic Fatty Liver Disease in Adults: a Cohort-Based Case-Control Study

Previous studies have shown that calcium (Ca), magnesium (Mg), and Ca/Mg ratio are associated with inflammation and metabolic disorders, but their relationship with non-alcoholic fatty liver disease (NAFLD) is unclear. Thus, we aimed to explore the association between Ca, Mg, Ca/Mg ratio, and NAFLD in Chinese adults. We conducted a case-control study based on the Kailuan Cohort in China, including 1816 cases and 1111 gender- and age-matched controls. Dose-response relationships between blood Ca, Mg, Ca/Mg ratio, and NAFLD were evaluated using restricted cubic splines. Odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated by logistic regression models. A negative association between blood Ca (overall association P < 0.001 and linear association P < 0.001) and NAFLD as well as Ca/Mg ratio (overall association P = 0.002 and linear association P = 0.024) and NAFLD was observed. Compared with the highest quartile, the adjusted OR (95% CI) for the lowest quartile of Ca and Ca/Mg ratio was 2.116 (1.679-2.667) and 1.358 (1.076-1.713), respectively. A U-shaped relationship was found for blood Mg and NAFLD, with the highest OR of 1.685 in the lowest quartile group when using the second quartile as a reference. Additionally, we observed the interaction between alanine aminotransferase and blood Ca (P = 0.024), total cholesterol (P = 0.017), low-density lipoprotein-cholesterol (P = 0.013), and blood Mg, as well as total cholesterol and Ca/Mg ratio (P = 0.014). Lower blood Ca and Ca/Mg ratio were significantly associated with the risk of NAFLD. Liver function or lipid metabolism parameters may modify their association, suggesting an individualized prevention strategy for NAFLD.

A Practical Guide to Adjust Micronutrient Biomarkers for Inflammation Using the BRINDA Method

The Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) research group was formed over a decade ago to improve the interpretation of micronutrient biomarkers in settings with inflammation. The BRINDA inflammation adjustment method uses regression correction to adjust for the confounding effects of inflammation on select micronutrient biomarkers and has provided important insights to micronutrient research, policy, and programming. However, users may face challenges when applying the BRINDA inflammation adjustment methods to their own data due to varying guidance on the adjustment approach for different biomarkers and the need to develop statistical programming to conduct these analyses. This may result in lost opportunities to have results of micronutrient data readily available during critical decision-making periods. Our research objectives are to 1) provide an all-in-one summary of the BRINDA method in adjusting multiple micronutrient biomarkers for inflammation, 2) evaluate whether malaria as a binary variable should be included in the BRINDA inflammation adjustment method, and 3) present standardized and user-friendly BRINDA adjustment R package and SAS macro. This paper serves as a practical guidebook for the BRINDA inflammation adjustment approach and aids users to use the BRINDA R package and SAS to streamline their analyses.

Data processing pipeline for cardiogenic shock prediction using machine learning

Introduction

Recent advances in machine learning provide new possibilities to process and analyse observational patient data to predict patient outcomes. In this paper, we introduce a data processing pipeline for cardiogenic shock (CS) prediction from the MIMIC III database of intensive cardiac care unit patients with acute coronary syndrome. The ability to identify high-risk patients could possibly allow taking pre-emptive measures and thus prevent the development of CS.

Methods

We mainly focus on techniques for the imputation of missing data by generating a pipeline for imputation and comparing the performance of various multivariate imputation algorithms, including k-nearest neighbours, two singular value decomposition (SVD)-based methods, and Multiple Imputation by Chained Equations. After imputation, we select the final subjects and variables from the imputed dataset and showcase the performance of the gradient-boosted framework that uses a tree-based classifier for cardiogenic shock prediction.

Results

We achieved good classification performance thanks to data cleaning and imputation (cross-validated mean area under the curve 0.805) without hyperparameter optimization.

Conclusion

We believe our pre-processing pipeline would prove helpful also for other classification and regression experiments.

Circulating inflammatory markers, cell-free mitochondrial DNA, cortisol, endocannabinoids, and N-acylethanolamines in female depressed outpatients

OBJECTIVES

Major depressive disorder (MDD) involves peripheral low-grade pro-inflammatory activity. This multi-biomarker case-control study characterises the proinflammatory status in MDD beyond C-reactive protein (CRP) and Interleukin (IL)-6 levels through investigating concomitant alterations of immunoregulatory biomolecules.

