| 1. |
- Granér, Marit, et al.
(författare)
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Biomarkers and prediction of myocardial triglyceride content in non-diabetic men
- 2016
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Ingår i: NMCD. Nutrition Metabolism and Cardiovascular Diseases. - : Elsevier BV. - 0939-4753 .- 1590-3729. ; 26:2, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Lipid oversupply to cardiomyocytes or decreased utilization of lipids leads to cardiac steatosis. We aimed to examine the role of different circulating metabolic biomarkers as predictors of myocardial triglyceride (TG) content in non-diabetic men. Methods and Results Myocardial and hepatic TG contents were measured with 1.5 T magnetic resonance (MR) spectroscopy, and LV function, visceral adipose tissue (VAT), abdominal subcutaneous tissue (SAT), epicardial and pericardial fat by MR imaging in 76 non-diabetic men. Serum concentration of circulating metabolic biomarkers [adiponectin, leptin, adipocyte-fatty acid binding protein 4 (A-FABP 4), resistin, and lipocalin-2] including ß-hydroxybuturate (ß-OHB) were measured. Subjects were stratified by tertiles of myocardial TG into low, moderate, and high myocardial TG content groups. Concentrations of ß-OHB were lower (p=0.003) and serum levels of A-FABP 4 were higher (p<0.001) in the group with high myocardial TG content compared with the group with low myocardial TG content. ß-OHB was negatively correlated with myocardial TG content (r= -0.316, p=0.006), whereas A-FABP 4 was not correlated with myocardial TG content (r=0.192, p=0.103). In multivariable analyses ß-OHB and plasma glucose levels were the best predictors of myocardial TG content independently of VAT and hepatic TG content. The model explained 58.8% of the variance in myocardial TG content. Conclusion Our data showed that ß-OHB and fasting gluocse were the best predictors of myocardial TG content in non-diabetic men. These data suggest that hyperglycemia and alterations in lipid oxidation may be associated with cardiac steatosis in humans.
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| 2. |
- Gustavsson, Sara, 1985
(författare)
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Evaluation of regression methods for log-normal data - linear models for environmental exposure and biomarker outcomes
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The identification and quantification of associations between variables is often of interest in occupational and environmental research, and regression analysis is commonly used to assess these associations. While exposures and biological data often have a positive skewness and can be approximated with the log-normal distribution, much of the inference in regression analysis is based on the normal distribution. A common approach is therefore to log-transform the data before the regression analysis. However, if the regression model contains quantitative predictors, a transformation often gives a more complex interpretation of the coefficients. A linear model in original scale (non-transformed data) estimates the additive effect of the predictor, while linear regression on a log-transformed response estimates the relative effect. The overall aim of this thesis was to develop and evaluate a maximum likelihood method (denoted MLLN) for estimating the absolute effects for the predictors in a regression model where the outcome follows a log-normal distribution. The MLLN estimates were compared to estimates using common regression methods, both using large-scale simulation studies, and by applying the method to a number of real-life datasets. The method was also further developed to handle repeated measurements data. Our results show that when the association is linear and the sample size is large (> 100 observations), MLLN provides basically unbiased point estimates and has accurate coverage for both confidence and predictor intervals. Our results also showed that, if the relationship is linear, log-transformation, which is the most commonly used method for regression on log-normal data, leads to erroneous point estimates, liberal prediction intervals, and erroneous confidence intervals. For independent samples, we also studied small-sample properties of the MLLN-estimates; we suggest the use of bootstrap methods when samples are too small for the estimates to achieve the asymptotic properties.
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| 3. |
- Gustavsson, Sara, 1985, et al.