METHODS

In 20 female MDD patients and 24 non-depressed women, circulating levels of CRP, IL-6, cortisol, selected endocannabinoids (ECs; anandamide [AEA], 2-arachidonylglycerol [2-AG]), and N-acylethanolamines (NAEs), as well as circulating cell-free mitochondrial DNA (ccf-mtDNA) were measured.

RESULTS

We found higher serum CRP and plasma AEA levels in MDD and a positive association of CRP and AEA levels with current depressive symptoms. Blood levels of cortisol, ccf-mtDNA, 2-AG, and NAEs did depend on MDD diagnosis nor correlated with the severity of current depressive symptoms. CRP correlated positively with AEA, and AEA showed positive associations with 2-AG and NAE levels.

CONCLUSIONS

In this study, female MDD outpatients with mild to moderate disorder severity did not substantially differ from non-depressed controls in the resting levels of multiple immunoregulatory markers in peripheral blood. Instead of investigating resting levels, future research on the role of inflammatory activity in MDD should focus on investigating the reactivity of pathways modulating the immune system upon exposure to physical and psychosocial stressors.

Cross-sectional relation of long-term glucocorticoids in hair with anthropometric measurements and their possible determinants: A systematic review and meta-analysis

BACKGROUND

Long-term glucocorticoids (HairGC) measured in scalp hair have been associated with body mass index (BMI), waist circumference (WC), and waist-hip-ratio (WHR) in several cross-sectional studies. We aimed to investigate the magnitude, strength, and clinical relevance of these relations across all ages.

METHODS

We performed a systematic review and meta-analysis (PROSPERO registration CRD42020205187) searching for articles relating HairGC to measures of obesity. Main outcomes were bivariate correlation coefficients and unadjusted simple linear regression coefficients relating hair cortisol (HairF) and hair cortisone (HairE) to BMI, WC, and WHR.

RESULTS

We included k = 146 cohorts (n = 34,342 individuals). HairGC were positively related to all anthropometric measurements. The strongest correlation and largest effect size were seen for HairE-WC: pooled correlation 0.18 (95%CI 0.11-0.24; k = 7; n = 3,158; I²  = 45.7%) and pooled regression coefficient 11.0 cm increase in WC per point increase in 10-log-transformed HairE (pg/mg) on liquid-chromatography-(tandem) mass spectrometry (LC-MS) (95%CI 10.1-11.9 cm; k = 6; n = 3,102). Pooled correlation for HairF-BMI was 0.10 (95%CI 0.08-0.13; k = 122; n = 26,527; I²  = 51.2%) and pooled regression coefficient 0.049 kg/m² per point increase in 10-log-transformed HairF (pg/mg) on LC-MS (95%CI 0.045-0.054 kg/m² ; k = 26; n = 11,635).

DISCUSSION

There is a consistent positive association between HairGC and BMI, WC, and WHR, most prominently and clinically relevant for HairE-WC. These findings overall suggest an altered setpoint of the hypothalamic-pituitary-adrenal axis with increasing central adiposity.

Chronic stress and executive functioning: A specification-curve analysis

To investigate the association between chronic stress and executive functioning (EF), we assessed 514 young to middle-aged adults in three EF tasks (i.e., Number-Letter, 2-Back, Go/Nogo) that assessed shifting, updating, and inhibition. Chronic stress was assessed by various self-report measures and hair cortisol concentrations as indicators of subjective and objective chronic stress, respectively. In order to test the association between chronic stress and EF, we fit a structural equation model with a latent common EF factor predicted by subjective and objective chronic stress on Kaplan-Meier estimates of response times. Controlling for participants' sex, age household income and the delay between cognitive testing and hair sample collection, neither subjective nor objective chronic stress showed a meaningful association with common EF. Exploratory analyses suggested a moderation effect of income on the association between subjective chronic stress and common EF, with a smaller association for high-income participants. Additionally, we conducted a specification-curve analysis on the association between chronic stress and EF to assess the influence of different analysis choices on results in our dataset. This analysis confirmed the absence of a coherent association between chronic stress and EF by showing that the majority of analytical choices produced null effects and only a small number of analytical choices produced meaningful associations (negative or positive). Taken together, our findings suggest that common EF likely remains preserved under the influence of chronic stress. Our specification-curve analysis, however, also shows that chronic stress may also have either a positive or a negative effect on EF, depending on the choice of covariates and measures of chronic stress and EF. Consequently, more research on the role of these factors for the association between chronic stress and EF is needed to avoid the interpretation of non-replicable stress-EF associations caused by analytical choices or selection bias.