(författare)
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Linear Maximum Likelihood Regression Analysis For Untransformed Log-Normally Distributed Data
- 2012
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Ingår i: Open Journal of Statistics. - : Scientific Research Publishing, Inc.. - 2161-718X .- 2161-7198. ; 2:4, s. 389-400
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Tidskriftsartikel (refereegranskat)abstract
- Medical research data are often skewed and heteroscedastic. It has therefore become practice to log-transform data in regression analysis, in order to stabilize the variance. Regression analysis on log-transformed data estimates the relative effect, whereas it is often the absolute effect of a predictor that is of interest. We propose a maximum likelihood (ML)-based approach to estimate a linear regression model on log-normal, heteroscedastic data. The new method was evaluated with a large simulation study. Log-normal observations were generated according to the simulation models and parameters were estimated using the new ML method, ordinary least-squares regression (LS) and weighed least-squares regression (WLS). All three methods produced unbiased estimates of parameters and expected response, and ML and WLS yielded smaller standard errors than LS. The approximate normality of the Wald statistic, used for tests of the ML estimates, in most situations produced correct type I error risk. Only ML and WLS produced correct confidence intervals for the estimated expected value. ML had the highest power for tests regarding
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| 4. |
- Gustavsson, Sara, 1985, et al.
(författare)
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Regression Models for Log-Normal Data: Comparing Different Methods for Quantifying the Association between Abdominal Adiposity and Biomarkers of Inflammation
- 2014
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601. ; 11:4, s. 3521-3539
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Tidskriftsartikel (refereegranskat)abstract
- We compared six methods for regression on log-normal heteroscedastic data with respect to the estimated associations with explanatory factors (bias and standard error) and the estimated expected outcome (bias and confidence interval). Method comparisons were based on results from a simulation study, and also the estimation of the association between abdominal adiposity and two biomarkers; C-Reactive Protein (CRP) (inflammation marker,) and Insulin Resistance (HOMA-IR) (marker of insulin resistance). Five of the methods provide unbiased estimates of the associations and the expected outcome; two of them provide confidence intervals with correct coverage.
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| 5. |
- Hedna, Khedidja, 1978, et al.
(författare)
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Antidepressants and suicidal behaviour in late life: a prospective population-based study of use patterns in new users aged 75 and above.
- 2018
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Ingår i: European journal of clinical pharmacology. - : Springer Science and Business Media LLC. - 1432-1041 .- 0031-6970. ; 74, s. 201-208
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Tidskriftsartikel (refereegranskat)abstract
- To investigate associations between antidepressant use patterns and risk of fatal and non-fatal suicidal behaviours in older adults who initiated antidepressant therapy.A national population-based cohort study conducted among Swedish residents aged ≥75years who initiated antidepressant treatment. Patients who filled antidepressant prescriptions between January 1, 2007 and December 31, 2013 (N=185,225) were followed until December 31, 2014. Sub-hazard ratios of suicides and suicide attempts associated with use patterns of antidepressants, adjusting for potential confounders such as serious depression were calculated using the Fine and Gray regression models.During follow-up, 295 suicides and 654 suicide attempts occurred. Adjusted sub-hazard ratios (aSHRs) were increased for both outcomes in those who switched to another antidepressant (aSHR for suicide 2.42, 95% confidence interval 1.65 to 3.55, and for attempt 1.76, 1.32 to 2.34). Elevated suicide risks were also observed in those who concomitantly filled anxiolytics (1.54, 1.20 to 1.96) and hypnotics (2.20, 1.69 to 2.85). Similar patterns were observed for the outcome suicide attempt. Decreased risk of attempt was observed among those with concomitant use of anti-dementia drugs (0.40, 0.27 to 0.59).Switching antidepressants, as well as concomitant use of anxiolytics or hypnotics, may constitute markers of increased risk of suicidal behaviours in those who initiate antidepressant treatment in very late life. Future research should consider indication biases and the clinical characteristics of patients initiating antidepressant therapy.
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| 6. |
- Hedna, Khedidja, 1978, et al.
(författare)
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Late-life suicidal behaviours among new users of antidepressants: A prospective population-based study of sociodemographic and gender factors in those aged 75 and above
- 2018
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Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- To investigate sociodemographic and gender factors associated with suicide and suicide attempts among new users of antidepressants aged 75 and above.DesignRegister-based cohort study.SettingNational population-based cohort of Swedish residents aged ≥75 years.Participants185 225 patients who initiated antidepressant medication between 1 January 2007 and 31 December 2013 were followed until 31 December 2014.Main outcome measuresSuicide and suicide attempts. Fine and Gray regression models were used to analyse the sociodemographic factors (age, country of birth, marital status, education level, last occupation, income and social allowance) associated with suicidal behaviours in the entire cohort and by gender.ResultsDuring follow-up, 295 suicides and 654 suicide attempts occurred. Adjusted sub-hazard ratios (aSHRs) for suicide were lower among older age groups (aSHR 0.73, 95% CI 0.53 to 0.99 for those 85–89 years; and aSHR 0.53, 95% CI 0.33 to 0.86 for those ≥90 years). A similar pattern was observed for suicide attempts. Suicide attempts were more common among those born in foreign countries (aSHR 1.58, 95% CI 1.16 to 2.15 for those born in another Nordic country; and aSHR 1.43, 95% CI 1.06 to 1.93 for those born in non-Nordic countries). In the gender-stratified analyses, being single or divorced, and born in another Nordic country was associated with a higher risk of suicide among men. Educational and occupational history and being born in a non-Nordic country influenced risk of suicidal behaviours in women.ConclusionSuicidal behaviours occurred more commonly among new users who were ‘younger’ old adults and those with foreign background, suggesting that those groups might require greater support when initiating antidepressant therapy. Our findings suggest the need for gender-specific, multifaceted approaches to the prevention of suicidal behaviours in late life.
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| 7. |
- Markström, Urban, et al.
(författare)
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Developing sustainable service user involvement practices in mental health services in Sweden : the “Userinvolve” research program protocol
- 2023
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Ingår i: Frontiers in Psychiatry. - Lausanne : Frontiers Media S.A.. - 1664-0640. ; 14, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Background: The purpose of this paper is to outline the protocol for the research program “UserInvolve,” with the aim of developing sustainable, service user involvement practices in mental health services in Sweden. Methods: This protocol outlines the knowledge gap and aim of the UserInvolve-program. It further provides an overview of the research infrastructure, with specific focus on the organization and management of the program as well as the design of the six underlying research projects. These six research projects form the core of the UserInvolve-program and will be carried out during a six-year period (2022–2027). The projects are focused on examining articulations of experiential knowledge in user collectives, on four specific user involvement interventions (shared decision-making, peer support, user-focused monitoring, and systemic involvement methods) and on developing theory and method on co-production in mental health research and practice. Results or conclusion: The knowledge gained through the co-production approach will be disseminated throughout the program years, targeting service users, welfare actors and the research community. Based on these research activities, our impact goals relate to strengthening the legitimacy of and methods for co-production in the mental health research and practice field. Copyright © 2023 Markström, Näslund, Schön, Rosenberg, Bejerholm, Gustavsson, Jansson, Argentzell, Grim, Engdahl, Nouf, Lilliehorn and Svedberg.
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| 8. |
- Nyberg, Jenny, 1976, et al.
(författare)
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Late-adolescent risk factors for suicide and self-harm in middle-aged men: explorative prospective population-based study.
- 2020
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Ingår i: The British journal of psychiatry : the journal of mental science. - : Royal College of Psychiatrists. - 1472-1465. ; 217:1, s. 370-376
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Tidskriftsartikel (refereegranskat)abstract
- Recent reports show alarmingly high rates of suicide in middle-aged men, yet there are few long-term prospective studies that focus on suicidal behaviour in men in this age group.To prospectively explore associations of potential risk factors at age 18 with suicide and self-harm in middle-aged men.A population-based Swedish longitudinal cohort study of male conscripts with no history of self-harm at enlistment in 1968-1989 (n = 987 583). Conscription examinations included measures of cognitive performance, stress resilience, psychiatric diagnoses, body mass index (BMI), cardiovascular fitness and muscle strength. Suicides and self-harm at age 45-65 years were identified in the National Hospital Register and Swedish Cause of Death Register. Risks were calculated using Cox proportional hazards models.Low stress resilience (cause-specific hazard ratio CHR = 2.31, 95% CI 1.95-2.74), low cognitive ability (CHR = 2.01, 95% CI 1.71-2.37) as well as psychiatric disorders and low cardiovascular fitness in late adolescence were associated with increased risk for suicide in middle-aged men. Similar risk estimates were obtained for self-harm. In addition, high and low BMI as well as low muscle strength were associated with increased risk of self-harm. Associations also remained significant after exclusion of men with self-harm before age 45.This prospective study provides life-course perspective support that psychological and physical characteristics in late adolescence may have long-lasting consequences for suicidal behaviour in middle-aged men, a very large population at heightened risk of suicide.
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| 9. |
- Söderberg, Mia, 1977, et al.
(författare)
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Psychosocial job conditions, fear avoidance beliefs and expected return to work following acute coronary syndrome : A cross-sectional study of fear-avoidance as a potential mediator
- 2015
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Despite improvements in treatment, acute coronary syndrome remains a substantial cause for prolonged sick absences and premature retirement. Knowledge regarding what benefits return to work is limited, especially the effect of psychological processes and psychosocial work factors. The purposes of this cross-sectional study were two-fold: to examine associations between adverse psychosocial job conditions and fear-avoidance beliefs towards work, and to determine whether such beliefs mediated the relationship between work conditions and expected return to work in acute coronary syndrome survivors.Methods: Study inclusion criteria: acute myocardial infarction or unstable angina diagnosis, below 65 years of age, being a resident in the West county of Sweden and currently working. In all, 509 individuals (21.8 % women) accepted study participation and for whom all data of study interest were available for analysis. Psychosocial work variables; job demand-control and effort-reward imbalance, were assessed with standard questionnaire batteries. Linear regression models were used to investigate relationships between psychosocial factors and fear-avoidance, and to evaluate mediator effects for fear-avoidance. Both total sample and gender stratified analyses were calculated.Results: Fear-avoidance beliefs about work were associated to psychosocial job environments characterized by high strain (β 1.4; CI 1.2–1.6), active and passive work and high effort-reward imbalance (β 0.6; CI 0.5–0.7). Further, such beliefs also mediated the relationship between adverse work conditions and expected time for return to work. However, these results were only observed in total sample analyses or among or male participants. For women only high strain was linked to fear-avoidance, and these relationships became non-significant when entering chosen confounders.Conclusions: This cross-sectional study showed that acute coronary syndrome survivors, who laboured under adverse psychosocial work conditions, held fear-avoidance beliefs towards their workplace. Furthermore, these beliefs mediated the relationships between - high strained or high effort-reward imbalanced work - and expected return to work. However, mentioned results were primarily found among men, which could results from few female study participants or gender differences in return to work mechanisms. Still, an earlier return to work might be promoted by interventions focusing on improved psychosocial work conditions and cognitive behavioural therapy targeting fear-avoidance beliefs.
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| 10. |
- Ögren, Mikael, 1972, et al.
(författare)
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Comparison of annoyance from railway noise and railway vibration
- 2017
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601. ; 14:7
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to compare vibration exposure to noise exposure from railway traffic in terms of equal annoyance, i.e., to determine when a certain noise level is equally annoying as a corresponding vibration velocity. Based on questionnaire data from the Train Vibration and Noise Effects (TVANE) research project from residential areas exposed to railway noise and vibration, the dose response relationship for annoyance was estimated. By comparing the relationships between exposure and annoyance for areas both with and without significant vibration exposure, the noise levels and vibration velocities that had an equal probability of causing annoyance was determined using logistic regression. The comparison gives a continuous mapping between vibration velocity in the ground and a corresponding noise level at the facade that are equally annoying. For equivalent noise level at the facade compared to maximum weighted vibration velocity in the ground the probability of annoyance is approximately 20% for 59 dB or 0.48 mm/s, and about 40% for 63 dB or 0.98 mm/s.
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